Thermal conductance measurement method and thermal conductance measurement system

Abstract

To grasp the heat conductance of a heat source and contribute to the effective utilization of unused heat energy.SOLUTION: The other end of a heat conduction path having a cooling source at one end is connected to a heat source which is the object to be measured (S10). A heater element controllable so as to cause a generated heat amount to change by adding fluctuating heating energy is installed in the heat conduction path, the temperature in the heat conduction path is measured, and a first temperature when affected by heat generation by the heater element and a second temperature when unaffected are acquired (S30, S50). On the basis of the difference between the first and the second temperatures (S60) and the heating energy at the time the first temperature is measured, the heat conductance of the heat source is calculated (S80). Thus, since the heat conductance of the heat source can be calculated without the need for grasping the specific heat or mass or the like of the heat source, it is possible to contribute to effective utilization of the unused heat energy that the heat source possesses.SELECTED DRAWING: Figure 4

Description

[Technical Field]

[0001] The present invention relates to a thermal conductance measurement method and a thermal conductance measurement system for measuring the thermal conductance of a heat source. [Background technology]

[0002] For example, thermal energy is discarded as waste heat in industrial plants that handle thermal energy, various devices that use heat sources, combustion devices, internal combustion engines, incinerators, hot spring water flow paths, exhaust ducts, chimneys, steam pipes, etc. Research into the effective use of such unused thermal energy has been conducted for some time (see, for example, Patent Documents 1 and 2), but a large amount of thermal energy is still being released into the atmosphere, which is one of the causes of global warming and other issues. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 5299324 [Patent Document 2] Japanese Patent Application Laid-Open No. 2014-174027 Summary of the Invention [Problem to be solved by the invention]

[0004] To effectively utilize unused thermal energy from a heat source, it is effective to conduct a simulation based on basic information such as the heat receiving area and amount of heat received per unit area of ​​the high-temperature heat source where a heat exchanger or the like is attached, the heat dissipation on the cold heat source side, and information on the heat exhaust system. The most important factor in such a simulation is the thermal conductance at the heat receiving point, which represents the thermal resistance of the heat source, and is necessary to measure and estimate the amount of heat received through a heat exchanger or the like in advance. However, the importance of thermal conductance in effectively utilizing unused thermal energy has been overlooked. The present invention has been made in view of the above-mentioned problems, and its object is to grasp the thermal conductance of a heat source and contribute to the effective use of unused thermal energy. [Means for solving the problem]

[0005] (Aspects of the invention) The following embodiments of the present invention are examples of the configuration of the present invention and are described in terms to facilitate understanding of the various configurations of the present invention. Each term does not limit the technical scope of the present invention. Therefore, while taking into consideration the best mode for carrying out the invention, some of the components of each term may be replaced or deleted, or other components may be added, and these may also be included in the technical scope of the present invention.

[0006] (1) A method for measuring the thermal conductance of a heat source, comprising: connecting one end of a heat conduction path having a cooling source at the other end to the heat source; placing a heat generating element in the heat conduction path that can be controlled so that the amount of heat generated varies when a varying heating energy is applied; measuring the temperature in the heat conduction path to obtain a first temperature when the heat generated by the heat generating element is affected; and a second temperature when the heat source is not affected; and calculating the thermal conductance of the heat source based on the difference between the first temperature and the second temperature and the heating energy used when the first temperature was measured.

[0007] The thermal conductance measurement method described in this section measures the thermal conductance of a heat source having unused thermal energy that is being discarded. Specifically, a heat conduction path having a cooling source at one end is connected to the heat source at the other end, thereby diverting heat so that it flows from the heat source toward the cooling source. The heat conduction path used in this case is formed of a material whose properties, such as thermal conductivity, are known in advance. Furthermore, a heating element is installed in the heat conduction path, i.e., 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 installed heating element is one that can be controlled so that the amount of heat generated varies when a varying heating energy is applied. Here, the heat conduction path on which the heating element is installed in advance may be connected to the heat source.

[0008] Furthermore, the temperature in the heat conduction path configured as described above is measured to obtain a first temperature when the heat conduction path is affected by the heat generated by the heating element and a second temperature when the heat conduction path is not affected by the heat generated by the heating element. Here, the first temperature may be a temperature measured in the heat conduction path when the heating element is controlled to vary its heat output. Depending on the circumstances, the second temperature may be calculated from the first temperature measurement result to eliminate the influence of heat generated by the heating element, or may be a temperature measured in the heat conduction path when the heating element is not generating heat. Next, the difference between the first and second temperatures obtained as described above is calculated to extract temperature change data that has changed due to the influence of the fluctuating heat generated by the heating element. The thermal conductance of the heat source is then calculated based on the extracted temperature change data and the heating energy applied to the heating element when the first temperature was measured.

[0009] Regarding the relationship between heat quantity and temperature, in the range of infinitesimal temperature change without phase change, heat quantity is proportional to temperature, with mass and specific heat as constants. Therefore, considering that the addition of heat energy results in no change in mass or specific heat but an increase in temperature equal to the temperature change data, the "product of mass and specific heat" can be expressed as the value obtained by dividing the "heat quantity without receiving heat energy" by the "temperature without receiving heat energy (second temperature)," or the value obtained by dividing the "heat quantity with receiving heat energy" by the "temperature with receiving heat energy (first temperature)." Furthermore, if radiation and thermal conduction, which create errors, are so small that they can be ignored, 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.

[0010] Furthermore, because thermal resistance is the temperature difference between two points divided by the heat flow rate (amount of heat flowing per unit time) between the two points, the temperature change data can be expressed as a value divided by the heating energy in the above relationship. Furthermore, because this thermal resistance includes all thermal resistances from the heat source to the heat conduction path, thermal conductance can be expressed as the reciprocal of thermal resistance, and considering the heat-receiving area of ​​the heat conduction path, it is clear that the thermal conductance per unit area can be calculated from the temperature change data and heating energy. This allows the thermal conductance of a heat source to be calculated based on the temperature change data caused by the heating element and the heating energy applied to the heating element at that time, without the need to know the specific heat or mass of the heat source. Knowing the thermal conductance in this way contributes to the effective utilization of unused thermal energy in the heat source. Furthermore, thermal conductance can be determined even when internal information about the heat source, such as its specific heat, pressure, or density, is unknown, or even when the pressure and density fluctuate over time.

[0011] (2) In the above (1), a Peltier element is used as the heat generating element, 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, and the thermal conductance of the heat source is calculated based on the extraction result. The thermal conductance measurement method described in this section utilizes a Peltier element as a heating element installed in a heat conduction path. Furthermore, AC power of a predetermined frequency is applied to the Peltier element as heating energy, thereby fluctuating the amount of heat generated by the Peltier element in an AC manner. The predetermined frequency of the AC power is set to a frequency different from the fluctuating frequency of the heat flow from the heat source to the heat conduction path.

[0012] Then, after calculating the difference between the first temperature when affected by heat generation from the heating element and the second temperature when not affected by heat generation from the heating element, data on the frequency component of the above-mentioned predetermined frequency is extracted from the calculation result.The thermal conductance of the heat source is calculated based on the temperature difference data extracted in this way and the AC power applied to the Peltier element.That is, by applying modulation power to the Peltier element with a frequency different from the fluctuation frequency of the heat flow from the heat source, and extracting and using data on the frequency component of that modulation frequency, the thermal conductance is calculated while eliminating the fluctuation component of the heat flow, etc.This allows for more accurate calculation of the thermal conductance.

