Heat flux measurement method and heat flux measurement system

Abstract

[Problem] To grasp the heat flux of a heat source, thereby contributing to effective utilization of unused thermal energy. [Solution] The other end of a thermal conduction path having a cooling source at one end is connected to a heat source (S10). A heating element with which the calorific value varies depending on varying heating energy and a power generation element that generates an electromotive voltage by the Seebeck effect are installed in the thermal conduction path, the temperature in the thermal conduction path and the electromotive voltage generated by the power generation element are measured, and a first temperature and a first electromotive voltage under the influence of the heat generation by the heating element, as well as a second temperature and a second electromotive voltage not under the influence of the heat generation by the heating element, are acquired (S30, S50). The thermal conductance and the heat flux of the heat source are calculated on the basis of the difference between the first temperature and the second temperature, the difference between the first electromotive voltage and the second electromotive voltage (S60), and the heating energy at the time of the measurement of the first temperature and the first electromotive voltage (S80, S100). This makes it possible to calculate the thermal conductance and the heat flux of the heat source without having to grasp the specific heat, the mass, etc. of the heat source.

Description

Heat flux measurement method and heat flux measurement system

[0001] The present invention relates to a heat flux measurement method and a heat flux measurement system for measuring the heat flow rate (heat flux) leaking from a heat source.

[0002] For example, in industrial plants that handle thermal energy, various devices that use heat sources, combustion devices, internal combustion engines, incinerators, hot spring water channels, exhaust ducts, chimneys, and steam pipes, there is thermal energy that is wasted as high-temperature waste heat. Research on effectively utilizing such unused thermal energy has been conducted for a long time (see, for example, Patent Documents 1 and 2), but as a result of excessive consumption of large amounts of thermal energy, excess thermal energy is still released into the atmosphere, which is one of the causes of global warming.

[0003] Japanese Patent Publication No. 5299324, Japanese Unexamined Patent Publication No. 2014-174027

[0004] To effectively utilize unused thermal energy from a heat source, it is effective to measure the amount of heat leaking from the heat channel walls, exhaust pipe surfaces, and insulation surfaces of the high-temperature heat source where heat exchangers are installed, i.e., the heat flux, and then perform simulations based on basic information such as information on heat dissipation and exhaust systems. The most important factor in such simulations is to calculate the amount of heat received to flow in through the heat exchanger in advance, in accordance with the thermal energy equipment to be used, and to determine the amount of heat that can be extracted from the assumed heat channel. At this time, in order to accurately calculate the usable heat amount by calculating the conditions on the cooling source side and the relationship with the thermal energy equipment, it is necessary to grasp the heat flux at the heat receiving point, which represents the specific amount of heat from the heat source.

[0005] However, in the effective utilization of unused thermal energy, it has been overlooked that measuring the thermal conductance on the heat channel of the heat-receiving surface, which serves as the heat source, is crucial, as is measuring the heat flux passing between the heat-receiving surface and the cooling source from the heat-exhaust heat channel. This is because it is necessary to know in advance how much the temperature of the heat-receiving surface will drop when the required amount of heat is extracted, and when discussing the utilization of surplus heat and the heat source margin, it is necessary to evaluate this together with the temperature drop that occurs when a certain amount of heat is extracted from the heat-receiving surface. In other words, unless the thermal conductance of the heat-receiving surface and the amount of thermal energy (heat flux) transferred from it can be measured simultaneously, it is impossible to determine the specifications of the thermal energy equipment to be used.

[0006] This invention has been made in view of the above-mentioned problems, and its purpose is to understand the heat flux of a heat source and contribute to the effective utilization of unused thermal energy.

[0007] (Modes of the Invention) The following modes of the invention are illustrative of the configuration of the present invention and are described in separate sections to facilitate understanding of the diverse configurations of the present invention. Each section does not limit the technical scope of the present invention. Therefore, while taking into consideration the best mode for carrying out the invention, the technical scope of the present invention may also include those in which some of the components of each section are replaced, deleted, or other components are added.

[0008] (1) A method for measuring the heat flux on a heat receiving surface of a heat source, wherein the other end of a heat conduction path, one end of which is provided with a cooling source controlled to a constant temperature, is connected to an arbitrary heat receiving surface of the heat source, and a heating element that can be controlled so as to fluctuate in the amount of heat generated by applying fluctuating heating energy, and a power generator that generates an electromotive force by the Seebeck effect are installed in the heat conduction path, the temperature in the heat conduction path and the electromotive force at the power generator are measured, a first temperature and a first electromotive force when the heat is being generated by the heating element are obtained, and a second temperature and a second electromotive force when the heat is not being generated are obtained, the thermal conductance on the heat receiving surface is calculated based on the difference between the first temperature and the second temperature and the heating energy when the first temperature was measured, and the heat flux on the heat receiving surface is calculated based on the difference between the first electromotive force and the second electromotive force and the heating energy when the first electromotive force was measured.

[0009] The heat flux measurement method described in this section measures the thermal conductance and heat flux at an arbitrary heat-receiving surface of a heat source that possesses unused thermal energy that is being wastefully generated. Specifically, a cooling source controlled to a constant temperature is installed at one end of a heat conduction path, and the other end of the heat conduction path is connected to the aforementioned heat-receiving surface of the heat source, thereby diverting the heat to flow from the heat source towards the cooling source. The heat conduction path used in this case shall be made of a material whose properties, such as thermal conductivity, are known in advance. Furthermore, a heat-generating element and a power-generating element are installed in the heat conduction path, that is, between one end of the heat conduction path where the cooling source is installed and the other end of the heat conduction path connected to the heat source. The heat-generating element to be installed is one that can be controlled so that the amount of heat generated fluctuates when fluctuating heating energy is applied. Furthermore, the power-generating element to be installed is one that generates an electromotive force by the Seebeck effect, which generates a voltage from a temperature difference. Here, the heat conduction path in which the heat-generating element and power-generating element are pre-installed may be connected to the heat source.

[0010] Furthermore, the temperature in the heat conduction path configured as described above and the electromotive force at the power generator are measured to obtain a first temperature and first electromotive force when affected by the heat generated by the heat source, and a second temperature and second electromotive force when not affected by the heat generated by the heat source. In this case, the first temperature and first electromotive force only need to be measured when the heat source is under control that causes the amount of heat generated to fluctuate. On the other hand, the second temperature and second electromotive force may be calculated from the measurement results of the first temperature and first electromotive force in a way that eliminates the effect of heat generated by the heat source, depending on the situation, or they may be measured when the temperature in the heat conduction path and the electromotive force at the power generator are not generating heat. Next, the difference between the first temperature and the second temperature obtained as described above is calculated to extract temperature change data that has changed due to the effect of fluctuating heat generated by the heat source. Then, the thermal conductance of the heat source is calculated based on the extracted temperature change data and the heating energy given to the heat source when the first temperature was measured.

[0011] Here, regarding the relationship between heat quantity and temperature, within a range of small temperature changes without phase change, the heat quantity is proportional to the temperature, with mass and specific heat being constants. Therefore, considering that the mass and specific heat do not change when heating energy is added, and the temperature rises by the amount of the temperature change data, the "product of mass and specific heat" can be expressed as the value obtained by dividing the "heat quantity in the state without receiving heating energy" by the "temperature in the state without receiving heating energy (second temperature)" or the value obtained by dividing the "heat quantity in the state with heating energy" by the "temperature in the state with heating energy (first temperature)". Furthermore, if radiation and heat conduction, which cause errors, are negligibly small, the "product of mass and specific heat" can also be expressed as the value obtained by dividing the heating energy by the temperature change data.

[0012] Furthermore, since thermal resistance is the value obtained by dividing the temperature difference between two points by the heat flow rate (amount of heat flowing per unit time) between the two points, in the relationship described above, temperature change data can be expressed as a value obtained by dividing it by heating energy. Considering that this thermal resistance includes all thermal resistance from the heat source to the heat conduction path, that thermal conductance can be expressed as the reciprocal of thermal resistance, and that the heat-receiving area of ​​the heat conduction path can be taken into account, it can be seen that thermal conductance per unit area can be calculated from temperature change data and heating energy. As a result, without needing to know the specific heat or mass of the heat source, the thermal conductance at the heat-receiving surface of the heat source can be calculated based on the temperature change data changed by the influence of the heat-generating element and the heating energy supplied to the heat-generating element at that time.

[0013] On the other hand, regarding the heat flux, the difference between the first and second electromotive forces obtained as described above is calculated to extract the electromotive force change data that has changed due to the fluctuating heat generation of the heat source. Then, the heat flux of the heat source is calculated based on the extracted electromotive force change data and the heating energy supplied to the heat source when the first electromotive force was measured. In other words, since the electromotive force generated by the Seebeck effect in a power generator is proportional to the amount of heat passing through the power generator, by configuring the power generator to be highly sensitive and generating a high electromotive force, an electromotive force that reflects the passing heat flux with high sensitivity can be obtained. For this reason, similar to thermal conductance, the heat flux at the heat receiving surface of the heat source can be calculated based on the electromotive force change data that has changed due to the influence of the heat source and the heating energy supplied to the heat source at that time, without needing to know the specific heat or mass of the heat source. In this way, the thermal conductance and heat flux at the heat receiving surface of the heat source can be determined, which contributes to the effective utilization of the unused thermal energy of the heat source. Furthermore, even when internal information about the heat source, such as its specific heat, pressure, and physical properties (density), is unknown, or when the pressure and density of the heat source fluctuate over time, the thermal conductance and heat flux can be determined from a heat-receiving surface, even if it is only a small area, as long as the aforementioned heat conduction path can be connected.

[0014] (2) A heat flux measurement method in which a Peltier element is used as the heating element and the power generator in the above item (1), an AC power of a predetermined frequency different from the fluctuation frequency of the heat flow from the heat source is applied as the heating energy, data of the frequency component of the predetermined frequency is extracted from the calculation result of the difference between the first temperature and the second temperature, the thermal conductance at the heat receiving surface is calculated based on the extraction result, data of the frequency component of the predetermined frequency is extracted from the calculation result of the difference between the first electromotive force and the second electromotive force, and the heat flux at the heat receiving surface is calculated based on the extraction result. The heat flux measurement method described in this item uses a Peltier element as the heating element and the power generator installed in the heat conduction path. Furthermore, by applying AC power of a predetermined frequency as the heating energy to the Peltier element as the heating element, the amount of heat generated from the Peltier element as the heating element is varied in an AC manner. The predetermined frequency of the AC power at this time is set to a frequency different from the fluctuation frequency of the heat flow that flows from the heat source to the heat conduction path.

[0015] Then, the difference between the first temperature when affected by the heat source and the second temperature when not affected by the heat source is calculated, and from this calculation result, data of the frequency component at the predetermined frequency described above is extracted. Based on the temperature difference data extracted in this way and the AC power supplied to the Peltier element as a heat source, the thermal conductance at the heat receiving surface is calculated. Similarly, the difference between the first electromotive force when affected by the heat source and the second electromotive force when not affected by the heat source is calculated, and from this calculation result, data of the frequency component at the predetermined frequency described above is extracted. Based on the electromotive force difference data extracted in this way and the AC power supplied to the Peltier element as a heat source, the heat flux at the heat receiving surface is calculated. In other words, by supplying the Peltier element as a heat source with modulated power at a frequency different from the fluctuation frequency of the heat flow from the heat source, and extracting and using the data of the frequency component at that modulated frequency, the thermal conductance and heat flux are calculated while eliminating the fluctuation components of the heat flow. This allows for more accurate calculation of thermal conductance and heat flux.

[0016] (3) A heat flux measurement method for which, in the heat source described in item (2) above, two heat conduction paths on which the heating element and the power generating element are installed are connected to two heat receiving surfaces set at different locations of the heat source, and AC power synchronized at the same predetermined frequency but with different phases is applied to the heating element of one heat conduction path and the heating element of the other heat conduction path, and the heat conductance and heat flux in the heat source are calculated based on the heat conductance and heat flux calculated from one heat conduction path and the heat conductance and heat flux calculated from the other heat conduction path. The heat flux measurement method described in this item connects two heat conduction paths on which the heating element and power generating element are installed to two heat receiving surfaces set at different locations of the heat source, as mentioned in item (1) above. Furthermore, an AC power of a predetermined frequency different from the fluctuation frequency of the heat flow from the heat source as described in item (2) above is applied to the heating element of one heat conduction path, and an AC power of the other heat conduction path is applied to the heating element of the other heat conduction path at the same predetermined frequency as the AC power applied to the heating element of the first heat conduction path, but with a different phase.

[0017] Then, the thermal conductance and heat flux at the heat receiving surface to which one heat conduction path is connected, and the thermal conductance and heat flux at the heat receiving surface to which the other heat conduction path is connected are calculated. When the thermal conductance and heat flux calculated in this way are reflected in the thermal circuit model of the heat source and the two heat conduction paths connected to it, this thermal circuit model becomes equivalent to a Wheatstone bridge circuit in electrical circuits. Furthermore, if the phase difference between the AC power supplied to the heat source of one heat conduction path and the AC power supplied to the heat source of the other heat conduction path is, for example, 180°, the timing of the increase and decrease in heat flow rate in one heat conduction path and the other heat conduction path is reversed. As a result, a heat flow wave that fluctuates up and down like a seesaw is generated within the heat source to which both heat conduction paths are connected. Therefore, taking this into consideration, the thermal conductance and heat flux within the heat source can also be calculated from the electrical circuit model described above. This allows for the determination of thermal conductance and heat flux within a heat source without needing to know the specific heat or mass of the heat source.

[0018] (4) A method for measuring the heat flux on a heat receiving surface of a heat source, wherein the other end of a heat conduction path, which has a cooling source controlled to a constant temperature at one end, is connected to an arbitrary heat receiving surface of the heat source, a power generator that generates an electromotive force by the Seebeck effect is installed in the heat conduction path, the temperature in the heat conduction path and the electromotive force at the power generator are measured, the heat flux passing through the power generator is calculated based on the measurement results and the temperature dependence of the material properties of the thermoelectric conversion material used in the power generator which has been known in advance, and the heat flux at the heat receiving surface is calculated based on the calculation results. The heat flux measurement method described in this section measures the heat flux at an arbitrary heat receiving surface of a heat source that has unused thermal energy that is being discharged.

[0019] Specifically, a cooling source controlled to a constant temperature is installed at one end of a heat conduction path, and the other end of this path is connected to the aforementioned heat-receiving surface of the heat source, thereby diverting the heat flow from the heat source to the cooling source. The heat conduction path used in this case shall be made of a material whose properties, such as thermal conductivity, are known in advance. A power generator is installed in the heat conduction path, that is, between the end of the heat conduction path where the cooling source is installed and the other end of the heat conduction path connected to the heat source. The power generator to be installed is one that generates an electromotive force through the Seebeck effect, which generates a voltage from the temperature difference. Alternatively, the heat conduction path in which the power generator is installed may be connected to the heat source.

[0020] Furthermore, by measuring the temperature in the heat conduction path with the above configuration and the electromotive force in the power generator, the operating temperature affected by the heat flow from the heat source to the cooling source, and the electromotive force generated by the Seebeck effect due to the heat flow from the heat source to the cooling source are determined. Then, based on these measurement results and the temperature dependence of the material properties of the thermoelectric conversion material used in the power generator, which have been determined in advance, the heat flux passing through the power generator is calculated. Here, in a power generator that generates an electromotive force due to the Seebeck effect, the relationship between the heat flux passing through and the electromotive force generated in response to it is not a linear relationship but a functional nonlinear relationship. Since this nonlinear characteristic is due to the temperature dependence of the material properties of the thermoelectric conversion material forming the power generator, this characteristic is determined in advance, and taking it into account, the heat flux passing through the power generator is calculated using the measured temperature, which serves as the reference temperature, and the electromotive force generated by the heat flux that has passed through.

[0021] In conventional methods of measuring heat flux using thermoelectric conversion module elements, the electromotive force directly obtained from the flowing heat flux is acquired as a signal, and the heat flux is measured by dividing this electromotive force by a sensitivity coefficient (constant). The sensitivity coefficient used in this case is a coefficient that changes depending on the temperature, and when using a heat flux sensor using this method, it is necessary to measure the surface temperature of the heat source to be measured, such as an industrial furnace, and the temperature around the heat source in advance, and perform calibration according to the temperature to determine the sensitivity coefficient. In such conventional methods, the reason why the sensitivity coefficient needs to be calculated each time within the measurement temperature range of the target heat source is that the sensor principle structure does not take into account the temperature dependence (nonlinear characteristics) of the material properties of the thermoelectric conversion material.

[0022] Therefore, the heat flux measurement method described in this section, with the configuration described above, allows for the calculation of the heat flux passing through the power generator using only the measured electromotive force output value and operating temperature information, without the need for a sensitivity coefficient. From this calculation result, the heat flux at the heat receiving surface of the heat source connected to the heat conduction path containing the power generator is calculated by taking into account the radiation in the heat conduction path from the heat source's heat receiving surface to the power generator, the thermal conductivity of the heat conduction path, etc. Moreover, while there is concern that temperature measurement results using thermocouples, etc., are subject to a lot of noise in the field environment where the heat source to be measured is located, the Seebeck electromotive force measured at the power generator is less affected by noise in the field environment. For this reason, using such a Seebeck electromotive force improves the accuracy of heat flux calculation.

[0023] (5) A heat flux measurement method in item (4) above, which uses the temperature characteristics of the Seebeck coefficient of the thermoelectric conversion material and the temperature characteristics of the thermal conductivity of the thermoelectric conversion material as the temperature dependence of the material properties of the thermoelectric conversion material. The heat flux measurement method described in this item uses the temperature characteristics of the Seebeck coefficient of the thermoelectric conversion material and the temperature characteristics of the thermal conductivity of the thermoelectric conversion material as the temperature dependence of the material properties of the thermoelectric conversion material forming the power generation body, which is used when calculating the heat flux passing through the power generation body. That is, these temperature characteristics have nonlinear characteristics which are the reason why the relationship between the heat flux passing through the power generation body and the electromotive force generated in response to it is nonlinear, and the heat flux is calculated by taking them into account. As a result, no matter what kind of thermoelectric conversion material the power generation body is made of, the heat flux can be calculated without any problems as long as the temperature characteristics of the Seebeck coefficient and the temperature characteristics of the thermal conductivity of the thermoelectric conversion material are known in advance.

[0024] (6) A heat flux measurement method for calculating the heat flux passing through a power generator, which takes into account the temperature dependence of the material properties of the thermoelectric conversion material, and pre-establishes the relationship between the temperature in the heat conduction path, the electromotive force at the power generator, and the heat flux passing through the power generator by formulating or creating a table of the relationship, and applies the measured results of the temperature in the heat conduction path and the electromotive force at the power generator to the formulated or table of the relationship. The heat flux measurement method described in this section takes into account the temperature in the heat conduction path used when calculating the heat flux, the electromotive force at the power generator used when calculating the heat flux, and the relationship between the heat flux passing through the power generator calculated from them, and pre-establishes the relationship by formulating or creating a table of the relationship.

[0025] Furthermore, the temperature in the heat conduction path used to understand the relationship is the same as the location in the heat conduction path where temperature measurements are taken when calculating the heat flux, and these temperature measurement locations are positions where the ambient temperature of the power generator can be detected. When calculating the heat flux passing through the power generator, the measured results of the temperature in the heat conduction path and the electromotive force at the power generator are applied to the mathematical formula or table-based relationship described above. As a result, the heat flux passing through the power generator can be calculated simply by applying the measurement results to the mathematical formula or table-based relationship, making it easy to understand the heat flux. Therefore, the calculation process is simplified and the processing time is shortened. Also, unlike conventional systems, there is no need to recreate the same conditions as the temperature of the object under test before measurement, thus eliminating the need for such complicated preparation work for measurement.

[0026] (7) A method for measuring the heat flux on a heat receiving surface of a heat source, comprising: connecting the other end of a heat conduction path, one end of which is provided with a cooling source controlled to a constant temperature, to an arbitrary heat receiving surface of the heat source; installing a heating element in the heat conduction path that can be controlled to vary the amount of heat generated by applying fluctuating heating energy; virtually constructing an electrical circuit model including a plurality of circuit elements corresponding to a thermal circuit model from the heat source to the cooling source, including the heat conduction path; corresponding the temperature, heat flux, and thermal resistance in the thermal circuit model to the voltage, current, and resistance in the electrical circuit model; continuously measuring the temperature at a temperature measurement point in the heat conduction path while varying the amount of heat generated from the heating element; calculating parameter values ​​for the plurality of circuit elements in the electrical circuit model such that the measurement results and the voltage at a voltage monitoring point corresponding to the temperature measurement point in the thermal circuit model in the operating state exhibit similar behavior; and estimating the heat flux on the heat receiving surface using the electrical circuit model to which the calculated parameter values ​​have been applied.

[0027] The heat flux measurement method described in this section measures the heat flux at any heat receiving surface of a heat source that has unused thermal energy being dissipated. Specifically, a cooling source controlled to a constant temperature is installed at one end of a heat conduction path, and the other end of the heat conduction path is connected to the aforementioned heat receiving surface of the heat source, thereby diverting the heat to flow from the heat source towards the cooling source. The heat conduction path used in this case shall be made of a material whose properties, such as thermal conductivity, are known in advance. Furthermore, a heat-generating element is installed in the heat conduction path, that is, between the end of the heat conduction path where the cooling source is installed and the other end of the heat conduction path connected to the heat source. The heat-generating element to be installed shall be one that can be controlled so that the amount of heat generated changes when a fluctuating heating energy is applied, and multiple heat-generating elements may be installed. In addition, the heat conduction path with the heat-generating element already installed may be connected to the heat source.

[0028] Furthermore, a virtual electrical circuit model is constructed that includes multiple circuit elements corresponding to the actual thermal circuit model from the heat source to the cooling source, including the heat conduction path described above. In this model, the temperature, heat flux, and thermal resistance in the thermal circuit model are made to correspond to the voltage, current, and resistance in the electrical circuit model. That is, the multiple circuit elements in the electrical circuit model include resistors corresponding to thermal resistance, which represents the difficulty of heat transfer in the thermal circuit model, and power supplies corresponding to the heat source, heat-generating element, and cooling source that generate heat in the thermal circuit model. Subsequently, in the actual thermal circuit model, the temperature of temperature measurement points in the heat conduction path is continuously measured while varying the amount of heat generated from the heat-generating element. That is, with heat flowing from the heat-receiving surface of the heat source towards the cooling source, fluctuating heat is also supplied from the heat-generating element, and the temperature of preset temperature measurement points in the heat conduction path is continuously measured to obtain time-series temperature measurement results at the temperature measurement points.

[0029] Furthermore, an electrical circuit model corresponding to the thermal circuit model is virtually operated by setting each power supply to the operating state, and in this state, the voltage of the voltage monitoring point in the electrical circuit model that corresponds to the temperature measurement point in the thermal circuit model is acquired. Then, the parameter values ​​of multiple circuit elements in the electrical circuit model are calculated so that the measured temperature at the temperature measurement point in the actual thermal circuit model and the acquired voltage at the voltage monitoring point in the virtual electrical circuit model exhibit similar behavior (fit). Here, the parameter value refers to the resistance value in the case of a resistor, and the output voltage value in the case of a power supply.

[0030] The electrical circuit model to which the multiple parameter values ​​calculated as described above are applied exhibits behavior similar to that of an actual thermal circuit model. In an actual thermal circuit model, the heat source and its thermal resistance are unknown, and all other circuit parameters are independent of the heat source. Therefore, considering that the thermal conductivity of the materials forming the heat conduction path is known, the parameter values ​​of the circuit elements in the electrical circuit corresponding to these are fixed to optimal values. As a result, the heat flux at the heat receiving surface of the heat source can be easily estimated using the electrical circuit model to which the calculated parameter values ​​are applied. Furthermore, the thermal conductance and thermal resistance at the heat receiving surface of the heat source can also be easily estimated as needed. In addition, by using the electrical circuit model to which the calculated parameter values ​​are applied, it is possible to formulate mathematical equations for time-series waveform data of temperature in an actual thermal circuit model.

[0031] (8) A method for measuring the heat flux on the heat receiving surface of a heat source, wherein the other end of a heat conduction path, one end of which is provided with a cooling source controlled to a constant temperature, is connected to an arbitrary heat receiving surface of the heat source, and a heating element that can be controlled so as to fluctuate in the amount of heat generated by applying fluctuating heating energy, and a power generation element that generates an electromotive force by the Seebeck effect are installed in the heat conduction path, and an electrical circuit model including a plurality of circuit elements corresponding to a thermal circuit model from the heat source to the cooling source including the heat conduction path is virtually constructed, and in this case, the temperature, heat flux, and thermal resistance in the thermal circuit model are measured A heat flux measurement method comprising: relating resistors to voltage, current, and resistance in the electrical circuit model, relating the power generator to a voltage detector, continuously measuring the electromotive force in the power generator while varying the amount of heat generated from the heat source, calculating parameter values ​​for the plurality of circuit elements in the electrical circuit model such that the measurement results and the voltage at the voltage detector in the operating electrical circuit model exhibit similar behavior, and estimating the heat flux at the heat receiving surface using the electrical circuit model to which the calculated parameter values ​​have been applied.

[0032] The heat flux measurement method described in this section measures the heat flux at any heat receiving surface of a heat source that has unused thermal energy being waste heat. Specifically, a cooling source controlled to a constant temperature is installed at one end of a heat conduction path, and the other end of the heat conduction path is connected to the aforementioned heat receiving surface of the heat source, thereby diverting the heat to flow from the heat source to the cooling source. The heat conduction path used in this case shall be made of a material whose properties, such as thermal conductivity, are known in advance. Furthermore, a heat-generating element and a power-generating element are installed in the heat conduction path, that is, between one end of the heat conduction path where the cooling source is installed and the other end of the heat conduction path connected to the heat source. The heat-generating element to be installed shall be one that can be controlled so that the amount of heat generated fluctuates when fluctuating heating energy is applied, and multiple heat-generating elements may be installed. Furthermore, the power-generating element to be installed shall be one that generates an electromotive force by the Seebeck effect, which generates a voltage from a temperature difference, and multiple power-generating elements may be installed. In addition, the heat conduction path in which the heat-generating element and power-generating element are pre-installed may be connected to the heat source.

