Cooling system using non-azeotropic refrigerant mixture

Abstract

This invention provides a cooling system using a non-azeotropic mixed refrigerant that can prevent self-decomposition (disproportionation) and suppress the occurrence of liquid compression by improving the accuracy of the detection process for the generation of flash gas. [Solution] This cooling device 100 includes a processing unit 8 that performs determination processing regarding the generation of flash gas, which is a mixture of a gaseous non-azeotropic mixed refrigerant and a liquid non-azeotropic mixed refrigerant, based on the correlation between the resistance value (valve opening) of the intermediate pressure electronic expansion valve 6 (first resistance part) and the pipe temperature, and the measured value of the pipe temperature.

Description

Technical Field

[0001] This invention relates to a cooling device using azeotropic refrigerant mixtures, which are refrigerants in which low-boiling refrigerants and high-boiling refrigerants are mixed.

Background Art

[0002] Conventionally, cooling devices using refrigerants have been known (see, for example, Patent Document 1).

[0003] Patent Document 1 discloses a refrigeration cycle device (cooling device) including a compressor, a condenser, and an expansion valve, and using a refrigerant that is not an azeotropic refrigerant mixture. In Patent Document 1, an estimated value of the condensation temperature when the refrigerant is completely condensed in the condenser is obtained based on the pressure of the refrigerant compressed in the compressor. Further, in Patent Document 1, a first temperature difference between the obtained estimated value of the condensation temperature and the measured value of the temperature of the refrigerant on the inlet side of the condenser, and a second temperature difference between the obtained estimated value of the condensation temperature and the measured value of the temperature of the refrigerant on the outlet side of the condenser are obtained. Furthermore, in Patent Document 1, when the second temperature difference is larger than the first temperature difference, it is detected that a flash gas in which a gaseous refrigerant and a liquid-phase refrigerant are mixed has occurred.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] Although not disclosed in Patent Document 1 mentioned above, a cooling system is known in which the refrigerant circuit branches downstream of the condenser and a non-azeotropic mixed refrigerant, which is a mixture of a low-boiling-point refrigerant and a high-boiling-point refrigerant, is used as the refrigerant. In such a cooling system, when flash gas is generated, the gaseous low-boiling-point refrigerant may flow unevenly to one side of the branched flow path. Also, when flash gas is generated, the liquid-phase high-boiling-point refrigerant may not flow at the branching point, causing a liquid accumulation. As a result, the amount of high-boiling-point refrigerant supplied to the compressor decreases, and the concentration of the low-boiling-point refrigerant in the compressor increases, which may cause an autodecomposition reaction. Furthermore, if the flow rate of the refrigerant supplied to the compressor is rapidly increased in order to suppress the increase in the concentration of low-boiling-point refrigerant in the compressor, the amount of liquid-phase high-boiling-point refrigerant supplied to the compressor may become excessive, causing liquid compression. Therefore, it is desirable to detect the generation of flash gas.

[0006] However, if the measured temperature of the refrigerant at the condenser outlet is within the margin of error compared to the temperature at which the refrigerant is completely condensed in the condenser, flash gas may or may not be generated. Therefore, in cooling systems that determine the presence or absence of flash gas based on the difference between the temperature at the condenser outlet and the temperature at which complete condensation occurs, it may be difficult to accurately determine the presence or absence of flash gas, as it may be incorrectly determined that flash gas has not occurred even when it has actually been generated. Thus, there is a need for a cooling system that can prevent self-decomposition (disproportionation) and suppress the occurrence of liquid compression by improving the accuracy of the flash gas generation determination process.

[0007] This invention was made to solve the above-mentioned problems, and one objective of this invention is to provide a cooling device using a non-azeotropic mixed refrigerant that can prevent self-decomposition (disproportionation) and suppress the occurrence of liquid compression by improving the accuracy of the determination process regarding the generation of flash gas. [Means for solving the problem]