[0013] (3) In the above (1) or (2), when calculating the thermal conductance of the heat source, a total thermal resistance from the heat source to the heat conduction path is calculated based on the difference between the first temperature and the second temperature and the heating energy when the first temperature is measured, and the thermal conductance measurement method calculates the thermal resistance inside the heat source based on the total thermal resistance. The thermal conductance measurement method described in this section measures the thermal resistance inside the heat source in addition to the thermal conductance of the heat source. As mentioned in section (1) above, the thermal resistance calculated from the temperature change data (the difference between the first temperature and the second temperature) and the heating energy (the heating energy used when measuring the first temperature) is the total thermal resistance, including all thermal resistances from the heat source to the heat conduction path. That is, this total thermal resistance includes the thermal resistance inside the heat source, whose information such as specific heat, pressure, and physical density is unknown, the thermal resistance of the heat-receiving portion of the heat conduction path, which is made of a material with known properties such as thermal conductivity, and the thermal resistance of the heat-conducting portion of the heat conduction path. Therefore, the thermal resistance inside the heat source is calculated based on the total thermal resistance and the thermal resistance of the heat conduction path, which is known because it is made of a material with known properties such as thermal conductivity. As a result, even if the information inside the heat source is unknown, the thermal resistance inside the heat source can be determined from the calculated total thermal resistance and the known thermal resistance information.

[0014] (4) A system for measuring the thermal conductance of a heat source, comprising: a heat generating element that can be controlled to vary the amount of heat generated, sandwiched between two heat conducting media made of materials with known thermal conductivities; a heat conduction modulation unit that is installed so that heat is conducted from the heat source to one of the two heat conducting media; a cooling source that has a lower temperature than the heat source and is installed so that heat is conducted from the other of the two heat conducting media; a heat generating element control unit that controls the heat generating element by applying varying heating energy to the heat generating element; a temperature measurement unit that measures the temperature of a temperature measurement point set at a predetermined position on either or both of the two heat conducting media; and a calculation processing unit that performs calculation processing, wherein the calculation processing unit calculates, from the measurement results of the temperature measurement unit, a difference between a first temperature when affected by heat generated by the heat generating element and a second temperature when not affected, and calculates the thermal conductance of the heat source based on the difference and the heating energy when the first temperature was measured.

[0015] The thermal conductance measurement system described herein measures the thermal conductance per unit area of ​​a heat-receiving surface that can be extracted from a heat source having unused thermal energy. It includes a thermal conductance modulation unit, a cooling source, a heating element control unit, a temperature measurement unit, and a calculation processing unit. The thermal conductance modulation unit has a configuration in which a heating element is sandwiched between two thermally conductive media, and the heating element is controllable so that its heat generation amount varies. The two thermally conductive media are formed of materials with known thermal conductivities. The thermal conductance modulation unit configured as described above is installed so that heat is conducted from the heat source to one of the two thermally conductive 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 two thermally conductive media. In other words, the thermal conductance modulation unit and the cooling source are installed as part of a heat conduction path that shunts heat from the heat source so that heat flows from the heat source to the cooling source.

[0016] The heating element control unit controls the heating element of the thermal conduction modulation unit, and controls the heating element so that the amount of heat generated by the heating element varies by providing the heating element with fluctuating heating energy. The temperature measurement unit measures the temperature at the temperature measurement point, which is set at a predetermined position on either or both of the two thermal conduction media of the thermal conduction modulation unit. The calculation processing unit performs various calculation processes in this system, and as part of these processes, performs the following calculations. That is, the calculation processing unit obtains, from the measurement results of the temperature measurement point by the temperature measurement unit, a first temperature when affected by heat generated by the heating element and a second temperature when not affected by heat generated by the heating element, as described in section (1) above. Then, by calculating the difference between these values, temperature change data that has changed due to the influence of the fluctuating heat generated by the heating element is extracted.

[0017] Furthermore, the calculation processing unit calculates the thermal conductance of the heat source to be measured, as described in (1) above, based on the extracted temperature change data and the heating energy applied to the heat source by the heat source control unit when the temperature measurement unit measures the first temperature. This allows the thermal conductance of the heat receiving surface that 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, since the structure shunts heat from the heat source to be measured through a heat conduction path including a thermal conduction modulation unit and a cooling source and measures the temperature at the thermal conduction modulation unit in the heat conduction path, it is possible to measure heat sources in various environments, including heat sources through which corrosive gases and gas-liquid mixtures with fluctuating medium densities flow. Furthermore, there is no need to consider durability, such as corrosion, and durability and reliability are significantly improved.

[0018] (5) In the thermal conductance measurement system according to the above paragraph (4), the heating element is a Peltier element, the heating element control unit applies AC power of a predetermined frequency different from a fluctuation frequency of the heat flow from the heat source as the heating energy, and the calculation processing unit extracts data of a frequency component of the predetermined frequency from a calculation result of the difference between the first temperature and the second temperature, and calculates the thermal conductance of the heat source based on the extraction result. In the thermal conductance measurement system described in this section, the heating element of the thermal conduction modulation unit is a Peltier element, and the heating energy provided to this Peltier element from the heating element control unit is AC power of a predetermined frequency, so that the amount of heat generated by the Peltier element fluctuates in an AC manner. The predetermined frequency of the AC power in this case is set to a frequency different from the fluctuating frequency of the heat flow flowing from the heat source to the thermal conduction modulation unit, etc.

[0019] The calculation processor then calculates the difference between the first temperature when affected by heat generation from the heating element and the second temperature when not affected by heat generation from the heating element, and extracts data on the frequency component of the above-mentioned predetermined frequency from the calculation result. Furthermore, the calculation processor calculates the thermal conductance of the heat source based on the extracted temperature difference data and the AC power applied to the Peltier element from the heating element control unit. That is, as mentioned in (2) above, by applying modulation power to the Peltier element at a frequency different from the fluctuation frequency of the heat flow from the heat source and extracting and using data on the frequency component of that modulation frequency, the thermal conductance is calculated while eliminating fluctuation components of the heat flow. This allows the thermal conductance to be calculated more accurately.

[0020] (6) In the above item (4), at least three temperature measurement points are set on the one heat conduction medium at intervals along the direction of heat conduction from the heat source, and the calculation processing unit uses the temperatures measured at the at least three temperature measurement points by the temperature measurement unit and the intervals between the at least three temperature measurement points to determine whether the heat flow from the heat source is in a steady state, and calculates the thermal conductance of the heat source if it is determined to be in a steady state. In the thermal conductance measurement system described in this section, at least three temperature measurement points are set in one of the two thermal conduction media of the thermal conduction modulation unit, which is to be arranged on the heat source side. These at least three temperature measurement points are set at intervals in the one thermal conduction medium along the conduction direction of heat flowing from the heat source.

[0021] The calculation processor then uses the temperatures measured by the temperature measurement unit at the at least three temperature measurement points and the spacing between the at least three temperature measurement points to determine whether the heat flow from the heat source is in a steady state. That is, the temperatures measured at the at least three temperature measurement points, all set on one heat conduction medium, are considered to decrease linearly from the heat source side depending on the spacing between the temperature measurement points, provided that the heat flow from the heat source is in a steady state rather than a transient state. For example, if there are three temperature measurement points set at equal intervals, and the heat flow from the heat source is in a steady state, the temperature difference between the temperature measurement point on the heat source side and the central temperature measurement point is considered to be approximately equal to the temperature difference between the central temperature measurement point and the temperature measurement point on the cooling source side. Therefore, the calculation processor uses this relationship to determine whether the heat flow from the heat source is in a steady state, and calculates the thermal conductance if it is determined to be in a steady state. This prevents thermal conductance from being measured even when the heat flow from the heat source is in a transient state, and thermal conductance is measured only when the heat flow is in a steady state, thereby improving the reliability of thermal conductance measurements.