[0033] Furthermore, a virtual electrical circuit model is constructed that includes multiple circuit elements corresponding to the actual thermal circuit model from the heat source to the cooling source, including the heat conduction path described above. In this model, the temperature, heat flux, and thermal resistance in the thermal circuit model are made to correspond to the voltage, current, and resistance in the electrical circuit model. That is, the multiple circuit elements in the electrical circuit model include resistors corresponding to thermal resistance, which represents the difficulty of heat transfer in the thermal circuit model, and power supplies corresponding to the heat source, heat-generating element, and cooling source that generate heat in the thermal circuit model. Furthermore, the power generator in the thermal circuit model is made to correspond to a voltage detector in the electrical circuit model, taking into account that it generates voltage in response to a temperature difference. Subsequently, in the actual thermal circuit model, the electromotive force at the power generator is continuously measured while varying the amount of heat generated from the heat-generating element. That is, with heat flowing from the heat-receiving surface of the heat source towards the cooling source, and with fluctuating heat also supplied from the heat-generating element, the electromotive force generated by the Seebeck effect due to the influence of the heat flowing through the power generator is continuously measured, and the time-series electromotive force measurement results at the power generator are obtained.

[0034] Furthermore, the electrical circuit model corresponding to the thermal circuit model is virtually operated by setting each power supply to the operating state, and in this state, the voltage at the voltage detector corresponding to the generator in the thermal circuit model is obtained. Then, the parameter values ​​of multiple circuit elements in the electrical circuit model are calculated so that the measured electromotive force at the generator in the actual thermal circuit model and the detected voltage at the voltage detector in the virtual electrical circuit model exhibit similar behavior (fit). Here, the parameter value refers to the resistance value in the case of a resistor, and the output voltage value in the case of a power supply.

[0035] The electrical circuit model to which the multiple parameter values ​​calculated as described above are applied exhibits behavior similar to that of an actual thermal circuit model. In an actual thermal circuit model, the heat source and its thermal resistance are unknown, and all other circuit parameters are independent of the heat source. Therefore, considering that the thermal conductivity of the material forming the heat conduction path is known, the parameter values ​​of the circuit elements in the electrical circuit corresponding to these are fixed to optimal values. Moreover, the obtained parameter values ​​reflect the temperature characteristics of the thermoelectric conversion material forming the power generation body. As a result, using the electrical circuit model to which the calculated parameter values ​​are applied, the heat flux at the heat receiving surface of the heat source can be easily estimated, regardless of whether it is in a transient or steady state, without using sensitivity coefficients as in conventional methods. Furthermore, the thermal conductance and thermal resistance at the heat receiving surface of the heat source can also be easily estimated as needed.

[0036] Here, the heat flux measurement method described in this section differs from the heat flux measurement method described in section (7) above in that it measures the electromotive force generated by the power generator instead of measuring the temperature using an actual thermal circuit model. Furthermore, considering measurements in actual field environments, there is concern that temperature measurement results using thermocouples, etc., will contain a lot of noise. However, the Seebeck electromotive force measured by the power generator is less affected by noise in the field environment. For this reason, the parameter values ​​of multiple circuit elements calculated using such a Seebeck electromotive force will have improved calculation accuracy, and consequently, the calculation accuracy of heat flux, thermal conductance, and thermal resistance at the heat receiving surface of the heat source will also be improved.

[0037] (9) A heat flux measurement method in which, when measuring the temperature in the heat conduction path or the electromotive force at the power generator in the above item (7) or (8), AC power of a predetermined frequency is applied to the heat-generating element as the heating energy, and when constructing the electrical circuit model, the heat source and the cooling source are made to correspond to DC power sources, and the heat-generating element is made to correspond to AC power sources that output AC power of the predetermined frequency. The heat flux measurement method described in this item, when measuring the temperature in the heat conduction path (in the case of item (7) above) or the electromotive force at the power generator (in the case of item (8) above) in an actual thermal circuit model, AC power of a predetermined frequency is applied to the heat-generating element as the heating energy to vary the amount of heat generated, thereby AC-variing the amount of heat generated from the heat-generating element at a predetermined frequency. When constructing the electrical circuit model virtually, the heat source and the cooling source in the thermal circuit model are made to correspond to DC power sources, and the heat-generating element in the thermal circuit model is made to correspond to AC power sources that output AC power at the same predetermined frequency as the AC power applied to the heat-generating element. This allows the heat generation (or absorption) state by the heat source, cooling source, and heat-generating element in the thermal circuit model to be more accurately reflected in the electrical circuit model, resulting in more appropriate parameter values ​​for the electrical circuit model.

[0038] (10) A heat flux measurement method for calculating the parameter values ​​in item (7) or (8) above, which utilizes a circuit simulator loaded with the electrical circuit model and an optimization algorithm. The heat flux measurement method described in this item utilizes a circuit simulator and an optimization algorithm when calculating the parameter values ​​of multiple circuit elements of an electrical circuit model. Specifically, the constructed electrical circuit model is loaded into a circuit simulator, and while the electrical circuit model is operated on the circuit simulator, an arbitrary optimization algorithm is used to calculate the optimal parameter values ​​so that it behaves similarly to an actual thermal circuit model. In this way, the parameter values ​​of the electrical circuit model can be obtained in a black-box manner without deriving the circuit equations of the electrical circuit model.

[0039] (11) A heat flux measurement method for calculating the parameter values ​​in item (7) or (8) above, which utilizes circuit equations derived from the electrical circuit model and an optimization algorithm. The heat flux measurement method described in this item utilizes circuit equations and an optimization algorithm when calculating the parameter values ​​of multiple circuit elements in an electrical circuit model. Specifically, circuit equations are derived from the constructed electrical circuit model using Kirchhoff's laws, etc., and the optimal parameter values ​​of the circuit elements in the circuit equations are calculated using an arbitrary optimization algorithm. This makes it possible to obtain the parameter values ​​of the electrical circuit model in a white-box manner without using a circuit simulator or the like.

[0040] (12) A heat flux measurement method in which, when measuring the temperature in the heat conduction path in item (7) above, the temperatures of a plurality of temperature measurement points are measured and the parameter values ​​are calculated such that the measurement results at each of the plurality of temperature measurement points and the voltages at the voltage measurement points corresponding to each of the plurality of temperature measurement points in the operating state of the electrical circuit model exhibit similar behavior. The heat flux measurement method described in this item measures the temperature in the heat conduction path in an actual thermal circuit model by continuously measuring the temperatures at a plurality of pre-set temperature measurement points while varying the amount of heat generated from the heat source, and obtaining time-series temperature measurement results at each of the temperature measurement points.

[0041] Furthermore, the constructed electrical circuit model is virtually operated by setting each power supply to operating state, and in this state, the voltages of multiple voltage monitoring points corresponding to multiple temperature measurement points in the thermal circuit model are acquired. Then, the parameter values ​​of multiple circuit elements in the electrical circuit model are calculated so that the measured temperatures at the multiple temperature measurement points of the thermal circuit model measured as described above and the acquired voltages at the multiple voltage monitoring points of the virtual electrical circuit model exhibit similar behavior for corresponding elements. As a result, the number of indicators for fitting the virtual electrical circuit model to the actual thermal circuit model increases by the number of temperature measurement points and their corresponding voltage monitoring points, thus obtaining more appropriate parameter values ​​for the electrical circuit model.

[0042] (13) A heat flux measurement method in which, when calculating the parameter values ​​in item (12) above, weights a specific voltage measurement point among the multiple voltage measurement points of the electrical circuit model corresponding to the multiple temperature measurement points. The heat flux measurement method described in this item performs weighting as necessary when calculating the parameter values ​​of multiple circuit elements of the electrical circuit model. That is, weights are assigned to an arbitrary specific voltage monitoring point among a plurality of voltage monitoring points that serve as indicators for fitting the electrical circuit model to the thermal circuit model, and the parameter values ​​of the electrical circuit model are calculated with an increased priority for fitting at the weighted voltage monitoring point. At this time, each of the multiple voltage monitoring points may be weighted with a different proportion. This improves the fitting accuracy at the weighted voltage monitoring point and the voltage monitoring point with a high weighting proportion, so that the parameter values ​​of the electrical circuit model can be calculated in response to various situations.

[0043] (14) A system for measuring the heat flux at the heat receiving surface of a heat source, comprising three heat conduction media formed of a material with known thermal conductivity, wherein a heat-generating element that can be controlled to vary the amount of heat generated and a power-generating element that generates an electromotive force by the Seebeck effect are alternately sandwiched between them, the system comprising: a heat conduction modulation unit installed so as to conduct heat from any heat receiving surface of the heat source to one of the three heat conduction media; a cooling source having a constant temperature lower than the heat source and installed so as to conduct heat from the other of the three heat conduction media; a heat-generating element control unit that controls the heat-generating element by supplying it with fluctuating heating energy; and a heat-generating element control unit set at a predetermined position on at least one of the three heat conduction media. A heat flux measurement system comprising: a temperature measurement unit for measuring the temperature of a temperature measurement point; an electromotive force measurement unit for measuring the electromotive force in the power generation body; and a calculation processing unit for performing calculation processing, wherein the calculation processing unit calculates the difference between a first temperature when affected by heat generation from the heat generation element and a second temperature when not affected, based on the measurement results of the temperature measurement unit, calculates the thermal conductance at the heat receiving surface based on the difference and the heating energy when the first temperature was measured; and calculates the difference between a first electromotive force when affected by heat generation from the heat generation element and a second electromotive force when not affected, based on the measurement results of the electromotive force measurement unit, and calculates the heat flux at the heat receiving surface based on the difference and the heating energy when the first electromotive force was measured.

[0044] The heat flux measurement system described in this section measures the thermal conductance and heat flux per unit area at the heat receiving surface, which can be obtained from a heat source with unused thermal energy, and includes a heat conduction modulation unit, a cooling source, a heat-generating element control unit, a temperature measurement unit, an electromotive force measurement unit, and a calculation processing unit. The heat conduction modulation unit has a configuration in which a heat-generating element and a power-generating element are alternately sandwiched between three heat-conducting media. That is, the heat-conducting media, heat-generating element, heat-conducting media, power-generating element, and heat-conducting media are arranged in close proximity in series in this order or the reverse order. The heat-generating element is controllable so that its heat generation amount fluctuates, the power-generating element generates an electromotive force by the Seebeck effect, and the three heat-conducting media are made of materials with known thermal conductivity. The heat conduction modulation unit with this configuration is installed so that heat is conducted from any heat receiving surface of the heat source to be measured to one of the three heat-conducting media. The cooling source has a lower temperature than the heat source to be measured and is installed so that heat is conducted from the other of the three heat-conducting media. In other words, the heat conduction modulation unit and the cooling source are installed as part of a heat conduction path that diverts heat from the heat source so that heat flows from the heat source to the cooling source.

[0045] The heating element control unit controls the heating element of the heat conduction modulation unit, and controls the heating element so that the amount of heat generated from the heating element fluctuates by supplying it with fluctuating heating energy. The temperature measurement unit measures the temperature of the temperature measurement point, which is set at a predetermined position in at least one of the three heat conduction media of the heat conduction modulation unit. The electromotive force measurement unit measures the electromotive force generated in the power generator in response to the temperature difference applied to the power generator through the heat conduction media that sandwich the power generator. The calculation processing unit performs various calculation processes in this system, and as part of these, it performs the following calculations.

[0046] Specifically, the calculation processing unit obtains a first temperature when the system is affected by the heat generated by the heating element, and a second temperature when the system is not affected by the heat generated by the heating element, from the temperature measurement results of the temperature measurement point by the temperature measurement unit, as described in item (1) above. Then, by calculating the difference between these two temperatures, it extracts temperature change data that has changed due to the fluctuating heat generated by the heating element. Furthermore, the calculation processing unit calculates the thermal conductance of the heat source to be measured, as described in item (1) above, based on the extracted temperature change data and the heating energy supplied to the heating element by the heating element control unit when the temperature measurement unit measured the first temperature. This allows the thermal conductance at the heat receiving surface from which data can be collected from the heat source to be calculated without needing to know the specific heat or mass of the heat source.

[0047] In addition, the calculation processing unit obtains the first electromotive force when the power generator is affected by the heat generated by the heat source, and the second electromotive force when it is not affected by the heat generated by the heat source, from the measurement results of the electromotive force measurement unit, as described in item (1) above. Then, by calculating the difference between these, it extracts the electromotive force change data that has changed due to the fluctuating heat generated by the heat source. Furthermore, the calculation processing unit calculates the heat flux of the heat source to be measured, as described in item (1) above, based on the extracted electromotive force change data and the heating energy supplied to the heat source from the heat source control unit when the first electromotive force was measured by the electromotive force measurement unit. This allows the heat flux at the heat receiving surface from which heat can be collected from the heat source to be calculated without the need to know the specific heat or mass of the heat source. Moreover, because the structure involves separating heat from the heat source to be measured via a heat conduction path including a heat conduction modulation unit and a cooling source, and measuring temperature and electromotive force in the heat conduction modulation unit in the heat conduction path, it can measure heat sources in various environments, including heat sources through which corrosive gases or gas / liquid mixtures with fluid density fluctuations flow. Furthermore, there is no need to consider durability against corrosion, resulting in a significant improvement in durability and reliability.

[0048] (15) A heat flux measurement system in which, in item (14) above, the heating element and the power generator are Peltier elements, the heating element control unit provides AC power of a predetermined frequency different from the fluctuation frequency of the heat flow from the heat source as the heating energy, the calculation processing unit extracts data of the frequency component of the predetermined frequency from the calculation result of the difference between the first temperature and the second temperature, calculates the thermal conductance on the heat receiving surface based on the extraction result, extracts data of the frequency component of the predetermined frequency from the calculation result of the difference between the first electromotive force and the second electromotive force, and calculates the heat flux on the heat receiving surface based on the extraction result. In the heat flux measurement system described in this item, the heating element and power generator of the heat conduction modulation unit are Peltier elements, and the heating energy provided to the Peltier element as a heating element from the heating element control unit is AC power of a predetermined frequency, so that the amount of heat generated from the Peltier element as a heating element fluctuates AC. The predetermined frequency of the AC power at this time is set to be a frequency different from the fluctuation frequency of the heat flow that flows from the heat source to the heat conduction modulation unit, etc.

[0049] The calculation processing unit then calculates the difference between the first temperature when affected by the heat generated by the heating element and the second temperature when not affected by the heat generated by the heating element, and extracts the frequency component data of the predetermined frequency mentioned above from the calculation result. Furthermore, the calculation processing unit calculates the thermal conductance at the heat receiving surface based on the temperature difference data extracted in this way and the AC power supplied from the heating element control unit to the Peltier element as a heating element. Similarly, the calculation processing unit calculates the difference between the first electromotive force when affected by the heat generated by the heating element and the second electromotive force when not affected by the heat generated by the heating element, and extracts the frequency component data of the predetermined frequency mentioned above from the calculation result. Furthermore, the calculation processing unit calculates the heat flux at the heat receiving surface based on the electromotive force difference data extracted in this way and the AC power supplied from the heating element control unit to the Peltier element as a heating element. In other words, as mentioned in item (2) above, a modulated power with a frequency different from the fluctuation frequency of the heat flow from the heat source is applied to the Peltier element, which acts as a heat source. By extracting and using the data of the frequency component of that modulated frequency, the thermal conductance and heat flux are calculated by eliminating the fluctuation components of the heat flow. This allows for a more accurate calculation of thermal conductance and heat flux.

[0050] (16) The heat conduction modulation system in item (15) above, comprising two heat conduction modulation units installed such that heat is conducted separately from two heat receiving surfaces set at different positions of the heat source, wherein the heating element control unit provides AC power with the same predetermined frequency but with a phase difference of 180° to the heating element of one of the heat conduction modulation units and the heating element of the other heat conduction modulation unit, and the calculation processing unit calculates the heat conductance and heat flux in the heat source based on the heat conductance and heat flux calculated from the one heat conduction modulation unit and the heat conductance and heat flux calculated from the other heat conduction modulation unit.

[0051] The heat flux measurement system described in this section includes two heat conduction modulation units as mentioned in section (14) above, and these two heat conduction modulation units are installed so that heat is conducted separately from two heat receiving surfaces set at different locations on the heat source. The heat generation control unit is configured to control the heat generation elements of both heat conduction modulation units. Specifically, the heat generation control unit provides the heat generation element of one heat conduction modulation unit with AC power at a predetermined frequency different from the fluctuation frequency of the heat flow from the heat source as mentioned in section (15) above, and provides the heat generation element of the other heat conduction modulation unit with AC power at the same predetermined frequency as the AC power provided to the heat generation element of the first heat conduction modulation unit, but with a phase difference of 180°.

[0052] The calculation processing unit then calculates the thermal conductance and heat flux at the heat receiving surface to which one heat conduction modulation unit is connected, and the thermal conductance and heat flux at the heat receiving surface to which the other heat conduction modulation unit is connected. As mentioned in item (3) above, when the thermal conductance and heat flux calculated in this way are reflected in the thermal circuit model of the heat source and the two heat conduction modulation units connected thereto, this thermal circuit model becomes equivalent to a Wheatstone bridge circuit in an electrical circuit. For this reason, the calculation processing unit calculates the thermal conductance and heat flux within the heat source from such an electrical circuit model. This makes it possible to determine the thermal conductance and heat flux within the heat source without having to know the specific heat or mass of the heat source.

[0053] (17) The heat conduction modulation unit in the above item (14) includes four heat conduction media, two heat-generating elements, and one power-generating element, and the two heat-generating elements and the one power-generating element are sandwiched between the four heat conduction media in any order. The heat conduction modulation unit in this item includes four heat conduction media, two heat-generating elements, and one power-generating element. The two heat-generating elements and the one power-generating element are sandwiched between the four heat conduction media in any order. That is, the two heat-generating elements and the one power-generating element are placed in close contact with each heat conduction media in three gaps between the four heat conduction media arranged in series, in the order of heat-generating element, power-generating element, heat-generating element, heat-generating element, or the reverse order.

[0054] Therefore, the heating element control unit controls the two heating elements in the heat conduction modulation unit, and in doing so, controls the two heating elements in the same way. That is, for example, when controlling the heating elements by applying AC power, the frequency, phase, and amplitude are controlled to be the same. As a result, fluctuations in amplitude are introduced into the temperature measured in the heat conduction medium and the electromotive force measured in the generator, depending on the positional relationship between the two heating elements and the one power generator. By utilizing these fluctuations in the measurement, the sensitivity of the heat conduction modulation unit is increased, and the thermal conductance and heat flux of the heat source are calculated with greater accuracy.

[0055] (18) A system for measuring the heat flux at the heat receiving surface of a heat source, comprising: a configuration in which a power generation body that generates an electromotive force by the Seebeck effect is sandwiched between two heat conducting media formed of a material with known thermal conductivity, the system comprising: a heat conduction modulation unit installed so as to conduct heat to one of the two heat conducting media from an arbitrary heat receiving surface of the heat source; a cooling source having a constant temperature lower than the heat source and installed so as to conduct heat to the other of the two heat conducting media; a temperature measurement unit that measures the temperature of a temperature measurement point set at a predetermined position on at least one of the two heat conducting media; an electromotive force measurement unit that measures the electromotive force at the power generation body; and a calculation processing unit that performs calculation processing, wherein the calculation processing unit calculates the heat flux passing through the power generation body based on the measurement result by the temperature measurement unit, the measurement result by the electromotive force measurement unit, and the temperature dependence of the material properties of the thermoelectric conversion material used in the power generation body which has been set in advance, and calculates the heat flux at the heat receiving surface based on the calculation result.

[0056] The heat flux measurement system described in this section measures the heat flux per unit area at a heat receiving surface, which can be obtained from a heat source having unused thermal energy, and includes a heat conduction modulation unit, a cooling source, a temperature measurement unit, an electromotive force measurement unit, and a calculation processing unit. The heat conduction modulation unit has a configuration in which a power generation body is sandwiched between two heat conducting media, and the heat conducting media, power generation body, and heat conducting media are arranged in close proximity in this order. The power generation body generates an electromotive force by the Seebeck effect, and the two heat conducting media are made of materials with known thermal conductivity. The heat conduction modulation unit with this configuration is installed so that heat is conducted from any heat receiving surface of the heat source to be measured to one of the two heat conducting media.

[0057] The cooling source has a lower temperature than the heat source being measured and is installed so that heat is conducted from the other of the two heat conduction media. That is, the heat conduction modulation unit and the cooling source are installed as part of a heat conduction path that diverts heat from the heat source so that heat flows from the heat source to the cooling source. The temperature measurement unit measures the temperature at a temperature measurement point, which is set at a predetermined position in at least one of the two heat conduction media of the heat conduction modulation unit. The electromotive force measurement unit measures the electromotive force generated in the power generator in response to the temperature difference applied to the power generator through the heat conduction media that sandwich the power generator.

[0058] The calculation processing unit performs various calculation processes in this system, and as part of these, it performs the following calculations. Specifically, the calculation processing unit calculates the heat flux passing through the power generator as described in item (4) above, based on the temperature of the temperature measurement point in the heat conduction path measured by the temperature measurement unit, the electromotive force at the power generator measured by the electromotive force measurement unit, and the temperature dependence of the material properties of the thermoelectric conversion material used in the power generator, which are set in advance. Furthermore, the calculation processing unit calculates the heat flux at the heat receiving surface of the heat source to which the heat conduction path including the heat conduction modulation unit is connected, from the calculated heat flux passing through the power generator, as described in item (4) above. This produces the same effect as the heat flux measurement method in item (4) above.

[0059] (19) A system for measuring the heat flux at the heat receiving surface of a heat source, comprising a configuration in which at least one heating element capable of controlling the amount of heat generated is sandwiched between at least two heat conducting media made of a material with known thermal conductivity, the system comprising: a heat conduction modulation unit installed so as to conduct heat from any heat receiving surface of the heat source to one of the at least two heat conducting media; a cooling source having a constant temperature lower than the heat source and installed so as to conduct heat from the other of the at least two heat conducting media; a heating element control unit that controls the at least one heating element by supplying fluctuating heating energy to the at least one heating element; a temperature measurement unit that measures the temperature of a temperature measurement point set at a predetermined position on at least one of the at least two heat conducting media; and a calculation unit that performs calculation processing. A heat flux measurement system comprising a processing unit, the calculation processing unit virtually constructs an electrical circuit model including a plurality of circuit elements corresponding to a thermal circuit model from the heat source including the heat conduction modulation unit to the cooling source, and at this time, the temperature, heat flux, and thermal resistance in the thermal circuit model are made to correspond to the voltage, current, and resistance in the electrical circuit model, and the calculation processing unit calculates the parameter values ​​of the plurality of circuit elements in the electrical circuit model such that the temperature of the temperature measurement point, continuously measured by the temperature measurement unit, and the voltage of the voltage monitoring point corresponding to the temperature measurement point of the thermal circuit model in the operating electrical circuit model exhibit similar behavior while the amount of heat generated from at least one heat source is fluctuated by the heat generation control unit, and estimates the heat flux on the heat receiving surface using the electrical circuit model to which the calculated parameter values ​​have been applied.

[0060] The heat flux measurement system described in this section measures the heat flux per unit area on a heat-receiving surface, which can be obtained from a heat source having unused thermal energy, and includes a heat conduction modulation unit, a cooling source, a heat-generating element control unit, a temperature measurement unit, and a calculation processing unit. The heat conduction modulation unit has a configuration in which at least one heat-generating element is alternately sandwiched between at least two heat-conducting media. That is, for example, if there is one heat-generating element, the heat-conducting media, heat-generating element, and heat-conducting media are arranged in close proximity in series in this order, and if there are two heat-generating elements, the heat-conducting media, heat-generating element, heat-conducting media, heat-generating element, and heat-conducting media are arranged in close proximity in series in this order. The heat-generating element is controllable so that its heat generation amount fluctuates, and at least two heat-conducting media are made of materials with known thermal conductivity. The heat conduction modulation unit with such a configuration is installed so that heat is conducted from any heat-receiving surface of the heat source to be measured to one of the at least two heat-conducting media. The cooling source has a lower temperature than the heat source being measured and is installed so that heat is conducted from the other of at least two heat conduction media. In other words, the heat conduction modulation unit and the cooling source are installed as part of a heat conduction path that diverts heat from the heat source so that heat flows from the heat source to the cooling source.

[0061] The heating element control unit controls at least one heating element of the heat conduction modulation unit, and controls the heating element so that the amount of heat generated from the heating element fluctuates by supplying it with fluctuating heating energy. The temperature measurement unit measures the temperature of a temperature measurement point, which is set at a predetermined position in at least one of the at least two heat conduction media of the heat conduction modulation unit. The calculation processing unit performs various calculation processes in this system, and as part of these, it performs the following calculations. That is, the calculation processing unit virtually constructs an electrical circuit model including multiple circuit elements that corresponds to a thermal circuit model from a heat source including the heat conduction modulation unit to a cooling source, as described in item (7) above.

[0062] Furthermore, the calculation processing unit calculates the parameter values ​​of multiple circuit elements in the electrical circuit model as described in item (7) above, so that the temperature at the temperature measurement point in the actual thermal circuit model and the voltage at the voltage monitoring point corresponding to the temperature measurement point in the operating electrical circuit model exhibit similar behavior. The temperature at the temperature measurement point in the thermal circuit model used at this time is the temperature continuously measured by the temperature measurement unit while the amount of heat generated from at least one heat source is fluctuated by the heat source control unit, and the electrical circuit model is virtually operated by setting each power source to the operating state. Furthermore, the calculation processing unit uses the electrical circuit model to which the parameter values ​​calculated as described above are applied to estimate the heat flux, thermal conductance, and thermal resistance at the heat receiving surface of the heat source. This produces the same effect as the heat flux measurement method in item (7) above.

