HEAT TRANSFER SYSTEM AND METHOD OF OPERATION OF A HEAT TRANSFER SYSTEM - Patent application

Abstract

To provide a heat transfer system and a method for operating a heat transfer system in which a heat transfer fluid comprising or consisting of a phase change material (PCM) circulates in a cooling circuit.SOLUTION: A combined phase state value of a heat transfer fluid is determined based on information obtained from a sensor system that is located in a cooling circuit. The sensor system includes a temperature sensor and an electrical resistance sensor realized as two separate sensors or as one combined temperature and electrical resistance sensor, or consists of these sensors. "Phase state" means the quality of the heat transfer fluid regarding the amount of crystallisation / solidification of its PCM, and provides information as to whether crystallisation is occurring within the heat transfer fluid. The present system and method can securely and effectively prevent a possible blocking of channels of an indoor heat exchanger of the system by solidified PCM, and undesirable deposition of solid PCM (crystals) on heat transfer surfaces of the indoor heat exchanger.SELECTED DRAWING: Figure 6

Description

[Technical Field]

[0001] This disclosure relates to a heat transfer system and a method for operating the heat transfer system, wherein a heat transfer fluid containing or consisting of a phase change material (PCM) circulates within a cooling circuit. In this system and method, a composite phase state value of the heat transfer fluid is determined based on information obtained from a sensor system located within the cooling circuit. This sensor system comprises or consists of a temperature sensor and an electrical resistance sensor, which are implemented as two separate sensors or as a single temperature-electrical resistance combined sensor. "Phase state" refers to the quality of the heat transfer fluid with respect to the amount of crystallization / solidification of the PCM, and provides information on whether crystallization is occurring within the heat transfer fluid. This system and method can reliably and effectively prevent blockage of the flow path in the indoor heat exchanger of the system due to solidified PCM and the undesirable deposition of solid PCM (crystals) on the heat transfer surface of the indoor heat exchanger. [Background technology]

[0002] In static heat storage systems using phase-change materials (PCMs), or in dynamic heat transfer systems (i.e., fluid systems) with enclosed PCMs, the phase change process presents fewer problems compared to dynamic heat transfer systems (i.e., fluid systems) without enclosed PCMs. This is because the phase change / crystallization of unenclosed PCMs in the heat transfer fluid within the narrow transfer channels of the system can lead to channel blockage or undesirable crystal deposition on the heat transfer surface. Accurate determination of the phase (or charge) state during the flow of the PCM slurry would allow for better control of the transfer system. Furthermore, to avoid the aforementioned adverse effects, it is desirable to manipulate the solid-liquid transition at multiple specific points in the transfer path.

[0003] The first challenge is the accurate determination of the charge / phase state (SOC / P). In particular, when the phase transition temperature during a transition from liquid to solid / slurry, and vice versa, is nearly constant, the traditional direct method of directly measuring the temperature of the slurry flow is disadvantageous. When the phase transition occurs over a wide temperature range, measuring temperature as a single parameter will lead to errors in SOC / P determination.

[0004] Over the past few years, various SOC / P determination methods have been published or patented. However, these methods are either extremely complex or introduce large margins of error. To fully realize the potential of PCM slurries in practical applications, a more accurate and cost-effective method is needed for evaluating the phase state in heat transfer systems.

[0005] Many single-component phase-change materials used for non-fluidized thermal energy storage applications have an extremely narrow temperature range during the phase transition. As a result, temperature measurements of the PCM are not very useful for predicting its phase state (SOP) during the phase transition.

[0006] To circumvent this problem, a known prior art approach involves switching separately between temperature and other thermophysical properties (e.g., pressure) depending on whether the PCM state is inside or outside the phase transition region. For phase transition slurries such as TBAB that undergo a phase transition over a small but non-negligible temperature range (~8°C for 20 wt% TBAB), temperature measurements within the phase transition region still provide useful information for predicting the State of Operation (SOP). However, the accuracy of the determination is low.

[0007] Patent Document 1 discloses a heat storage device and a method for measuring the amount of heat stored in a heat storage tank for storing heat by heat exchange between a heat storage medium and a refrigerant, which can accurately measure the amount of heat stored. This device and method determine the heat capacity ("amount of heat stored") of a heat transfer fluid containing PCM and actually use it to control the heat storage device, but it does not use the quality of the heat transfer fluid determined in terms of the amount of crystallization / solidification of the PCM to control the heat storage device. In other words, the control and method disclosed in this document cannot prevent the various drawbacks associated with the crystallization / solidification of PCM in the heat transfer fluid. [Prior art documents] [Patent Documents]

[0008] [Patent Document 1] Japanese Patent Publication No. 2007-240130 [Overview of the project] [Problems that the invention aims to solve]

[0009] Therefore, the object of this disclosure was to provide a heat transfer system and a method for operating the heat transfer system that does not have the drawbacks of prior art systems and methods. Specifically, the system and method must ensure high-precision determination of the quality of the heat transfer fluid used in the system and / or method with respect to the amount of crystallization / solidification of its PCM. Furthermore, the system and method must ensure that the narrow flow paths inside the indoor heat exchanger used in the system and method are not blocked by solid phase change material, and furthermore, that the undesirable deposition of solid phase change material (crystals) on the heat transfer surface of the indoor heat exchanger used in the system and method is prevented. Preferably, the system and method must also ensure that the amount of cooling supplied to the indoor heat exchanger is (linearly) dependent on the flow rate of the heat transfer fluid into the indoor heat exchanger. [Means for solving the problem]

[0010] This problem is solved by the heat transfer system described in claim 1 and by the method described in claim 9. Dependent claims illustrate advantageous embodiments.

[0011] According to this disclosure, a heat transfer system is provided. This heat transfer system is a) A refrigeration circuit comprising a first heat transfer fluid, a compressor, a condenser, an expansion device, and an outdoor heat exchanger, b) A cooling circuit comprising a second heat transfer fluid having or consisting of a phase change material, a pump for circulating the second heat transfer fluid around the cooling circuit, a heat exchanger for transferring heat from the second heat transfer fluid to the first heat transfer fluid, and at least one indoor heat exchanger for transferring heat from the space to be cooled to the second heat transfer fluid, c) A sensor system in a cooling circuit comprising a temperature sensor and an electrical resistance sensor, or consisting of a temperature sensor and an electrical resistance sensor, wherein the temperature sensor and the electrical resistance sensor are implemented as two separate sensors or as a single temperature / electrical resistance combined sensor, d) A control device configured to acquire temperature information and electrical resistance information from a sensor system, Equipped with, The control device is Based on the acquired temperature information and electrical resistance information, the composite phase state value (SOP) is calculated. flow ) seek, The calculated composite phase state value (SOP flow Based on this, the operation of the heat transfer system is controlled. It is structured in this way.

[0012] Based on the acquired temperature information and electrical resistance information, a composite phase state value (SOP) is calculated. flow By configuring the control device to determine the SOP of the heat transfer fluid, the control device can determine the SOP of the heat transfer fluid in the phase transition region of the PCM with higher accuracy compared to when only the temperature or electrical resistance of the heat transfer fluid is used to determine the SOP of the heat transfer fluid.