[0022] (7) In the above item (4), at least one temperature measurement point is set in one of the heat conduction media, and at least one temperature measurement point is set in the other heat conduction medium, and the calculation processing unit determines whether the amount of heat passing through the heat conduction modulation unit is normal or not based on the magnitude relationship between the temperature measured by the temperature measurement unit at the temperature measurement point of one of the heat conduction media and the temperature measured at the temperature measurement point of the other heat conduction medium, and calculates the thermal conductance of the heat source if it is determined to be normal. In the thermal conductance measurement system described in this section, at least one temperature measurement point is set in one of the two thermal conduction media of the thermal conduction modulation unit, which is to be placed on the heat source side, and at least one temperature measurement point is set in the other thermal conduction medium, which is to be placed on the cooling source side.The calculation processing unit then determines whether the amount of heat passing through the thermal conduction modulation unit is normal based on the magnitude relationship between the temperature measured by the temperature measurement unit at the temperature measurement point of one of the thermal conduction media and the temperature measured at the temperature measurement point of the other thermal conduction medium.

[0023] That is, if the amount of heat passing through the thermal conduction modulation unit is normal, the temperature measured at the temperature measurement point of one of the heat conduction media on the heat source side will be higher than the temperature measured at the temperature measurement point of the other heat conduction media on the cooling source side. On the other hand, if the amount of heat passing through the heat source is insufficient or if the influence of the heat source is transient, the temperature measured at the temperature measurement point of the other heat conduction media on the cooling source side will be higher than the temperature measured at the temperature measurement point of one of the heat conduction media on the heat source side. This temperature magnitude relationship also applies to the temperature measurement point closest to the heat source and the temperature measurement point closest to the cooling source when multiple temperature measurement points are set for one of the heat conduction media and the other heat conduction media. Therefore, the calculation processing unit uses this relationship to determine whether the amount of heat passing through the thermal conduction modulation unit is normal and, if determined to be normal, calculates the thermal conductance. This prevents thermal conductance from being measured even when the amount of heat passing through the thermal conduction modulation section is abnormal, and thermal conductance is measured only when the amount of heat passing through is normal, thereby improving the reliability of thermal conductance measurements.

[0024] (8) In the above items (4) to (7), when calculating the thermal conductance of the heat source, the calculation processing unit further calculates the thermal conductance of the heat source based on the difference between the first temperature and the second temperature and the heating energy when the first temperature is measured. 、 The aforementioned The heat conduction modulation unit and the cooling sourceA thermal conductance measurement system that calculates the overall thermal resistance up to the heat conduction path and calculates the thermal resistance inside the heat source based on the overall thermal resistance. The thermal conductance measurement system described in this section calculates the thermal resistance inside the heat source in addition to the thermal conductance of the heat source by the calculation processing unit. That is, as mentioned in the above sections (1) and (3), the total thermal resistance calculated from the temperature change data and the heating energy includes the thermal resistance inside the heat source, Includes a thermal conduction modulation section and a cooling source The thermal resistance of the heat source is calculated based on the total thermal resistance of the heat conduction path and the thermal resistance of the heat conducting portion of the heat conduction path. The calculation processing unit uses this information to calculate the thermal resistance of the heat source based on the total thermal resistance and the thermal resistance of the heat conduction path, which is determined by the fact that the heat conduction path is made of a material with known thermal conductivity. This allows the thermal resistance of the heat source to be determined even if the information about the heat source is unknown. [Effects of the Invention]

[0025] Since the present invention is configured as described above, it is possible to grasp the thermal conductance of the heat source and contribute to the effective use of unused thermal energy. [Brief explanation of the drawings]

[0026] [Figure 1] 1 is a block diagram showing an example of the configuration of a thermal conductance measurement system according to an embodiment of the present invention; [Figure 2] 1 is an image diagram showing an example of the placement of a heat conduction path used in a thermal conductance measurement system according to an embodiment of the present invention, together with a model of thermal resistance from a heat source to the heat conduction path; [Figure 3] 1 shows an example of the structure of a thermal conductance modulation unit used in a thermal conductance measurement system according to an embodiment of the present invention, where (a) is a top view, (b) is a side view, (c) is a bottom view, and (d) is a cross-sectional view taken along the line AA in (b). [Figure 4] FIG. 2 is a flowchart showing an example of a procedure of a thermal conductance measurement method according to an embodiment of the present invention. [Figure 5](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). DETAILED DESCRIPTION OF THE INVENTION

[0027] Hereinafter, embodiments of the present invention will be described with reference to the drawings. Hereinafter, identical or corresponding parts will be designated by the same reference numerals throughout the drawings. Furthermore, detailed descriptions of parts that are identical or corresponding to those in the prior art will be omitted. 1 shows an example of the configuration of a thermal conductance measurement system 10 according to an embodiment of the present invention, for measuring the thermal conductance at a heat-receiving surface that can be extracted from a heat source 50 (see FIG. 2) that is the measurement target, as well as measuring the thermal resistance inside the heat source 50. As shown in the figure, the thermal conductance measurement system 10 includes a thermal conduction modulation unit 12, a cooling source 36, a heating element control unit 40, a temperature measurement unit 44, and a calculation processing unit 48. The thermal conduction modulation unit 12 also includes a heating element 14 and two heat conduction media 16, and FIG. 3 shows an example of the detailed structure of the thermal conduction modulation unit 12.

[0028] As shown in FIG. 3, the thermal conduction modulation unit 12 has a configuration in which a heating element 14 is sandwiched between two heat conductive media 16. In this embodiment, two cylindrical heat conductive media 16 are connected by four bolts 24, with the heating element 14 disposed between them. The heating element 14 receives varying heating energy to vary its heat output. In this embodiment, the heating element 14 is formed by a Peltier element 14A, and a control line 32 is connected to supply power as heating energy to the Peltier element 14A. Furthermore, as can be seen in FIG. 3(d), a heat dissipation sheet 28 is disposed between the Peltier element 14A and the two heat conductive media 16, thereby enhancing thermal conductivity. Recesses are provided on the opposing surfaces of the two heat conductive media 16 for accommodating the heat dissipation sheet 28 and a portion of the Peltier element 14A.

[0029] The two heat conduction media 16 are formed of a material with a known thermal conductivity, such as, but not limited to, aluminum or copper. Furthermore, one of the two heat conduction media 16, heat conduction medium 16A, has three measurement holes 20 drilled therein. In this embodiment, these three measurement holes 20 are spaced equally apart in the vertical direction in FIGS. 3(b) and 3(d) and extend toward the center of the heat conduction medium 16A, which is circular in plan view as shown in FIG. 3(a). Temperature measurement points MP1 to MP3 are set in the three measurement holes 20 at positions near the center of the circular heat conduction medium 16A in plan view. Therefore, the three temperature measurement points MP1 to MP3 are spaced equally apart in the vertical direction in FIG. 3(d).

[0030] In contrast, one measurement hole 20 is drilled in the other of the two heat conduction media 16, the heat conduction medium 16B, and this measurement hole 20 extends toward the center of the heat conduction medium 16B, which is circular in bottom view as shown in FIG. 3(c). A temperature measurement point MP4 is also set in the measurement hole 20 of this heat conduction medium 16B, at a position near the center of the circular heat conduction medium 16B in bottom view. That is, the temperature measurement points MP1 to MP4 are set near the heat conduction element 14, with the heat conduction element 14 sandwiched between them. Due to the number of measurement holes 20 and temperature measurement points MP as described above, the heat conduction medium 16A has a larger vertical width in FIGS. 3(b) and 3(d) than the other heat conduction medium 16B.

[0031] As shown in FIG. 2, the thermal 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 FIG. 2, a heat exchanger is installed via a heat outlet from the heat source 50, and the thermal conduction modulation unit 12 is further installed there via a thermal junction member. In this case, the thermal conduction modulation unit 12 is installed so that heat from the heat source 50 is conducted to one of the heat conduction media 16A, in other words, so that one of the heat conduction media 16A is arranged on the upper side in FIG. 2. Therefore, in the thermal conduction modulation unit 12, heat is conducted from the upper side to the lower side in FIGS. 3(b) and (d). The other heat conduction medium 16B of the thermal conduction modulation unit 12, which is arranged on the lower side in FIG. 2, is connected to the cooling source 36, also shown in FIG. 1, via a thermal junction member.