[0063] (20) A system for measuring the heat flux at the heat receiving surface of a heat source, comprising: a configuration in which at least one heat-generating element capable of controlling the amount of heat generated to fluctuate and at least one power-generating element that generates an electromotive force by the Seebeck effect are alternately sandwiched between at least three heat-conducting media formed of a material with known thermal conductivity, the system comprising: a heat conduction modulation unit installed so as to conduct heat from any heat receiving surface of the heat source to one of the at least three heat-conducting media; a cooling source having a constant temperature lower than the heat source and installed so as to conduct heat from the other of the at least three heat-conducting media; a heat-generating element control unit that controls the at least one heat-generating element by supplying fluctuating heating energy to the at least one heat-generating element; an electromotive force measurement unit that measures the electromotive force at the at least one power-generating element; and a calculation processing unit that performs calculation processing. The calculation processing unit virtually constructs an electrical circuit model including a plurality of circuit elements corresponding to a thermal circuit model from the heat source including the heat conduction modulation unit to the cooling source, and at this time, the temperature, heat flux, and thermal resistance in the thermal circuit model are made to correspond to the voltage, current, and resistance in the electrical circuit model, and the at least one power generator is made to correspond to a voltage detector, and the parameter values ​​of the plurality of circuit elements in the electrical circuit model are calculated such that the electromotive force in the at least one power generator, which is continuously measured by the electromotive force measurement unit while the amount of heat generated from the at least one heat generator is fluctuating by the heat generation control unit, and the voltage at the voltage detector in the operating electrical circuit model exhibit similar behavior, and the heat flux measurement system estimates the heat flux at the heat receiving surface using the electrical circuit model to which the calculated parameter values ​​are applied.

[0064] The heat flux measurement system described in this section measures the heat flux per unit area on a heat receiving surface, which can be collected from a heat source having unused thermal energy, and includes a heat conduction modulation unit, a cooling source, a heat-generating element control unit, an electromotive force measurement unit, and a calculation processing unit. The heat conduction modulation unit has a configuration in which at least one heat-generating element and at least one power-generating element are alternately sandwiched between at least three heat-conducting media. That is, for example, if there is one heat-generating element and one power-generating element, the heat-conducting media, heat-generating element, heat-conducting media, power-generating element, and heat-conducting media are arranged in close proximity in series in this order or the reverse order. If there are two or more of either the heat-generating element or the power-generating element, the number of heat-conducting media increases accordingly, and heat-conducting media are interposed between the heat-generating elements, the power-generating elements, or the heat-generating elements and power-generating elements so that they are not continuous, and all of them are sandwiched between heat-conducting media.

[0065] The heat-generating element is controllable so that its heat output fluctuates, the power-generating element generates an electromotive force by the Seebeck effect, and at least three heat conduction media are made of materials with known thermal conductivity. The heat conduction modulation unit with this configuration is installed so that heat is conducted from any heat-receiving surface of the heat source being measured to one of the at least three heat conduction media. The cooling source has a lower temperature than the heat source being measured and is installed so that heat is conducted from the other of the at least three heat conduction media. In other words, the heat conduction modulation unit and the cooling source are installed as part of a heat conduction path that diverts heat from the heat source so that heat flows from the heat source to the cooling source.

[0066] The heating element control unit controls at least one heating element of the heat conduction modulation unit, and controls the heating element so that the amount of heat generated from the heating element fluctuates by supplying it with fluctuating heating energy. The electromotive force measurement unit measures the electromotive force generated in the power generator, which is caused by the temperature difference applied to the power generator through the heat conduction medium that holds the power generator. The calculation processing unit performs various calculation processes in this system, and as part of these, it performs the following calculations. That is, the calculation processing unit virtually constructs an electrical circuit model including multiple circuit elements that corresponds to the thermal circuit model from the heat source, including the heat conduction modulation unit, to the cooling source, as described in item (8) above.

[0067] Furthermore, the calculation processing unit calculates the parameter values ​​of multiple circuit elements in the electrical circuit model as described in item (8) above, so that the electromotive force generated by the power generator in the actual thermal circuit model and the voltage at the voltage detector corresponding to the power generator in the operating electrical circuit model exhibit similar behavior. The electromotive force at the power generator in the thermal circuit model used at this time is the electromotive force continuously measured by the electromotive force measurement unit while the amount of heat generated from at least one heat source is varied by the heat source control unit, and the electrical circuit model is virtually operated by setting each power source to the operating state. Furthermore, the calculation processing unit uses the electrical circuit model to which the parameter values ​​calculated as described above are applied to estimate the heat flux, thermal conductance, and thermal resistance at the heat receiving surface of the heat source. This produces the same effect as the heat flux measurement method in item (8) above.

[0068] With this configuration, the present invention can grasp the heat flux of the heat source and contribute to the effective utilization of unused thermal energy.

[0069] This is a block diagram showing an example of the configuration of a heat flux measurement system according to an embodiment of the present invention. This is an image diagram showing an example of the installation of a heat conduction path used in a heat flux measurement system according to an embodiment of the present invention, along with a model of thermal resistance from the heat source to the heat conduction path. This shows an example of the structure of a heat conduction modulation unit used in a heat flux measurement system according to an embodiment of the present invention, where (a) is a perspective view and (b) is an exploded perspective view. This is an image diagram showing an example of an installation where two heat conduction paths are installed in a heat flux measurement system according to an embodiment of the present invention. (a) is a front view of a heat conduction medium in another embodiment, and (b) is a front view of a heat conduction modulation unit in another embodiment. These are perspective views of a heat conduction modulation unit in yet another embodiment, with (a) to (e) having different forms from each other. This is a flow chart showing an example of the procedure of a heat flux measurement method according to an embodiment of the present invention. (a) is a schematic diagram showing the relationship between heat quantity and temperature, and (b) is an excerpt showing the thermal conductance in the schematic diagram of (a). This is an image diagram showing an electrical circuit model equivalent to the thermal circuit model of the embodiment in Figure 4. Figure 4 shows the measurement results of the heat flux wave in the embodiment, where (a) is the measurement result in the heat conduction path connected to the upstream side of the heat source, and (b) is the measurement result in the heat conduction path connected to the downstream side of the heat source. This is a block diagram showing an example of the configuration of a heat flux measurement system according to another embodiment of the present invention. This is an image diagram showing an example of the installation of a heat conduction path used in the heat flux measurement system of Figure 11. This is a flowchart showing an example of the procedure for a heat flux measurement method according to another embodiment of the present invention. This is a graph illustrating the temperature dependence of the material properties of a thermoelectric conversion material, where (a) is the temperature characteristic of the Seebeck electromotive force and (b) is the temperature characteristic of the thermal conductivity. This is a graph illustrating the relationship between the temperature in the heat conduction path and the electromotive force in the power generator, and (b) is a graph illustrating the relationship between the temperature in the heat conduction path and the heat flux passing through the power generator. This is a table illustrating an example of the relationship between the temperature in the heat conduction path, the electromotive force in the power generator, and the heat flux passing through the power generator. (a) is a graph illustrating the temperature measurement results using a thermocouple, and (b) is a graph illustrating the Seebeck voltage measurement results using the heat flux measurement system in Figure 11. This is a block diagram showing an example of the configuration of a heat flux measurement system according to yet another embodiment of the present invention. This is a flowchart showing an example of the procedure for a heat flux measurement method according to yet another embodiment of the present invention.This diagram illustrates the concept of constructing an electrical circuit model from a thermal circuit model, with (a) being an illustrative diagram of the thermal circuit model and (b) being an illustrative diagram of the electrical circuit model. This is an illustrative diagram showing an example of a constructed electrical circuit model. (a) is an example of the output result of an electrical circuit model using parameter values ​​calculated without weighting, and (b) is an example of the output result of an electrical circuit model using parameter values ​​calculated with weighting. This is a block diagram showing an example of the configuration of a heat flux measurement system according to yet another embodiment of the present invention. This is an illustrative diagram of a thermal circuit model. This is a flowchart showing an example of the procedure for a heat flux measurement method according to yet another embodiment of the present invention. This is an illustrative diagram showing an example of a constructed electrical circuit model. This shows an example of the measurement result of the electromotive force in a power generator, with (a) being the case when there are two power generators and (b) being the case when there is one power generator.

[0070] Embodiments of the present invention will be described below with reference to the drawings. Here, throughout the drawings, the same or corresponding parts are indicated by the same reference numerals. Furthermore, detailed explanations of parts that are the same as or equivalent to those in the prior art will be omitted. Figure 1 shows an example of the configuration of a heat flux measurement system 10 (10A) according to an embodiment of the present invention for measuring the thermal conductance on a heat receiving surface, the thermal resistance inside the heat source 50, and the heat flux on the heat receiving surface, which can be collected from a heat source 50 (see Figures 2 and 4) to be measured. As shown in the figure, the heat flux measurement system 10A includes a heat conduction modulation unit 12, a cooling source 36, a heat-generating element control unit 40, a temperature measurement unit 44, an electromotive force measurement unit 46, and a calculation processing unit 48. The heat conduction modulation unit 12 also includes two heat-generating elements 14, a power-generating element 18, and four heat-conducting media 16, and Figure 3 shows an example of the detailed structure of the heat conduction modulation unit 12.

[0071] As shown in Figure 3, the heat conduction modulation section 12 has a configuration in which two heating elements 14 (14A, 14B) and a power generation element 18 are sandwiched between four heat conduction media 16 (16A to 16D). In this embodiment, the four heat conduction media 16 are connected by bolts or the like, and the two heating elements 14 and the power generation element 18 are arranged between them. More specifically, the heat conduction media 16B and 16C are cylindrical, while the heat conduction media 16A and 16D are shaped like a combination of a cylinder with the same diameter as the heat conduction media 16B and 16C and a thinner cylinder. Heat element 14A is arranged between the heat conduction media 16A and 16B, the power generation element 18 is arranged between the heat conduction media 16B and 16C, and heat element 14B is arranged between the heat conduction media 16C and 16D.

[0072] Each of the heating elements 14A and 14B is designed to receive fluctuating heating energy, causing the amount of heat generated to fluctuate. In this embodiment, they are formed by Peltier elements, and a control line 32 is connected to the Peltier elements to supply power as heating energy. The power generator 18 generates an electromotive force by the Seebeck effect. In this embodiment, it is also formed by a Peltier element, similar to the heating element 14, and a measurement line 34 is connected to the Peltier element to acquire the electromotive force. The power generator 18 may have a modular structure in which, for example, several dozen Peltier elements are connected in series, in order to increase the sensitivity of the electromotive force generated from the heat flow.

[0073] A heat dissipation sheet or the like may be placed between each of the Peltier elements constituting the heating element 14 and the power generation element 18, and the heat conductive medium 16 that sandwiches them, in order to improve thermal conductivity. Also, as can be seen in Figure 3(b), recesses are provided on the opposing surfaces of the two heat conductive mediums 16 that sandwich each Peltier element for positioning a heat dissipation sheet or a part of the Peltier element. The four heat conductive mediums 16 are not limited to these, but are made of materials with known thermal conductivity, such as aluminum or copper. A measurement hole 20 is drilled in each of the four heat conductive mediums 16, and this measurement hole 20 extends toward the center of the heat conductive medium 16, which is circular in plan view. A temperature measurement point is set at the position of the measurement hole 20 of each heat conductive medium 16, near the center of the circular heat conductive medium 16 in plan view.

[0074] As shown in Figure 2, the heat conduction modulation unit 12, configured as described above, is used as part of a heat conduction path 54 that is installed to divert heat from the heat source 50 to be measured. In the embodiment shown in Figure 2, a heat exchanger is installed via a heat outlet (heat receiving surface) from the heat source 50, and the heat conduction modulation unit 12 is further installed therevia a thermal bonding member. At this time, the heat conduction modulation unit 12 is installed so that heat from the heat source 50 is conducted to the heat conduction medium 16A on one side, in other words, the heat conduction medium 16A on one side is positioned on the upper side in Figure 2. Therefore, in the heat conduction modulation unit 12, heat is conducted from the front left to the back right in Figure 3(a). The other heat conduction medium 16D of the heat conduction modulation unit 12, which is positioned on the lower side in Figure 2, is connected to the cooling source 36 shown in Figure 1 via a thermal bonding member.

[0075] The cooling source 36 has a constant temperature lower than the heat source 50 being measured, which generates a heat flow in which heat diverted from the heat source 50 flows towards the cooling source 36. For this reason, the right side of Figure 2 shows a model evaluation circuit that visualizes the heat flow as an electrical flow, with the heat flowing from the heat source V through multiple resistors R to GND. As can be seen from this circuit, each component constituting the heat conduction path 54 through which heat flows has thermal resistance, and their thermal resistance can be determined by knowing the thermal conductivity of the materials constituting each component except the heat source 50. Here, the heat source 50 being measured, as shown in Figure 2, can be any one that contains unused thermal energy. Such heat sources 50 are not limited to these, but examples include equipment in industrial plants that handle thermal energy, various devices that use heat sources, combustion devices, internal combustion engines, incinerators, passages through which hot spring water flows, exhaust ducts, chimneys, steam pipes, etc.

[0076] Returning to Figure 1, the heating element control unit 40 controls the heating elements 14A and 14B of the heat conduction modulation unit 12 by supplying them with fluctuating heating energy. In this embodiment, AC power (modulated power) of a predetermined frequency is supplied to the Peltier element, which is the heating element 14, as heating energy via the control line 32 shown in Figure 3(b). The predetermined frequency of the AC power at this time is set to a frequency different from the fluctuating frequency of the heat flow from the heat source 50, which is known in advance. Furthermore, AC power (modulated power) with equal frequency, phase, and amplitude is supplied to the two heating elements 14A and 14B.

[0077] The temperature measurement unit 44 measures the temperature of the temperature measurement points set as described above in each heat conduction medium 16 of the heat conduction modulation unit 12. The temperature measurement unit 44 in this embodiment is not limited to this, but for example, it is configured to acquire the temperature of the temperature measurement points via platinum Pt100 as a resistance thermometer or a thermocouple and measure it at high speed over a wide temperature range. The electromotive force measurement unit 46 measures the electromotive force generated in the power generator 18 by the Seebeck effect in response to the heat flowing through the heat conduction modulation unit 12. For this purpose, the electromotive force measurement unit 46 acquires the electromotive force from the power generator 18 via a measurement line 34 as shown in Figure 3(b) and performs the measurement. Any voltmeter or the like capable of measuring the electromotive force with high sensitivity can be used in the electromotive force measurement unit 46. The calculation processing unit 48 performs various calculation processing in the heat flux measurement system 10A. Details of some of the calculation processing performed by such calculation processing unit 48 will be described later. Furthermore, the calculation processing unit 48 may be configured to perform calculations offline after acquiring the data necessary for the calculation. In Figure 1 (and in Figures 11, 18, and 23 described later), this configuration is illustrated by the dashed lines indicating its connections to other components.

[0078] Here, the heat flux measurement system 10A according to an embodiment of the present invention may correspond to the configuration shown in Figure 4. That is, in Figure 4, two heat conduction paths 54, as shown in Figure 2, are connected to different locations on the heat source 50 to be measured. In other words, two heat conduction modulation units 12 are installed so that heat is conducted separately from two heat receiving surfaces set at different locations on the heat source 50, and two cooling sources 36 are also installed accordingly. To correspond to this configuration, the heat generation control unit 40 is configured to control the heat generation element 14 of one heat conduction modulation unit 12 and the heat generation element 14 of the other heat conduction modulation unit 12. Similarly, the temperature measurement unit 44 is configured to measure the temperature measurement point set on the heat conduction medium 16 of one heat conduction modulation unit 12 and the temperature measurement point set on the heat conduction medium 16 of the other heat conduction modulation unit 12. Furthermore, the electromotive force measurement unit 46 is configured to measure the electromotive force generated by the power generator 18 of one heat conduction modulation unit 12 and the electromotive force generated by the power generator 18 of the other heat conduction modulation unit 12. The calculation processing unit 48 then performs various calculations based on the results measured by both the one heat conduction modulation unit 12 and the other heat conduction modulation unit 12, as will be described in detail later. Here, more than two heat conduction paths 54 may be connected to the heat source 50 to be measured.

[0079] Furthermore, the heat flux measurement system 10A according to the embodiment of the present invention is not limited to the configuration shown in Figures 1 to 4. Some of the components shown in Figures 1 to 4 may be deleted or replaced, and new components may be added. Moreover, each component in Figure 1 is a functional division of the configuration of the heat flux measurement system 10A and does not represent the individual devices that make up the heat flux measurement system 10A as they are, but rather is composed of various hardware, software, or combinations thereof. For example, the heating element 14 may be composed of something other than a Peltier element, such as a simple sheet resistor or ceramic heater, as long as the amount of heat generated can be controlled to fluctuate. Also, the heat conduction path 54 may differ from the configuration in Figures 2 and 4, as long as it includes the heat conduction modulation unit 12 and the cooling source 36. Furthermore, the shape, number, and arrangement order of each component of the heat conduction modulation unit 12 may differ from the embodiment in Figure 3, and the number and position of temperature measurement points may be set arbitrarily.

[0080] For example, Figure 5(a) shows another embodiment in which the four heat conduction media 16 can be. The heat conduction media 16 in Figure 5(a) is cylindrical and has three measurement holes 20 drilled in it. These three measurement holes 20 are positioned at equal intervals from each other in the axial direction of the cylinder and extend toward the center of the heat conduction media 16, which is circular in plan view. A temperature measurement point is set in each of the three measurement holes 20, near the center of the circular heat conduction media 16 in plan view. Therefore, the distance between these three temperature measurement points in the axial direction of the cylinder is equal. Some or all of the four heat conduction media 16 of the heat conduction modulation unit 12 shown in Figure 3(a) may be the heat conduction media 16 as shown in Figure 5(a).

[0081] Furthermore, Figure 5(b) shows another embodiment that the heat conduction modulation unit 12 can take. The heat conduction modulation unit 12 in Figure 5(b) has a heat conduction medium 16E similar to the heat conduction medium 16 shown in Figure 5(a), and a heat conduction medium 16F similar to the heat conduction mediums 16B and 16C shown in Figure 3. As a result, three temperature measurement points are set in the three measurement holes 20 of the heat conduction medium 16E, and one temperature measurement point is set in the one measurement hole 20 of the heat conduction medium 16F. The Peltier element, which serves as both the heat heating element 14 and the power generating element 18, is sandwiched between these heat conduction mediums 16E and 16F. As a result, the wiring extending from the Peltier element serves as both the control line 32 and the measurement line 34, and is connected to both the heat heating element control unit 40 and the electromotive force measurement unit 46, or a device that serves both functions. Thus, the Peltier element used in the heat conduction modulation section 12 may serve as both the heat generating element 14 and the power generating element 18, or there may be only two heat conduction media 16.

[0082] In addition, Figure 6 shows yet another embodiment of the heat conduction modulation unit 12. The heat conduction modulation unit 12 in Figures 6(a) to (e) has a configuration in which a Peltier element is sandwiched between two to four heat conduction media 16. However, each of these Peltier elements may function as a heat source 14, as a power source 18, or as both a heat source 14 and a power source 18. In the heat conduction modulation unit 12 in Figures 6(a) to (c), two to four heat conduction media 16 similar to the heat conduction media 16B and 16C shown in Figure 3 are used. In the heat conduction modulation unit 12 in Figures 6(d) and (e), a heat conduction media 16 similar to the heat conduction media 16B and 16C shown in Figure 3 and a heat conduction media 16 similar to the heat conduction media 16 shown in Figure 5(a) are used. Thus, the heat conduction modulation unit 12 can take on various arbitrary forms depending on the purpose.

[0083] Next, with reference to Figure 7, a heat flux measurement method according to an embodiment of the present invention, which is performed using the heat flux measurement system 10A described above, will be explained. For the configuration of the heat flux measurement system 10A, please refer to Figures 1 to 6 as appropriate. Note that the flowchart shown in Figure 7 is an example of the procedure flow of the heat flux measurement method, and the procedure of the heat flux measurement method according to an embodiment of the present invention is not limited to this flowchart. Therefore, some of the steps shown in Figure 7 may be changed, deleted, or rearranged, and new steps may be added.

[0084] S10 (Heat conduction path connection): For example, as shown in Figure 2, the other end of a heat conduction path 54, which has a cooling source 36 at one end and a heat conduction modulation section 12 in the middle, is connected to the heat source 50 to be measured. In this embodiment, as shown in Figure 4, two heat conduction paths 54 are connected to different heat receiving surfaces of the heat source 50. In Figure 4, the heat conduction path 54 on the left is connected to the upstream side of the heat source 50, and the heat conduction path 54 on the right is connected to the downstream side of the heat source 50, but the direction of heat flow within the heat source 50 may be unknown. At the same time, the other components of the heat flux measurement system 10A are installed and connected. For example, the heat acquisition portion of the temperature measurement unit 44 may be installed at the temperature measurement point set in the heat conduction medium 16 of both heat conduction modulation units 12, or the control lines 32 extending from the heat-generating elements 14 of both heat conduction modulation units 12 may be connected to the heat-generating element control unit 40, or the measurement lines 34 extending from the power-generating elements 18 of both heat conduction modulation units 12 may be connected to the electromotive force measurement unit 46.

[0085] S20 (Heating element control): The heating element control unit 40 starts controlling the heating elements 14 of both heat conduction modulation units 12. That is, in this embodiment, a total of four heating elements 14 are controlled: the two heating elements 14A and 14B of one heat conduction modulation unit 12 and the two heating elements 14A and 14B of the other heat conduction modulation unit 12. Specifically, AC power having a predetermined frequency (modulation frequency) different from the fluctuation frequency of the heat flow from the heat source 50 is supplied to the Peltier elements constituting each heating element 14, for example, so that the current waveform becomes a sine wave. At this time, the heating element control unit 40 provides AC power with the same predetermined frequency but a phase difference of 180° to the two heating elements 14A and 14B of one heat conduction modulation unit 12 and the two heating elements 14A and 14B of the other heat conduction modulation unit 12. Note that the phase difference at this time may be other than 180°.

[0086] S30 (Temperature and Voltage Measurement): The temperature measurement unit 44 measures the temperature of the temperature measurement points set on the heat conduction medium 16 of the two heat conduction modulation units 12. Specifically, it measures the temperature of the temperature measurement points set on the four heat conduction mediums 16A to 16D of one heat conduction modulation unit 12 and the temperature measurement points set on the heat conduction medium 16A to 16D of the other heat conduction modulation unit 12. At this time, the measurement is performed with a sampling interval of at least twice the modulation frequency of the AC power supplied from the heat-generating element control unit 40 to each heat-generating element 14. Furthermore, for subsequent processing, the measured analog temperature data is converted into digital temperature data by the calculation processing unit 48 or a separately provided A / D converter. It is preferable to perform the A / D conversion at this time with the highest possible resolution. The temperature measured in this step corresponds to the first temperature (see the symbol TW in Figure 8(a)) when it is affected by the heat generated by the heat-generating element 14 (when it is modulated).

[0087] In addition, the electromotive force measurement unit 46 measures the electromotive force generated by the power generators 18 of the two heat conduction modulation units 12. At this time, similar to temperature measurement, the measurement is performed at a sampling interval of at least twice the modulation frequency of the AC power supplied from the heat-generating element control unit 40 to each heat-generating element 14. Furthermore, for subsequent processing, the measured analog voltage data is converted into digital voltage data by the calculation processing unit 48 or a separately provided A / D converter. It is preferable that the A / D conversion at this time be performed with the highest possible resolution. The electromotive force measured in this step corresponds to the first electromotive force when it is affected by the heat generated by the heat-generating elements 14 (when it is modulated).

[0088] S40 (State Determination): The calculation processing unit 48 determines whether the heat flow from the heat source 50 is in a steady state and whether the amount of heat passing through the heat conduction modulation unit 12 is normal. First, regarding the determination of the heat flow, this determination is performed when at least one of the four heat conduction media 16A to 16D in each of the two heat conduction modulation units 12 is a heat conduction media 16 equipped with three measurement holes 20 as shown in Figure 5(a). In such a case, the calculation processing unit 48 determines the heat flow for each of the two heat conduction modulation units 12 using the temperature measured at the three temperature measurement points of the heat conduction media 16 and the interval between those three temperature measurement points. Specifically, if the heat flow from the heat source 50 is in a steady state, it is assumed that the heat flow from the heat source 50 to the cooling source 36 will decrease linearly. Therefore, in this embodiment, where the three temperature measurement points of the heat conduction medium 16 are set at equal intervals, it is considered that the temperature difference between the temperature measurement point on the heat source 50 side and the central temperature measurement point in the heat conduction medium 16 will be approximately equal to the temperature difference between the central temperature measurement point and the temperature measurement point on the cooling source 36 side in the heat conduction medium 16.

[0089] In contrast, if the heat flow from the heat source 50 is in a transient state, the above relationship breaks down, and the value obtained by dividing the temperature difference between the temperature measurement point on the heat source 50 side and the temperature measurement point on the cooling source 36 side by 2 will not be equal to the temperature difference between the temperature measurement point on the heat source 50 side and the central temperature measurement point, or the temperature difference between the central temperature measurement point and the temperature measurement point on the cooling source 36 side. Using these, the calculation processing unit 48 determines whether the heat flow flowing from the heat source 50 is in a steady state or not. Even if four or more temperature measurement points are set on a single heat conduction medium 16, the heat flow can be determined using the above relationship.

[0090] Next, regarding the determination of heat quantity, the calculation processing unit 48 determines the heat quantity for each of the two heat conduction modulation units 12 by utilizing the relative magnitudes of the temperatures measured at the temperature measurement points of each heat conduction medium 16. Specifically, if the amount of heat passing through each of the heat conduction modulation units 12 is normal, it is assumed that the temperature will gradually decrease from the heat source 50 side to the cooling source 36 side. For this reason, it is assumed that the measured temperatures at multiple temperature measurement points arranged along the temperature transfer direction from the heat source 50 side to the cooling source 36 side in each of the two heat conduction modulation units 12 will be in descending order of their arrangement.