[0008] A cooling apparatus using a non-azeotropic mixed refrigerant in the first aspect of this invention includes a compressor for compressing a non-azeotropic mixed refrigerant, which is a mixture of a low-boiling-point refrigerant and a high-boiling-point refrigerant; a condenser for condensing the non-azeotropic mixed refrigerant compressed in the compressor; an evaporator for evaporating the non-azeotropic mixed refrigerant condensed in the condenser; a first resistor for adjusting the pressure of the non-azeotropic mixed refrigerant supplied from the condenser to the compressor; a second resistor for adjusting the pressure of the non-azeotropic mixed refrigerant supplied from the condenser to the evaporator; a first pipe connecting the compressor and the condenser; a second pipe connecting the condenser and the second resistor; and a third pipe branching from the second pipe and connecting the condenser and the first resistor, through which a high-pressure refrigerant, which is a non-azeotropic mixed refrigerant that has reached a pressure higher than the non-azeotropic mixed refrigerant evaporated in the evaporator by being compressed by the compressor, flows. The system includes a path, an intermediate pressure circuit which includes a fourth pipe connecting a first resistance section and a compressor, through which an intermediate pressure refrigerant, which is a non-azeotropic mixed refrigerant whose pressure is lower than that of the high-pressure refrigerant flowing through the high-pressure circuit after passing through the first resistance section, flows; a low-pressure circuit which includes a fifth pipe connecting a second resistance section and an evaporator, and a sixth pipe connecting the evaporator and a compressor, through which a low-pressure refrigerant, which is a non-azeotropic mixed refrigerant whose pressure is lower than that of the high-pressure refrigerant and the intermediate pressure refrigerant after passing through the second resistance section, flows; a temperature detection unit located in the fourth pipe of the intermediate pressure circuit which detects the pipe temperature, which is the temperature of the fourth pipe; and a processing unit which performs determination processing regarding the generation of flash gas, which is a mixture of gas-phase non-azeotropic mixed refrigerant and liquid-phase non-azeotropic mixed refrigerant, based on the resistance-temperature correlation between the resistance value of the first resistance section and the pipe temperature, and the measured value of the pipe temperature.

[0009] In the cooling device using a non-azeotropic mixed refrigerant according to the first aspect of this invention, as described above, a processing unit is provided that performs a determination process regarding the generation of flash gas, which is a mixture of gaseous non-azeotropic mixed refrigerant and liquid-phase non-azeotropic mixed refrigerant, based on the resistance-temperature correlation between the resistance value of the first resistance section and the pipe temperature, and the measured value of the pipe temperature. As a result, because the pressure loss at the first resistance section is greater for gaseous non-azeotropic mixed refrigerant than for liquid-phase non-azeotropic mixed refrigerant, when flash gas is generated, the pressure of the non-azeotropic mixed refrigerant at the first resistance section drops significantly compared to when flash gas is not generated, and the temperature of the piping between the first resistance section and the compressor becomes significantly lower. Therefore, by obtaining the pipe temperature when flash gas is not generated based on the resistance-temperature correlation between the resistance value of the first resistance section and the pipe temperature, and comparing it with the measured value of the pipe temperature, the generation of flash gas can be clearly detected. Furthermore, because the generation of flash gas can be clearly detected, the condenser can be controlled to eliminate the flash gas, and the concentration of low-boiling point refrigerant supplied to the intermediate pressure circuit and the low-pressure circuit can be made approximately the same. This prevents the concentration of low-boiling-point refrigerant supplied to the compressor from increasing, thereby suppressing the occurrence of autodecomposition (disproportionation). Furthermore, because autodecomposition (disproportionation) is suppressed, there is no need to rapidly increase the flow rate of refrigerant supplied to the compressor, thus suppressing liquid compression. As a result, by improving the accuracy of the flash gas generation detection process, it is possible to prevent autodecomposition (disproportionation) and suppress the occurrence of liquid compression.