[0032] The cooling source 36 has a lower temperature than the heat source 50 being measured, which causes a heat flow in which heat diverted from the heat source 50 flows toward the cooling source 36. For this reason, on the right side of Figure 2, a model evaluation circuit is shown that likens the heat flow to an electrical flow, extending from the V heat source to GND via multiple R resistors. As can be seen from this circuit, each member that makes up the heat conduction path 54 through which heat flows has a thermal resistance, and these thermal resistances can be determined by knowing the thermal conductivity, etc., of the materials that make up each member except for the heat source 50. 2 may be any heat source that contains unused thermal energy. Examples of such heat sources 50 include, but are not limited to, industrial plant equipment that handles thermal energy, various devices that use heat sources, combustion devices, internal combustion engines, incinerators, flow paths for hot spring water, exhaust ducts, chimneys, steam pipes, etc.

[0033] Returning to FIG. 1 , the heating element control unit 40 controls the heating element 14 of the thermal conduction modulation unit 12 by applying fluctuating heating energy to the heating element 14. In this embodiment, AC power (modulation power) of a predetermined frequency is supplied to the Peltier element 14A as heating energy via a control line 32 as shown in FIG. 3 . The predetermined frequency of the AC power is set to a frequency different from the fluctuating frequency of the heat flow from the heat source 50, which is previously determined. The temperature measurement unit 44 measures the temperature of the temperature measurement point MP set as described above in the thermal conduction medium 16 of the thermal conduction modulation unit 12. The temperature measurement unit 44 of this embodiment is configured to acquire the temperature of the temperature measurement point MP via, for example, a platinum Pt100 resistance temperature detector or a thermocouple, and measure the temperature at the temperature measurement point MP over a wide temperature range at high speed, although this is not limited thereto. The calculation processing unit 48 performs various arithmetic operations in the thermal conductance measurement system 10. Details of some of the calculation operations performed by the calculation processing unit 48 will be described later.

[0034] The thermal conductance measurement system 10 according to the embodiment of the present invention is not limited to the configuration shown in FIGS. 1 to 3. Some of the components shown in FIGS. 1 to 3 may be omitted or replaced, or new components may be added. Furthermore, the components in FIG. 1 represent the functional divisions of the thermal conductance measurement system 10 and do not directly represent the individual devices constituting the thermal conductance measurement system 10. The thermal conductance measurement system 10 may be configured with various hardware, software, or a combination thereof. For example, the heating element 14 may be configured with something other than a Peltier element 14A, as long as it can be controlled to vary the amount of heat generated. Furthermore, the heat conduction path 54 may have a different configuration from that shown in FIG. 2, as long as it includes the thermal conduction modulation unit 12 and the cooling source 36. Furthermore, the shape and number of components of the thermal conduction modulation unit 12 may be different from those in the embodiment shown in FIG. 3, and the number and positions of the temperature measurement points MP may be arbitrarily set.

[0035] Next, with reference to Fig. 4, a thermal conductance measurement method according to an embodiment of the present invention, which is executed using the above-described thermal conductance measurement system 10, will be described. For the configuration of the thermal conductance measurement system 10, please refer to Figs. 1 to 3 as appropriate. Note that the flow diagram shown in Fig. 4 shows an example of the flow of steps in the thermal conductance measurement method, and the steps in the thermal conductance measurement method are not limited to this flow diagram. Therefore, some of the steps shown in Fig. 4 may be changed, deleted, or rearranged, and new steps may be added.

[0036] S10 (connecting the heat conduction path): For example, as shown in Figure 2, connect the other end of a heat conduction path 54, which has a cooling source 36 at one end and a heat conduction modulation unit 12 in the middle, to the heat source 50 to be measured. At the same time, install and connect other components of the thermal conductance measurement system 10. For example, install the heat acquisition part of the temperature measurement unit 44 at the temperature measurement point MP set in the heat conduction medium 16 of the heat conduction modulation unit 12. S20 (heating element control): The heating element control unit 40 starts to control the heating element 14 of the thermal conduction modulation unit 12. That is, in this embodiment, 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 element 14A so that the current waveform becomes a sine wave, for example.

[0037] S30 (Temperature Measurement): The temperature measurement unit 44 measures the temperatures at the temperature measurement points MP set in the heat conduction medium 16. Specifically, the temperatures are measured at temperature measurement points MP1 to MP3 set in one heat conduction medium 16A of the heat conduction modulation unit 12 and at temperature measurement point MP4 set in the other heat conduction medium 16B. The measurements are performed at a sampling interval that is at least twice the modulation frequency of the AC power supplied from the heating element control unit 40 to the Peltier element 14A. Furthermore, the measured analog temperature data is converted to digital temperature data by the calculation processing unit 48 or a separately provided A / D converter for subsequent processing. It is preferable to perform the A / D conversion at this time with as high a resolution as possible. The temperature measured in this step corresponds to the first temperature (see symbol TW in FIG. 5(a)) when the temperature is affected (modulated) by the heat generated by the heating element 14.

[0038] 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 thermal conduction modulation unit 12 is normal. First, the heat flow determination will be explained. The calculation processing unit 48 determines the heat flow using the temperatures measured at the three temperature measurement points MP1 to MP3 of one of the heat conduction media 16A and the intervals between these three temperature measurement points MP1 to MP3. 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 side to the cooling source 36 side decreases linearly. Therefore, in this embodiment, in which the three temperature measurement points MP1 to MP3 are set at equal intervals, it is assumed that the temperature difference between the temperature measurement point MP1 on the heat source 50 side and the central temperature measurement point MP2 on the heat conduction medium 16A is approximately equal to the temperature difference between the central temperature measurement point MP2 on the heat conduction medium 16A and the temperature measurement point MP3 on the cooling source 36 side. On the other hand, if the heat flow from the heat source 50 is in a transient state, the above relationship breaks down, and an event occurs in which the temperature difference between the temperature measurement points MP1 and MP3 divided by 2 is not equal to the temperature difference between the temperature measurement points MP1 and MP2 or the temperature difference between the temperature measurement points MP2 and MP3. Using this, the calculation processing unit 48 determines whether the heat flow from the heat source 50 is in a steady state. Note that even if four or more temperature measurement points MP are set on one heat conduction medium 16A, the heat flow can be determined using the above relationship.

[0039] Next, the determination of the amount of heat will be explained. The calculation processing unit 48 determines the amount of heat based on the magnitude relationship between the temperatures measured at three temperature measurement points MP1 to MP3 of one heat conduction medium 16A and the temperature measured at temperature measurement point MP4 of the other heat conduction medium 16B. Specifically, if the amount of heat passing through the thermal conduction modulation unit 12 is normal, it is assumed that the temperature gradually decreases from the heat source 50 side toward the cooling source 36 side. For this reason, in this embodiment, it is assumed that the measured temperatures at temperature measurement points MP1, MP2, MP3, and MP4, which are lined up along the temperature transfer direction from the heat source 50 side to the cooling source 36 side, are arranged in descending order.

[0040] On the other hand, if the amount of heat is abnormal due to excessive modulation by the heating element 14 (Peltier element 14A), the above relationship will be disrupted, and, for example, the temperatures at temperature measurement points MP1 to MP3 will be approximately equal, or these temperatures will be lower than the temperature at temperature measurement point MP4. Using this, the calculation processing unit 48 determines whether the amount of heat passing through the thermal conduction modulation unit 12 is normal. Even when two or fewer or four or more temperature measurement points MP are set on one thermal conduction medium 16A, or when two or more temperature measurement points MP are set on the other thermal conduction medium 16B, the amount of heat can be determined using the above relationship. Then, in this step S40, if it is determined that the heat flow from the heat source 50 is in a steady state and that the amount of heat passing through the thermal conduction modulation unit 12 is normal, the process proceeds to the next step. Note that if a transient state of the heat flow or an abnormality in the amount of heat is detected, the configuration of the heat conduction path 54, the measurement timing, the AC power supplied to the Peltier element 14A, etc. are reviewed.