[0091] Conversely, if the amount of heat is abnormal due to excessive modulation by the heat-generating element 14 (Peltier element), the above relationship breaks down, and phenomena such as the temperatures of adjacent temperature measurement points becoming approximately equal, or the temperature at a certain temperature measurement point becoming lower than the temperature at a temperature measurement point located closer to the cooling source 36, occur. Using these, the calculation processing unit 48 determines whether the amount of heat passing through each of the heat conduction modulation units 12 is normal. Then, in step S40, if it is determined that the heat flow from the heat source 50 is in a steady state and the amount of heat passing through each of the heat conduction modulation units 12 is normal, the process proceeds to the next step. If a transient state of heat flow or an abnormality in the amount of heat is detected, the configuration of the heat conduction path 54, the measurement timing, and the AC power supplied to the Peltier element as the heat-generating element 14 are reviewed.

[0092] S50 (Calculation of average temperature and average electromotive force): The calculation processing unit 48 calculates the average temperature and average electromotive force measured in S30. In other words, in this embodiment, AC power is applied to the Peltier element to change the amount of heat generated, so the effect of temperature fluctuations (modulation) by the Peltier element gives a temperature change that swings up and down in an AC manner. Therefore, by calculating the average temperature and average electromotive force using, for example, a moving average, temperature data and electromotive force data that have the effect of temperature fluctuations by the Peltier element are extracted. At this time, processing is performed using a low-pass filter or the like, which is set to filter characteristics that do not change the component that is fluctuating due to modulation. The calculation of the average temperature and average electromotive force is performed for each temperature measurement point and for each power generation unit 18, or in the case of temperature, only for a specific temperature measurement point, and subsequent processing is performed using the data from the temperature measurement point and power generation unit 18 for which the average temperature was calculated in this step. The temperature and electromotive force calculated in this step correspond to the second temperature (see reference numeral T0 in Figure 8(a)) and second electromotive force when there is no influence from the heat generated by the heat generation unit 14 (unmodulated state).

[0093] S60 (Difference Calculation): The calculation processing unit 48 calculates the difference between the temperature measured in S30 (first temperature) and the average temperature calculated in S50 (second temperature) for each of the two heat conduction paths 54. This extracts temperature change data (see symbol ΔT in Figure 8(a)) that has changed due to the influence (modulation) of temperature fluctuations caused by the Peltier element as the heat-generating element 14. Similarly, the calculation processing unit 48 calculates the difference between the electromotive force measured in S30 (first electromotive force) and the average electromotive force calculated in S50 (second electromotive force) for each of the two heat conduction paths 54. This extracts electromotive force change data that has changed due to the influence (modulation) of temperature fluctuations caused by the Peltier element as the heat-generating element 14.

[0094] S70 (Frequency component extraction): The calculation processing unit 48 extracts data of the frequency component of the AC power supplied to the Peltier element as the heat source 14 from the temperature change data and electromotive force change data calculated in S60 for each of the two heat conduction paths 54. This eliminates noise such as fluctuating components in the heat flow from the heat source 50. Examples of extraction methods here include using a low-pass filter to extract only the vicinity of the modulation frequency, using a band-pass filter centered on the modulation frequency, performing synchronous detection (baseband detection), and performing two-stage shift detection using multiple stages of baseband detection or PSN modulators, but a detailed explanation is omitted here.

[0095] S80 (Thermal Conductance Calculation): The calculation processing unit 48 calculates the thermal conductance of the heat source 50 to be measured at the heat receiving surface where the two heat conduction paths 54 shown in Figure 4 are connected. Here, Figure 8(a) schematically shows the relationship between heat quantity (unit: J) and temperature (unit: K), where the mass of the heat source 50 is denoted by m, the specific heat of the heat source 50 is denoted by c, the temperature in the modulated state (first temperature) is denoted by TW, the temperature in the unmodulated state (second temperature) is denoted by T0, the original heat quantity of the heat source 50 is denoted by Q0, and the heat quantity including the heat generated by the heating element 14 is denoted by QW. That is, in a range of small temperature changes without phase change, the heat quantity is proportional to the temperature with mass m and specific heat c as constants, resulting in the relationship shown in Figure 8(a), which can be expressed by the following equation. Q0 (J) = m・c・T0 (K) QW (J) = m・c・TW (K) Figure 8(a) shows that the heating energy supplied to the Peltier element 14 as a heat source during modulation is denoted by W (unit: J), and the difference between the temperature TW in the modulated state and the temperature T0 in the unmodulated state is denoted by ΔT. The relationship shown in the following equation is also shown, and that the temperature increased by ΔT when the heating energy W is added. QW (J) = Q0 (J) + W (J)

[0096] From the above relationship, the following equation holds: m・c = Q0 (J) / T0 (K) = QW (J) / TW (K) Furthermore, the following equation also holds for the temperature change ΔT caused by the response to the heating energy W: m・c = W (J) / ΔT (K) From these equations, the following relationship holds: Q0 (J) / T0 (K) = W (J) / ΔT (K) Q0 (J) = T0 (K) / ΔT (K)・W (J) However, since this equation does not include the thermal resistance ratios in the heat conduction path 54 shown in Figure 2, it is necessary to take the modulation efficiency into account. Furthermore, the heating energy W given to the Peltier element as the heat source 14 during modulation is actually the modulation power (AC power), so its sign is set to P (unit is W), and considering the conversion between heating energy W (J) and modulation power P (W), the modulation efficiency is expressed by the sign η, resulting in the following equation. Q0 (J) = T0 (K) / ΔT (K) * P (W) * η (%) This equation shows that the amount of heat possessed by the heat source 50 can be estimated using only temperature information that changes with modulation. If the modulated power P and modulation efficiency η are values ​​specific to the heat flux measurement system 10A, then only the thermal resistance of the heat source 50 is unknown, and therefore the thermal conductance of the heat source 50 can be estimated based on this equation.

[0097] Here, thermal resistance is the value obtained by dividing the temperature difference between two points by the heat flow rate (amount of heat per unit time) between the two points, and is shown as the slope of the graph represented by "m・c" in Figure 8(a) (see the sign θ in Figure 8(b)). Therefore, if we denote the thermal resistance by sign Rth, it can be calculated by the following formula: Rth (°C / W) = ΔT (K) / W (J) Since this thermal resistance Rth includes all the thermal resistance in the heat conduction path 54 shown on the right side of Figure 2, if we denote the unknown thermal resistance of the heat source 50 by sign Rrs and the thermal resistance present in the measurement system by sign Rse, the thermal resistance Rrs of the heat source 50 can be found as follows: Rrs (°C / W) = Rth (°C / W) - Rse (°C / W)

[0098] Furthermore, as a general-purpose unit, the thermal conductance of the heat conduction path 54 relative to the heat source 50, excluding the heat-receiving area, is expressed as the reciprocal of the thermal resistance. That is, "tanθ" in Figure 8(b) corresponds to the thermal conductance at the heat-receiving surface where each heat conduction path 54 is in contact with the heat source 50. The calculation processing unit 48 calculates the thermal conductance for each heat conduction path 54 of the heat source 50 in this manner. At this time, it is important to handle the heat quantity value including the modulation efficiency η, and it should be noted that the modulation power P (W) shown here is a value specific to the measurement system. Since the heat quantity is defined as the amount of heat per unit time, if the modulation power P can be adjusted and converted to 1 (J), the value of ΔT can be used directly. Therefore, by properly adjusting the ratio with the modulation power P, the calculation formula can be further simplified, and the load on the microcomputer and other components constituting the calculation processing unit 48 can be further reduced.

[0099] S90 (Thermal Resistance Calculation): The calculation processing unit 48 calculates the thermal resistance inside the heat source 50 to be measured from each of the two heat conduction paths 54 shown in Figure 4. As mentioned in S80 above, the thermal resistance Rth (°C / W), which includes all the thermal resistances in the heat conduction path 54 shown on the right side of Figure 2, is obtained as a combined resistance value corresponding to the following formula: Rth (°C / W) = (R heat source + R bonding material + R device) × (R device + R bonding material + R cooling source) ÷ ((R heat source + R bonding material + R device) + (R device + R bonding material + R cooling source))

[0100] This is the thermal resistance obtained from the temperature measurement point, and Kirchhoff's first and second laws (Ohm's law), which are used in electrical circuits, can be applied to the thermal resistance. This Rth is the value obtained by connecting the thermal resistances on the heat source side in series, i.e., the sum of the R heat source + the R bonding material on the heat source side + the R device on the heat source side and the sum of the R cooling source + the R bonding material on the cooling source side + the R device on the cooling source side, in parallel. For this reason, Rth can be calculated in the same way as the parallel resistance calculation formula for resistors R1 and R2, for example, R = (R1 × R2) / (R1 + R2). However, the thermal resistance value R device of the modulation device (thermal conduction modulation unit 12) is added to both the heat source side and the cooling source side, and its ratio takes a device-specific value, but here it is shown as a common value. Of the thermal resistances that constitute the thermal resistance Rth as described above, all except the R heat source can be determined by knowing the thermal conductivity of the materials that constitute each of them. Therefore, the calculation processing unit 48 uses these to calculate the thermal resistance (R heat source) inside the heat source 50 for each heat conduction path 54.

[0101] In this case, if the thermal conductivity and shape dimensions of the heat exchanger connected to the heat source 50 and the heat-conducting member that conducts heat from it are measured in advance, and the heat flow is divided to form a heat flow circuit as shown in Figure 2, the only unknown thermal resistance will be the thermal resistance inside the heat source 50. In other words, the thermal resistance value inside the heat source 50 can be calculated without having to determine the physical properties such as mass, specific heat, density, and pressure of the material that acts as a medium for thermal energy in the aforementioned device, such as the industrial plant equipment given as an example of the heat source 50. Furthermore, the R cooling source, which is the thermal resistance value of the cooling source 36, can be treated as close to zero as possible when a function that keeps the cooling side temperature constant, such as a circulator, is used, thus simplifying the calculation formula. Moreover, if the shape of the heat-conducting member connected to the heat exchanger on the heat source 50 side and the heat-conducting member connected to the cooling source 36 are made the same, and the heat conduction path 54 is configured so that their respective thermal resistance values ​​(R bonding material) are the same, the calculation is simplified even further.

[0102] Furthermore, when determining the thermal resistance of known values, it is necessary to consider the characteristics of the heat exchanger and the heat conduction modulation unit 12, which have a temperature function, and to estimate the temperature of the V heat source based on the temperature information measured at the temperature measurement points. In other words, since the temperature of the heat outlet to which the heat exchanger that serves as the V heat source is attached is not generally measured, the thermal resistance of the known material having the above temperature characteristics must be estimated from the temperature information at the temperature measurement points. In this estimation process, an electrical circuit as an equivalent model evaluation circuit shown on the right side of Figure 2 is used to implement, for example, the temperature information observed at the temperature measurement points set on the heat conduction medium 16 of the heat conduction modulation unit 12 into the electrical circuit simulator. Then, a simulation is performed to simulate the transient phenomenon in which the V heat source changes from 0 volts to a predetermined voltage, and the changes at the observed temperature measurement points and the temperature functions of the heat exchanger and the heat conduction modulation unit 12, which have a temperature coefficient, are analyzed using an arbitrary optimization method. Next, a method is employed to reconcile the temperature fluctuations observed at the temperature measurement points with the results of a simulation performed using a circuit simulator with the V heat source as the circuit power supply voltage, thereby adopting a thermal resistance value table that is subject to an appropriate temperature function. As a result, even if the temperature of the heat outlet of the heat exchanger is not measured, the thermal resistance inside the heat source 50 can be calculated using the temperature change at the temperature measurement points, regardless of the temperature of the heat source 50. The calculation method using an electrical circuit will be explained in detail in the embodiment described later with reference to Figures 18 to 22.

[0103] Furthermore, in this embodiment, as shown in Figure 4, two heat conduction paths 54 are connected to the heat source 50, and this is used to refine the thermal conductance and thermal resistance of the heat source 50. Specifically, the configuration in which two heat conduction paths 54 are connected to the heat source 50 can be likened to an evaluation circuit as shown in Figure 9, where two evaluation circuits shown on the right side of Figure 2 are connected in parallel. In Figure 9, for further simplification, the resistance on the heat source 50 side and the resistance on the cooling source 36 side of the heat conduction path 54 on the right side of Figure 4 are shown as R1, and the resistance on the cooling source 36 side is shown as R3, while the resistance on the heat source 50 side and the resistance on the cooling source 36 side of the heat conduction path 54 on the left side of Figure 4 are shown as R2, and the resistance inside the heat source 50 is Rx. The evaluation circuit shown in Figure 9 is equivalent to a Wheatstone bridge circuit in electrical circuits. Therefore, by taking into account the details mentioned in S80 and S90 above, and considering that the modulations generated in the two heat conduction paths 54 influence each other, the values ​​of R1 to R4 in the Wheatstone bridge circuit are set to calculate the internal resistance Rx of the heat source 50. Then, similar to the internal thermal resistance of the heat source 50, the internal thermal conductance of the heat source 50 is determined. These calculations are performed by the calculation processing unit 48.

[0104] S100 (Heat Flux Calculation): The calculation processing unit 48 calculates the heat flux at the heat receiving surface to which each of the two heat conduction paths 54 of the heat source 50 to be measured is connected, and the heat flux inside the heat source 50. First, for each of the two heat conduction paths 54, the heat flux at the heat receiving surface of the heat source 50 is calculated using the results obtained by extracting the frequency component data of the modulation frequency by the heating element 14 from the electromotive force change data calculated in S70 above. That is, since the calculated electromotive force change data reflects the amount of heat passing through the heat conduction modulation unit 12, the heat flux at the heat receiving surface to which each heat conduction path 54 is connected is calculated from such electromotive force change data.

[0105] Specifically, the energy passing through a unit area is W (W / cm²). ２)If the electromotive force measured by the power generator 18 is ΔV, the correction constant is α, and the correction constant temperature coefficient is k, then it can be expressed as follows: W = ΔV × α(k) That is, in order to convert from electromotive force to heat flux through, a constant with a temperature coefficient must be used, and it has been found that this constant is nonlinear with respect to temperature changes and its characteristics can generally be expressed by a fifth-order equation. For this reason, the temperature characteristics are replaced with an approximate formula in advance, or a wide range of temperature tables are created in advance so that the heat flux through can be determined from the electromotive force. In this way, the heat flux passing through the heat receiving surface of the heat source 50 to which the two heat conduction paths 54 are connected is calculated from the electromotive force change data calculated in S70 above. The conversion from electromotive force to heat flux through will be explained in detail in the embodiment described later with reference to Figures 11 to 17, although the calculation conditions and other aspects differ from those of this embodiment.

[0106] Furthermore, as mentioned in S90 above, the configuration of this embodiment shown in Figure 4 can be likened to an evaluation circuit shown in Figure 9, which is equivalent to a Wheatstone bridge circuit. Therefore, the current value flowing through the resistor Rx inside the heat source 50 in Figure 9 is equivalent to the heat flow flowing inside the heat source 50. Also, as mentioned in S20 above, in this embodiment, the AC power P supplied to the heating element 14 of one heat conduction path 54 in Figure 4 and the AC power P supplied to the heating element 14 of the other heat conduction path 54 have a phase difference of 180°. As a result, the timing of the increase and decrease in the heat flow rate of the modulated heat flow wave supplied by the two heat conduction modulation units 12 is reversed, and this effect appears in the connected heat source 50. Therefore, the heat flow value (heat flux) along the heat flow path within the heat source 50 is calculated based on the circuit in Figure 9, which applies the resistance values ​​set and calculated in S90 above, the heat flux passing through the heat receiving surface of the heat source 50 to which the two heat conduction paths 54 are connected, and the influence of modulated heat flow waves with a phase difference of 180°.

[0107] S110 (Heat Flow Direction Calculation): The calculation processing unit 48 calculates the direction of the heat flow medium flowing within the heat source 50. In Figure 4, the direction of flow of the heat flow medium within the heat source 50 is indicated by an arrow, but this direction is actually unknown. In this embodiment, as shown in Figure 4, two heat conduction paths 54 are connected to the heat source 50, and modulated heat flow waves from the two heat conduction modulation units 12 influence each other as they pass through the heat source 50. It has been found that the response of the modulation frequency measured by the heat conduction modulation unit 12 changes (the frequency changes) depending on the relative position between the two heat conduction modulation units 12 and the heat flow within the heat source 50. Here, Figure 10 shows the spectral distribution of the modulated heat flow wave obtained from the electromotive force measured at the power generator 18 of the heat conduction modulation unit 12. Figure 10(a) corresponds to the heat conduction path 54 on the left side of Figure 4, which is connected to the upstream side of the heat source 50, and Figure 10(b) corresponds to the heat conduction path 54 on the right side of Figure 4, which is connected to the downstream side of the heat source 50.

[0108] Referring to Figures 10(a) and (b), it can be seen that both figures show a peak-like increase at two frequency positions, which correspond to the modulation frequencies by the two heat conduction modulation units 12. In both figures, the frequency indicated by the peak on the left corresponds to the modulation frequency by the heat conduction modulation unit 12 of the heat conduction path 54 connected downstream of the heat source 50, as shown on the right side in Figure 4. Also, the frequency indicated by the peak on the right side in Figures 10(a) and (b) corresponds to the modulation frequency by the heat conduction modulation unit 12 of the heat conduction path 54 connected upstream of the heat source 50, as shown on the left side in Figure 4. Comparing Figures 10(a) and (b), it can be seen that the downstream modulation frequency, indicated by the peak on the left, is lower in Figure 10(a) than in Figure 10(b). Conversely, the upstream modulation frequency, indicated by the peak on the right, is higher in Figure 10(b) than in Figure 10(a). This indicates that if the path through which the modulated heat wave propagates is reversed from the heat flow within the heat source 50, the frequency of the modulated heat wave decreases, and if the path through which the modulated heat wave propagates is forward from the heat flow within the heat source 50, the frequency of the modulated heat wave increases. Because such phenomena occur, the direction of the heat flow medium flowing within the heat source 50 can be determined from the measurement results shown in Figure 10.

[0109] Now, according to the embodiment of the present invention having the above configuration, the following effects can be obtained. That is, the heat flux measurement method according to the embodiment of the present invention uses a system 10A, for example as shown in Figures 1 to 6, to measure the thermal conductance and heat flux at an arbitrary heat receiving surface of a heat source 50 that has unused thermal energy being dissipated. Specifically, as shown in Figure 2, a cooling source 36 controlled to a constant temperature is provided at one end of a heat conduction path 54, and the other end of the heat conduction path 54 is connected to the aforementioned heat receiving surface of the heat source 50, thereby diverting the heat to flow from the heat source 50 toward the cooling source 36 (see S10 in Figure 7). The heat conduction path 54 used at this time shall be made of a material whose properties such as thermal conductivity are known in advance. In addition, the heat generating element 14 and the power generating element 18 (see Figures 1 and 3(b)) are installed in the heat conduction path 54, that is, between one end of the heat conduction path 54 where the cooling source 36 is installed and the other end of the heat conduction path 54 connected to the heat source 50. The heat-generating element 14 to be installed is one that can be controlled so that the amount of heat generated fluctuates when a fluctuating heating energy W (see Figure 8(a)) is applied. The power-generating element 18 to be installed is one that generates an electromotive force by the Seebeck effect, which generates voltage from a temperature difference.

[0110] Furthermore, the temperature in the heat conduction path 54 with the above configuration and the electromotive force at the power generator 18 are measured to obtain a first temperature TW and first electromotive force when affected by the heat generated by the heat generating element 14, and a second temperature T0 and second electromotive force when not affected by the heat generated by the heat generating element 14 (see S30, S50 in Figure 7 and Figure 8(a)). Subsequently, the difference ΔT between the obtained first temperature TW and second temperature T0 is calculated to extract the temperature change data ΔT that has changed due to the fluctuating heat generated by the heat generating element 14 (see S60 in Figure 7 and Figure 8(a)). Then, the thermal conductance of the heat source 50 is calculated based on the extracted temperature change data ΔT and the heating energy W that was supplied to the heat generating element 14 when the first temperature TW was measured.

[0111] In other words, as shown in Figure 8(a), the "product of mass and specific heat" m·c can be expressed as the value obtained by dividing the "amount of heat in a state without heating energy" Q0 by the "temperature in a state without heating energy (second temperature)" T0, or by dividing the "amount of heat in a state with heating energy" QW by the "temperature in a state with heating energy (first temperature)" TW. Furthermore, if radiation and heat conduction that causes errors are small enough to be negligible, the "product of mass and specific heat" m·c can also be expressed as the value obtained by dividing the heating energy W by the temperature change data ΔT.

[0112] Furthermore, since thermal resistance is the value obtained by dividing the temperature difference between two points by the heat flow rate (amount of heat flowing per unit time) between the two points, in the relationship described above, it can be expressed as the value obtained by dividing the temperature change data ΔT by the heating energy W. Considering that this thermal resistance includes all thermal resistance from the heat source 50 to the heat conduction path 54, that thermal conductance can be expressed as the reciprocal of thermal resistance, and the heat receiving area of ​​the heat conduction path 54, it can be seen that the thermal conductance per unit area can be calculated from the temperature change data ΔT and the heating energy W (see S80 in Figure 7). As a result, without needing to know the specific heat c or mass m of the heat source 50, the thermal conductance at the heat receiving surface of the heat source 50 can be calculated based on the temperature change data ΔT that has changed due to the influence of the heating element 14 and the heating energy W that was supplied to the heating element 14 at that time.

[0113] On the other hand, with respect to the heat flux, the difference between the first and second electromotive force obtained as described above is calculated to extract the electromotive force change data that has changed due to the fluctuating heat generation of the heat-generating element 14 (see S60 in Figure 7). Then, the heat flux of the heat source 50 is calculated based on the extracted electromotive force change data and the heating energy W that was supplied to the heat-generating element 14 when the first electromotive force was measured. In other words, since the electromotive force generated by the Seebeck effect in the power generator 18 corresponds to the amount of heat passing through the power generator 18, by configuring the power generator 18 to be highly sensitive and generating a high electromotive force, an electromotive force that reflects the passing heat flux with high sensitivity can be obtained. For this reason, similar to thermal conductance, it is not necessary to know the specific heat c or mass m of the heat source 50, and the heat flux at the heat receiving surface of the heat source 50 can be calculated based on the electromotive force change data that has changed due to the influence of the heat-generating element 14 and the heating energy W supplied to the heat-generating element 14 at that time (see S100 in Figure 7).

[0114] In this way, the thermal conductance and heat flux at the heat receiving surface of the heat source 50 can be determined, thereby contributing to the effective utilization of the unused thermal energy possessed by the heat source 50. Moreover, even if information about the inside of the heat source 50, such as the specific heat c, pressure, and physical properties of the heat source 50, is unknown, or if the pressure and density of the heat source 50 fluctuate over time, the thermal conductance and heat flux can be determined from a heat receiving surface that can be connected even in a small area, as long as the heat conduction path 54 described above can be connected. Furthermore, as shown in Figures 1 and 3(b), since the heat generating element 14 and the power generating element 18 are separate, modulation and Seebeck voltage measurement can be performed independently and simultaneously, thereby achieving high sensitivity.

[0115] Furthermore, the heat flux measurement method according to an embodiment of the present invention utilizes a Peltier element as the heating element 14 and power generator 18 installed in the heat conduction path 54. In addition, by applying an AC power (modulated power) P of a predetermined frequency as the heating energy W to the Peltier element as the heating element 14, the amount of heat generated from the Peltier element as the heating element 14 is varied AC-wise. The predetermined frequency of the AC power P at this time is set to a frequency different from the fluctuation frequency of the heat flow from the heat source 50 to the heat conduction path 54. Then, after calculating the difference ΔT between the first temperature TW when affected by the heat generated by the heating element 14 and the second temperature T0 when not affected by the heat generated by the heating element 14, the frequency component data of the predetermined frequency described above is extracted from the calculation result (see S70 in Figure 7). Based on the temperature difference data extracted in this way and the AC power P applied to the Peltier element as the heating element 14, the thermal conductance of the heat source 50 at the heat receiving surface is calculated.

[0116] Similarly, after calculating the difference between the first electromotive force when affected by the heat generated by the heating element 14 and the second electromotive force when not affected by the heat generated by the heating element 14, the frequency component data of the predetermined frequency described above is extracted from the calculation result (see S70 in Figure 7). Based on the difference data of the electromotive force extracted in this way and the AC power P supplied to the Peltier element as the heating element 14, the heat flux at the heat receiving surface is calculated. That is, by supplying the Peltier element as the heating element 14 with modulated power P of a frequency different from the fluctuation frequency of the heat flow from the heat source 50, and extracting and using the frequency component data of that modulated frequency, it is possible to calculate the thermal conductance and heat flux while eliminating the fluctuation components of the heat flow. This makes it possible to calculate the thermal conductance and heat flux with greater accuracy.

[0117] In addition, as shown in Figure 4, the heat flux measurement method according to an embodiment of the present invention involves connecting two heat conduction paths 54, each equipped with a heat-generating element 14 and a power-generating element 18 as described above, to two heat-receiving surfaces set at different locations on the heat source 50. Furthermore, an AC power P of a predetermined frequency different from the fluctuation frequency of the heat flow from the heat source 50 as described above is applied to the heat-generating element 14 of one heat conduction path 54, while an AC power P of the other heat conduction path 54 is applied to the heat-generating element 14 of the other heat conduction path 54 at the same predetermined frequency as the AC power P applied to the heat-generating element 14 of the first heat conduction path 54, but with a phase difference of 180°. Then, the thermal conductance and heat flux at the heat-receiving surface to which one heat conduction path 54 is connected, and the thermal conductance and heat flux at the heat-receiving surface to which the other heat conduction path 54 is connected are calculated.