[0013] According to this disclosure, the term "phase state" refers to the quality of the heat transfer fluid with respect to the amount of crystallization / solidification of the PCM, rather than the amount of remaining heat capacity of the PCM in the heat transfer fluid. Therefore, the determination of the phase state of the heat transfer fluid according to this disclosure enables the determination of when crystallization of the PCM in the heat transfer fluid is occurring.

[0014] By controlling the operation of the heat transfer system based on the aforementioned SOP values, the system can prevent blockage of the flow path of the indoor heat exchanger and further prevent the undesirable deposition of crystals on its heat transfer surface. The system of this disclosure is simple and effective and does not require expensive equipment.

[0015] In this system, the temperature sensor of the sensor system can be selected from a group consisting of thermocouple-based sensors, thermistor sensors, RTD-based sensors, and combinations thereof. The electrical resistance sensor can be selected from a group consisting of conductivity sensors (since resistance is the reciprocal of conductivity), calibrated RTD-based sensors, and combinations thereof. The temperature-electrical resistance combined sensor can be a calibrated RTD.

[0016] In this system, the PCM of the heat transfer fluid is preferably an unsealed PCM. The PCM may include an inorganic PCM, preferably a salt, more preferably a clathrate hydrate, or may consist of an inorganic PCM, preferably a salt, more preferably a clathrate hydrate. The electrical resistance of clathrate hydrates (CHS), such as tetrabutylammonium bromide (TBAB) and trimethylolethane (TME), has been found to be correlateable with the SOP of the clathrate hydrate.

[0017] This system uses composite phase state values ​​(SOP). flow In order to determine this, the control device, i) Temperature of the heat transfer fluid (T me ) is obtained from the sensor system, ii) Electrical resistance of the heat transfer fluid (R me ) is obtained from the sensor system, iii) Determine the temperature component (SOP T ) of the phase state (SOP) of the heat transfer medium from the temperature (T me ), and iv) Determine the electrical resistance component (SOP E ) of the phase state (SOP) of the heat transfer medium from the electrical resistance (R me ), and v) Calculate the weighted temperature component by calculating the product of the temperature component (SOP T ) and the temperature coefficient (β), vi) Calculate the weighted electrical resistance component by calculating the product of the first electrical resistance component (SOP E ) and the difference between 1 and the temperature coefficient (β), vii) Calculate the composite phase state value (SOP flow ) by calculating the sum of the first weighted temperature component and the first weighted electrical resistance component, which may be characterized as being configured as such.

[0018] The application of the temperature coefficient (β) to the temperature component (SOP T ) and the application of the difference between 1 and the temperature coefficient (β) (i.e., 1 minus β) to the electrical resistance component (SOP E ) for weighting the temperature component (SOP T ) and the electrical resistance component (SOP E ) result in a continuous composite function applicable across the entire two-phase region of the PCM.

[0019] This system may be characterized in that the sensor system is located upstream of at least one indoor heat exchanger. This system may include a second sensor system located downstream of at least one indoor heat exchanger. This second sensor system includes a temperature sensor and an electrical resistance sensor, and these sensors are realized as two separate sensors or as one temperature - electrical resistance composite sensor. In this case, the control device i) obtains temperature information from the sensor system and the second sensor system, and obtains electrical resistance information from the sensor system and the second sensor system, ii) Based on the acquired temperature information and the acquired electrical resistance information, determine the difference in phase state (ΔSOP) of the heat transfer fluid between the ends of at least one indoor heat exchanger. iii) Control the operation of the heat transfer system based on the calculated phase state difference (ΔSOP). It is configured in this way.

[0020] The advantage of determining the difference in phase states (ΔSOP) of the heat transfer fluid between the ends of at least one indoor heat exchanger and controlling the system operation based on the determined ΔSOP is that it can be guaranteed that the cooling supplied to the indoor heat exchanger is (linearly) dependent on the flow rate of the heat transfer fluid. In other words, the cooling efficiency can be controlled more precisely.

[0021] To determine the difference in phase states (ΔSOP) of the heat transfer fluid between the ends of at least one indoor heat exchanger, the control device preferably: i) First temperature of the heat transfer fluid (T me The second temperature (T) of the heat transfer fluid is obtained from the sensor system. me ) is acquired from the second sensor system, ii) The first electrical resistance (R) of the heat transfer fluid me The second electrical resistance (R) is obtained from the sensor system and the second electrical resistance (R) is obtained from the sensor system. me ) is acquired from the second sensor system, iii) The first temperature component of the phase state (SOP) of the heat transfer fluid (SOP) T ) to the first temperature (T me ) is used to determine the second temperature component (SOP) of the phase state (SOP) of the heat transfer fluid. T ) to the second temperature (T me ) obtained from, iv) The first electrical resistance component of the phase state (SOP) of the heat transfer fluid (SOP) E ) is the first electrical resistance (R me ) is used to determine the second electrical resistance component of the phase state (SOP) of the heat transfer fluid (SOP) E ) is the second electrical resistance (R me ) obtained from, v) First temperature component (SOP T The first weighted temperature component is obtained by calculating the product of () and the temperature coefficient (β), and the second temperature component (SOPT By calculating the product of () and the temperature coefficient (β), we obtain the second weighted temperature component. vi) First electrical resistance component (SOP E The first weighted electrical resistance component is obtained by calculating the product of ( ) and the difference between 1 and the temperature coefficient (β), and the second electrical resistance component (SOP E By calculating the product of the difference between ) and the temperature coefficient (β), we can obtain the second weighted electrical resistance component. vii) The first composite phase state value (SOP) is calculated by summing the first weighted temperature component and the first weighted electrical resistance component. flow The second composite phase state value (SOP) is obtained by calculating the sum of the second weighted temperature component and the second weighted electrical resistance component. return ) seek, viii) Second phase state value (SOP return ) and the first phase state value (SOP flow By calculating the difference between ) and ), the difference in phase states (ΔSOP) of the heat transfer fluid between the ends of at least one indoor heat exchanger is determined. It is configured in this way.

[0022] This system uses the temperature component of the phase state (SOP) of the heat transfer fluid (SOP). T In order to determine this, the control device, T me >(T eq If it is +u(+), then SOP T = 0, T me <(T eq If -u(-)), then SOP T = 1, T me ≧((T eq -u(-)) and ≤(T eq If it is +u(+), then SOP T This range is >0 and <1, preferably 0.1 to 0.9, more preferably 0.2 to 0.8, even more preferably 0.3 to 0.7, particularly preferably 0.4 to 0.6, and particularly 0.5. It is configured in such a way, During the ceremony, T me This is the measured temperature value, T eq This is the phase change temperature of a phase change material. u(+) is the temperature deviation from the equilibrium temperature at the upper limit of the phase transition state during the phase transition process, for example, during melting. u(-) is the temperature deviation from the equilibrium temperature at the lower limit of the phase transition state during a phase transition process, for example, during crystallization. This can be a distinguishing feature.