[0041] S50 (Calculate Average Temperature): The calculation processor 48 calculates the average temperature of the temperatures measured in S30. In other words, in this embodiment, AC power is applied to the Peltier element 14A to vary the heat generation amount. Therefore, the influence (modulation) of temperature fluctuations by the Peltier element 14A causes temperature changes that fluctuate up and down in an AC manner. Therefore, by calculating the average temperature using, for example, a moving average, temperature data that eliminates the influence of temperature fluctuations by the Peltier element 14A is extracted. At this time, processing is performed using a low-pass filter or the like with filter characteristics that do not fluctuate components that fluctuate due to modulation. Such calculation of the average temperature is performed for each temperature measurement point MP, or for only specific temperature measurement points MP. Subsequent processing is performed using the data at the temperature measurement points MP where the average temperature was calculated in this step. Note that the temperature calculated in this step corresponds to the second temperature (see symbol T0 in FIG. 5(a)) when there is no influence from heat generation by the heating element 14 (unmodulated state).

[0042] S60 (difference calculation): The calculation processing unit 48 calculates the difference between the temperature (first temperature) measured in S30 and the average temperature (second temperature) calculated in S50. This extracts temperature change data (see symbol ΔT in FIG. 5(a)) that has changed due to the influence (modulation) of temperature fluctuations caused by the Peltier element 14A. S70 (frequency component extraction): The calculation processing unit 48 extracts data on the frequency component of the frequency (modulation frequency) of the AC power applied to the Peltier element 14A from the temperature change data calculated in S60. This eliminates noise such as fluctuation components of the heat flow from the heat source 50. Note that the extraction method used here can be, for example, a method of extracting only the vicinity of the modulation frequency using a low-pass filter, a method of extracting using a band-pass filter centered on the modulation frequency, a method of performing synchronous detection (baseband detection), or a method of performing two-stage shift detection using baseband detection or multiple stages of PSN modulators, but a detailed description of these methods will be omitted here.

[0043] S80 (calculate thermal conductance): The calculation processing unit 48 calculates the thermal conductance of the heat source 50 to be measured. Here, FIG. 5(a) shows a schematic diagram of the relationship between the heat quantity (unit: J) and the temperature (unit: K), where the mass of the heat source 50 is indicated by symbol m, the specific heat of the heat source 50 by symbol c, the temperature in the modulated state (first temperature) by symbol TW, the temperature in the unmodulated state (second temperature) by symbol T0, the original heat quantity of the heat source 50 by symbol Q0, and the heat quantity taking into account the heat generated by the heating element 14 by symbol QW. That is, within a range where there is no phase change and the temperature changes very little, the heat quantity is proportional to the temperature with the mass m and specific heat c as constants, resulting in the relationship shown in FIG. 5(a) and expressed by the following equation: Q0(J)=m·c·T0(K) QW(J)=m c TW(K) Furthermore, Figure 5(a) shows the relationship of the following formula, where the heating energy applied to the Peltier element 14A during modulation is represented by the symbol W (unit: J), and the difference between the temperature TW in the modulated state and the temperature TO in the unmodulated state is represented by the symbol ΔT, and shows that the temperature has increased by ΔT due to the addition of the heating energy W. QW(J)=Q0(J)+W(J)

[0044] 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 that occurs in 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 formula does not include the ratio of each thermal resistance in the heat conduction path 54 shown in Fig. 2, it is necessary to take modulation efficiency into consideration. Furthermore, since the heating energy W given to the Peltier element 14A during modulation is actually modulation power (AC power), the symbol for this is set to P (unit: W), and the modulation efficiency is expressed by the symbol η, taking into consideration the conversion between the heating energy W (J) and modulation power P (W), resulting in the following formula: Q0(J)=T0(K) / ΔT(K)·P(W)·η(%) This equation shows that the heat quantity possessed by the heat source 50 can be estimated using only the temperature information that changes due to modulation, and that if the modulation power P and modulation efficiency η are values ​​specific to the thermal conductance measurement system 10, then the only unknown quantity is the thermal resistance of the heat source 50, and therefore the thermal conductance of the heat source 50 can be estimated based on this equation.

[0045] Here, thermal resistance is the temperature difference between two points divided by the heat flow rate (amount of heat per unit time) flowing between the two points, and is therefore shown as the slope of the graph represented by "m·c" in Figure 5(a) (see symbol θ in Figure 5(b)). Therefore, if thermal resistance is designated as Rth, it can be calculated using the following formula. Rth(℃ / W)=ΔT(K) / W(J) This thermal resistance Rth includes all thermal resistances within the heat conduction path 54 shown on the right side of Figure 2. Therefore, if the unknown thermal resistance of the heat source 50 is denoted by Rrs and the thermal resistance present in the measurement system is denoted by Rse, the thermal resistance Rrs of the heat source 50 can be calculated as follows: Rrs(℃ / W)=Rth(℃ / W)-Rse(℃ / W)

[0046] Furthermore, as a general-purpose unit, thermal conductance, excluding the heat-receiving area of ​​the heat conduction path 54 relative to the heat source 50, is expressed as the reciprocal of thermal resistance. In other words, "tan θ" in FIG. 5(b) corresponds to the thermal conductance of the heat-receiving surface in contact with the heat source 50. The calculation processing unit 48 calculates the thermal conductance of the heat source 50 in this manner. It is important to handle heat values ​​that also include the modulation efficiency η. Note that the modulation power P (W) shown here is a value specific to the measurement system. Since 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 as is. Therefore, by appropriately adjusting the ratio with the modulation power P, the calculation formula can be simplified, further reducing the load on the microcomputer and other components of the calculation processing unit 48.

[0047] S80 (calculate thermal resistance): The calculation processing unit 48 calculates the thermal resistance inside the heat source 50 to be measured. As mentioned in S80 above, the thermal resistance Rth (°C / W) including all the thermal resistances in the heat conduction path 54 shown on the right side of FIG. 2 is calculated as a combined resistance value corresponding to the following formula: Rth(℃ / 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)) This is the thermal resistance found from the temperature measurement point MP, and Kirchhoff's first and second laws (Ohm's law) used in electrical circuit networks can be applied to thermal resistance. This Rth is the value obtained by connecting the thermal resistance on the heat source side in series, that is, the parallel connection of the series values ​​of the R heat source + the thermal resistance value of the R bonding material on the heat source side + the total value of the R device on the heat source side, and the R cold source + the R bonding material on the cold source side + the total value of the R device on the cold source side. This is the formula for calculating the parallel resistance of the electrical circuit R1 and R2. Rth can be calculated as R = (R1 x R2) / (R1 + R2). However, the thermal resistance R of the modulation device is added to both the hot and cold source sides, and the ratio is a device-specific value, but here it is shown as a common value. Of the thermal resistors constituting the thermal resistance Rth as described above, all except for the R heat source are known in terms of the thermal conductivity of the material constituting each, so the thermal resistances can be grasped. Therefore, the calculation processing unit 48 uses these to calculate the thermal resistance (R heat source) inside the heat source 50.