[0118] When the calculated thermal conductance and heat flux are reflected in the thermal circuit model of the heat source 50 and the two heat conduction paths 54 connected thereto, this thermal circuit model becomes equivalent to a Wheatstone bridge circuit in an electrical circuit, such as the one shown in Figure 9. Furthermore, since the AC power P supplied to the heat source 14 of one heat conduction path 54 and the AC power P supplied to the heat source 14 of the other heat conduction path 54 have a phase difference of 180°, the timing of the increase and decrease in heat flow is reversed between the two heat conduction paths 54. As a result, a heat flow wave that fluctuates up and down like a seesaw is generated within the heat source 50 where both heat conduction paths 54 are connected. Therefore, taking this into consideration, the thermal conductance and heat flux within the heat source 50 can be calculated from the electrical circuit model described above. This makes it possible to determine the thermal conductance and heat flux within the heat source 50 without needing to know the specific heat c or mass m of the heat source 50.

[0119] On the other hand, the heat flux measurement system 10A according to an embodiment of the present invention measures the thermal conductance and heat flux per unit area on the heat receiving surface, which can be collected from a heat source 50 having unused thermal energy. As shown in Figure 1, it includes a heat conduction modulation unit 12, a cooling source 36, a heat-generating element control unit 40, a temperature measurement unit 44, an electromotive force measurement unit 46, and a calculation processing unit 48. As also shown in Figure 3, the heat conduction modulation unit 12 has a configuration in which a heat-generating element 14 and a power-generating element 18 are sandwiched between heat-conducting media 16. In this embodiment, two heat-generating elements 14 and one power-generating element 18 are alternately sandwiched between four heat-conducting media 16.

[0120] The heat-generating element 14 is controllable so that its heat output fluctuates, the power-generating element 18 generates an electromotive force by the Seebeck effect, and the heat-conducting medium 16 is made of a material with a known thermal conductivity. The heat conduction modulation unit 12, with this configuration, is installed so that heat is conducted from the heat source 50 to be measured to one of the two heat-conducting mediums 16A at both ends. The cooling source 36 has a lower temperature than the heat source 50 to be measured and is installed so that heat is conducted from the other heat-conducting medium 16D at both ends. That is, as shown in Figure 2, the heat conduction modulation unit 12 and the cooling source 36 are installed as part of a heat conduction path 54 that diverts heat from the heat source 50 so that heat flows from the heat source 50 to the cooling source 36.

[0121] The heating element control unit 40 controls the heating element 14 of the heat conduction modulation unit 12, and controls the heating element 14 so that the amount of heat generated from the heating element 14 fluctuates by supplying the heating element 14 with fluctuating heating energy W. The temperature measurement unit 44 measures the temperature of the temperature measurement points, which are set at predetermined positions (within the measurement holes 20) of the heat conduction medium 16 of the heat conduction modulation unit 12, as shown in Figure 3. The electromotive force measurement unit 46 measures the electromotive force generated in the power generator 18 in response to the temperature difference applied to the power generator 18 via the heat conduction medium 16 that sandwiches the power generator 18.

[0122] The calculation processing unit 48 performs various calculation processes in the system 10A, and as part of these, it performs the following calculations. Specifically, the calculation processing unit 48 obtains a first temperature TW when affected by the heat generated by the heat source 14 and a second temperature T0 when not affected by the heat generated by the heat source 14 from the temperature measurement results of the temperature measurement point by the temperature measurement unit 44, as described in the heat flux measurement method. Then, by calculating the difference ΔT between them, it extracts temperature change data ΔT that has changed due to the fluctuating heat generated by the heat source 14. Furthermore, the calculation processing unit 48 calculates the thermal conductance of the heat source 50 to be measured, as described in the heat flux measurement method, based on the extracted temperature change data ΔT and the heating energy W supplied to the heat source 14 by the heat source control unit 40 when the first temperature TW was measured by the temperature measurement unit 44. This makes it possible to calculate the thermal conductance on the heat receiving surface from the heat source 50 without needing to know the specific heat c or mass m of the heat source 50.

[0123] In addition, the calculation processing unit 48 obtains, from the measurement results of the power generator 18 by the electromotive force measurement unit 46, a first electromotive force when affected by the heat generated

[0124] This makes it possible to calculate the heat flux at the heat receiving surface from the heat source 50 without needing to know the specific heat c or mass m of the heat source 50. Moreover, because the structure involves diverting heat from the heat source 50 to be measured via a heat conduction path 54 including the heat conduction modulation unit 12 and the cooling source 36, and measuring the temperature and electromotive force in the heat conduction modulation unit 12 within the heat conduction path 54, it can handle the measurement of heat sources 50 in various environments, including heat sources 50 through which corrosive gases or gas / liquid mixtures with fluid density fluctuations flow. Furthermore, it eliminates the need to consider durability such as corrosion, making it possible to significantly improve durability and reliability.

[0125] Furthermore, in the heat flux measurement system 10A according to an embodiment of the present invention, the heat-generating element 14 and power-generating element 18 of the heat conduction modulation unit 12 are Peltier elements, and the heating energy W supplied from the heat-generating element control unit 40 to the Peltier element as the heat-generating element 14 is AC power P of a predetermined frequency, so that the amount of heat generated from the Peltier element as the heat-generating element 14 fluctuates AC. The predetermined frequency of the AC power P at this time is set to a frequency different from the fluctuating frequency of the heat flow that flows from the heat source 50 to the heat conduction modulation unit 12, etc. The calculation processing unit 48 calculates the difference ΔT between the first temperature TW when affected by the heat generated by the heat-generating element 14 and the second temperature T0 when not affected by the heat generated by the heat-generating element 14, and then extracts the frequency component data of the predetermined frequency mentioned above from the calculation result. Furthermore, the calculation processing unit 48 calculates the thermal conductance on the heat-receiving surface based on the temperature difference data ΔT extracted in this way and the AC power P supplied from the heat-generating element control unit 40 to the Peltier element as the heat-generating element 14.

[0126] Similarly, the calculation processing unit 48 calculates the difference between the first electromotive force when affected by the heat generated by the heating element 14 and the second electromotive force when not affected by the heat generated by the heating element 14, and then extracts the frequency component data of the predetermined frequency described above from the calculation result. Furthermore, the calculation processing unit 48 calculates the heat flux at the heat receiving surface based on the difference data of the electromotive force extracted in this way and the AC power P supplied from the heating element control unit 40 to the Peltier element as the heating element 14. That is, as mentioned in the heat flux measurement method, by supplying the Peltier element as the heating element 14 with modulated power P of a frequency different from the fluctuation frequency of the heat flow from the heat source 50, and extracting and using the frequency component data of that modulated frequency, it is possible to calculate the thermal conductance and heat flux while excluding the fluctuation components of the heat flow. This makes it possible to calculate the thermal conductance and heat flux with greater accuracy.

[0127] In addition, the heat flux measurement system 10A according to an embodiment of the present invention includes two heat conduction modulation units 12 as described above, and these two heat conduction modulation units 12 are installed so that heat is conducted separately from two heat receiving surfaces set at different positions on the heat source 50, as shown in Figure 4. Furthermore, the heat heating element control unit 40 is configured to control the heat heating elements 14 of both heat conduction modulation units 12. Specifically, the heat heating element control unit 40 provides the heat heating element 14 of one heat conduction modulation unit 12 with an AC power P of a predetermined frequency different from the fluctuation frequency of the heat flow from the heat source 50 as described above, and provides the heat heating element 14 of the other heat conduction modulation unit 12 with an AC power P of the same predetermined frequency as the AC power P provided to the heat heating element 14 of the first heat conduction modulation unit 12, but with a phase difference of 180°.

[0128] The calculation processing unit 48 then calculates the thermal conductance and heat flux at the heat receiving surface to which one heat conduction modulation unit 12 is connected, and the thermal conductance and heat flux at the heat receiving surface to which the other heat conduction modulation unit 12 is connected. As mentioned in the heat flux measurement method, when the thermal conductance and heat flux calculated in this way are reflected in the thermal circuit model of the heat source 50 and the two heat conduction modulation units 12 connected thereto, this thermal circuit model becomes equivalent to a Wheatstone bridge circuit of an electrical circuit as shown in Figure 9. Therefore, the calculation processing unit 48 can calculate the thermal conductance and heat flux within the heat source 50 from such an electrical circuit model. This makes it possible to determine the thermal conductance and heat flux within the heat source 50 without having to know the specific heat c or mass m of the heat source 50.

[0129] Furthermore, in the heat flux measurement system 10A according to an embodiment of the present invention, the heat conduction modulation unit 12 includes four heat conduction media 16, two heat-generating elements 14, and one power-generating element 18, as shown in Figure 3(b). In this embodiment, the two heat-generating elements 14 and the one power-generating element 18 are arranged in close contact with each heat conduction media in three gaps between the four heat conduction media 16 arranged in series in the order of heat-generating element 14, power-generating element 18, heat-generating element 14. Therefore, the heat-generating element control unit 40 controls the two heat-generating elements 14 of the heat conduction modulation unit 12, and controls the two heat-generating elements 14 in the same way. That is, when controlling the heat-generating elements 14 by applying AC power P, the frequency, phase, and amplitude are controlled to be the same. As a result, fluctuations in amplitude, such as decreasing or increasing, can be applied to the temperature measured in the heat conduction media 16 and the electromotive force measured in the power-generating element 18, depending on the positional relationship between the two heat-generating elements 14 and the one power-generating element 18. By utilizing these fluctuations for measurement, the sensitivity of the heat conduction modulation unit 12 can be increased, making it possible to calculate the thermal conductance and heat flux of the heat source 50 with greater accuracy.

[0130] Next, with reference to Figures 11 to 17, a heat flux measurement system 10 (10B) and a heat flux measurement method according to another embodiment of the present invention, which differs from the embodiments described above, will be explained. In Figures 11 to 17, the same reference numerals are used for parts that are the same as or correspond to the embodiments shown in Figures 1 to 10. In this embodiment, the explanation will focus on the differences from the embodiments shown in Figures 1 to 10, and the explanation of the configuration and effects of parts that are the same as those in the embodiments shown in Figures 1 to 10 will be simplified or omitted.

[0131] First, referring to Figure 11, the heat flux measurement system 10B according to an embodiment of the present invention includes a heat conduction modulation unit 12, a cooling source 36, a temperature measurement unit 44, an electromotive force measurement unit 46, and a calculation processing unit 48. The heat conduction modulation unit 12 includes a power generator 18 and two heat conduction media 16, and has a configuration in which the power generator 18 is sandwiched between the two heat conduction media 16, for example, the two heat conduction media 16 are connected by bolts or the like, and the power generator 18 is placed between them. The power generator 18 generates an electromotive force by the Seebeck effect, and in this embodiment is formed by a Peltier element, and a measurement line 34 (see Figures 3(b) and 5(b)) for acquiring the electromotive force is connected to the Peltier element. In order to increase the sensitivity of the electromotive force generated from the heat flow, the power generator 18 may have a module structure in which, for example, several dozen Peltier elements are connected in series.

[0132] The two heat conduction media 16 are made of materials with known thermal conductivity, such as aluminum or copper, although this is not limited to these materials. The heat conduction modulation section 12 is visually equivalent to the heat conduction modulation section 12 shown in Figure 5(b) and Figure 6(a). Therefore, each of the heat conduction media 16 has a measurement hole 20, and temperature measurement points are set inside these measurement holes 20. Note that the heat conduction modulation section 12 in this embodiment differs from the heat conduction modulation section 12 shown in Figures 1 to 6 in that it does not have a heating element 14, and therefore does not substantially perform modulation control, but for the sake of explanation, it is referred to as a "heat conduction modulation section" here.

[0133] As shown in Figure 12, the heat conduction modulation unit 12 configured as described above is used as part of a heat conduction path 54 installed so that heat is diverted from the heat source 50 to be measured. In the embodiment shown in Figure 12, for example, the heat conduction modulation unit 12 is connected to the heat outlet (heat receiving surface) from the heat source 50 via a heat transfer path including a heat exchanger and a thermal bonding member. At this time, the heat conduction modulation unit 12 is installed so that heat from the heat source 50 is conducted to the heat conduction medium 16 on one side (upper side in Figure 11, left side in Figure 12). A cooling source 36, also shown in Figure 11, is connected to the heat conduction medium 16 on the other side of the heat conduction modulation unit 12, which is located on the right side of Figure 12, via a heat transfer path including a thermal bonding member. The cooling source 36 has a constant temperature lower than the heat source 50 to be measured, and this generates a heat flow in which the heat diverted from the heat source 50 flows towards the cooling source 36.

[0134] Returning to Figure 11, the temperature measurement unit 44 measures the temperature of a temperature measurement point set on the heat conduction medium 16 of the heat conduction modulation unit 12. The temperature measurement unit 44 in this embodiment is not limited to this, but measures the temperature of one temperature measurement point on the heat conduction medium 16 installed on the cooling source 36 side (lower side in Figure 11, right side in Figure 12) of the two heat conduction mediums 16. The electromotive force measurement unit 46 measures the electromotive force generated in the power generator 18 by the Seebeck effect in response to the heat flowing through the heat conduction modulation unit 12, and performs the measurement by acquiring the electromotive force from the power generator 18 via the measurement line 34. The calculation processing unit 48 performs various calculation processing in the heat flux measurement system 10B. Details of some of the calculation processing performed by such calculation processing unit 48 will be described later. The heat conduction modulation unit 12 may also be formed as a single element comprising a power generator 18 that generates an electromotive force, a heat conduction medium 16 that transfers heat to the power generator 18 and whose temperature is measured, and a temperature measuring unit 44 that measures the temperature of the heat conduction medium 16.

[0135] Furthermore, the heat flux measurement system 10B according to the embodiment of the present invention is not limited to the configuration shown in Figures 11 and 12. Some of the components shown therein may be deleted or replaced, or new components may be added. Moreover, each component in Figure 11 is a functional division of the configuration of the heat flux measurement system 10B and does not represent the individual devices that make up the heat flux measurement system 10B as they are, but rather is composed of various hardware, software, or combinations thereof. For example, the heat conduction path 54 may differ from the configuration in Figure 12 as long as it includes the heat conduction modulation unit 12 and the cooling source 36. Furthermore, the heat conduction path 54 of this embodiment may also be connected to two or more different locations on the heat source 50 to be measured, as shown in the embodiment in Figure 4.

[0136] Next, with reference to Figure 13, a heat flux measurement method according to an embodiment of the present invention, which is performed using the heat flux measurement system 10B described above, will be explained. For the configuration of the heat flux measurement system 10B, please refer to Figures 11 and 12 as appropriate. Note that the flowchart shown in Figure 13 is an example of the procedure flow of the heat flux measurement method, and the procedure of the heat flux measurement method according to an embodiment of the present invention is not limited to this flowchart. For this reason, some of the steps shown in Figure 13 may be changed, deleted, or rearranged, and new steps may be added.

[0137] S200 (Understanding Relationships): In the heat conduction path 54 including the heat conduction modulation section 12 and the cooling source 36, the relationship between the temperature in the heat conduction path 54, the electromotive force at the power generator 18, and the heat flux passing through the power generator 18 is understood when a heat flow is applied toward the cooling source 36. At this time, the temperature dependence (nonlinear characteristics) of the material properties of the thermoelectric conversion material forming the power generator 18 (Peltier element) is taken into consideration when understanding the above relationship. Here, Figure 14 shows that the thermoelectric conversion material of the power generator 18 is "n-type, p-type Bi ２ Te ３ This shows the temperature dependence of material properties when "" and (a) is "n-type, p-type Bi ２ Te ３The temperature characteristics of the Seebeck coefficient S [μV / K] of "", and (b) is "n-type, p-type Bi ２ Te ３ " is the temperature characteristic of the thermal conductivity k [W / mK]. Note that the temperature dependence of the material physical property values shown in FIG. 14 is an example, and even if the thermoelectric conversion material forming the power generation body 18 is a Mg-Ag-Sb system, Mg-Si system, Mg-Ag system, Mn-Si system, Co-Sb system, half-Heusler system, Pb-Te system, Si-Ge system, etc., it has been clarified that its physical property values exhibit temperature dependence.

[0138] In order to clarify the above relationship, for example, a test device having a simulated heat source 50 is used to actually flow a heat current through the heat conduction path 54, and at that time, the heat flux flowing through the power generation body 18, the electromotive voltage generated in the power generation body 18 due to the flow of the heat flux, and the temperature of one location in the heat conduction path 54 as the reference temperature are measured respectively. The reference temperature in this embodiment is the temperature measured at the temperature measurement point set in the heat conduction medium 16 on the cooling source 36 side that the temperature measurement unit 44 is measuring as the measurement target. Then, using the measurement results of the three parameters as described above and the temperature dependence of the material physical property values of the thermoelectric conversion material of the power generation body 18 as shown in FIG. 14, the relationship of the three parameters is grasped. FIG. 15 shows an example of the relationship grasped in this way. That is, FIG. 15(a) shows the relationship between the temperature T ｌｏｗ [°C] of the heat conduction medium 16 on the cooling source 36 side and the electromotive voltage V ＯＣ [V] generated in the power generation body 18, and FIG. 15(b) shows the relationship between the temperature T ｌｏｗ [°C] of the heat conduction medium 16 on the cooling source 36 side and the heat flux q [W / m ２ ] flowing through the power generation body 18.

[0139] Then, based on the relationship shown in Figure 15, the relationship between the temperature of the heat conduction medium 16 on the cooling source 36 side, the electromotive force generated in the power generator 18, and the heat flux flowing through the power generator 18 is understood by formulating or creating a table. When formulating, for example, a three-dimensional curve showing the relationship between the three parameters is created, and an approximate relationship equation is calculated from it. Although the specific details of this relationship equation are not shown here, it has been revealed that it can be expressed as a fifth-order equation exhibiting nonlinear characteristics. When creating a table of the relationship, for example, the information from the three-dimensional curve showing the relationship between the three parameters is expanded into an FPGA or ROM and created as a lookup table. The table in Figure 16 shows the temperature T of the heat conduction medium 16 on the cooling source 36 side. ｌｏｗ [°C] and the electromotive force V generated by the power generator 18. ＯＣ [V] and the heat flux q [W / m] that flowed through the power generator 18. ２ An example of a table showing the relationship between [ ] is presented.

[0140] The relationships between the three parameters identified in this step shall be set in the calculation processing unit 48 in the form of a mathematical formula or table. Naturally, the relationships between these three parameters will change depending on various conditions such as the thermoelectric conversion material forming the power generator 18 and the shape of the power generator 18. Therefore, when determining these relationships, a heat conduction modulation unit 12 with a similar configuration to that used in the heat conduction path 54 connected to the heat source 50 to be measured in S210 (described later) shall be used. Furthermore, when determining the relationships between the three parameters, a delay in heat propagation, considering the non-steady state, may be taken into account to approximate the actual field environment.

[0141] S210 (Heat conduction path connection): For example, as shown in Figure 12, the other end of a heat conduction path 54, which has a cooling source 36 at one end and a heat conduction modulation section 12 in the middle, is connected to the heat receiving surface of the heat source 50 to be measured. This separates the heat from the heat source 50 to be measured, causing that heat to flow through the heat conduction modulation section 12 towards the cooling source 36. At the same time, other components of the heat flux measurement system 10B are installed and connected. For example, the heat acquisition part of the temperature measurement unit 44 is installed at the temperature measurement point set in the heat conduction medium 16 of the heat conduction modulation section 12, or the measurement line 34 extending from the power generator 18 of the heat conduction modulation section 12 is connected to the electromotive force measurement unit 46.

[0142] S220 (Temperature and electromotive force measurement): The temperature measurement unit 44 measures the temperature of the temperature measurement point set on the heat conduction medium 16 of the heat conduction modulation unit 12. Specifically, it measures the temperature of the temperature measurement point set on the heat conduction medium 16 on the cooling source 36 side, one of the two heat conduction mediums 16 used to measure the temperature in the heat conduction path 54 in S200. Then, for subsequent processing, the calculation processing unit 48 or a separately provided A / D converter converts the measured analog temperature data into digital temperature data. In addition, the electromotive force measurement unit 46 measures the electromotive force generated by the power generator 18 of the heat conduction modulation unit 12. Then, for subsequent processing, the calculation processing unit 48 or a separately provided A / D converter converts the measured analog voltage data into digital voltage data.

[0143] S230 (Calculation of heat flux): The calculation processing unit 48 calculates the heat flux that has passed through the power generator 18 of the heat conduction modulation unit 12. Specifically, the temperature of the heat conduction medium 16 on the cooling source 36 side and the electromotive force generated in the power generator 18, which were measured in S220, are applied to the relationship between the temperature of the heat conduction medium 16 on the cooling source 36 side, the electromotive force generated in the power generator 18, and the heat flux that flowed through the power generator 18, which were determined in S200. In other words, since two of the three parameters whose relationship has been determined have been measured, the remaining parameter, the heat flux that flowed through the power generator 18, can be determined by applying these two parameters. At this time, if the relationship was determined by formulating it in S200, the measurement results from S220 are applied to that relationship formula to calculate the heat flux that flowed through the power generator 18. In contrast, if the relationships were understood by creating a table in S200, the measurement results from S220 can be applied to a table, for example, as shown in Figure 16, to calculate the heat flux that flowed through the power generator 18. In this way, software sensing is used to calculate the heat flux that passed through the power generator 18 of the heat conduction modulation unit 12.

[0144] S240 (Calculation of heat flux on the heat receiving surface): The calculation processing unit 48 calculates the heat flux on the heat receiving surface of the heat source 50 to be measured. That is, the heat flux separated from the heat receiving surface of the heat source 50 passes through a part of the heat conduction path 54 before reaching the power generator 18 of the heat conduction modulation unit 12, but the thermal conductivity, shape, size, etc. of the material forming the heat conduction path 54 are known. For this reason, taking into account the radiation and thermal conductivity in the heat conduction path 54 up to the power generator 18, and whether or not it is in a steady state, the heat flux on the heat receiving surface of the heat source 50 is calculated from the heat flux that has passed through the power generator 18 calculated in S230.

[0145] Now, according to the embodiment of the present invention having the above configuration, the following effects can be obtained. That is, the heat flux measurement method according to the embodiment of the present invention uses a heat flux measurement system 10B, for example, as shown in Figures 11 and 12, to measure the heat flux at an arbitrary heat receiving surface of a heat source 50 that has unused thermal energy being dissipated. Specifically, a cooling source 36 controlled to a constant temperature is provided at one end of a heat conduction path 54, and the other end of the heat conduction path 54 is connected to the aforementioned heat receiving surface of the heat source 50, thereby diverting the heat to flow from the heat source 50 toward the cooling source 36 (see S210 in Figure 13). The heat conduction path 54 used at this time shall be made of a material whose properties such as thermal conductivity are known in advance. Furthermore, a power generator 18 is installed in the heat conduction path 54, that is, between one end of the heat conduction path 54 where the cooling source 36 is installed and the other end of the heat conduction path 54 connected to the heat source 50. The power generator 18 to be installed is one that generates an electromotive force by the Seebeck effect, which generates a voltage from a temperature difference.

[0146] Furthermore, by measuring the temperature in the heat conduction path 54 with the above configuration and the electromotive force in the power generator 18, the operating temperature affected by the heat flow from the heat source 50 to the cooling source 36 and the electromotive force generated by the Seebeck effect due to the heat flow from the heat source 50 to the cooling source 36 are determined (see S220 in Figure 13). Then, based on these measurement results and the temperature dependence of the material properties of the thermoelectric conversion material used in the power generator 18, which have been determined in advance, the heat flux passing through the power generator 18 is calculated (see S230 in Figure 13). Here, in the power generator 18 that generates an electromotive force due to the Seebeck effect, the relationship between the heat flux passing through and the electromotive force generated in response to it is not a linear relationship but a functional nonlinear relationship. Since this nonlinear characteristic is due to the temperature dependence of the material properties of the thermoelectric conversion material forming the power generator 18, this characteristic is determined in advance and taken into account, and the heat flux that has passed through the power generator 18 is calculated using the measured temperature which serves as the reference temperature and the electromotive force generated by the heat flux that has passed through.

[0147] In conventional methods of measuring heat flux using thermoelectric conversion module elements, the electromotive force directly obtained from the flowing heat flux is acquired as a signal, and the heat flux is measured by dividing this electromotive force by a sensitivity coefficient (constant). The sensitivity coefficient used in this case is a coefficient that changes depending on the temperature, and when using a heat flux sensor using this method, it is necessary to measure the surface temperature of the heat source 50, such as an industrial furnace, and the temperature around the heat source 50 in advance, and perform calibration according to the temperature to determine the sensitivity coefficient. In such conventional methods, the reason why the sensitivity coefficient needs to be calculated each time within the measurement temperature range of the target heat source is that the sensor principle structure does not take into account the temperature dependence (nonlinear characteristics) of the material properties of the thermoelectric conversion material.

[0148] Therefore, the heat flux measurement method according to the embodiment of the present invention, with the configuration described above, can calculate the heat flux passing through the power generator 18 using only the measured electromotive force output value and operating temperature information, without using a sensitivity coefficient. Then, by taking into account the radiation in the heat conduction path 54 from the heat receiving surface of the heat source 50 to the power generator 18, the thermal conductivity of the heat conduction path 54, etc., the heat flux at the heat receiving surface of the heat source 50 to which the heat conduction path 54 having the power generator 18 is connected can be calculated (see S240 in Figure 13). Moreover, in the field environment where the heat source 50 to be measured is located, there is concern that the temperature measurement results using thermocouples, etc., will contain a lot of noise, but the Seebeck electromotive force measured by the power generator 18 is less affected by noise in the field environment. For example, Figure 17(a) shows an example of temperature measurement results using a thermocouple, and it can be seen that it is buried in noise. In contrast, Figure 17(b) shows an example of the measurement results of the Seebeck electromotive force generated in the power generator 18, and it can be seen that it is not significantly affected by noise. Therefore, by using such a Seebeck electromotive force, it is possible to improve the accuracy of heat flux calculation.