[0023] Furthermore, this system uses a control device to determine the electrical resistance component (SOP) of the phase state (SOP) of the heat transfer fluid. E )of, SOP E =SOP0+α·(R me -R0) It is structured to be as follows: During the ceremony, SOP0 is a reference phase state value, and when the heat transfer fluid is liquid and no solid crystals are present, SOP0 is preferably 0. α is a coefficient used to convert the measured change in electrical resistance relative to the reference resistance value R0 into a phase state. R me This is the measured value of electrical resistance, R0 is the reference resistance value. This can be a distinguishing feature.

[0024] Furthermore, this system uses a control device that provides a composite phase state value (SOP). flow SOP return )of, SOP flow SOP return =β·SOP T +(1-β)·SOP E It is structured to be as follows: During the ceremony, β is a coefficient representing a weighting value for a particular phase-changing substance that yields the most accurate prediction of the phase state measurement based on enthalpy, and β is preferably, Tme >(T eq If +u(+), then β=1, T me <(T eq If -u(-), then β=1, T me ≧((T eq -u(-)) and ≤(T eq If +u(+), then β is within the range of >0 and <1, preferably within the range of 0.01 to 0.8, more preferably within the range of 0.05 to 0.6, even more preferably within the range of 0.10 to 0.4, particularly preferably within the range of 0.15 to 0.3, and particularly preferably within the range of 0.2. They were asked to do so. During the ceremony, T me This is the measured temperature value, T eq This is the phase change temperature of a phase change material. u(+) is the temperature deviation from the equilibrium temperature at the upper limit of the phase transition state during the phase transition process, for example, during melting. u(-) is the temperature deviation from the equilibrium temperature at the lower limit of the phase transition state during a phase transition process, for example, during crystallization. This can be a distinguishing feature.

[0025] Furthermore, this system has a control unit, i) Preferably, the composite phase state value (SOP) obtained by controlling the compressor speed according to the highest cooling load of the indoor heat exchanger in this system. flow ), and / or, ii) The difference in phase states (ΔSOP) between the ends of the at least one heat exchanger is determined by controlling the fan of at least one indoor heat exchanger to switch on or off (for example, whether to switch on at a predetermined rotational speed), and / or by controlling the flow velocity of the thermal fluid through at least one indoor heat exchanger, preferably by controlling the pump speed of a pump fluid-connected to the indoor heat exchanger, and / or the opening of a valve fluid-connected to the indoor heat exchanger. It may be characterized by being configured to control the operation of the heat transfer system based on this.

[0026] In addition, the system comprises a cooling circuit with at least one further indoor heat exchanger, a third sensor system disposed downstream of the further indoor heat exchanger in the cooling circuit, the third sensor system comprising a temperature sensor and an electrical resistance sensor, or comprising these sensors, either as two separate sensors or as a single temperature-electrical resistance composite sensor, and a control device, i) Preferably, the composite phase state value (SOP) obtained by controlling the compressor speed according to the highest cooling load of the indoor heat exchanger in this system. flow ), and / or, ii) The difference in phase states (ΔSOP) between the ends of the at least one additional heat exchanger is determined by controlling the fan of at least one additional indoor heat exchanger to be switched on or off (for example, whether to be switched on at a predetermined rotational speed), and / or by controlling the flow rate of the heat transfer fluid through at least one additional indoor heat exchanger, preferably by controlling the pump speed of a pump fluid-connected to the at least one additional indoor heat exchanger, and / or the opening of a valve fluid-connected to the at least one additional indoor heat exchanger. It may be characterized by being configured to control the operation of the heat transfer system based on this.

[0027] If the system is configured such that the temperature and pressure of the heat transfer fluid entering the further indoor heat exchanger are the same as the temperature and pressure of the heat transfer fluid entering the indoor heat exchanger, the control device can be configured to determine the difference in phase states (ΔSOP) of the heat transfer fluid between the ends of the further indoor heat exchanger based on temperature information obtained from the sensor system and the third sensor system, and based on electrical resistance information obtained from the sensor system and the third sensor system. If the system is configured such that the temperature and pressure of the heat transfer fluid entering the further indoor heat exchanger are different from the temperature and pressure of the heat transfer fluid entering the indoor heat exchanger, the control device can be configured to determine the difference in phase states (ΔSOP) of the heat transfer fluid between the ends of the further indoor heat exchanger based on temperature information obtained from the third sensor system and the fourth sensor system, and based on electrical resistance information obtained from the third sensor system and the fourth sensor system. The fourth sensor system is located upstream of the further indoor heat exchanger in the cooling circuit. The fourth sensor system comprises, or consists of, a temperature sensor and an electrical resistance sensor, either as two separate sensors or as a single temperature-electrical resistance combined sensor. In this case, ΔSOP can be determined in the same way as ΔSOP for the indoor heat exchanger described above.

[0028] According to this disclosure, a method for operating a heat transfer system in which a heat transfer fluid, comprising or consisting of a phase change material, circulates within a cooling circuit is: A step of obtaining temperature information and electrical resistance information from a sensor system located in a cooling circuit of a heat transfer system in which a heat transfer fluid circulates therein, wherein the sensor system comprises, or comprises, two separate sensors or one temperature-electrical resistance combined sensor, a temperature sensor and an electrical resistance sensor, or comprises these sensors. This method, Based on the acquired temperature information and electrical resistance information, the composite phase state value (SOP) is calculated. flow The steps to find ) and The calculated phase state value (SOP flow Based on this, the steps include controlling the operation of the heat transfer system, It is characterized by including.

[0029] The method described herein has the same advantages as the system described herein. Specifically, based on the acquired temperature information and the acquired electrical resistance information, a composite phase state value (SOP) is obtained. flow By taking the step of determining the SOP of the heat transfer fluid, the control device can determine the SOP of the heat transfer fluid in the phase transition region of the PCM with greater accuracy than when only the temperature or electrical resistance of the heat transfer fluid is used to determine the SOP of the heat transfer fluid. By taking the step of controlling the operation of the heat transfer system based on the determined value, the method can prevent blockage of the flow path of the indoor heat exchanger and further prevent the undesirable deposition of crystals on its heat transfer surface. The method of this disclosure is simple and effective and does not require expensive equipment.

[0030] In this system, the temperature sensor of the sensor system can be selected from a group consisting of thermocouple-based sensors, thermistor sensors, RTD-based sensors, and combinations thereof. The electrical resistance sensor can be selected from a group consisting of conductivity sensors (since resistance is the reciprocal of conductivity), calibrated RTD-based sensors, and combinations thereof. The temperature-electrical resistance combined sensor can be a calibrated RTD.

[0031] In this method, the PCM of the heat transfer fluid is preferably an unsealed PCM. The PCM may include or consist of an inorganic PCM, preferably a salt, more preferably an inclusion hydrate. The electrical resistance of inclusion hydrates (CHS), such as tetrabutylammonium bromide (TBAB) and trimethylolethane (TME), has been found to be correlateable with the SOP of the inclusion hydrate.