[0048] In this case, if the thermal conductivity and geometry of the heat exchanger connected to the heat source 50 and the thermal interface material that conducts heat from there are measured in advance, and the heat flow is diverted to form a heat flow circuit as shown in Figure 2, the only unknown thermal resistance is the thermal resistance within the heat source 50. In other words, the thermal resistance within the heat source 50 can be calculated without determining the physical properties required to calculate thermal energy, such as mass, specific heat, density, and pressure, of the material that transfers heat energy within the above-mentioned equipment, such as the industrial plant equipment cited as an example of the heat source 50. Furthermore, the thermal resistance value R of the cooling source 36 can be treated as nearly zero if a function that maintains a constant cooling side temperature, such as a circulator, is used, further simplifying the calculation formula. Furthermore, if the thermal interface material connected to the heat exchanger on the heat source 50 side and the thermal interface material connected to the cooling source 36 have the same shape and are configured as the heat conduction path 54 so that their thermal resistance values ​​(R) are the same, the calculation is further simplified.

[0049] Furthermore, when determining the thermal resistance of a known value, it is necessary to estimate the temperature of the V heat source based on the temperature information measured at the temperature measurement point MP, taking into account the characteristics of the heat exchanger and thermal conduction modulation unit 12, which have temperature functions. In other words, because the temperature of the heat outlet where the V heat source heat exchanger is attached is generally not measured, the thermal resistance of a known material with the above temperature characteristics must be estimated from the temperature information at the temperature measurement point MP. For this estimation, an electrical circuit is used as an equivalent model evaluation circuit, as shown on the right side of Figure 2. For example, the temperature information observed at temperature measurement points MP1–MP4 of the thermal conduction modulation unit 12 is implemented in an electrical circuit simulator. A simulation is then performed to simulate the transient phenomenon in which the V heat source changes from 0 volts to a predetermined voltage, and a parametric analysis is performed on the observed changes at the temperature measurement points MP1–MP4 and the temperature functions of the heat exchanger and thermal conduction modulation unit 12, which have temperature coefficients. Next, a thermal resistance value table with an appropriate temperature function is adopted as a method for matching the temperature fluctuations observed at the temperature measurement point MP with the results of a simulation performed on a circuit simulator using V as the heat source voltage for the circuit. As a result, even if the temperature of the heat exchanger's heat outlet is not measured, the temperature changes at the temperature measurement points MP1 to MP4 are used to calculate the thermal resistance inside the heat source 50 regardless of the temperature of the heat source 50.

[0050] The embodiment of the present invention having the above-described configuration can achieve the following effects. Specifically, a thermal conductance measurement method according to the embodiment of the present invention uses a system 10, such as that shown in FIGS. 1 to 3, to measure the thermal conductance of a heat source 50 having unused thermal energy that is being exhausted. Specifically, a heat conduction path 54 having a cooling source 36 at one end is connected to the heat source 50 at the other end, thereby diverting heat so that it flows from the heat source 50 toward the cooling source 36 (see S10 in FIG. 4). The heat conduction path 54 used in this case is formed of a material whose properties, such as thermal conductivity, are known in advance. Furthermore, a heating element 14 is installed in the heat conduction path 54, i.e., 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 heating element 14 to be installed can be controlled so that the amount of heat generated varies when a varying heating energy W is applied.

[0051] Furthermore, the temperature in the heat conduction path 54 configured as described above is measured to obtain a first temperature TW when affected by the heat generated by the heating element 14 and a second temperature T0 when not affected by the heat generated by the heating element 14 (see S30 and S50 in FIG. 4 and FIG. 5(a)). Next, the difference ΔT between the obtained first temperature TW and second temperature T0 is calculated to extract temperature change data ΔT that has changed due to the influence of the fluctuating heat generated by the heating element 14 (see S60 in FIG. 4 and FIG. 5(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 applied to the heating element 14 when the first temperature TW was measured.

[0052] That is, from the relationship shown in Figure 5(a), the "product of mass and specific heat" m·c can be expressed as the value obtained by dividing the "amount of heat when not receiving heat energy" Q0 by the "temperature when not receiving heat energy (second temperature)" T0, or the value obtained by dividing the "amount of heat when receiving heat energy" QW by the "temperature when receiving heat energy (first temperature)" TW. Furthermore, if radiation and thermal conduction that generates errors are so small that they can be ignored, 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.

[0053] Furthermore, because thermal resistance is the temperature difference between two points divided by the heat flow rate (amount of heat flowing per unit time) between the two points, in the above relationship, it can be expressed as the temperature change data ΔT divided by the heating energy W. Taking into account that this thermal resistance includes all thermal resistances from the heat source 50 to the heat conduction path 54, that thermal conductance can be expressed as the reciprocal of thermal resistance, and that the heat-receiving area of ​​the heat conduction path 54, it is clear that the thermal conductance per unit area can be calculated from the temperature change data ΔT and the heating energy W (see S80 in FIG. 4). This allows the thermal conductance of the heat source 50 to 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 applied to the heating element 14 at that time, without needing to know the specific heat c or mass m of the heat source 50. Knowing the thermal conductance in this way contributes to the effective use of unused thermal energy in the heat source 50. Furthermore, the thermal conductance can be determined even when information about the inside of the heat source 50, such as the specific heat c, pressure, and physical density of the heat source 50, is unknown, or even when the pressure and density of the heat source 50 fluctuate over time.

[0054] Furthermore, the thermal conductance measurement method according to the embodiment of the present invention utilizes a Peltier element 14A as the heating element 14 installed in the heat conduction path 54. The amount of heat generated by the Peltier element 14A is alternating-currently varied by applying AC power (modulated power) P of a predetermined frequency to the Peltier element 14A as heating energy W. The predetermined frequency of the AC power P is set to a frequency different from the fluctuating frequency of the heat flow from the heat source 50 to the heat conduction path 54. After calculating the difference ΔT between the first temperature TW when the temperature is affected by the heat generated by the heating element 14 and the second temperature TO when the temperature is not affected by the heat generated by the heating element 14, data of the frequency component of the predetermined frequency is extracted from the calculation result (see S70 in FIG. 4). The thermal conductance of the heat source 50 is calculated based on the temperature difference data extracted in this manner and the AC power P applied to the Peltier element 14A. That is, by applying modulated power P to Peltier element 14A with a frequency different from the fluctuation frequency of the heat flow from heat source 50 and extracting and using data on the frequency component of that modulated frequency, it is possible to calculate the thermal conductance while eliminating the fluctuation component of the heat flow, etc. This makes it possible to calculate the thermal conductance with greater accuracy.

[0055] Additionally, the thermal conductance measurement method according to the embodiment of the present invention measures the thermal resistance inside the heat source 50 in addition to the thermal conductance of the heat source 50. As described above, the thermal resistance calculated from the temperature change data ΔT (the difference between the first temperature TW and the second temperature TO) and the heating energy W (the heating energy used to measure the first temperature TW) is a total thermal resistance that includes all the thermal resistances from the heat source 50 to the heat conduction path 54. That is, this total thermal resistance includes the thermal resistance inside the heat source 50, whose information such as specific heat, pressure, and physical density is unknown, the thermal resistance of the heat-receiving portion of the heat conduction path 54, which is made of a material with known properties such as thermal conductivity, and the thermal resistance of the heat-conducting portion of the heat conduction path 54. Therefore, the thermal resistance inside the heat source 50 can be calculated based on the total thermal resistance and the thermal resistance of the heat conduction path 54, which is made of a material with known properties such as thermal conductivity. As a result, even if the information about the inside of the heat source 50 is unknown, it is possible to grasp the thermal resistance as information about the inside of the heat source 50 from the calculated total thermal resistance and the known thermal resistance information.