[0149] Furthermore, the heat flux measurement method according to the embodiment of the present invention uses the temperature dependence of the material properties of the thermoelectric conversion material forming the power generator 18 (see Figure 14(a)) and the temperature characteristics of the thermal conductivity of the thermoelectric conversion material (see Figure 14(b)) as the temperature dependence of the material properties of the thermoelectric conversion material used when calculating the heat flux passing through the power generator 18. In other words, these temperature characteristics have nonlinear characteristics that cause the relationship between the heat flux passing through the power generator 18 and the electromotive force generated by it to be nonlinear, and the heat flux is calculated by taking these into account. As a result, regardless of what thermoelectric conversion material the power generator 18 is made of, the heat flux can be calculated without any problems by knowing in advance the temperature characteristics of the Seebeck coefficient and the thermal conductivity of the thermoelectric conversion material.

[0150] Furthermore, the heat flux measurement method according to the embodiment of the present invention pre-establishes the relationship (see Figure 15) between the temperature in the heat conduction path 54 used in calculating the heat flux, the electromotive force at the power generator 18 used in calculating the heat flux, and the heat flux passing through the power generator 18 calculated from these, by formulating it mathematically or creating a table (see Figure 16) (see S200 in Figure 13). At this time, the temperature dependence of the material properties of the thermoelectric conversion material forming the power generator 18 is taken into consideration when determining these relationships. That is, the characteristics over a wide temperature range are measured in advance, and these temperature characteristics are incorporated as material properties to determine the relationship by formulating it mathematically or creating a table. In addition, the temperature in the heat conduction path 54 for which the relationship is determined is the same position in the heat conduction path 54 where temperature measurements are taken when calculating the heat flux, and the measurement positions for these temperatures are positions where the ambient temperature in which the power generator 18 is placed can be detected. Then, when calculating the heat flux passing through the power generator 18, the measured results of the temperature in the heat conduction path 54 and the electromotive force at the power generator 18 are applied to the mathematical formula or table relationship described above (see S230 in Figure 13). As a result, the heat flux passing through the power generator 18 can be calculated simply by applying the measured results to the mathematical formula or table relationship, making it easy to grasp the heat flux. Therefore, the calculation process can be simplified and the processing time can be shortened. In addition, unlike conventional systems, there is no need to recreate the same conditions as the temperature of the object under test before measurement, thus eliminating the need for such complicated preparation work for measurement.

[0151] On the other hand, the heat flux measurement system 10B according to an embodiment of the present invention, as shown in Figures 11 and 12, measures the heat flux per unit area on a heat receiving surface that can be collected from a heat source 50 having unused thermal energy, and includes a heat conduction modulation unit 12, a cooling source 36, a temperature measurement unit 44, an electromotive force measurement unit 46, and a calculation processing unit 48. The heat conduction modulation unit 12 has a configuration in which a power generation body 18 is sandwiched between two heat conducting media 16, and the heat conducting media 16, power generation body 18, and heat conducting media 16 are arranged in close proximity in series in this order. The power generation body 18 generates an electromotive force by the Seebeck effect, and the two heat conducting media 16 are made of materials with known thermal conductivity. The heat conduction modulation unit 12 with such a configuration is installed so that heat is conducted from an arbitrary heat receiving surface of the heat source 50 to be measured to one of the two heat conducting media 16.

[0152] The cooling source 36 has a lower temperature than the heat source 50 being measured, and is installed so that heat is conducted from the other of the two heat conduction media 16. That is, the heat conduction modulation unit 12 and the cooling source 36 are installed as part of a heat conduction path 54 that diverts heat from the heat source 50 so that heat flows from the heat source 50 to the cooling source 36. The temperature measurement unit 44 measures the temperature of a temperature measurement point, which is set at a predetermined position on at least one of the two heat conduction media 16 of the heat conduction modulation unit 12. The electromotive force measurement unit 46 measures the electromotive force generated in the power generator 18 in response to the temperature difference applied to the power generator 18 via the heat conduction media 16 that sandwich the power generator 18.

[0153] The calculation processing unit 48 performs various calculation processes in the system 10B, and as part of these, it performs the following calculations. Specifically, the calculation processing unit 48 calculates the heat flux passing through the power generator 18 in the same manner as the heat flux measurement method described above, based on the temperature of the temperature measurement point in the heat conduction path 54 measured by the temperature measurement unit 44, the electromotive force at the power generator 18 measured by the electromotive force measurement unit 46, and the temperature dependence of the material properties of the thermoelectric conversion material used in the power generator 18, which are set in advance (see S230 in Figure 13). Furthermore, the calculation processing unit 48 calculates the heat flux at the heat receiving surface of the heat source 50 to which the heat conduction path 54 including the heat conduction modulation unit 12 is connected, from the calculated heat flux passing through the power generator 18, in the same manner as the heat flux measurement method described above (see S240 in Figure 13). This makes it possible to achieve the same effects as the heat flux measurement method described above.

[0154] Next, with reference to Figures 18 to 22, a heat flux measurement system 10 (10C) and a heat flux measurement method according to yet another embodiment of the present invention, which differs from the embodiments described above, will be described. In Figures 18 to 22, the same reference numerals are used for parts that are the same as or corresponding to the embodiments shown in Figures 1 to 17. In this embodiment, the explanation will focus on the differences from the embodiments shown in Figures 1 to 17, and the explanation of the configuration and effects of parts that are the same as those in the embodiments shown in Figures 1 to 17 will be simplified or omitted.

[0155] First, referring to Figure 18, the heat flux measurement system 10C according to an embodiment of the present invention includes a heat conduction modulation unit 12, a cooling source 36, a heat-generating element control unit 40, a temperature measurement unit 44, and a calculation processing unit 48. The heat conduction modulation unit 12 of this embodiment includes three heat-generating elements 14 and four heat-conducting media 16, and each heat-generating element 14 is sandwiched between the heat-conducting media 16. For example, the four heat-conducting media 16 are connected by bolts or the like, and the three heat-generating elements 14 are arranged between them. Each of the heat-generating elements 14 is configured to generate heat in response to fluctuating heating energy, and in this embodiment, it is formed by a Peltier element, and a control line 32 (see Figures 3(b) and 5(b)) for supplying power as heating energy to the Peltier element is connected. The four heat-conducting media 16 are not limited to these, but are formed from materials with known thermal conductivity, such as aluminum or copper. Furthermore, the heat conduction modulation unit 12 of this embodiment is visually equivalent to the heat conduction modulation unit 12 shown in Figure 3 and the heat conduction modulation unit 12 shown in Figures 6(c) and 6(e). For this reason, each of the heat conduction media 16 has a measurement hole 20, and temperature measurement points are set inside these measurement holes 20.

[0156] The heat conduction modulation unit 12, configured as described above, is used as part of a heat conduction path 54, which is installed to divert heat from the heat source 50 to be measured, as shown in Figure 20(a). In the embodiment shown in Figure 20(a), for example, the heat conduction modulation unit 12 is connected to the heat outlet (heat receiving surface) from the heat source 50 via a heat exchanger and a thermal bonding member. At this time, the heat conduction modulation unit 12 is installed so that heat from the heat source 50 is conducted to the heat conduction medium 16 on one side (the upper side in Figure 18, the left side in Figure 20(a)). A cooling source 36, also shown in Figure 18, is connected to the heat conduction medium 16 on the other side of the heat conduction modulation unit 12, which is located on the right side of Figure 20(a), via a thermal bonding member. The cooling source 36 has a constant temperature lower than the heat source 50 to be measured, and this generates a heat flow in which the heat diverted from the heat source 50 flows towards the cooling source 36.

[0157] Returning to Figure 18, the heating element control unit 40 controls each heating element 14 of the heat conduction modulation unit 12 by supplying fluctuating heating energy to each heating element 14. In this embodiment, AC power (modulated power) of a predetermined frequency is supplied to the Peltier elements, which are heating elements 14, as heating energy via control lines 32 connected to each heating element 14. Preferably, the predetermined frequency of the AC power at this time is different from the fluctuating frequency of the heat flow from the heat source 50, which is known in advance. Furthermore, AC power (modulated power) with equal frequency, phase, and amplitude is supplied to the three heating elements 14. The temperature measurement unit 44 measures the temperature at temperature measurement points set in each heat conduction medium 16 of the heat conduction modulation unit 12. For example, the temperature measurement unit 44 measures the temperature at one temperature measurement point in each of the four heat conduction mediums 16, although this is not limited to the above. Furthermore, the temperature measurement unit 44 may also measure the temperature at temperature measurement points set in locations other than the heat conduction medium 16 in the heat conduction path 54. The calculation processing unit 48 performs various calculations in the heat flux measurement system 10C. Details of some of the calculations performed by the calculation processing unit 48 will be described later.

[0158] Furthermore, the heat flux measurement system 10C according to the embodiment of the present invention is not limited to the configuration shown in Figures 18 and 20(a). Some of the components shown therein may be deleted or replaced, or new components may be added. Moreover, each component in Figure 18 is a functional division of the configuration of the heat flux measurement system 10C and does not represent the individual devices that make up the heat flux measurement system 10C as they are, but rather consists of various hardware, software, or combinations thereof. For example, the heat conduction path 54 may differ from the configuration in Figure 20(a) as long as it includes the heat conduction modulation unit 12 and the cooling source 36. Furthermore, the heat conduction path 54 of this embodiment may also be connected to two or more different locations on the heat source 50 to be measured, as in the embodiment shown in Figure 4.

[0159] In addition, the shape, number, and arrangement order of each component of the heat conduction modulation unit 12 may differ from that of the embodiment in Figure 18. That is, the heat conduction modulation unit 12 may be configured such that one heating element 14 is sandwiched between two heat conduction media 16, or two heating elements 14 are sandwiched between three heat conduction media 16, or four or more heating elements 14 are sandwiched between five or more heat conduction media 16. Furthermore, the number and position of temperature measurement points measured by the temperature measurement unit 44 may also be arbitrarily set. For example, the temperature measurement unit 44 may measure one to three temperature measurement points, or five or more temperature measurement points, depending on the number and shape of the heat conduction media 16. Moreover, the heating element control unit 40 may also control two or fewer heating elements 14, or four or more heating elements 14, depending on the number of heating elements 14.

[0160] Next, with reference to Figure 19, a heat flux measurement method according to an embodiment of the present invention, which is performed using the heat flux measurement system 10C described above, will be explained. For the configuration of the heat flux measurement system 10C, please refer to Figures 18 and 20(a) as appropriate. Note that the flowchart shown in Figure 19 is an example of the procedure flow of the heat flux measurement method, and the procedure of the heat flux measurement method according to an embodiment of the present invention is not limited to this flowchart. For this reason, some of the steps shown in Figure 19 may be changed, deleted, or rearranged, and new steps may be added.

[0161] S400 (Heat conduction path connection): For example, as shown in Figure 20(a), the other end of a heat conduction path 54, which has a cooling source 36 at one end and a heat conduction modulation section 12 in the middle, is connected to the heat source 50 to be measured. This separates the heat from the heat source 50 to be measured, causing that heat to flow through the heat conduction modulation section 12 towards the cooling source 36. At the same time, other components of the heat flux measurement system 10C are installed and connected. For example, the heat acquisition part of the temperature measurement unit 44 is installed at the temperature measurement points set for each of the four heat conduction media 16 of the heat conduction modulation section 12, or the control line 32 extending from the heat-generating element 14 of the heat conduction modulation section 12 is connected to the heat-generating element control unit 40.

[0162] S410 (Construction of electrical circuit model): The calculation processing unit 48 virtually constructs an electrical circuit model 70 including multiple circuit elements that corresponds to the thermal circuit model 60 from the heat source 50 to the cooling source 36, including the heat conduction path 54 connected in S400. That is, the temperature, heat flux, and thermal resistance in the thermal circuit model 60 are converted to voltage, current, and resistance to construct the electrical circuit model 70. For example, Figure 20(b) shows a simplified electrical circuit model 70 corresponding to the thermal circuit model 60 in Figure 20(a). In the electrical circuit model 70 of Figure 20(b), the heat source 50 and the cooling source 36 are represented by DC power supplies, because it is assumed that the heat source 50 and the cooling source 36 emit heat at a constant temperature.

[0163] Furthermore, in the electrical circuit model 70 of Figure 20(b), the connection between the heat source 50 and the heat conduction modulation unit 12, and between the heat conduction modulation unit 12 and the cooling source 36, is represented by resistors and capacitors. This is because the resistance to heat transfer (thermal resistance) and radiation in the heat conduction path 54 before and after the heat conduction modulation unit 12 are represented by resistors, and the rate of heat transfer (time constant) is represented by capacitors. Moreover, in the electrical circuit model 70 of Figure 20(b), the heat conduction modulation unit 12 is represented by resistors and AC power supplies. This is because the resistance to heat transfer and radiation in the heat conduction medium 16 of the heat conduction modulation unit 12 are represented by resistors, and the heat-generating element 14 of the heat conduction modulation unit 12 is represented by an AC power supply, which is controlled by the heat-generating element control unit 40 to provide AC power of a predetermined frequency so that the amount of heat generated fluctuates.

[0164] Furthermore, Figure 21 shows a detailed example of an electrical circuit model 70 in which the heat conduction modulation unit 12 of the thermal circuit model 60 in Figure 20(a) is replaced with the heat conduction modulation unit 12 shown in Figure 18. Note that in the electrical circuit model 70 in Figure 21 (and Figure 26, which will be described later), some of the reference numerals of the circuit elements overlap with those of the circuit shown in Figure 9, but they represent different elements. First, in the electrical circuit model 70 of Figure 21, the heat source 50 is connected to a DC power supply Vdc １ , Cooling source 36 is DC power supply Vdc ２ The three heating elements 14 of the heat conduction modulation unit 12 are powered by the AC power supply Vac １ ~Vac ３This is represented as shown, and this point is the same as the electrical circuit model 70 in Figure 20(b).

[0165] Furthermore, in the electrical circuit model 70 of Figure 21, the heat conduction path 54 on the heat source 50 side has a resistance R １ , R ２ and capacitor C １ This is represented by the heat conduction path 54 on the cooling source 36 side having a resistance R １６ and capacitor C ２ This is represented as shown, and this point is the same as in the electrical circuit model 70 in Figure 20(b). Furthermore, in the electrical circuit model 70 in Figure 21, the four heat conduction media 16 of the heat conduction modulation section 12 are represented as R, which indicates their thermal resistance and radiation. ４ ~R １５ This is represented as follows. Specifically, the uppermost heat conductive medium 16 in Figure 18 is R ４ ~R ６ Represented by, the second heat conduction medium 16 from the top in Figure 18 is R ７ ~R ９ Represented by, the third heat conduction medium 16 from the top in Figure 18 is R １０ ~R １２ Represented by, the bottom heat conduction medium 16 in Figure 18 is R １３ ~R １５ It is represented as follows.

[0166] Here, in the electrical circuit model 70 of Figure 21, the symbol V １ ~V ５ These are also illustrated. Of these, the symbol V ２ ~V ５ This indicates the voltage at four voltage monitoring points corresponding to the temperature measurement points set for each of the four heat conduction media 16 of the heat conduction modulation unit 12, which are measured by the temperature measurement unit 44 in S430 described later. Specifically, the symbol V ２ However, the voltage at the voltage monitoring point corresponding to the temperature measurement point set on the uppermost heat conduction medium 16 in Figure 18 is indicated by the symbol V. ３ However, the voltage shown is at the voltage monitoring point corresponding to the temperature measurement point set on the second heat conduction medium 16 from the top in Figure 18. Also, the symbol V ４ However, the voltage at the voltage monitoring point corresponding to the temperature measurement point set on the third heat conduction medium 16 from the top in Figure 18 is indicated by the symbol V. ５However, the voltage shown in Figure 18 corresponds to the voltage monitoring point at the temperature measurement point set on the bottom heat conduction medium 16. Furthermore, the remaining symbol V １ This indicates the voltage at the voltage monitoring point corresponding to the temperature measurement point set between the heat source 50 and the heat conduction modulation unit 12, which will be measured by the temperature measurement unit 44 in S430 described later.

[0167] Furthermore, when constructing the electrical circuit model 70, capacitors and coils may be used to take into account phase differences, etc. Also, when constructing the electrical circuit model 70 based on the thermal circuit model 60, the calculation processing unit 48 may perform the construction work while receiving input from operators, etc., or it may perform the construction work using a circuit simulator. In the latter case, the circuit simulator may form part of the calculation processing unit 48. Moreover, the construction of the electrical circuit model 70 may be performed before connecting the heat conduction path 54, if the configuration of the heat conduction path 54 connected to the heat source 50 is known in advance. Also, the electrical circuit model 70 shown in Figure 21 (and Figure 26 described later) is just an example, and naturally, the type, quantity, and position of the circuit elements may differ from those shown to correspond to the actual thermal circuit model 60.

[0168] S420 (Heating element control): The heating element control unit 40 starts controlling the three heating elements 14 of the heat conduction modulation unit 12. That is, in this embodiment, AC power having a predetermined frequency (modulation frequency) is supplied to each Peltier element constituting the heating element 14 with the same phase and amplitude, for example, so that the current waveform becomes a sine wave. At this time, the predetermined frequency of the AC power may be different from the fluctuation frequency of the heat flow from the heat source 50.

[0169] S430 (Temperature Measurement): The temperature measurement unit 44 continuously measures the temperature at the temperature measurement points set on each of the four heat conduction media 16 of the heat conduction modulation unit 12. Furthermore, in this embodiment, a temperature measurement point is also set between the heat source 50 and the heat conduction modulation unit 12, and the temperature there is also continuously measured. During these measurements, the sampling interval shall be at least twice the modulation frequency of the AC power supplied from the heating element control unit 40 to each heating element 14. Furthermore, for subsequent processing, the measured analog temperature data is converted into digital temperature data by the calculation processing unit 48 or a separately provided A / D converter. Note that in S420, if the heating element 14 is supplied with AC power of a predetermined frequency different from the fluctuation frequency of the heat flow from the heat source 50, the frequency component data of the frequency (modulation frequency) of the AC power supplied to the heating element 14 may be extracted from the temperature measurement results as described above to reduce noise.

[0170] S440 (Use of circuit simulator or derivation of circuit equations): In S470, described later, a decision is made as to whether to use a circuit simulator or circuit equations to calculate the parameter values ​​of multiple circuit elements of the electrical circuit model 70. If a circuit simulator is used, the electrical circuit model 70 as shown in Figure 21, constructed in S410, is loaded into the circuit simulator. At this time, any circuit simulator may be used, and as mentioned in S410, the circuit simulator to be used may be pre-built into the calculation processing unit 48. Hereafter, when a circuit simulator is used, it will be assumed that it is built into the calculation processing unit 48. On the other hand, if circuit equations are used, circuit equations are derived from the electrical circuit model 70 constructed in S410 using Kirchhoff's laws, etc. For example, the V shown in the electrical circuit model 70 of Figure 21 １ ~V ５ Derive the circuit equations that will yield the desired result. Note that the calculation processing unit 48 or the circuit simulator may be used to derive the circuit equations.

[0171] S450 (Selection of weighting target): In S470, described later, when calculating the parameter values ​​of multiple circuit elements of the electrical circuit model 70, it is decided whether or not to perform weighting in order to improve the fitting accuracy of some voltage monitoring points. If weighting is performed, the V of the electrical circuit model 70 in Figure 21 that corresponds to the five temperature measurement points where temperature measurements were taken in S430 above is determined. １ ~V ５ From the five voltage monitoring points where the voltage is measured, select the voltage monitoring point for which you want to improve the fitting accuracy and set it in the calculation processing unit 48. Alternatively, assign different weights to these five voltage monitoring points according to the fitting priority and set them in the calculation processing unit 48. If you do not want to assign weights, you do not need to do anything here.

[0172] S460 (Optimization Algorithm Selection): In order to calculate the parameter values ​​of multiple circuit elements of the electrical circuit model 70 in S470, which will be described later, an optimization algorithm (fitting method) is selected to be used together with the circuit simulator or circuit equations decided to be used in S440. Candidates for such an optimization algorithm include, for example, a particle swarm optimization method that can obtain a solution close to the optimal solution while suppressing time, and a full solution search that is time-consuming but reliable. However, any optimization algorithm may be selected depending on the situation. The selected optimization algorithm is then set in the calculation processing unit 48.

[0173] S470 (Parameter Value Calculation): The calculation processing unit 48 calculates the parameter values ​​of multiple circuit elements of the electrical circuit model 70 constructed in S410, using the circuit simulator or circuit equation to be used in S440 and the optimization algorithm selected in S460. First, regarding the case where a circuit simulator is used, in S440, the circuit simulator loaded with the electrical circuit model 70 as shown in Figure 21 is operated. At this time, the DC power supply Vdc corresponding to the heat source 50 １ The DC power supply Vdc corresponding to the cooling source 36 is configured to output a voltage within the expected range. ２This is to output a voltage within the expected range. Also, the AC power supply Vac corresponding to the three heating elements 14 １ ~Vac ３ This is configured to output a voltage (amplitude) within a specified range at the same predetermined frequency as the AC power supplied to the three heating elements 14 in S420 above. The waveform of this output is, for example, a sine wave, square wave, sawtooth wave, or triangular wave.

[0174] Furthermore, the remaining circuit elements of the electrical circuit model 70 are made to reflect, as much as possible, the known thermal conductivity of each component included in the heat conduction path 54 of the thermal circuit model 60. In this state, the circuit simulator is operated, and the voltages V at the five voltage monitoring points of the electrical circuit model 70 as shown in Figure 21 are measured. １ ~V ５ The following are acquired continuously. Then, the temperatures at the five temperature measurement points measured in S430 and the voltages at the five voltage monitoring points of the electrical circuit model 70 by the circuit simulator are obtained. １ ~V ５ The parameter values ​​of multiple circuit elements of the electrical circuit model 70 are calculated using the optimization algorithm selected in S460 above, so that corresponding elements exhibit similar behavior. Here, parameter values ​​include the resistance of a resistor, the capacitance of a capacitor, the output voltage of a DC power supply, and the phase and amplitude of an AC power supply.

[0175] Next, we will explain the case where the circuit equation derived in S440 above is used, and the voltage V of the derived electrical circuit model 70 １ ~V ５ To find the voltage V, we substitute the parameter values ​​of each circuit element to the extent possible into the circuit equation that solves the circuit equation. １ ~V ５ We will find the DC power supply Vdc corresponding to the heat source 50 in each circuit equation. １ The output voltage is set to the DC power supply Vdc corresponding to the cooling source 36, with the expected voltage range applied. ２ The output voltage is set to a voltage within the expected range. Also, in each circuit equation, the AC power supply Vac corresponding to the three heating elements 14 is used. １ ~Vac ３The output is set to a voltage (amplitude) within the expected range, at the same predetermined frequency as the AC power supplied to the three heating elements 14 in S420 above.

[0176] Furthermore, in each circuit equation, the remaining circuit elements of the electrical circuit model 70 are made to reflect, as much as possible, the known thermal conductivity of each component included in the heat conduction path 54 of the thermal circuit model 60. Solving each circuit equation in this state yields the voltage V over time at five voltage monitoring points of the electrical circuit model 70 as shown in Figure 21. １ ~V ５ The change is determined. Then, the temperature at the five temperature measurement points measured in S430 above and the voltage V at the five voltage monitoring points of the electrical circuit model 70 obtained by solving the circuit equations are calculated. １ ~V ５ The parameter values ​​of multiple circuit elements of the electrical circuit model 70 are calculated using the optimization algorithm selected in S460 above, so that corresponding elements exhibit similar behavior.

[0177] In both cases, whether using the circuit simulator or circuit equations, the expression "they should exhibit similar behavior" is used. The criterion for determining whether they exhibit similar behavior is the degree of agreement in amplitude, frequency, and phase when the temperature and voltage are shown as waveforms over time. However, since the measurement results for temperature and the output results for voltage depend heavily on the accuracy of the equipment used, it is not possible to define a general degree of agreement. Therefore, although this is merely an example, if the amplitude, frequency, and phase of the temperature and voltage being compared are aligned within an error of, for example, ±5%, it can be judged that they exhibit similar behavior. Furthermore, if there is a phase difference between temperature and voltage, adjustments such as adding a coil component to the electrical circuit model 70 may be made before performing fitting or simulation.

[0178] Here, whether using a circuit simulator or circuit equations, if it is decided to weight the parameters in S450, the parameter values ​​of the multiple circuit elements of the electrical circuit model 70 are calculated to reflect this. That is, in S450, the voltage V１ ~V ５ If a voltage monitoring point is selected from among the five voltage monitoring points where the voltage is measured, the parameter values ​​of multiple circuit elements of the electrical circuit model 70 are calculated so that the fitting accuracy of the voltage at the selected voltage monitoring point is improved. Furthermore, if different weights are assigned to the five voltage monitoring points in S450 according to the fitting priority, the parameter values ​​of multiple circuit elements of the electrical circuit model 70 are calculated so that the fitting is performed according to those priorities.

[0179] For example, Figure 22 shows the voltage V at five voltage monitoring points after fitting by the circuit simulator. １ ~V ５ The output results and the temperature measurement results at the five corresponding temperature measurement points T １ ~T ５ The following are examples. Figure 22(a) shows the case where no weighting is applied during fitting, and Figure 22(b) shows the case where different weights are assigned to the five voltage monitoring points according to the fitting priority. That is, in Figure 22(b), the voltage V ３ The voltage monitoring point is given the greatest weighting, and the voltage V ２ and voltage V ４ The voltage monitoring point is given the next largest weighting, and the voltage V １ and voltage V ５ The voltage monitoring point is given the smallest weighting.