[0032] This method uses a composite phase state value (SOP flow In order to find ), i) Temperature of the heat transfer fluid (T me The steps include obtaining the data from the sensor system, ii) Electrical resistance of the heat transfer fluid (R me The steps include obtaining the data from the sensor system, iii) Temperature component of the phase state (SOP) of the heat transfer fluid (SOP) T ) temperature (T me ) and the steps to be obtained from, iv) Electrical resistance component of the phase state (SOP) of the heat transfer fluid (SOP) E ) is the electrical resistance (R me ) and the steps to be obtained from, v) Temperature component (SOP T The steps include calculating the product of () and the temperature coefficient (β) to obtain the weighted temperature component, vi) First electrical resistance component (SOP E The steps include calculating the product of ( ) and the difference between 1 and the temperature coefficient (β) to determine the weighted electrical resistance component, vii) The combined phase state value (SOP) is calculated by summing the first weighted temperature component and the first weighted electrical resistance component. flow The steps to find ) and It may be characterized by including

[0033] Furthermore, the system may be characterized in that the sensor system is located upstream of at least one indoor heat exchanger. The system may also include a second sensor system located downstream of at least one indoor heat exchanger. This second sensor system comprises, or consists of, a temperature sensor and an electrical resistance sensor, which are implemented as two separate sensors or as a single temperature-electrical resistance combined sensor. i) A step of acquiring temperature information from the sensor system and the second sensor system, and acquiring electrical resistance information from the sensor system and the second sensor system, ii) A step of determining the difference in phase states (ΔSOP) of the heat transfer fluid between the ends of at least one indoor heat exchanger based on the acquired temperature information and the acquired electrical resistance information, iii) A step of controlling the operation of the heat transfer system based on the obtained phase state difference (ΔSOP), Includes.

[0034] Determining the difference in the phase state (ΔSOP) of the heat transfer medium at both ends of at least one indoor heat exchanger and controlling the operation of the system based on the determined ΔSOP has the advantage of ensuring that the cooling supplied to the indoor heat exchanger is (linearly) dependent on the flow rate of the heat transfer medium. That is, the cooling efficiency can be controlled more precisely.

[0035] To determine the difference in the phase state (ΔSOP), the method preferably a) obtaining the first temperature (T me ) of the heat transfer medium from a sensor system and obtaining the second temperature (T me ) of the heat transfer medium from a second sensor system; b) obtaining the electrical resistance (R me ) of the first heat transfer medium from a sensor system and obtaining the second electrical resistance (R me ) of the second heat transfer medium from a second sensor system; c) obtaining the first temperature component (SOP T ) of the phase state (SOP) of the heat transfer medium from the first temperature (T me ) and obtaining the second temperature component (SOP T ) of the phase state (SOP) of the heat transfer medium from the second temperature (T me ); d) obtaining the first electrical resistance component (SOP E ) of the phase state (SOP) of the heat transfer medium from the first electrical resistance (R me ) and obtaining the second electrical resistance component (SOP E ) of the phase state (SOP) of the heat transfer medium from the second electrical resistance (R me ); e) obtaining a first weighted temperature component by calculating the product of the first temperature component (SOP T ) and the temperature coefficient (β), and obtaining a second weighted temperature component by calculating the product of the second temperature component (SOP T ) and the temperature coefficient (β); f) obtaining a first weighted electrical resistance component by calculating the product of the first electrical resistance component (SOP E ) and the difference between 1 and the temperature coefficient (β), and EThe second weighted electrical resistance component is determined by calculating the product of ( ) and the difference between 1 and the temperature coefficient (β). g) The first composite phase state value (SOP) is calculated by summing the first weighted temperature component and the first weighted electrical resistance component. flow The second composite phase state value (SOP) is obtained by calculating the sum of the second weighted temperature component and the second weighted electrical resistance component. return The steps to find ) and h) Second phase state value (SOP return ) and the first phase state value (SOP flow The steps include: determining the difference in phase states (ΔSOP) of the heat transfer fluid between the ends of at least one indoor heat exchanger by calculating the difference between ) and Includes.

[0036] This method involves the temperature component (SOP) of the phase state (SOP) of the heat transfer fluid. T )but, T me >(T eq If it is +u(+), then SOP T = 0, T me <(T eq If -u(-)), then SOP T = 1, T me ≧((T eq -u(-)) and ≤(T eq If it is +u(+), then SOP T This range is >0 and <1, preferably 0.1 to 0.9, more preferably 0.2 to 0.8, even more preferably 0.3 to 0.7, particularly preferably 0.4 to 0.6, and particularly 0.5. They were asked to do so. During the ceremony, T me This is the measured temperature value, T eq This is the phase change temperature of a phase change material. u(+) is the temperature deviation from the equilibrium temperature at the upper limit of the phase transition state during the phase transition process, for example, during melting. u(-) is the temperature deviation from the equilibrium temperature at the lower limit of the phase transition state during a phase transition process, for example, during crystallization. This can be a distinguishing feature.

[0037] Furthermore, this method involves the electrical resistance component (SOP) of the phase state (SOP) of the heat transfer fluid. E )but, SOP E =SOP0+α·(R me -R0) It is requested as follows: During the ceremony, SOP0 is a reference phase state value, and when the heat transfer fluid is liquid and no solid crystals are present, SOP0 is preferably 0. α is a coefficient used to convert the measured change in electrical resistance relative to the reference resistance value R0 into a phase state. R me This is the measured value of electrical resistance, R0 is the reference resistance value. This can be a distinguishing feature.

[0038] Furthermore, this method uses a composite phase state value (SOP). flow SOP return )but, SOP flow SOP return =β·SOP T +(1-β)·SOP E It is requested as follows: During the ceremony, β is a coefficient relating to the weighting value of a particular phase-changing substance that yields the most accurate prediction of the phase state measurement based on enthalpy, and β is preferably, T me >(T eq If +u(+), then β=1, T me <(T eq If -u(-), then β=1, T me ≧((T eq -u(-)) and ≤(T eqIf +u(+), then β is within the range of >0 and <1, preferably within the range of 0.01 to 0.8, more preferably within the range of 0.05 to 0.6, even more preferably within the range of 0.10 to 0.4, particularly preferably within the range of 0.15 to 0.3, and particularly 0.2. During the ceremony, T me This is the measured temperature value, T eq This is the phase change temperature of a phase change material. u(+) is the temperature deviation from the equilibrium temperature at the upper limit of the phase transition state during the phase transition process, for example, during melting. u(-) is the temperature deviation from the equilibrium temperature at the lower limit of the phase transition state during a phase transition process, for example, during crystallization. This can be a distinguishing feature.

[0039] Furthermore, this method, i) Preferably, the composite phase state value (SOP) obtained by controlling the compressor speed according to the highest cooling load of the indoor heat exchanger in this system. flow ), and / or, ii) The difference in phase states (ΔSOP) between the ends of at least one heat exchanger is determined by controlling the fan of at least one indoor heat exchanger to be switched on or off (for example, whether to be switched on at a predetermined rotational speed), and / or by controlling the flow rate of the heat transfer fluid through at least one indoor heat exchanger, preferably by controlling the pump speed of a pump fluid-connected to the indoor heat exchanger, and / or the opening of a valve fluid-connected to the indoor heat exchanger. Based on this, the operation of the heat transfer system may be characterized by being controlled.