[0056] On the other hand, a thermal conductance measurement system 10 according to an embodiment of the present invention measures the thermal conductance per unit area of ​​a heat-receiving surface that can be extracted from a heat source 50 having unused thermal energy. As shown in FIG. 1, the thermal conductance measurement system 10 includes a thermal conduction modulation unit 12, a cooling source 36, a heating element control unit 40, a temperature measurement unit 44, and a calculation processing unit 48. As also shown in FIG. 3, the thermal conduction modulation unit 12 has a configuration in which a heating element 14 is sandwiched between two heat conduction media 16. The heating element 14 is controllable so that its heat generation amount varies, and the two heat conduction media 16 are formed of materials with known thermal conductivities. The thermal conduction modulation unit 12 having such a configuration is installed so that heat is conducted from the heat source 50 to one of the two heat conduction media 16, heat conduction medium 16A. 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 two heat conduction media 16, heat conduction medium 16B. That is, the thermal 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 toward the cooling source 36, as shown in FIG.

[0057] The heating element control unit 40 controls the heating element 14 of the thermal conduction modulation unit 12, applying a fluctuating heating energy W to the heating element 14 to vary the amount of heat generated by the heating element 14. The temperature measurement unit 44 measures the temperature at a temperature measurement point MP, which is set at a predetermined position on one or both of the two thermal conduction media 16A and 16B of the thermal conduction modulation unit 12, as shown in FIG. 3(d). The calculation processing unit 48 performs various calculation processes in the system 10, including the following calculations. That is, the calculation processing unit 48 obtains a first temperature TW when the temperature is affected by the heat generated by the heating element 14 and a second temperature T0 when the temperature is not affected by the heat generated by the heating element 14 from the measurement results of the temperature measurement point MP by the temperature measurement unit 44, as described in the thermal conductance measurement method. Then, the calculation processing unit 48 calculates the difference ΔT between the first temperature TW and the second temperature T0 when the temperature is not affected by the heat generated by the heating element 14, thereby extracting temperature change data ΔT due to the fluctuating heat generated by the heating element 14.

[0058] Furthermore, the calculation processing unit 48 calculates the thermal conductance of the heat source 50 to be measured, as described in the thermal conductance measurement method, based on the extracted temperature change data ΔT and the heating energy W applied to the heat source 14 by the heat source control unit 40 when the temperature measurement unit 44 measures the first temperature TW. This makes it possible to calculate the thermal conductance at the heat-receiving surface that can be sampled from the heat source 50 without having to know the specific heat c or mass m of the heat source 50. Furthermore, since the structure shunts heat from the heat source 50 to be measured through the heat conduction path 54 including the thermal conduction modulation unit 12 and the cooling source 36 and measures the temperature in the thermal conduction modulation unit 12 in the heat conduction path 54, it is possible to measure heat sources 50 in various environments, including heat sources 50 through which corrosive gases and gas-liquid mixtures with fluctuating medium densities flow. Furthermore, there is no need to consider durability, such as corrosion, and durability and reliability can be significantly improved.

[0059] Furthermore, in the thermal conductance measurement system 10 according to the embodiment of the present invention, the heating element 14 of the thermal conduction modulation unit 12 is a Peltier element 14A, and the heating energy W provided to this Peltier element 14A by the heating element control unit 40 is AC power P of a predetermined frequency, causing the amount of heat generated by the Peltier element 14A to fluctuate in an AC manner. The predetermined frequency of the AC power P is set to a frequency that is different from the fluctuating frequency of the heat flow from the heat source 50 to the thermal conduction modulation unit 12, etc. Then, the calculation processing unit 48 calculates 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, and then extracts data on the frequency component of the above-mentioned predetermined frequency from the calculation result.

[0060] Furthermore, the calculation processing unit 48 calculates the thermal conductance of the heat source 50 based on the temperature difference data ΔT extracted in this manner and the AC power P applied to the Peltier element 14A by the heating element control unit 40. That is, as mentioned in the thermal conductance measurement method, by applying to the Peltier element 14A a modulated power P with a frequency different from the fluctuation frequency of the heat flow from the heat source 50 and extracting and using data on the frequency component of that modulated frequency, it is possible to calculate the thermal conductance while excluding the fluctuation component of the heat flow, etc. This makes it possible to calculate the thermal conductance with greater accuracy.

[0061] 3, in the thermal conductance measurement system 10 according to the embodiment of the present invention, three temperature measurement points MP1 to MP3 are set in one heat conduction medium 16A, which is disposed on the heat source 50 side of the two heat conduction media 16 in the heat conduction modulation unit 12. These three temperature measurement points MP1 to MP3 are set at intervals in the one heat conduction medium 16A along the conduction direction of heat flowing from the heat source 50 (the up and down direction in FIG. 3(d)). Then, the calculation processing unit 48 uses the temperatures measured at the three temperature measurement points MP1 to MP3 by the temperature measurement unit 44 and the intervals between the three temperature measurement points MP1 to MP3 to determine whether the heat flow from the heat source 50 is in a steady state (see S40 in FIG. 4). In other words, the temperatures measured at the three temperature measurement points MP1 to MP3 set on one of the heat conduction media 16A are considered to decrease linearly from the heat source 50 side depending on the spacing between the temperature measurement points MP1 to MP3, provided that the heat flow from the heat source 50 is in a steady state rather than a transient state.

[0062] For example, in the embodiment of FIG. 3 , when three temperature measurement points MP1 to MP3 are set at equal intervals, it is considered that, if the heat flow from the heat source 50 is in a steady state, the temperature difference between the temperature measurement point MP1 on the heat source 50 side and the central temperature measurement point MP2 will be approximately equal to the temperature difference between the central temperature measurement point MP2 and the temperature measurement point MP3 on the cooling source 36 side. Therefore, the calculation processing unit 48 uses this relationship to determine whether the heat flow from the heat source 50 is in a steady state, and calculates the thermal conductance if it is determined to be in a steady state. This prevents the thermal conductance from being measured even when the heat flow from the heat source 50 is in a transient state, and allows the thermal conductance to be measured only when the heat flow is in a steady state, thereby improving the reliability of the thermal conductance measurement.

[0063] Furthermore, in the thermal conductance measurement system 10 according to the embodiment of the present invention, one temperature measurement point MP4 is set in the other heat conduction medium 16B, which is disposed on the cooling source 36 side of the two heat conduction media 16 in the heat conduction modulation unit 12. The calculation processing unit 48 determines whether the amount of heat passing through the heat conduction modulation unit 12 is normal based on the magnitude relationship between the temperature measured by the temperature measurement unit 44 at the temperature measurement points MP1 to MP3 of one heat conduction medium 16A and the temperature measured at the temperature measurement point MP4 of the other heat conduction medium 16B (see S40 in FIG. 4). In other words, if the amount of heat passing through the thermal conduction modulation unit 12 is normal, the temperatures measured at the temperature measurement points MP1 to MP3 of one heat conduction medium 16A on the heat source 50 side will be higher than the temperature measured at the temperature measurement point MP4 of the other heat conduction medium 16B on the cooling source 36 side.

[0064] On the other hand, if the amount of heat passing through the heat source 50 is insufficient or if the influence of the heat generating element 14 is transient, it is expected that the temperature measured at the temperature measurement point MP4 of the heat conduction medium 16B on the cooling source 36 side will be higher than the temperature measured at the temperature measurement points MP1 to MP3 of the heat conduction medium 16A on the heat source 50 side. This temperature magnitude relationship also applies to the three temperature measurement points MP1 to MP3 set on the heat conduction medium 16A on the other side. Therefore, the calculation processing unit 48 uses this relationship to determine whether the amount of heat passing through the thermal conduction modulation unit 12 is normal and calculates the thermal conductance if it is determined to be normal. This prevents the thermal conductance from being measured even when the amount of heat passing through the thermal conduction modulation unit 12 is abnormal. Instead, the thermal conductance can be measured only when the amount of heat passing through is normal, improving the reliability of the thermal conductance measurement.