[0180] In both Figures 22(a) and (b), the graph in the upper left is the voltage V. １ and temperature T １ The graph in the upper right shows the voltage V. ２ and temperature T ２ The graph in the middle left shows the voltage V. ３ and temperature T ３ The graph in the middle right shows the voltage V. ４ and temperature T ４ The graph in the lower left shows the voltage V. ５ and temperature T ５is shown. Also, in each graph, the solid line indicates the output voltage at each voltage monitoring point by the circuit simulator, and the dashed line indicates the measured temperature at the temperature measurement point. Comparing FIGS. 22(a) and (b), it can be seen that the voltage V of the voltage monitoring point given the largest proportion with the highest fitting priority ３ (the graph on the left in the middle) has clearly higher fitting accuracy compared to other voltage monitoring points.

[0181] S480 (Parameter Value Application): Cause the circuit simulator to load the electrical circuit model 70 constructed in S410 above, and further apply the parameter values of the plurality of circuit elements of the electrical circuit model 70 calculated in S470 above thereto. At this time, when the circuit simulator was used in S470 above, the calculated parameter values may be reflected therein. S490 (Simulation Execution): Execute the simulation of the electrical circuit model 70 by the circuit simulator to which the parameter values were applied in S480 above. As a result, for example, the time-series data of the voltages V １ ~V ５ at five voltage monitoring points are obtained.

[0182] S500 (Circuit Equation Derivation): The calculation processing unit 48 inversely analyzes and derives the circuit equation from the result of the simulation in S490 above. That is, since the equation of motion of the mechanical system or the solution trajectory representing the behavior can be estimated from the time-series data obtained as the result of the simulation, if such an algorithm is applied for fitting, the circuit equation can be obtained inversely analytically. For example, a method based on logistic regression or the like may be used. As a result, a circuit equation for obtaining the voltage and current at an arbitrary position in the electrical circuit model 70 is derived.

[0183] S510 (Heat Flux Estimation): The calculation processing unit 48 estimates the heat flux at the heat receiving surface of the heat source 50 using the circuit equation derived in S500. Specifically, in S500, the circuit equation for the part of the electrical circuit model 70 corresponding to the heat receiving surface of the heat source 50 in the thermal circuit model 60 is derived, and the current flowing through the part corresponding to the heat receiving surface is calculated from it. Since this current value corresponds to the heat flux flowing through the heat receiving surface of the heat source 50 in the thermal circuit model 60, the heat flux is estimated from it. In other words, if the circuit equation for the part of the electrical circuit model 70 corresponding to any part of the actual thermal circuit model 60 for which the temperature and heat flow are to be determined is derived in S500, the temperature and heat flow of any part of the thermal circuit model 60 can be estimated from that circuit equation. For example, the thermal conductance and thermal resistance at the heat receiving surface of the heat source 50 may be estimated. Furthermore, a digital twin model that estimates the heat flux in a virtual space may be constructed using such circuit equations.

[0184] Now, according to the embodiment of the present invention having the above configuration, the following effects can be obtained. That is, the heat flux measurement method according to the embodiment of the present invention uses a heat flux measurement system 10C, such as the one shown in Figures 18 and 20(a), to measure the heat flux at an arbitrary heat receiving surface of a heat source 50 that has unused thermal energy being dissipated. Specifically, a cooling source 36 controlled to a constant temperature is provided at one end of a heat conduction path 54, and the other end of the heat conduction path 54 is connected to the aforementioned heat receiving surface of the heat source 50, thereby diverting the heat to flow from the heat source 50 toward the cooling source 36 (see S400 in Figure 19). The heat conduction path 54 used at this time shall be made of a material whose properties such as thermal conductivity are known in advance. Furthermore, the heating element 14 is installed in the heat conduction path 54, that is, between one end of the heat conduction path 54 where the cooling source 36 is installed and the other end of the heat conduction path 54 connected to the heat source 50. The heat-generating element 14 to be installed should be one that can be controlled so that the amount of heat generated fluctuates when fluctuating heating energy is applied, and multiple heat-generating elements 14 may be installed.

[0185] Furthermore, an electrical circuit model 70 including multiple circuit elements, as shown in Figures 20(b) and 21, is virtually constructed, corresponding to the actual thermal circuit model 60 from the heat source 50, which includes the heat conduction path 54 described above, to the cooling source 36 (see S410 in Figure 19). At this time, the temperature, heat flux, and thermal resistance in the thermal circuit model 60 are made to correspond to the voltage, current, and resistance in the electrical circuit model 70. That is, the multiple circuit elements of the electrical circuit model 70 include resistors corresponding to the thermal resistance that represents the difficulty of heat transfer in the thermal circuit model 60, and power supplies corresponding to the heat source 50, heat-generating element 14, and cooling source 36 that generate heat in the thermal circuit model 60. Subsequently, in the actual thermal circuit model 60, the temperature of the temperature measurement point in the heat conduction path 54 is continuously measured while varying the amount of heat generated from the heat-generating element 14 (see S420 in Figure 19) (see S430 in Figure 19). In other words, with heat flowing from the heat receiving surface of the heat source 50 toward the cooling source 36, fluctuating heat is also supplied from the heat generating element 14, and the temperature at a preset temperature measurement point in the heat conduction path 54 is continuously measured to obtain a time-series temperature measurement result at the temperature measurement point.

[0186] Furthermore, the electrical circuit model 70 corresponding to the thermal circuit model 60 is virtually operated by setting each power supply to the operating state, and in this state, the voltage of the voltage monitoring point in the electrical circuit model 70 that corresponds to the temperature measurement point of the thermal circuit model 60 is acquired. Then, the parameter values ​​of multiple circuit elements of the electrical circuit model 70 are calculated so that the measured temperature at the temperature measurement point in the actual thermal circuit model 60 and the acquired voltage at the voltage monitoring point in the virtual electrical circuit model 70 exhibit similar behavior (fitting) (see S470 in Figure 19). The electrical circuit model 70 to which the multiple parameter values ​​calculated as described above are applied exhibits similar behavior to the actual thermal circuit model 60 (see S490 in Figure 19).

[0187] In the actual thermal circuit model 60, the heat source 50 and its thermal resistance are unknown, and all other circuit parameters are irrelevant to the heat source 50. Therefore, considering that the thermal conductivity of the material forming the heat conduction path 54 is known, the parameter values ​​of the circuit elements in the electrical circuit corresponding to them can be fixed to optimal values. This makes it possible to easily estimate the heat flux at the heat receiving surface of the heat source 50 using the electrical circuit model 70 to which the calculated parameter values ​​have been applied (see S510 in Figure 19). Furthermore, if necessary, the thermal conductance and thermal resistance at the heat receiving surface of the heat source 50 can also be easily estimated. In addition, by using the electrical circuit model 70 to which the calculated parameter values ​​have been applied, it is also possible to formulate mathematical equations for the time-series waveform data of temperature in the actual thermal circuit model 60 (see S500 in Figure 19).

[0188] Furthermore, in the heat flux measurement method according to the embodiment of the present invention, when measuring the temperature in the heat conduction path 54 in the actual thermal circuit model 60, AC power of a predetermined frequency is applied to the heating element 14 as heating energy to vary the amount of heat generated, thereby AC-variing the amount of heat generated from the heating element 14 at a predetermined frequency (see S420 in Figure 19). Then, when virtually constructing the electrical circuit model 70, the heat source 50 and cooling source 36 in the thermal circuit model 60 are made to correspond to DC power sources, and the heating element 14 in the thermal circuit model 60 is made to correspond to an AC power source that outputs AC power at the same predetermined frequency as the AC power supplied to the heating element 14 (see S410 in Figure 19). As a result, the heat generation (heat absorption) state by the heat source 50, cooling source 36, and heating element 14 in the thermal circuit model 60 can be more accurately reflected in the electrical circuit model 70, making it possible to obtain more appropriate parameter values ​​for the electrical circuit model 70.

[0189] Furthermore, the heat flux measurement method according to the embodiment of the present invention may utilize a circuit simulator and an optimization algorithm when calculating the parameter values ​​of multiple circuit elements of the electrical circuit model 70. Specifically, the constructed electrical circuit model 70 is loaded into a circuit simulator, and while operating the electrical circuit model 70 on the circuit simulator, an arbitrary optimization algorithm is used to calculate the optimal parameter values ​​so that it behaves similarly to the actual thermal circuit model 60 (see S440 and S470 in Figure 19). This makes it possible to obtain the parameter values ​​of the electrical circuit model 70 in a black-box manner without deriving the circuit equations of the electrical circuit model 70.

[0190] Furthermore, the heat flux measurement method according to the embodiment of the present invention may utilize circuit equations and optimization algorithms when calculating the parameter values ​​of multiple circuit elements in the electrical circuit model 70. Specifically, circuit equations are derived from the constructed electrical circuit model 70 using Kirchhoff's laws, etc., and the optimal parameter values ​​of the circuit elements in the circuit equations are calculated using an arbitrary optimization algorithm (see S440 and S470 in Figure 19). In this way, the parameter values ​​of the electrical circuit model 70 can be obtained in a white-box manner without using a circuit simulator or the like.

[0191] In addition, the heat flux measurement method according to the embodiment of the present invention measures the temperature in the heat conduction path 54 in the actual thermal circuit model 60 by continuously measuring the temperature at a plurality of pre-set temperature measurement points while varying the amount of heat generated from the heat-generating element 14, and obtaining a time-series temperature measurement result at each of the temperature measurement points (see S430 in Figure 19). Furthermore, the constructed electrical circuit model 70 is virtually operated by putting each power supply into an operating state, and in this state, the voltages of a plurality of voltage monitoring points in the electrical circuit model 70 that correspond to the plurality of temperature measurement points of the thermal circuit model 60 are acquired. Then, the parameter values ​​of a plurality of circuit elements in the electrical circuit model 70 are calculated so that the measured temperatures at the plurality of temperature measurement points of the thermal circuit model 60 measured as described above and the acquired voltages at the plurality of voltage monitoring points of the virtual electrical circuit model 70 exhibit similar behavior for corresponding elements (see S470 in Figure 19). This allows us to increase the number of indicators for fitting the virtual electrical circuit model 70 to the actual thermal circuit model 60 by the number of temperature measurement points and corresponding voltage monitoring points, thereby enabling us to obtain more appropriate parameter values ​​for the electrical circuit model 70.

[0192] Furthermore, the heat flux measurement method according to the embodiment of the present invention performs weighting as necessary when calculating the parameter values ​​of multiple circuit elements of the electrical circuit model 70 (see S450 in Figure 19). That is, weighting is applied to any specific voltage monitoring point among a plurality of voltage monitoring points that serve as indicators for fitting the electrical circuit model 70 to the thermal circuit model 60, and the parameter values ​​of the electrical circuit model 70 are calculated with the priority of fitting at the weighted voltage monitoring point increased. At this time, each of the plurality of voltage monitoring points may be weighted by assigning a different specific weight. This improves the fitting accuracy at the weighted voltage monitoring point and voltage monitoring points with a high specific weight, making it possible to calculate the parameter values ​​of the electrical circuit model 70 in response to various situations.

[0193] On the other hand, the heat flux measurement system 10C according to an embodiment of the present invention, as shown in Figures 18 and 20(a), measures the heat flux per unit area on a heat receiving surface that can be collected from a heat source 50 having unused thermal energy, and includes a heat conduction modulation unit 12, a cooling source 36, a heat-generating element control unit 40, a temperature measurement unit 44, and a calculation processing unit 48. The heat conduction modulation unit 12 has a configuration in which at least one (three in Figure 18) heat-generating elements 14 are alternately sandwiched by at least two (four in Figure 18) heat-conducting media 16. The heat-generating elements 14 are controllable so that their heat generation amount fluctuates, and at least two of the heat-conducting media 16 are made of materials with known thermal conductivity. The heat conduction modulation unit 12 with such a configuration is installed so that heat is conducted from an arbitrary heat-receiving surface of the heat source 50 to be measured to one of the at least two heat-conducting media 16. The cooling source 36 has a lower temperature than the heat source 50 being measured, and is installed so that heat is conducted from the other of the two heat conduction media 16. In other words, the heat conduction modulation unit 12 and the cooling source 36 are installed as part of a heat conduction path 54 that diverts heat from the heat source 50 so that heat flows from the heat source 50 to the cooling source 36.

[0194] The heating element control unit 40 controls at least one heating element 14 of the heat conduction modulation unit 12, and controls the heating element 14 so that the amount of heat generated from the heating element 14 fluctuates by supplying fluctuating heating energy to the heating element 14. The temperature measurement unit 44 measures the temperature of a temperature measurement point, and the temperature measurement point is set at a predetermined position on at least one of the at least two heat conduction media 16 of the heat conduction modulation unit 12. The calculation processing unit 48 performs various calculation processes in this system 10C, and as part of this, it performs the following calculation. That is, the calculation processing unit 48 virtually constructs an electrical circuit model 70 including a plurality of circuit elements corresponding to the thermal circuit model 60 from the heat source 50 including the heat conduction modulation unit 12 to the cooling source 36, in the same manner as the heat flux measurement method described above (see S410 in Figure 19).

[0195] Furthermore, the calculation processing unit 48 calculates the parameter values ​​of multiple circuit elements in the electrical circuit model 70 in the same manner as the heat flux measurement method described above, so that the temperature at the temperature measurement point in the actual thermal circuit model 60 and the voltage at the voltage monitoring point corresponding to the temperature measurement point in the operating electrical circuit model 70 exhibit similar behavior (see S470 in Figure 19). The temperature at the temperature measurement point of the thermal circuit model 60 used at this time is the temperature continuously measured by the temperature measurement unit 44 while the amount of heat generated from at least one heat source 14 is fluctuated by the heat source control unit 40, and the electrical circuit model 70 is virtually operated by setting each power source to the operating state. Furthermore, the calculation processing unit 48 uses the electrical circuit model 70 to which the parameter values ​​calculated above have been applied to estimate the heat flux, thermal conductance, and thermal resistance at the heat receiving surface of the heat source 50 (see S510 in Figure 19). This makes it possible to achieve the same effects as the heat flux measurement method described above.

[0196] Next, with reference to Figures 23 to 27, a heat flux measurement system 10 (10D) and a heat flux measurement method according to yet another embodiment of the present invention, which differs from the embodiments described above, will be described. In Figures 23 to 27, the same reference numerals are used for parts that are the same as or corresponding to the embodiments shown in Figures 1 to 22. In this embodiment, the explanation will focus on the differences from the embodiments shown in Figures 1 to 22, and the explanation of the configuration and effects of parts that are the same as those in the embodiments shown in Figures 1 to 22 will be simplified or omitted.

[0197] Referring to Figure 23, the heat flux measurement system 10D according to an embodiment of the present invention includes a heat conduction modulation unit 12, a cooling source 36, a heat-generating element control unit 40, an electromotive force measurement unit 46, and a calculation processing unit 48. The heat conduction modulation unit 12 of this embodiment includes a heat-generating element 14, two power-generating elements 18, and four heat-conducting media 16, with each of the heat-generating element 14 and power-generating elements 18 being sandwiched between the heat-conducting media 16. For example, the four heat-conducting media 16 are connected by bolts or the like, and the power-generating elements 18, heat-generating element 14, and power-generating element 18 are arranged between them in this order. The heat-generating element 14 is configured to generate heat that fluctuates in response to fluctuating heating energy, and in this embodiment it is formed by a Peltier element, and a control line 32 (see Figures 3(b) and 5(b)) for supplying power as heating energy to the Peltier element is connected. Furthermore, each of the power generation elements 18 generates an electromotive force by the Seebeck effect, and in this embodiment, it is formed by a Peltier element, similar to the heating element 14, and a measurement line 34 (see Figures 3(b) and 5(b)) for acquiring the electromotive force is connected to the Peltier element. The four heat conductive media 16 are not limited to these, but are formed from materials with known thermal conductivity, such as aluminum or copper.

[0198] The heat conduction modulation unit 12, configured as described above, is used as part of a heat conduction path 54, which is installed to divert heat from the heat source 50 being measured, as shown in Figure 24. That is, the heat conduction modulation unit 12 is connected to the heat outlet (heat receiving surface) from the heat source 50 via a heat exchanger and a thermal bonding member. At this time, the heat conduction modulation unit 12 is installed so that heat from the heat source 50 is conducted to the heat conduction medium 16 on one side (the upper side in Figure 23, the left side in Figure 24). A cooling source 36, also shown in Figure 23, is connected to the heat conduction medium 16 on the other side of the heat conduction modulation unit 12, which is located on the right side of Figure 24, via a thermal bonding member. The cooling source 36 has a constant temperature lower than the heat source 50 being measured, and this generates a heat flow in which the heat diverted from the heat source 50 flows towards the cooling source 36.

[0199] Returning to Figure 23, the heating element control unit 40 controls the heating element 14 of the heat conduction modulation unit 12 by supplying it with fluctuating heating energy. In this embodiment, AC power (modulated power) of a predetermined frequency is supplied to the Peltier element, which is the heating element 14, as heating energy via a control line 32 connected to the heating element 14. Preferably, the predetermined frequency of the AC power at this time is different from the fluctuating frequency of the heat flow from the heat source 50, which is known in advance. The electromotive force measurement unit 46 measures the electromotive force generated in each power generator 18 by the Seebeck effect in response to the heat flow flowing through the heat conduction modulation unit 12. For this purpose, the electromotive force measurement unit 46 acquires the electromotive force from each power generator 18 via a measurement line 34 and performs the measurement. The calculation processing unit 48 performs various calculation processing in the heat flux measurement system 10D. Details of some of the calculation processing performed by such calculation processing unit 48 will be described later.

[0200] Furthermore, the heat flux measurement system 10D according to the embodiment of the present invention is not limited to the configuration shown in Figures 23 and 24. Some of the components shown therein may be deleted or replaced, or new components may be added. Moreover, each component in Figure 23 is a functional division of the configuration of the heat flux measurement system 10D and does not represent the individual devices that constitute the heat flux measurement system 10D as they are, but rather is composed of various hardware, software, or combinations thereof. For example, the heat flux measurement system 10D may have a temperature measurement unit 44 as shown in Figure 18, in which case the temperature measurement unit 44 may measure the temperature at any position in the heat conduction path 54.

[0201] In addition, the thermal conduction modulation unit 12 may differ from the embodiment in Figure 23 in terms of the number and arrangement order of each component. That is, the thermal conduction modulation unit 12 may be configured such that one heating element 14 and one power generation element 18 are sandwiched between three thermal conductive media 16, or two heating elements 14 and one power generation element 18 are sandwiched between four thermal conductive media 16, or two or more heating elements 14 and two or more power generation elements 18 are sandwiched between five or more thermal conductive media 16. Furthermore, the thermal conduction modulation unit 12 may be configured such that a device that combines the functions of both a heating element 14 and a power generation element 18 is sandwiched between thermal conductive media 16. That is, the thermal conduction modulation unit 12 may be configured as shown in Figure 6, etc. Also, the heating element control unit 40 may control two or more heating elements 14 according to the number of heating elements 14, and the electromotive force measurement unit 46 may measure the electromotive force of one or three or more power generation elements 18 according to the number of power generation elements 18.

[0202] Next, with reference to Figure 25, a heat flux measurement method according to an embodiment of the present invention, which is performed using the heat flux measurement system 10D described above, will be explained. For the configuration of the heat flux measurement system 10D, please refer to Figures 23 and 24 as appropriate. Note that the flowchart shown in Figure 25 is an example of the procedure flow of the heat flux measurement method, and the procedure of the heat flux measurement method according to the embodiment of the present invention is not limited to this flowchart. For this reason, some of the steps shown in Figure 25 may be changed, deleted, or rearranged, and new steps may be added. Also, since the flowchart in Figure 25 is similar to the flowchart shown in Figure 19, some explanations of Figure 25 will be omitted by referring to the explanation of Figure 19.

[0203] S600 (Thermal conduction path connection): Since the same process as S400 in FIG. 19 is performed, detailed description is omitted. S610 (Electrical circuit model construction): The calculation processing unit 48 virtually constructs an electrical circuit model 70 including a plurality of circuit elements corresponding to the thermal circuit model 60 from the heat source 50 to the cooling source 36 of the measurement target including the thermal conduction path 54 connected in S600. That is, the electrical circuit model 70 is constructed by corresponding the temperature, heat flux, and thermal resistance in the thermal circuit model 60 to voltage, current, and resistance. Further, the power generator 18 in the thermal circuit model 60 is made to correspond to a voltage detector in the electrical circuit model 70. FIG. 26 shows an example of the electrical circuit model 70 constructed to correspond to the thermal circuit model 60 including the thermal conduction modulation unit 12 shown in FIG. 23.

[0204] In the electrical circuit model 70 of FIG. 26, the heat source 50 is a DC power supply Vdc １ , the cooling source 36 is a DC power supply Vdc ２ , the heating element 14 of the thermal conduction modulation unit 12 is represented by an AC power supply Vac, and the two power generators 18 of the thermal conduction modulation unit 12 are voltage detectors VD １ , VD ２ . Also, in the electrical circuit model 70 of FIG. 26, the thermal conduction path 54 on the heat source 50 side is represented by resistors R １ , R ２ and capacitor C １ , the thermal conduction path 54 on the cooling source 36 side is represented by resistors R １６ and capacitor C ２ . Further, in the electrical circuit model 70 of FIG. 26, the four thermal conduction media 16 of the thermal conduction modulation unit 12 are represented by R ４ to R １５ indicating their thermal resistance and radiation.

[0205] S620 (Heating element control): This is the same process as S420 in Figure 19, except that there is only one heating element 14 to be controlled, so a detailed explanation is omitted. S630 (Electrical voltage measurement): The electromotive voltage measurement unit 46 measures the electromotive voltage generated by the two power generators 18 of the heat conduction modulation unit 12. During this measurement, the sampling interval shall be at least twice the modulation frequency of the AC power supplied from the heating element control unit 40 to the heating element 14. Furthermore, for subsequent processing, the measured analog voltage data is converted into digital voltage data by the calculation processing unit 48 or a separately provided A / D converter.

[0206] Figure 27(a) shows an example of the measurement results of the electromotive force generated by the two power generators 18, where the solid line is the measurement result at the power generator 18 on the heat source 50 side (upper side in Figure 23), and the thick solid line is the measurement result at the power generator 18 on the cooling source 36 side (lower side in Figure 23). In step S620, if the heating element 14 is supplied with AC power of a predetermined frequency different from the fluctuation frequency of the heat flow from the heat source 50, the frequency component data of the frequency (modulation frequency) of the AC power supplied to the heating element 14 may be extracted from the voltage measurement results as described above to reduce noise. Also, when measuring the temperature using the temperature measurement unit 44 shown in Figure 18, the temperature in the heat conduction path 54 should be measured at this timing as shown in S430 of Figure 19.

[0207] S640 (Use of circuit simulator or derivation of circuit equations): In S670, described later, a decision is made on whether to use a circuit simulator or circuit equations to calculate the parameter values ​​of multiple circuit elements of the electrical circuit model 70. If a circuit simulator is used, the electrical circuit model 70 as shown in Figure 26, constructed in S610, is loaded into the circuit simulator. If circuit equations are used, circuit equations are derived from the electrical circuit model 70 constructed in S610 using Kirchhoff's laws, etc. For example, the voltage detector VD of the electrical circuit model 70 in Figure 26 １ , VD ２ We derive a circuit equation that determines the voltage value detected by this process.

[0208] S650 (Selection of weighting target): In S670, described later, when calculating the parameter values ​​of multiple circuit elements of the electrical circuit model 70, it is decided whether or not to perform weighting in order to improve the fitting accuracy of some voltage detectors. If weighting is performed, the voltage detectors VD of the electrical circuit model 70 in Figure 26 that correspond to the two generators 18 whose electromotive force was measured in S630 above are selected. １ , VD ２ From among them, select the voltage detector for which you want to improve fitting accuracy and set it in the calculation processing unit 48. Alternatively, the two voltage detectors VD １ , VD ２ A different weighting is assigned to each component according to the fitting priority, and this is set in the calculation processing unit 48. Note that if the temperature is being measured using the temperature measurement unit 44 shown in Figure 18, weighting may be applied to the voltage monitoring points corresponding to the temperature measurement points, as shown in S450 of Figure 19, or weighting may be applied to any circuit element of the electrical circuit model 70. If weighting is not performed, no action is required here.

[0209] S660 (Optimization Algorithm Selection): This is the same process as S460 in Figure 19, so a detailed explanation is omitted. S670 (Parameter Value Calculation): The calculation processing unit 48 uses the circuit simulator or circuit equation to be used in S640 and the optimization algorithm selected in S660 to calculate the parameter values ​​of multiple circuit elements of the electrical circuit model 70 constructed in S610. First, regarding the case where a circuit simulator is used, in S640, the circuit simulator loaded with the electrical circuit model 70 as shown in Figure 26 is operated. At this time, the DC power supply Vdc1 corresponding to the heat source 50 is set to output a voltage within the expected range, and the DC power supply Vdc2 corresponding to the cooling source 36 is set to output a voltage within the expected range. In addition, the AC power supply Vac corresponding to the heat element 14 is set to output a voltage (amplitude) within the expected range at the same predetermined frequency as the AC power supplied to the heat element 14 in S620.

[0210] Furthermore, the remaining circuit elements of the electrical circuit model 70 are made to reflect, as much as possible, the known thermal conductivity of each component included in the heat conduction path 54 of the thermal circuit model 60. In this state, the circuit simulator is operated, and the two voltage detectors VD of the electrical circuit model 70 as shown in Figure 26 are observed. １ , VD ２ The voltage at is continuously acquired. Then, the electromotive force at the two generators 18 measured in S630 (see Figure 27(a)) and the voltage at the two voltage detectors VD of the electrical circuit model 70 by the circuit simulator are used. １ , VD ２ The parameter values ​​of multiple circuit elements of the electrical circuit model 70 are calculated using the optimization algorithm selected in S660 above, such that the voltages and corresponding elements exhibit similar behavior.