[0010] Furthermore, in a cooling device using a non-azeotropic mixed refrigerant according to the first aspect described above, preferably, an intermediate heat exchanger is provided in the second piping between the condenser and the second resistance section, and performs heat exchange between the high-pressure refrigerant flowing through the second piping and the intermediate-pressure refrigerant flowing through the fourth piping via the third piping. The first resistance section is provided between the branching point of the second and third piping and the inlet of the intermediate heat exchanger connected to the fourth piping. The temperature detection section is provided between the first resistance section and the inlet of the intermediate heat exchanger connected to the fourth piping. The processing unit is configured to perform a determination process regarding the generation of flash gas based on the resistance-temperature correlation and the measured value of the pipe temperature of the fourth piping that supplies the non-azeotropic mixed refrigerant from the first resistance section to the intermediate heat exchanger. With this configuration, by obtaining the pipe temperature of the fourth piping between the first resistance section and the inlet of the intermediate heat exchanger connected to the fourth piping, it is possible to determine whether or not flash gas is being generated in the non-azeotropic mixed refrigerant supplied to the intermediate heat exchanger. Furthermore, when flash gas is supplied to the intermediate heat exchanger, the ability of the intermediate heat exchanger to cool the non-azeotropic refrigerant flowing through the second pipe is reduced compared to when liquid-phase non-azeotropic refrigerant is supplied, resulting in a decrease in heat exchange efficiency. Therefore, by detecting the generation of flash gas in the non-azeotropic refrigerant supplied to the intermediate heat exchanger, the non-azeotropic refrigerant can be processed to be completely condensed in the condenser, thereby suppressing the decrease in the heat exchange efficiency of the intermediate heat exchanger.

[0011] Furthermore, in a cooling device using a non-azeotropic mixed refrigerant according to the first aspect described above, preferably, the first resistance unit is an electronic expansion valve, and the processing unit is configured to perform a determination process regarding the generation of flash gas based on the resistance-temperature correlation between the valve opening of the electronic expansion valve (which is the resistance value of the first resistance unit) and the tube temperature, and the measured value of the tube temperature. With this configuration, since the tube temperature differs depending on the valve opening of the electronic expansion valve, it is possible to perform a determination process regarding the generation of flash gas according to the valve opening of the electronic expansion valve based on the resistance-temperature correlation between the valve opening of the electronic expansion valve (which is the resistance value of the first resistance unit) and the tube temperature, and the measured value of the tube temperature. As a result, the accuracy of the determination process regarding the generation of flash gas can be further improved.

[0012] Furthermore, in a cooling system using a non-azeotropic mixed refrigerant according to the first aspect described above, the processing unit is preferably configured to perform a process to determine whether the difference between the target value of the tube temperature and the actual value of the tube temperature is within an acceptable range, based on a target value of the tube temperature estimated to be the point at which the non-azeotropic mixed refrigerant has completely condensed in the condenser, which is set by the resistance-temperature correlation, and the actual value of the tube temperature. With this configuration, by setting an acceptable range for the difference between the target value of the tube temperature and the actual value of the tube temperature, the difference between the target value of the tube temperature and the actual value of the tube temperature where no flash gas is generated, and the difference between the target value of the tube temperature and the actual value of the tube temperature where it is judged that flash gas is generated but does not affect the cooling system, can be included in the acceptable range. As a result, when it is estimated that flash gas is being generated, the processing unit can determine whether it is acceptable or not, and thus the accuracy of the flash gas generation determination process can be further improved.

[0013] In this case, preferably, the processing unit is configured to perform a process to determine whether the difference between the target value of the pipe temperature and the measured value of the pipe temperature is within an acceptable range, based on a temperature change threshold, which is the upper limit of the acceptable range of the difference between the target value of the pipe temperature and the measured value of the pipe temperature. With this configuration, the processing unit can easily perform the determination process regarding the generation of flash gas by comparing the temperature change threshold with the difference between the target value of the pipe temperature and the measured value of the pipe temperature.

[0014] In a cooling device configured to perform a determination process regarding the generation of flash gas, the processing unit is preferably configured to perform a determination process regarding the generation of flash gas by determining whether the difference between the target value of the tube temperature and the measured value of the tube temperature is within an acceptable range, based on a temperature threshold, which is the lower limit of the acceptable measured value of the tube temperature, set so that the difference between the target value of the tube temperature and the measured value of the tube temperature is within an acceptable range, and the measured value of the tube temperature. With this configuration, the processing unit can compare the measured value of the tube temperature with the temperature threshold, and if the measured value of the tube temperature is lower than the temperature threshold, it can be determined that the difference between the target value of the tube temperature and the measured value of the tube temperature exceeds the acceptable range. Therefore, the processing unit can easily perform a determination process regarding the generation of flash gas based on the measured value of the tube temperature.