[0065] Furthermore, the thermal conductance measurement system 10 according to the embodiment of the present invention calculates the thermal resistance inside the heat source 50 in addition to the thermal conductance of the heat source 50 using the calculation processing unit 48. That is, as mentioned in the thermal conductance measurement method according to the embodiment of the present invention, the total thermal resistance calculated from the temperature change data ΔT and the heating energy W includes the thermal resistance inside the heat source 50, the thermal resistance of the heat-receiving portion of the heat conduction path 54, and the thermal resistance of the heat-conducting portion of the heat conduction path 54. Therefore, using this, the calculation processing unit 48 can calculate the thermal resistance inside the heat source 50 based on the total thermal resistance and the thermal resistance of the heat conduction path 54, which is known because it is made of a material with known thermal conductivity, etc. This makes it possible to determine the thermal resistance inside the heat source 50 even if information about the inside of the heat source 50 is unknown.

[0066] More specifically, it is common to represent the heat conduction circuit shown in Figure 2, which shows the total thermal resistance, as a thermal circuit network, and then to represent the thermal circuit network as an electrical circuit network. For example, a model can be created by replacing thermal resistance with electrical resistance and applying Kirchhoff's first and second laws. Then, the balance of heat at each junction can be calculated using Kirchhoff's first law. This calculation method allows for the thermal resistance of the heat receiving part, the thermal resistance of the heat conducting part, the thermal resistance of the thermoelectric modulator 12, and the thermal resistance of the cold heat source 36 to be determined in advance. This narrows the unknown thermal resistance to the internal thermal resistance of the heat source 50 as seen from the heat receiving part. Therefore, by utilizing Kirchhoff's theorem and the recently developed electronic circuit simulators and their inverse analysis tools, it is possible to identify the unknown part, i.e., calculate the internal thermal resistance of the heat source 50.

[0067] Going further, the thermal resistance can be considered a scalar quantity specific to the heat source 50, which can be captured as an instantaneous value from the thermal conductance measurement system 10. The ability to accurately measure this scalar quantity within the heat source 50 means that installing multiple thermal conductance measurement systems 10 along the same heat source 50 path allows for accurate measurement of the thermal resistance within the heat source 50 at measurement points with different positional information. Therefore, by further extending Kirchhoff's law, these multiple measurement points can be set, for example, between two points separated by a certain distance, and the thermal resistance within the heat source 50 can be determined at each point. This allows for the construction of a heat flow circuit equivalent to a Wheatstone bridge in an electrical circuit, and the unknown thermal resistance connecting two points in the Wheatstone bridge in an electrical circuit can be determined. Because this unknown thermal resistance represents the internal thermal resistance connecting two points along the heat flow path, the range of applications is expanded, enabling the measurement of the thermal resistance of heat media between installed heat flow paths.

[0068] Furthermore, by calculating the internal thermal resistance value not only as a scalar quantity but also as a vector quantity, and capturing the frequency fluctuation that occurs when the heat fluctuation frequency propagates between two points at the other end, it is possible to grasp the movement speed of the medium that generates the heat flux between these two points. This is because the time difference in the heat flow fluctuation between the two points is considered to be a mutual temperature fluctuation, the second temperature change mentioned above is considered to be a frequency change, and by capturing the phase change, it can be considered that the heat medium movement speed between these two points is indirectly measured, making it possible to calculate the heat medium movement speed within the heat source 50.

[0069] Furthermore, the ability to accurately measure the thermal resistance value inside the heat source 50 indicates that it is possible to grasp the amount of recoverable heat when reusing the surplus heat of the heat source 50. In other words, because it is possible to actually measure the thermal potential of the heat source 50, it is also possible to build a system that measures the amount of recoverable heat that can be reused from the heat source 50 being measured by setting a usable temperature range. [Explanation of symbols]

[0070] 10: thermal conductance measurement system, 12: thermal conduction modulation unit, 14: heating element, 14A: Peltier element, 16 (16A, 16B): thermal conduction medium, MP (MP1 to MP4): temperature measurement point, 36: cooling source, 40: heating element control unit, 44: temperature measurement unit, 48: calculation processing unit, 50: heat source, 54: thermal conduction path, 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 temperature and second temperature (temperature change data)

Claims

1. 1. A method for measuring thermal conductance of a heat source, comprising: a heat conduction path having a cooling source at one end and the other end connected to the heat source; a heat generating element that can be controlled so that the amount of heat generated varies when a varying amount of heating energy is applied to the heat conducting path; measuring a temperature in the heat conduction path to obtain a first temperature when the heat conduction path is affected by heat generated by the heat generating element and a second temperature when the heat conduction path is not affected by the heat generated by the heat generating element; A thermal conductance measurement method, comprising: calculating the thermal conductance of the heat source based on the difference between the first temperature and the second temperature and the heating energy when the first temperature is measured.

2. A Peltier element is used as the heating element, As the heating energy, AC power having a predetermined frequency different from the fluctuation frequency of the heat flow from the heat source is applied, 2. The thermal conductance measurement method according to claim 1, wherein 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, and the thermal conductance of the heat source is calculated based on the extraction result.

3. 3. A thermal conductance measurement method according to claim 1, further comprising the steps of: calculating a total thermal resistance from the heat source to the heat conduction path based on the difference between the first temperature and the second temperature and the heating energy when the first temperature is measured; and calculating the thermal resistance inside the heat source based on the total thermal resistance.

4. 1. A system for measuring thermal conductance of a heat source, comprising: a heat conduction modulation unit having a configuration in which a heat generating element that can be controlled to vary the amount of heat generated is sandwiched between two heat conducting media formed of materials with known thermal conductivities, and the heat conduction modulation unit is installed so that heat is conducted from the heat source to one of the two heat conducting media; a cooling source having a lower temperature than the heat source and installed so that heat is conducted from the other of the two heat conduction media; a heating element control unit that controls the heating element by applying varying heating energy to the heating element; a temperature measuring unit that measures the temperature at a temperature measuring point set at a predetermined position on either or both of the two heat conducting media; a calculation processing unit that performs calculation processing, The calculation processing unit calculating a difference between a first temperature when the device is affected by heat generated by the heating element and a second temperature when the device is not affected by heat generated by the heating element from the measurement result of the temperature measuring unit; A thermal conductance measurement system, characterized in that the thermal conductance of the heat source is calculated based on the difference and the heating energy when the first temperature is measured.

5. the heating element is a Peltier element, the heat generating element control unit applies, as the heating energy, AC power having a predetermined frequency different from a fluctuating frequency of the heat flow from the heat source, 5. The thermal conductance measurement system according to claim 4, wherein 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, and calculates the thermal conductance of the heat source based on the extraction result.

6. the one heat conduction medium has at least three temperature measurement points set at intervals along a direction of heat conduction from the heat source; The thermal conductance measurement system of claim 4, characterized in that the calculation processing unit determines whether the heat flow from the heat source is in a steady state using the temperatures measured at the at least three temperature measurement points by the temperature measurement unit and the intervals between the at least three temperature measurement points, and calculates the thermal conductance of the heat source if it is determined to be in a steady state.

7. At least one temperature measurement point is set in the one heat conduction medium, and at least one temperature measurement point is set in the other heat conduction medium, The thermal conductance measurement system according to claim 4, characterized in that the calculation processing unit determines whether the amount of heat passing through the thermal conduction modulation unit is normal based on the magnitude relationship between the temperature measured by the temperature measurement unit at the temperature measurement point of one of the thermal conduction media and the temperature measured at the temperature measurement point of the other thermal conduction medium, and calculates the thermal conductance of the heat source if it is determined to be normal.

8. A thermal conductance measurement system as described in any one of claims 4 to 7, characterized in that when calculating the thermal conductance of the heat source, the calculation processing unit further calculates a total thermal resistance from the heat source to a heat conduction path including the thermal conduction modulation unit and the cooling source based on the difference between the first temperature and the second temperature and the heating energy when the first temperature is measured, and calculates the thermal resistance inside the heat source based on the total thermal resistance.

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