[0040] In addition, the method comprises a cooling circuit comprising at least one further indoor heat exchanger, a third sensor system disposed downstream of the further indoor heat exchanger, the third sensor system comprising or consisting of a temperature sensor and an electrical resistance sensor, implemented as two separate sensors or as a single temperature-electrical resistance combined sensor, and a control device, i) Preferably, the composite phase state value (SOP) obtained by controlling the compressor speed according to the highest cooling load of the indoor heat exchanger in this system. flow ), and / or, ii) The difference in phase states (ΔSOP) between the ends of the at least one additional heat exchanger is determined by controlling the fan of at least one additional indoor heat exchanger to be switched on or off (for example, whether to be switched on at a predetermined rotational speed), and / or by controlling the flow rate of the heat transfer fluid through at least one additional indoor heat exchanger, preferably by controlling the pump speed of a pump fluid-connected to the at least one additional indoor heat exchanger, and / or the opening of a valve fluid-connected to the at least one additional indoor heat exchanger. It may be characterized by being configured to control the operation of the heat transfer system based on this.

[0041] If the temperature and pressure of the heat transfer fluid entering the further indoor heat exchanger are the same as the temperature and pressure of the heat transfer fluid entering the indoor heat exchanger, the difference in phase states (ΔSOP) of the heat transfer fluid between the ends of the further indoor heat exchanger can be determined based on the temperature information obtained from the sensor system and the third sensor system, and based on the electrical resistance information obtained from the sensor system and the third sensor system. If the temperature and pressure of the heat transfer fluid entering the further indoor heat exchanger are different from the temperature and pressure of the heat transfer fluid entering the indoor heat exchanger, the difference in phase states (ΔSOP) of the heat transfer fluid between the ends of the further indoor heat exchanger can be determined based on the temperature information obtained from the third sensor system and the fourth sensor system, and based on the electrical resistance information obtained from the third sensor system and the fourth sensor system. The fourth sensor system is located upstream of the further indoor heat exchanger in the cooling circuit, and the fourth sensor system comprises, or consists of, a temperature sensor and an electrical resistance sensor, which are implemented as two separate sensors or as a single temperature-electrical resistance combined sensor. This ΔSOP can be determined in the same way as in the case of the indoor heat exchanger described above.

[0042] The subject matter of this disclosure will be described in more detail with reference to the following figures and examples, without limiting the disclosure to the specific embodiments shown herein. [Brief explanation of the drawing]

[0043] [Figure 1] The phase diagram of PCM TBAB is shown. [Figure 2] The heat flow curve of the PCM TBAB obtained by DSC is shown. [Figure 3] Figure 3 shows the results of conductivity and temperature measurements of the PCM TBAB at multiple different points in time. The x-axis of the plot in Figure 3 represents time (in minutes) and indicates the time when the measurement points were taken. [Figure 4] This graph shows a plot of conductivity (y-axis) versus temperature (x-axis) obtained from conductivity and temperature measurements of the PCM TBAB over time. [Figure 5] This shows a heat transfer system without a heat storage device. [Figure 6] This shows a heat transfer system with a heat storage device. [Figure 7] This shows a heat transfer system with multiple different zones. [Figure 8] This shows the control diagram for the zone with the highest cooling load in the system. [Figure 9] This diagram shows the control zones of a system with a cooling load lower than the highest cooling load. [Figure 10] The control diagram for the remaining parts of the system (outdoor unit / hot water circulation box) is shown. [Modes for carrying out the invention]

[0044] Example 1 - Determining the properties of PCM TBAB

[0045] A conventional differential scanning calorimeter (DSC) was used to determine the phase transition temperature of the PCM TBAB. The results are shown in Figure 2.

[0046] To determine the SOC / P ratio, conductivity and temperature measurements were performed. For this purpose, a 20 wt% TBAB aqueous solution was held in a thermostat-controlled bath for temperature adjustment, and a conductivity probe was used to measure conductivity. The measurement results are shown in Figure 3 and were used to plot the conductivity versus temperature shown in Figure 4. It is worth noting that the conductivity versus temperature plot shown in Figure 4 shows that the relationship between the two parameters is unclear. This may suggest that temperature has limitations in elucidating the phase state during the phase transition period.

[0047] Example 2 - Determination of coefficients α and β

[0048] α is a coefficient used to convert the measured change in electrical resistance relative to the reference resistance value R0 into a phase state.

[0049] β is a coefficient that represents a weighting value for a particular phase-changing substance, which yields the most accurate prediction of the phase state based on enthalpy. T me >(T eq If +u(+), then β=1. T me <(T eq If -u(-), then β=1, T me ≧((T eq -u(-)) and ≤(T eq If +u(+), then β is within the range of >0 and <1, preferably within the range of 0.01 to 0.8, more preferably within the range of 0.05 to 0.6, even more preferably within the range of 0.10 to 0.4, particularly preferably within the range of 0.15 to 0.3, and particularly preferably within the range of 0.2. It can be requested in this way, During the ceremony, T me This is the measured temperature value, T eq This is the phase change temperature of a phase change material. u(+) is the temperature deviation from the equilibrium temperature at the upper limit of the phase transition state during the phase transition process, for example, during melting. u(-) is the temperature deviation from the equilibrium temperature at the lower limit of the phase transition state during a phase transition process, for example, during crystallization.

[0050] To adapt the coefficients α and β to a heat transfer fluid having a specific PCM, the enthalpy-based phase state can be plotted as a function of internal temperature and electrical resistance. For this purpose, a series of tests can be performed to measure the heating curve of a heat transfer fluid having a specific PCM in the phase transition region.

[0051] Example 3 - How the heat transfer system operates

[0052] To operate the heat transfer system, a control algorithm can be defined based on the following assumptions for the example heat transfer system shown in Figure 7. 1. There are two or more indoor units (fan coil units). Each indoor unit works for its own dedicated thermal zone (i.e., room), and each has its own thermostat that measures the room temperature. 2. The main components available for system control are the indoor unit fan, branch valve, compressor speed, and slurry pump speed. 3. The phase state (SOP) of the slurry is determined as a function of the measured electrical resistance (R) and temperature (T). 4. For each room / zone, approximately the same target ΔSOP is required at both ends of each indoor unit. This means that the cooling supplied to each zone changes (linearly) with the mass flow rate of slurry to each zone.

[0053] For the zone with the highest cooling load, the main algorithm can be described as follows (see also Figure 8, which uses PI as an illustrative control mechanism). • The indoor unit fan is always operating at a fixed speed (selected by the occupant). ·Target SOP flow To achieve this, the compressor speed is automatically adjusted. Target SOP flow This is set according to the ΔT between the set point in the room and the actual room temperature. • The valve position on the indoor unit's branch (either a diversion / bypass valve or a regulated ball valve) is set according to the target flow rate of the branch. The target flow rate to the indoor unit is set in order to achieve the target ΔSOP.