[0015] Furthermore, in a cooling device using a non-azeotropic mixed refrigerant according to the first aspect described above, preferably, the device further includes a storage unit that stores correlation information, which is information on the resistance-temperature correlation, and the processing unit is configured to determine whether the difference between the target value of the tube temperature set based on the correlation information stored in the storage unit and the measured value of the tube temperature is within an acceptable range. With this configuration, the processing unit can easily perform determination processing regarding the generation of flash gas based on the correlation information stored in the storage unit.

[0016] In this case, preferably, the storage unit is configured to update correlation information based on information obtained from the server, and the processing unit is configured to determine whether the difference between the target value of the tube temperature set based on the updated correlation information and the measured value of the tube temperature is within an acceptable range. With this configuration, the correlation information stored in the storage unit can be updated and made new, so for example, the target value used to determine whether the difference between the target value and the measured value of the tube temperature is within an acceptable range can be set to a more appropriate value based on information obtained by actually using the cooling device.

[0017] Furthermore, in a cooling system using a non-azeotropic mixed refrigerant according to the first aspect described above, preferably, the low-boiling-point refrigerant includes a refrigerant that is prone to self-decomposition at high concentrations, and the processing unit is configured to perform at least one of the following actions when it detects a malfunction in the generation of flash gas: adjusting the airflow of a fan installed in the condenser, stopping the compressor, and adjusting the valve opening of the electronic expansion valve as the first resistance unit. With this configuration, in a cooling system using a non-azeotropic mixed refrigerant in which the low-boiling-point refrigerant is prone to self-decomposition at high concentrations, it is possible to perform a determination process regarding the generation of flash gas, and thus process the system to prevent the generation of flash gas and the occurrence of self-decomposition. In addition, by adjusting the airflow of a fan installed in the condenser, the processing unit can promote further cooling and condensation of the non-azeotropic mixed refrigerant in the condenser, thereby suppressing the generation of flash gas. Furthermore, by stopping the compressor, the processing unit can prevent the cooling system from being affected by malfunctions caused by the generation of flash gas. Furthermore, the processing unit can adjust the flow rate of the non-azeotropic refrigerant mixture by adjusting the valve opening of the electronic expansion valve, which acts as a resistance unit, and can also prevent flash gas from flowing through the fourth pipe by closing the electronic expansion valve. As a result, malfunctions caused by the generation of flash gas can be addressed.

[0018] A cooling device using a non-azeotropic mixed refrigerant in the second aspect of this invention includes a compressor for compressing a non-azeotropic mixed refrigerant, which is a mixture of at least R1132(E) as a low-boiling point refrigerant and R1234yf as a high-boiling point refrigerant; a condenser for condensing the non-azeotropic mixed refrigerant compressed in the compressor; an evaporator for evaporating the non-azeotropic mixed refrigerant condensed in the condenser; a first resistor for adjusting the pressure of the non-azeotropic mixed refrigerant supplied from the condenser to the compressor; a second resistor for adjusting the pressure of the non-azeotropic mixed refrigerant supplied from the condenser to the evaporator; a first pipe connecting the compressor and the condenser; a second pipe connecting the condenser and the second resistor; and a third pipe branching from the second pipe and connecting the condenser and the first resistor, wherein the non-azeotropic mixed refrigerant, which has been compressed by the compressor and has reached a pressure higher than the non-azeotropic mixed refrigerant evaporated in the evaporator, is compressed by the compressor. The system includes a high-pressure circuit through which a high-pressure refrigerant flows, an intermediate-pressure circuit through which an intermediate-pressure refrigerant, which is a non-azeotropic mixed refrigerant whose pressure is lower than that of the high-pressure refrigerant flowing in the high-pressure circuit by passing through the first resistance section and including a fourth pipe connecting a first resistance section and a compressor, a low-pressure circuit through which a low-pressure refrigerant, which is a non-azeotropic mixed refrigerant whose pressure is lower than that of the high-pressure refrigerant and the intermediate-pressure refrigerant by passing through the second resistance section and including a fifth pipe connecting a second resistance section and an evaporator, and a sixth pipe connecting the evaporator and a compressor, flows, a temperature detection unit located in the fourth pipe of the intermediate-pressure circuit and detecting the pipe temperature, which is the temperature of the fourth pipe, and a processing unit that performs determination processing regarding the generation of flash gas, which is a mixture of gas-phase non-azeotropic mixed refrigerant and liquid-phase non-azeotropic mixed refrigerant, based on the resistance-temperature correlation between the resistance value of the first resistance section and the pipe temperature, and the measured value of the pipe temperature.