[0211] Next, we will explain the case where the circuit equation derived in S640 above is used, and the voltage detector VD of the derived electrical circuit model 70 １ , VD ２ To find the voltage at the voltage detector VD, the parameter values ​​of each circuit element are applied to the circuit equation as much as possible. １ , VD ２ The voltage is determined. That is, in each circuit equation, the output voltage of the DC power supply Vdc1 corresponding to the heat source 50 is set to a voltage within the assumed range, and the output voltage of the DC power supply Vdc2 corresponding to the cooling source 36 is set to a voltage within the assumed range. Also, in each circuit equation, the output of the AC power supply Vac corresponding to the heat source 14 is set to a voltage (amplitude) within the assumed range at the same predetermined frequency as the AC power supplied to the heat source 14 in S620 above.

[0212] Furthermore, in each circuit equation, the remaining circuit elements of the electrical circuit model 70 are made to reflect, as much as possible, the known thermal conductivity of each component included in the heat conduction path 54 of the thermal circuit model 60. Solving each circuit equation in this state yields the two voltage detectors VD of the electrical circuit model 70 as shown in Figure 26. １ , VD ２The change in voltage over time is determined. Then, the electromotive force at the two generators 18 measured in S630 (see Figure 27(a)) and the voltage at the two voltage detectors VD of the electrical circuit model 70 obtained by solving the circuit equations are used. １ , VD ２ The parameter values ​​of multiple circuit elements of the electrical circuit model 70 are calculated using the optimization algorithm selected in S660 above, such that the voltages and corresponding elements exhibit similar behavior.

[0213] Here, whether using a circuit simulator or circuit equations, if it is decided to weight the circuit in S650, the parameter values ​​of the multiple circuit elements of the electrical circuit model 70 are calculated to reflect this. That is, in S650, the two voltage detectors VD １ , VD ２ If a voltage detector is selected from among the options for which fitting accuracy is to be improved, the parameter values ​​of multiple circuit elements of the electrical circuit model 70 are calculated so that the fitting accuracy of the voltage at the selected voltage detector is improved. Also, in S650 above, two voltage detectors VD １ , VD ２ If different weights are assigned to the fitting priorities, the parameter values ​​of multiple circuit elements of the electrical circuit model 70 are calculated so that they are fitted according to those priorities.

[0214] In addition, if the temperature in the heat conduction path 54 is measured in S630 above, the result of that temperature measurement and the voltage calculated at the voltage monitoring point corresponding to the temperature measurement point may be used as one of the fitting indicators. Furthermore, if weighting is set for such voltage monitoring points, the parameter values ​​of the circuit elements are calculated taking that into account. Also, depending on the configuration of the heat conduction modulation unit 12, there may be one or three or more power generators 18 used as fitting indicators. Figure 27(b) shows an example of the measurement results at the power generator 18 when, for example, the heat conduction modulation unit 12 includes only one power generator 18. S680 (parameter value application) to S710 (heat flux estimation): Since this is the same process as S480 to S510 in Figure 19, a detailed explanation is omitted.

[0215] Now, according to the embodiment of the present invention having the above configuration, the following effects can be obtained. That is, the heat flux measurement method according to the embodiment of the present invention uses a heat flux measurement system 10D, such as the one shown in Figure 23, to measure the heat flux at an arbitrary heat receiving surface of a heat source 50 that has unused thermal energy being discharged. Specifically, as shown in Figure 24, a cooling source 36 controlled to a constant temperature is provided at one end of a heat conduction path 54, and the other end of the heat conduction path 54 is connected to the aforementioned heat receiving surface of the heat source 50, thereby diverting the heat to flow from the heat source 50 toward the cooling source 36 (see S600 in Figure 25). The heat conduction path 54 used at this time shall be made of a material whose properties such as thermal conductivity are known in advance. Furthermore, the heat generating element 14 and the power generating element 18 are installed in the heat conduction path 54, that is, between one end of the heat conduction path 54 where the cooling source 36 is installed and the other end of the heat conduction path 54 connected to the heat source 50. The heat-generating element 14 to be installed should be one that can be controlled so that the amount of heat generated fluctuates when fluctuating heating energy is applied, and multiple heat-generating elements 14 may be installed. In addition, the power generator 18 to be installed should be one that generates an electromotive force by the Seebeck effect, which generates voltage from a temperature difference, and multiple power generators 18 may be installed.

[0216] Furthermore, an electrical circuit model 70 including multiple circuit elements, as shown in Figure 26, is virtually constructed, corresponding to the actual thermal circuit model 60 from the heat source 50, including the heat conduction path 54 described above, to the cooling source 36 (see S610 in Figure 25). At this time, the temperature, heat flux, and thermal resistance in the thermal circuit model 60 are made to correspond to the voltage, current, and resistance in the electrical circuit model 70. That is, the multiple circuit elements of the electrical circuit model 70 include resistors corresponding to the thermal resistance that represents the difficulty of heat transfer in the thermal circuit model 60, and power supplies corresponding to the heat source 50, heat generating element 14, and cooling source 36 that generate heat in the thermal circuit model 60. Furthermore, considering that the power generator 18 in the thermal circuit model 60 generates voltage in response to a temperature difference, the voltage detector VD in the electrical circuit model 70 is also included. １ , VD ２This is then made to correspond to the actual thermal circuit model 60, while varying the amount of heat generated from the heat-generating element 14 (see S620 in Figure 25), the electromotive force at the power generator 18 is continuously measured (see S630 in Figure 25). That is, with heat flowing from the heat-receiving surface of the heat source 50 toward the cooling source 36, fluctuating heat is also supplied from the heat-generating element 14, and the electromotive force generated by the Seebeck effect due to the influence of the heat flowing through the power generator 18 is continuously measured to obtain the time-series electromotive force measurement results at the power generator 18 (see Figure 27).

[0217] Furthermore, the electrical circuit model 70 corresponding to the thermal circuit model 60 is virtually operated by setting each power supply to the operating state, and in this state, the voltage detector VD corresponding to the power generator 18 of the thermal circuit model 60 in the electrical circuit model 70 is set. １ , VD ２ The voltage is obtained at the following point. Then, the measured electromotive force at the generator 18 in the actual thermal circuit model 60 and the voltage detector VD in the virtual electrical circuit model 70 are obtained. １ , VD ２ The parameter values ​​of multiple circuit elements in the electrical circuit model 70 are calculated so that the detected voltage exhibits similar behavior (fits) (see S670 in Figure 25).

[0218] The electrical circuit model 70 to which the multiple parameter values ​​calculated as described above are applied exhibits the same behavior as the actual thermal circuit model 60. In the actual thermal circuit model 60, the heat source 50 and its thermal resistance are unknown, and all other circuit parameters are irrelevant to the heat source 50. Therefore, considering that the thermal conductivity of the material forming the heat conduction path 54 is known, the parameter values ​​of the circuit elements in the electrical circuit corresponding to them can be fixed to optimal values. Moreover, the temperature characteristics of the thermoelectric conversion material forming the power generator 18 can be reflected in the obtained parameter values. As a result, using the electrical circuit model 70 to which the calculated parameter values ​​are applied, the heat flux at the heat receiving surface of the heat source 50 can be easily estimated regardless of whether it is in a transient or steady state, without using sensitivity coefficients as in conventional methods (see S710 in Figure 25). Furthermore, if necessary, the thermal conductance and thermal resistance at the heat receiving surface of the heat source 50 can also be easily estimated.

[0219] Here, the heat flux measurement method according to the embodiment of the present invention, compared to the heat flux measurement method described with reference to Figure 19, measures the electromotive force generated by the power generator 18 instead of measuring the temperature in the actual thermal circuit model 60. Furthermore, considering measurements in an actual field environment, there is concern that temperature measurement results using thermocouples and the like will contain a lot of noise, but the Seebeck electromotive force measured by the power generator 18 is less affected by noise in the field environment (see Figure 17). For this reason, the calculation accuracy of the parameter values ​​of multiple circuit elements calculated using such a Seebeck electromotive force can be improved, and consequently, the calculation accuracy of the heat flux, thermal conductance, and thermal resistance at the heat receiving surface of the heat source 50 can also be improved.

[0220] On the other hand, the heat flux measurement system 10D according to an embodiment of the present invention, as shown in Figures 23 and 24, measures the heat flux on a heat receiving surface per unit area that can be collected from a heat source 50 having unused thermal energy, and includes a heat conduction modulation unit 12, a cooling source 36, a heat-generating element control unit 40, an electromotive force measurement unit 46, and a calculation processing unit 48. The heat conduction modulation unit 12 has a configuration in which at least one (one in Figure 23) heat-generating element 14 and at least one (two in Figure 23) power-generating element 18 are alternately sandwiched by at least three (four in Figure 23) heat-conducting media 16.

[0221] The heat-generating element 14 is controllable so that its heat output fluctuates, the power-generating element 18 generates an electromotive force by the Seebeck effect, and at least three heat-conducting media 16 are made of materials with known thermal conductivity. The heat conduction modulation unit 12, configured in this way, is installed so that heat is conducted from any heat-receiving surface of the heat source 50 to be measured to one of the at least three heat-conducting media 16. The cooling source 36 has a lower temperature than the heat source 50 to be measured and is installed so that heat is conducted from the other of the at least three heat-conducting media 16. In other words, the heat conduction modulation unit 12 and the cooling source 36 are installed as part of a heat conduction path 54 that diverts heat from the heat source 50 so that heat flows from the heat source 50 to the cooling source 36.

[0222] The heating element control unit 40 controls at least one heating element 14 of the heat conduction modulation unit 12, and controls the heating element 14 so that the amount of heat generated from the heating element 14 fluctuates by supplying fluctuating heating energy to the heating element 14. The electromotive force measurement unit 46 measures the electromotive force at the power generator 18, which is generated by the temperature difference applied to the power generator 18 through the heat conduction medium 16 that sandwiches the power generator 18. The calculation processing unit 48 performs various calculation processes in this system 10D, and as part of these, it performs the following calculation. That is, the calculation processing unit 48 virtually constructs an electrical circuit model 70 including multiple circuit elements, corresponding to the thermal circuit model 60 from the heat source 50 including the heat conduction modulation unit 12 to the cooling source 36, in the same manner as the heat flux measurement method described above (see S610 in Figure 25).

[0223] Furthermore, the calculation processing unit 48 calculates the electromotive force generated by the power generator 18 in the actual thermal circuit model 60 and the voltage detector VD corresponding to the power generator 18 in the operating electrical circuit model 70. １ , VD ２ The parameter values ​​of multiple circuit elements in the electrical circuit model 70 are calculated in the same manner as the heat flux measurement method described above, so that the voltages at the power source exhibit similar behavior (see S670 in Figure 25). The electromotive force at the power generator 18 of the thermal circuit model 60 used at this time is the electromotive force continuously measured by the electromotive force measurement unit 46 while the amount of heat generated from at least one heat source 14 is varied by the heat source control unit 40, and the electrical circuit model 70 is virtually operated by setting each power source to the operating state. Furthermore, the calculation processing unit 48 uses the electrical circuit model 70 to which the parameter values ​​calculated above have been applied to estimate the heat flux, thermal conductance, and thermal resistance at the heat receiving surface of the heat source 50 (see S710 in Figure 25). This makes it possible to achieve the same effects as the heat flux measurement method described above.

[0224] In the embodiments described above, the temperature measurement unit 44 measures the temperature at the necessary locations. However, in a real environment where a heat source 50 with unused thermal energy is located, a large number of noise components are superimposed on the measured temperature. Therefore, when using these measured temperatures, various noise reduction techniques, such as a sub-goal filter, should be employed to remove as much noise as possible. For example, noise reduction is performed as a pre-processing step for steps S50 in Figure 7, S200 and S230 in Figure 13, and S470 and S500 in Figure 19.

[0225] Furthermore, in actual field environments, temperature changes exhibit transient responses and are constantly accompanied by large fluctuations rather than being in a steady state. When temperatures are measured at multiple points, they are not typically synchronized, requiring processing that considers both the temperature at the same time and the heat propagation delay value. Incorrect processing can lead to overestimating the temperature drop when the temperature is rising, and underestimating it when the temperature is falling. Therefore, calculations that consider the heat propagation rate are necessary, and corrections should be made between observation times.

[0226] Although various embodiments of the present invention have been described above, these are illustrative examples, and the present invention is not limited to these embodiments. The components, processing content, conditions, numerical ranges, etc., described in each embodiment can be modified, substituted, added, or omitted as appropriate, within the scope that does not contradict the technical principles, and it is also possible to implement the invention by arbitrarily combining components from multiple embodiments. All of these modifications, variations, and combinations are within the scope of the technical idea of ​​the present invention.

[0227] 10 (10A-10D): Heat flux measurement system, 12: Thermal conduction modulation unit, 14 (14A, 14B): Heat-generating element, 16 (16A-16F): Thermal conduction medium, 18: Power generator, 36: Cooling source, 40: Heat-generating element control unit, 44: Temperature measurement unit, 46: Electromotive force measurement unit, 48: Calculation processing unit, 50: Heat source, 54: Heat conduction path, 60: Thermal circuit model, 70: Electrical circuit model, W: Heating energy, P: AC power (modulated power), TW: First temperature (temperature in modulated state), T0: Second temperature (temperature in unmodulated state), ΔT: Difference between first and second temperature (temperature change data)

Claims

1. A method for measuring the heat flux of a heat source's heat receiving surface, comprising: connecting the other end of a heat conduction path, one end of which is provided with a cooling source controlled to a constant temperature, to an arbitrary heat receiving surface of the heat source; installing a heating element that can be controlled to vary the amount of heat generated by applying fluctuating heating energy, and a power generator that generates an electromotive force by the Seebeck effect, in the heat conduction path; measuring the temperature in the heat conduction path and the electromotive force at the power generator to obtain a first temperature and a first electromotive force when the heat source is being affected by the heating element, and a second temperature and a second electromotive force when it is not being affected; calculating the thermal conductance at the heat receiving surface based on the difference between the first temperature and the second temperature and the heating energy when the first temperature was measured; and calculating the heat flux at the heat receiving surface based on the difference between the first electromotive force and the second electromotive force and the heating energy when the first electromotive force was measured.

2. The heat flux measurement method according to claim 1, characterized in that a Peltier element is used as the heating element and the power generator, AC power of a predetermined frequency different from the fluctuation frequency of the heat flow from the heat source is supplied as the heating energy, data of the frequency component of the predetermined frequency is extracted from the calculation result of the difference between the first temperature and the second temperature, the thermal conductance at the heat receiving surface is calculated based on the extracted result, data of the frequency component of the predetermined frequency is extracted from the calculation result of the difference between the first electromotive force and the second electromotive force, and the heat flux at the heat receiving surface is calculated based on the extracted result.

3. The heat flux measurement method according to claim 2, characterized in that two heat conduction paths, each having a heating element and a power generator installed, are connected to two heat receiving surfaces set at different locations on the heat source; AC power synchronized at the same predetermined frequency but with different phases is applied to the heating element in one heat conduction path and the heating element in the other heat conduction path; and the heat conductance and heat flux within the heat source are calculated based on the heat conductance and heat flux calculated from one heat conduction path and the heat conductance and heat flux calculated from the other heat conduction path.

4. A method for measuring the heat flux on a heat receiving surface of a heat source, comprising: connecting the other end of a heat conduction path, one end of which is provided with a cooling source controlled to a constant temperature, to an arbitrary heat receiving surface of the heat source; installing a power generator that generates an electromotive force by the Seebeck effect in the heat conduction path; measuring the temperature in the heat conduction path and the electromotive force at the power generator; calculating the heat flux passing through the power generator based on the measurement results and the temperature dependence of the material properties of the thermoelectric conversion material used in the power generator, which have been determined in advance; and calculating the heat flux at the heat receiving surface based on the calculation results.

5. The heat flux measurement method according to claim 4, characterized in that the temperature dependence of the material properties of the thermoelectric conversion material is determined by using the temperature characteristics of the Seebeck coefficient of the thermoelectric conversion material and the temperature characteristics of the thermal conductivity of the thermoelectric conversion material.

6. The heat flux measurement method according to claim 4, characterized in that, taking into account the temperature dependence of the material properties of the thermoelectric conversion material, the relationship between the temperature in the heat conduction path, the electromotive force at the power generator, and the heat flux passing through the power generator is determined in advance by formulating or creating a table, and the heat flux passing through the power generator is calculated by applying the measured results of the temperature in the heat conduction path and the electromotive force at the power generator to the formulated or table-formulated relationship.

7. A method for measuring the heat flux on a heat receiving surface of a heat source, comprising: connecting the other end of a heat conduction path, one end of which is provided with a cooling source controlled to a constant temperature, to an arbitrary heat receiving surface of the heat source; installing a heating element in the heat conduction path that can be controlled to vary the amount of heat generated by applying fluctuating heating energy; virtually constructing an electrical circuit model including a plurality of circuit elements corresponding to a thermal circuit model from the heat source to the cooling source, including the heat conduction path; corresponding the temperature, heat flux, and thermal resistance in the thermal circuit model to the voltage, current, and resistance in the electrical circuit model; continuously measuring the temperature at a temperature measurement point in the heat conduction path while varying the amount of heat generated from the heating element; calculating parameter values ​​for the plurality of circuit elements in the electrical circuit model such that the measurement results and the voltage at a voltage monitoring point corresponding to the temperature measurement point in the thermal circuit model in the operating state exhibit similar behavior; and estimating the heat flux on the heat receiving surface using the electrical circuit model to which the calculated parameter values ​​have been applied.

8. A method for measuring the heat flux of a heat source's heat receiving surface, comprising: connecting the other end of a heat conduction path, one end of which is provided with a cooling source controlled to a constant temperature, to an arbitrary heat receiving surface of the heat source; installing a heating element that can be controlled to vary the amount of heat generated by applying fluctuating heating energy, and a power generator that generates an electromotive force by the Seebeck effect, in the heat conduction path; virtually constructing an electrical circuit model including a plurality of circuit elements corresponding to a thermal circuit model from the heat source to the cooling source including the heat conduction path; at this time, corresponding the temperature, heat flux, and thermal resistance in the thermal circuit model to the voltage, current, and resistance in the electrical circuit model, and corresponding the power generator to a voltage detector; continuously measuring the electromotive force in the power generator while varying the amount of heat generated from the heating element; and calculating the parameter values ​​of the plurality of circuit elements in the electrical circuit model such that the measurement result and the voltage at the voltage detector in the operating electrical circuit model exhibit similar behavior. A method for measuring heat flux, characterized by estimating the heat flux at the heat receiving surface using the electrical circuit model to which the calculated parameter values ​​are applied.

9. The heat flux measurement method according to claim 7 or 8, characterized in that, when measuring the temperature in the heat conduction path or the electromotive force in the power generator, AC power of a predetermined frequency is supplied to the heating element as the heating energy, and when constructing the electrical circuit model, the heat source and the cooling source are made to correspond to a DC power source, and the heating element is made to correspond to an AC power source that outputs AC power of the predetermined frequency.

10. The heat flux measurement method according to claim 7 or 8, characterized in that when calculating the parameter values, the circuit simulator into which the electrical circuit model is loaded and the optimization algorithm are used to calculate the parameter values.

11. The heat flux measurement method according to claim 7 or 8, characterized in that the parameter values ​​are calculated using the circuit equations derived from the electrical circuit model and the optimization algorithm.

12. The heat flux measurement method according to claim 7, characterized in that when measuring the temperature in the heat conduction path, the temperatures of a plurality of temperature measurement points are measured, and when calculating the parameter values, the measurement results at each of the plurality of temperature measurement points and the voltages at the voltage measurement points corresponding to each of the plurality of temperature measurement points in the operating state of the electrical circuit model are calculated to exhibit similar behavior.

13. The heat flux measurement method according to claim 12, characterized in that when calculating the parameter value, weighting is applied to a specific voltage measurement point among the plurality of voltage measurement points of the electrical circuit model corresponding to the plurality of temperature measurement points.

14. A system for measuring the heat flux at the heat receiving surface of a heat source, comprising: a configuration in which a heat element that can be controlled to vary the amount of heat generated and a power generation element that generates an electromotive force by the Seebeck effect are alternately sandwiched between three heat conducting media formed of a material with known thermal conductivity, the system comprising: a heat conduction modulation unit installed so as to conduct heat from any heat receiving surface of the heat source to one of the three heat conducting media; a cooling source having a constant temperature lower than the heat source and installed so as to conduct heat from the other of the three heat conducting media; a heat element control unit that controls the heat element by supplying fluctuating heating energy to the heat element; a temperature measurement unit that measures the temperature of a temperature measurement point set at a predetermined position on at least one of the three heat conducting media; an electromotive force measurement unit that measures the electromotive force in the power generation element; and a calculation processing unit that performs calculation processing, the calculation processing unit A heat flux measurement system characterized by calculating the difference between a first temperature when affected by the heat generated by the heat source and a second temperature when not affected by the heat source, based on the measurement results of the temperature measurement unit, calculating the thermal conductance at the heat receiving surface based on the difference and the heating energy when the first temperature was measured, and calculating the difference between a first electromotive force when affected by the heat generated by the heat source and a second electromotive force when not affected by the heat source, based on the measurement results of the electromotive force measurement unit, and calculating the heat flux at the heat receiving surface based on the difference and the heating energy when the first electromotive force was measured.

15. The heat flux measurement system according to claim 14, characterized in that the heating element and the power generator are Peltier elements, the heating element control unit provides AC power of a predetermined frequency different from the fluctuation frequency of the heat flow from the heat source as the heating energy, the calculation processing unit extracts data of the frequency component of the predetermined frequency from the calculation result of the difference between the first temperature and the second temperature, calculates the thermal conductance on the heat receiving surface based on the extraction result, extracts data of the frequency component of the predetermined frequency from the calculation result of the difference between the first electromotive force and the second electromotive force, and calculates the heat flux on the heat receiving surface based on the extraction result.

16. A system for measuring the heat flux at the heat receiving surface of a heat source, comprising: a configuration in which a power generation body that generates an electromotive force by the Seebeck effect is sandwiched between two heat conducting media formed of a material with known thermal conductivity, the system comprising: a heat conduction modulation unit installed so as to conduct heat from an arbitrary heat receiving surface of the heat source to one of the two heat conducting media; a cooling source having a constant temperature lower than the heat source and installed so as to conduct heat from the other of the two heat conducting media; a temperature measurement unit that measures the temperature of a temperature measurement point set at a predetermined position on at least one of the two heat conducting media; an electromotive force measurement unit that measures the electromotive force in the power generation body; and a calculation processing unit that performs calculation processing, wherein the calculation processing unit calculates the heat flux passing through the power generation body based on the measurement result from the temperature measurement unit, the measurement result from the electromotive force measurement unit, and the temperature dependence of the material properties of the thermoelectric conversion material used in the power generation body, which are set in advance. A heat flux measurement system characterized by calculating the heat flux at the heat receiving surface based on the calculation result.

17. A system for measuring the heat flux at the heat receiving surface of a heat source, comprising: a configuration in which at least one heating element capable of controlling the amount of heat generated is sandwiched between at least two heat conducting media formed of a material with known thermal conductivity, the system comprising: a heat conduction modulation unit installed so as to conduct heat from any heat receiving surface of the heat source to one of the at least two heat conducting media; a cooling source having a constant temperature lower than the heat source and installed so as to conduct heat from the other of the at least two heat conducting media; a heating element control unit that controls the at least one heating element by supplying fluctuating heating energy to the at least one heating element; a temperature measurement unit that measures the temperature of a temperature measurement point set at a predetermined position on at least one of the at least two heat conducting media; and a calculation processing unit that performs calculation processing, the calculation processing unit A heat flux measurement system characterized by: virtually constructing an electrical circuit model including a plurality of circuit elements corresponding to a thermal circuit model from the heat source including the heat conduction modulation unit to the cooling source; corresponding the temperature, heat flux, and thermal resistance in the thermal circuit model to the voltage, current, and resistance in the electrical circuit model; calculating the parameter values ​​of the plurality of circuit elements in the electrical circuit model so that the temperature at the temperature measurement point, continuously measured by the thermometer side, and the voltage at the voltage monitoring point corresponding to the temperature measurement point in the operating electrical circuit model exhibit similar behavior while the amount of heat generated from at least one heat source is varied by the heat generation control unit; and estimating the heat flux at the heat receiving surface using the electrical circuit model to which the calculated parameter values ​​have been applied.

18. A system for measuring the heat flux at the heat receiving surface of a heat source, comprising: a configuration in which at least one heating element capable of controlling the amount of heat generated to vary and at least one power generation element that generates an electromotive force by the Seebeck effect are alternately sandwiched between at least three heat conducting media formed of a material with known thermal conductivity, the system comprising: a heat conduction modulation unit installed so as to conduct heat from any heat receiving surface of the heat source to one of the at least three heat conducting media; a cooling source having a constant temperature lower than the heat source and installed so as to conduct heat from the other of the at least three heat conducting media; a heating element control unit that controls the at least one heating element by supplying it with fluctuating heating energy; an electromotive force measurement unit that measures the electromotive force at the at least one power generation element; and a calculation processing unit that performs calculation processing, the calculation processing unit A heat flux measurement system characterized by virtually constructing an electrical circuit model including a plurality of circuit elements corresponding to a thermal circuit model from the heat source including the heat conduction modulation unit to the cooling source, and at this time, the temperature, heat flux, and thermal resistance in the thermal circuit model are made to correspond to the voltage, current, and resistance in the electrical circuit model, and the at least one power generator is made to correspond to a voltage detector, and the parameter values ​​of the plurality of circuit elements in the electrical circuit model are calculated such that the electromotive force in the at least one power generator, which is continuously measured by the electromotive force measurement unit while the amount of heat generated from the at least one heat generator is fluctuating by the heat generation control unit, and the voltage at the voltage detector in the operating electrical circuit model exhibit similar behavior, and the heat flux at the heat receiving surface is estimated using the electrical circuit model to which the calculated parameter values ​​are applied.

Images