[0054] For zones with lower cooling loads, the primary algorithm can be explained as follows (see also Figure 9). • To maintain a room temperature with a dead zone, the indoor unit fan switches on or off according to the thermostat. • Depending on the zone with the highest cooling load, SOP to the indoor unit flow It is fixed in place. The valve position on the indoor unit's branch is set according to the target flow rate of the branch. The target flow rate to the indoor unit is set in order to achieve the target ΔSOP.

[0055] The main control algorithm for the remaining parts of this system (outdoor unit / hot water circulation box) can be described as follows (see also Figure 10). • Pump speed set to achieve the target slurry flow rate in the indoor heat exchanger (PHEX) • The degree to which the valve (LEV) is set on the refrigerant side to achieve the target superheat. [Explanation of Symbols]

[0056] PCM phase change material, SOP phase state of heat transfer fluid containing PCM, SOP flow SOP value of the first composite phase state upstream of the indoor heat exchanger, SOP return The SOP value of the second composite phase state downstream of the indoor heat exchanger, ΔSOP SOP return From SOP flow The value obtained by subtracting T me Temperature of the heat transfer fluid, T eq PCM phase change temperature, R me Measured electrical resistance of the heat transfer fluid, R0 reference resistance value, SOP T SOP temperature components, SOP ESOP's electrical resistance component, SOP0 reference phase state value, α electrical coefficient for converting the measured electrical resistance change to the phase state relative to the reference resistance value R0, β temperature coefficient, u(+) temperature deviation from equilibrium temperature at the upper limit of the phase change state during the phase change process, e.g., melting, u(-) temperature deviation from equilibrium temperature at the lower limit of the phase change state during the phase change process, e.g., crystallization, TBAB tetrabutylammonium bromide, TME trimethylolethane, R SOP sensor, i.e., temperature and electrical resistance sensor, T thermocouple, P pressure sensor, PHEX plate heat exchanger, FCU fan coil unit, T indoor Room temperature, LEV linear expansion valve, RTD resistance temperature detector, SP setpoint, e(t) error value as the difference between the desired setpoint and the measured process variable, PI proportional-integral control device, V_flow volumetric flow rate, Super_Heat superheat measured as the difference between the actual temperature of the refrigerant vapor and the saturation temperature of the refrigerant.

Claims

1. 1. A heat transfer system comprising: a) a refrigeration circuit including a first heat transfer fluid, a compressor, a condenser, an expansion device, and an outdoor heat exchanger; b) a cooling circuit comprising a second heat transfer liquid comprising or consisting of a phase change material, a pump for circulating said second heat transfer liquid around said cooling circuit, a heat exchanger for transferring heat from said second heat transfer liquid to said first heat transfer liquid, and at least one indoor heat exchanger for transferring heat from a space to be cooled to said second heat transfer liquid; c) a sensor system in the cooling circuit comprising or consisting of a temperature sensor and an electrical resistance sensor, the temperature sensor and the electrical resistance sensor being realized as two separate sensors or as one combined temperature and electrical resistance sensor; d) a controller configured to obtain temperature and electrical resistance information from the sensor system; In a heat transfer system comprising: The control device A composite state of phase value (SOP) is calculated based on the acquired temperature information and the acquired electrical resistance information. ｆｌｏｗ ) and The obtained composite phase state value (SOP ｆｌｏｗ ) controlling operation of the heat transfer system based on A heat transfer system configured as follows:

2. The composite state of phase value (SOP ｆｌｏｗ ), the control device i) the temperature of the heat transfer liquid (T ｍｅ ) from the sensor system; ii) the electrical resistance (R ｍｅ ) from the sensor system; iii) the temperature component of the state of phase (SOP) of the heat transfer fluid (SOP Ｔ ) to the temperature (T ｍｅ ) and iv) the electrical resistance component (SOP) of the heat transfer liquid Ｅ ) to the electrical resistance (R ｍｅ ) and v) the temperature component (SOP Ｔ ) and the temperature coefficient (β) to obtain a weighted temperature component; vi) the first electrical resistance component (SOP Ｅ Calculating the weighted electrical resistance component by multiplying the difference between 1 and the temperature coefficient (β) by the product of vii) calculating a composite state-of-phase value (SOP) by calculating the sum of the first weighted temperature component and the first weighted electrical resistance component; ｆｌｏｗ ) The system of claim 1 , configured to:

3. The sensor system is located upstream of the at least one indoor heat exchanger, and the system comprises a second sensor system located downstream of the at least one indoor heat exchanger, the second sensor system comprising a temperature sensor and an electrical resistance sensor realized as two separate sensors or as one combined temperature and electrical resistance sensor, or consisting of the temperature sensor and the electrical resistance sensor, and the control device is i) acquiring temperature information from the sensor system and the second sensor system, and acquiring electrical resistance information from the sensor system and the second sensor system; ii) determining a difference in phase state (ΔSOP) of the heat transfer liquid between both ends of the at least one indoor heat exchanger based on the acquired temperature information and the acquired electrical resistance information; iii) controlling operation of the heat transfer system based on the determined difference in phase state (ΔSOP); It is configured as follows: In order to determine the difference in state of phase (ΔSOP) of the heat transfer fluid across the at least one indoor heat exchanger, the control device preferably comprises: i) a first temperature (T ｍｅ ) from the sensor system, and a second temperature (T ｍｅ ) from the second sensor system; ii) a first electrical resistance (R ｍｅ ) is obtained from the sensor system, and a second electrical resistance (R ｍｅ ) from the second sensor system; iii) a first temperature component (SOP) of the state of phase (SOP) of the heat transfer fluid; Ｔ ) to the first temperature (T ｍｅ ) and a second temperature component (SOP) of the state of phase (SOP) of the heat transfer body. Ｔ ) to the second temperature (T ｍｅ ) and iv) a first electrical resistance component (SOP) of the state of phase (SOP) of the heat transfer fluid; Ｅ ) to the first electrical resistance (R ｍｅ ) and a second electrical resistance component (SOP) of the heat transfer fluid Ｅ ) to the second electrical resistance (R ｍｅ ) and v) the first temperature component (SOP Ｔ ) and a temperature coefficient (β) to obtain a first weighted temperature component, and the second temperature component (SOP Ｔ deriving a second weighted temperature component by multiplying the temperature coefficient (β) by the temperature coefficient (β); vi) the first electrical resistance component (SOP Ｅ ) and the difference between 1 and the temperature coefficient (β) to obtain a first weighted electrical resistance component, and the second electrical resistance component (SOP Ｅ deriving a second weighted electrical resistance component by calculating the product of (β) and the difference between 1 and the temperature coefficient (β); vii) calculating a first composite state-of-phase value (SOP) by calculating the sum of the first weighted temperature component and the first weighted electrical resistance component; ｆｌｏｗ ) and calculating the sum of the second weighted temperature component and the second weighted electrical resistance component to obtain a second composite state-of-phase value (SOP ｒｅｔｕｒｎ ) and viii) the second state of phase value (SOP) ｒｅｔｕｒｎ ) and the first state of phase value (SOP ｆｌｏｗ ) to determine the difference in the state of phase (ΔSOP) of the heat transfer liquid between both ends of the at least one indoor heat exchanger; 3. The system according to claim 1 or 2, configured as follows:

4. The control device controls the temperature components (SOP) of the state of phase (SOP) of the heat transfer fluid. Ｔ )of, T ｍｅ >(T ｅｑ +u(+)), then SOP Ｔ = 0, T ｍｅ <(T ｅｑ -u(-)), then SOP Ｔ = 1, T ｍｅ ≧((T ｅｑ -u(-)) and ≦(T ｅｑ +u(+)), then SOP Ｔ is in the range of >0 and <1, preferably in the range of 0.1 to 0.9, more preferably in the range of 0.2 to 0.8, even more preferably in the range of 0.3 to 0.7, particularly preferably in the range of 0.4 to 0.6, in particular 0.5; It is configured to ask for During the ceremony, T ｍｅ is the measured temperature value, T ｅｑ is the phase change temperature of the phase change material, u(+) is the temperature deviation from the equilibrium temperature at the upper limit of the phase change state during the phase change process, e.g., during melting; 4. The system of claim 2, wherein u(-) is the temperature deviation from the equilibrium temperature at the lower limit of the phase change state during the phase change process, for example during crystallization.

5. The control device is configured to calculate an electrical resistance component (SOP) of the state of phase (SOP) of the heat transfer liquid. Ｅ )of, SOP Ｅ =SOP ０ +α・(R ｍｅ -R ０ ) It is configured to ask for During the ceremony, SOP ０ is the reference phase state value, and the SOP when the heat transfer fluid is liquid and no solid crystals are present ０ is preferably 0, α is the reference resistance value R ０ is a coefficient for converting the change in the measured electrical resistance with respect to a phase state; R ｍｅ is the measured electrical resistance value, R ０ The system according to any one of claims 2 to 4, wherein is a reference resistance value.

6. The control device controls the composite state of phase (SOP ｆｌｏｗ , SOP ｒｅｔｕｒｎ )of, SOP ｆｌｏｗ ,SOP ｒｅｔｕｒｎ =b・SOP Ｔ + (1-b)・SOP Ｅ It is configured to ask for During the ceremony, β is a coefficient representing a weighting value for a particular phase change material that provides the most accurate prediction of the enthalpy-based phase state measurement, and β is preferably T ｍｅ >(T ｅｑ +u(+)), then β=1 and T ｍｅ <(T ｅｑ -u(-)), then β=1, T ｍｅ ≧((T ｅｑ -u(-)) and ≦(T ｅｑ +u(+)), β is in the range of >0 and <1, preferably in the range of 0.01 to 0.8, more preferably in the range of 0.05 to 0.6, even more preferably in the range of 0.10 to 0.4, particularly preferably in the range of 0.15 to 0.3, in particular 0.2; It is asked to During the ceremony, T ｍｅ is the measured temperature value, T ｅｑ is the phase change temperature of the phase change material, u(+) is the temperature deviation from the equilibrium temperature at the upper limit of the phase change state during the phase change process, e.g., during melting; The system of any one of claims 2 to 5, wherein u(-) is the temperature deviation from the equilibrium temperature at the lower limit of the phase change state during the phase change process, for example during crystallization.

7. The control device i) the composite state of phase (SOP) value determined by controlling the compressor speed, preferably according to the highest cooling load of the indoor heat exchanger in the system; ｆｌｏｗ ), and / or ii) a difference in state of phase (ΔSOP) determined across the at least one heat exchanger by controlling the rotational speed of a fan of the at least one indoor heat exchanger and / or by controlling the flow rate of the heat transfer fluid through the at least one indoor heat exchanger, preferably by controlling the pumping speed of the pump fluidly connected to the indoor heat exchanger and / or the opening of a valve fluidly connected to the indoor heat exchanger; The system of any one of claims 1 to 6, configured to control operation of the heat transfer system based on:

8. the cooling circuit comprises at least one further indoor heat exchanger, a third sensor system is arranged in the cooling circuit downstream of the further indoor heat exchanger, the third sensor system comprises or consists of a temperature sensor and an electrical resistance sensor realized as two separate sensors or as one combined temperature and electrical resistance sensor, and the control device i) the composite state of phase (SOP) value determined by controlling the compressor speed, preferably according to the highest cooling load of the indoor heat exchanger in the system; ｆｌｏｗ ), and / or ii) a difference in state of phase (ΔSOP) determined across the at least one further heat exchanger by controlling the fan of the at least one further indoor heat exchanger to be switched on or off and / or by controlling the flow rate of the heat transfer fluid through the at least one further indoor heat exchanger, preferably by controlling the pumping speed of the pump fluidly connected to the at least one further indoor heat exchanger and / or the opening of a valve fluidly connected to the at least one further indoor heat exchanger, The system of any one of claims 1 to 7, configured to control operation of the heat transfer system based on:

9. 1. A method of operating a heat transfer system in which a heat transfer fluid circulates in a cooling circuit, the heat transfer fluid comprising or consisting of a phase change material, comprising:

1. A method comprising the steps of: acquiring temperature information and electrical resistance information from a sensor system located in a cooling circuit of a heat transfer system in which a heat transfer fluid circulates, the heat transfer system comprising or consisting of a phase change material, the sensor system comprising a temperature sensor and an electrical resistance sensor implemented as two separate sensors or as one combined temperature and electrical resistance sensor, A composite state of phase value (SOP) is calculated based on the acquired temperature information and the acquired electrical resistance information. ｆｌｏｗ ) and The obtained state of phase value (SOP ｆｌｏｗ controlling operation of the heat transfer system based on the The method further comprising:

10. The composite state of phase value (SOP ｆｌｏｗ ) to find i) the temperature of the heat transfer liquid (T ｍｅ ) from the sensor system; ii) the electrical resistance (R ｍｅ ) from the sensor system; iii) the temperature component of the state of phase (SOP) of the heat transfer fluid (SOP Ｔ ) to the temperature (T ｍｅ ) and iv) the electrical resistance component (SOP) of the heat transfer liquid Ｅ ) to the electrical resistance (R ｍｅ ) and v) the temperature component (SOP Ｔ ) and the temperature coefficient (β) to obtain a weighted temperature component; vi) the first electrical resistance component (SOP Ｅ Calculating the weighted electrical resistance component by multiplying the difference between 1 and the temperature coefficient (β) by the product of vii) calculating the composite state-of-phase value (SOP) by calculating the sum of the first weighted temperature component and the first weighted electrical resistance component; ｆｌｏｗ 10. The method of claim 9, wherein

11. The sensor system is located upstream of the at least one heat exchanger, the system comprising a second sensor system located downstream of the at least one indoor heat exchanger, the second sensor system comprising or consisting of a temperature sensor and an electrical resistance sensor realized as two separate sensors or as one combined temperature and electrical resistance sensor, the method comprising: i) acquiring temperature information from the sensor system and the second sensor system, and acquiring electrical resistance information from the sensor system and the second sensor system; ii) determining a difference in phase state (ΔSOP) of the heat transfer liquid between both ends of the at least one indoor heat exchanger based on the acquired temperature information and the acquired electrical resistance information; iii) controlling operation of the heat transfer system based on the determined difference in state of phase (ΔSOP); Including, To determine the difference in phase state (ΔSOP), the method preferably comprises: a) a first temperature (T ｍｅ ) from the sensor system, and a second temperature (T ｍｅ ) from the second sensor system; b) a first electrical resistance (R ｍｅ ) is obtained from the sensor system, and a second electrical resistance (R ｍｅ ) from the second sensor system; c) a first temperature component (SOP) of the state of phase (SOP) of the heat transfer fluid; Ｔ ) to the first temperature (T ｍｅ ) and a second temperature component (SOP) of the state of phase (SOP) of the heat transfer fluid. Ｔ ) to the second temperature (T ｍｅ ) and d) a first electrical resistance component (SOP) of the state of phase (SOP) of the heat transfer fluid; Ｅ ) to the first electrical resistance (R ｍｅ ) and a second electrical resistance component (SOP) of the heat transfer fluid Ｅ ) to the second electrical resistance (R ｍｅ ) and e) the first temperature component (SOP Ｔ ) and a temperature coefficient (β) to obtain a first weighted temperature component, and the second temperature component (SOP Ｔ determining a second weighted temperature component by calculating the product of (β) and the temperature coefficient (β); f) the first electrical resistance component (SOP Ｅ ) and the difference between 1 and the temperature coefficient (β) to obtain a first weighted electrical resistance component, and the second electrical resistance component (SOP Ｅ determining a second weighted electrical resistance component by calculating the product of (β) and the difference between 1 and the temperature coefficient (β); g) calculating a first composite state-of-phase value (SOP) by summing the first weighted temperature component and the first weighted electrical resistance component; ｆｌｏｗ ) and calculating the sum of the second weighted temperature component and the second weighted electrical resistance component to obtain a second composite state-of-phase value (SOP ｒｅｔｕｒｎ ) and h) the second state of phase value (SOP ｒｅｔｕｒｎ ) and the first state of phase value (SOP ｆｌｏｗ determining the difference in state of phase (ΔSOP) of the heat transfer fluid across the at least one indoor heat exchanger by calculating the difference between 11. The method of claim 9 or 10, comprising:

12. The temperature components (SOP) of the state of phase (SOP) of the heat transfer fluid Ｔ )teeth, T ｍｅ >(T ｅｑ +u(+)), then SOP Ｔ = 0, T ｍｅ <(T ｅｑ -u(-)), then SOP Ｔ = 1, T ｍｅ ≧((T ｅｑ -u(-)) and ≦(T ｅｑ +u(+)), then SOP Ｔ is in the range of >0 and <1, preferably in the range of 0.1 to 0.9, more preferably in the range of 0.2 to 0.8, even more preferably in the range of 0.3 to 0.7, particularly preferably in the range of 0.4 to 0.6, in particular 0.5; It is asked to During the ceremony, T ｍｅ is the measured temperature value, T ｅｑ is the phase change temperature of the phase change material, u(+) is the temperature deviation from the equilibrium temperature at the upper limit of the phase change state during the phase change process, e.g., during melting; 12. The method according to claim 10 or 11, wherein u(-) is the temperature deviation from the equilibrium temperature at the lower limit of the phase change state during the phase change process, for example during crystallization.

13. The electrical resistance component (SOP) of the state of phase (SOP) of the heat transfer liquid Ｅ ) is SOP Ｅ =SOP ０ +α・(R ｍｅ -R ０ ) and During the ceremony, SOP ０ is the reference phase state value, and the SOP when the heat transfer fluid is liquid and no solid crystals are present ０ is preferably 0, α is the reference resistance value R ０ is a coefficient for converting the measured electrical resistance change to a phase state, R ｍｅ is the measured electrical resistance value, R ０ The method according to any one of claims 10 to 12, wherein is a reference resistance value.

14. The composite state of phase value (SOP ｆｌｏｗ , SOP ｒｅｔｕｒｎ )teeth, SOP ｆｌｏｗ ,SOP ｒｅｔｕｒｎ =b・SOP Ｔ + (1-b)・SOP Ｅ It is asked like this, During the ceremony, β is a coefficient relating to the weighting value for a particular phase change material that results in the most accurate prediction of the enthalpy-based phase state measurement, and β is preferably T ｍｅ >(T ｅｑ +u(+)), then β=1, T ｍｅ <(T ｅｑ -u(-)), then β=1, T ｍｅ ≧((T ｅｑ -u(-)) and ≦(T ｅｑ +u(+)), β is in the range >0 and <1, preferably in the range of 0.01 to 0.8, more preferably in the range of 0.05 to 0.6, even more preferably in the range of 0.10 to 0.4, particularly preferably in the range of 0.15 to 0.3, in particular 0.2; During the ceremony, T ｍｅ is the measured temperature value, T ｅｑ is the phase change temperature of the phase change material, u(+) is the temperature deviation from the equilibrium temperature at the upper limit of the phase change state during the phase change process, e.g., during melting; The method according to any one of claims 10 to 13, wherein u(-) is the temperature deviation from the equilibrium temperature at the lower limit of the phase change state during the phase change process, for example during crystallization.

15. The operation of the heat transfer system comprises: i) the composite state of phase (SOP) value determined by controlling the compressor speed, preferably according to the highest cooling load of the indoor heat exchanger in the system; ｆｌｏｗ ), and / or ii) a difference in state of phase (ΔSOP) determined across the at least one heat exchanger by controlling the fan of the at least one indoor heat exchanger to be switched on or off and / or by controlling the flow rate of the heat transfer fluid through the at least one indoor heat exchanger, preferably by controlling the pumping speed of the pump fluidly connected to the indoor heat exchanger and / or the opening of a valve fluidly connected to the indoor heat exchanger; The method according to any one of claims 9 to 14, wherein the control is based on

16. the cooling circuit comprises at least one further indoor heat exchanger, a third sensor system is arranged in the cooling circuit downstream of the further indoor heat exchanger, the third sensor system comprises or consists of a temperature sensor and an electrical resistance sensor realized as two separate sensors or as one combined temperature and electrical resistance sensor, and the control device i) the composite state of phase (SOP) value determined by controlling the compressor speed, preferably according to the highest cooling load of the indoor heat exchanger in the system; ｆｌｏｗ ), and / or ii) a difference in state of phase (ΔSOP) across the at least one further heat exchanger, determined by controlling the fan of the at least one further indoor heat exchanger to be switched on or off and / or by controlling the flow rate of the heat transfer fluid through the at least one further indoor heat exchanger, preferably by controlling the pumping speed of the pump fluidly connected to the at least one further indoor heat exchanger and / or the opening of a valve fluidly connected to the at least one further indoor heat exchanger; The method according to any one of claims 9 to 15, configured to control operation of the heat transfer system based on

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