[0019] In the cooling device using a non-azeotropic mixed refrigerant according to the second aspect of this invention, as described above, a processing unit is provided that performs a determination process regarding the generation of flash gas, which is a mixture of gaseous non-azeotropic mixed refrigerant and liquid-phase non-azeotropic mixed refrigerant, based on the resistance-temperature correlation between the resistance value of the first resistance section and the pipe temperature, and the measured value of the pipe temperature. As a result, because the pressure loss at the first resistance section is greater for gaseous non-azeotropic mixed refrigerant than for liquid-phase non-azeotropic mixed refrigerant, when flash gas is generated, the pressure of the non-azeotropic mixed refrigerant at the first resistance section drops significantly compared to when flash gas is not generated, and the temperature of the piping between the first resistance section and the compressor becomes noticeably lower. Therefore, by obtaining the pipe temperature when flash gas is not generated based on the resistance-temperature correlation between the resistance value of the first resistance section and the pipe temperature, and comparing it with the measured value of the pipe temperature, the generation of flash gas can be clearly detected. Furthermore, because the generation of flash gas can be clearly detected, the condenser can be controlled to eliminate the flash gas, making it possible to keep the concentration of R1132(E), a low-boiling point refrigerant supplied to the intermediate-pressure circuit and the low-pressure circuit, approximately the same. This suppresses the concentration of R1132(E), a low-boiling point refrigerant supplied to the compressor from becoming too high, thereby suppressing the occurrence of autodecomposition (disproportionation). In addition, because the occurrence of autodecomposition (disproportionation) is suppressed, there is no need to rapidly increase the flow rate of the refrigerant supplied to the compressor, thus suppressing the occurrence of liquid compression. As a result, by improving the accuracy of the flash gas generation detection process, it is possible to prevent autodecomposition (disproportionation) and suppress the occurrence of liquid compression. [Effects of the Invention]

[0020] According to the present invention, as described above, by improving the accuracy of the determination process regarding the generation of flash gas, it is possible to provide a cooling device that can prevent self-decomposition (disproportionation) and suppress the occurrence of liquid compression. [Brief explanation of the drawing]

[0021] [Figure 1]It is a diagram showing the overall configuration of the cooling device according to the first embodiment. [Figure 2] It is a diagram showing the correlation information and the measured value of the tube temperature when flash gas is generated. [Figure 3] It is a diagram for explaining a process of determining whether the difference between the target value of the tube temperature and the measured value of the tube temperature is within an allowable range based on a temperature threshold which is the lower limit value of the measured value of the allowable tube temperature according to the first embodiment. [Figure 4] It is a diagram showing the overall configuration of the cooling device according to the second embodiment. [Figure 5] It is a diagram for explaining a process of determining whether the difference between the target value of the tube temperature and the measured value of the tube temperature is within an allowable range based on a temperature threshold which is the lower limit value of the measured value of the allowable tube temperature according to a modification.

Embodiments for Carrying Out the Invention

[0022] Hereinafter, embodiments embodying the present invention will be described based on the drawings.

[0023] [First Embodiment] The configuration of the cooling device 100 according to the first embodiment will be described with reference to FIG. 1. The cooling device 100 includes a compressor 1, a condenser 2, an evaporator 3, an intermediate-pressure electronic expansion valve 6, a temperature detection unit 7, a processing unit 8, an intermediate heat exchanger 9, a storage unit 10, a low-pressure electronic expansion valve 11, a high-pressure circuit 20, an intermediate-pressure circuit 30, and a low-pressure circuit 40. The cooling device 100 includes a refrigeration cycle in which a zeotropic mixture refrigerant circulates. The refrigeration cycle is composed of a compressor 1, a condenser 2, an evaporator 3, an intermediate-pressure electronic expansion valve 6, a temperature detection unit 7, an intermediate heat exchanger 9, a low-pressure electronic expansion valve 11, a high-pressure circuit 20, an intermediate-pressure circuit 30, and a low-pressure circuit 40. The refrigeration cycle is configured to cool an object with a zeotropic mixture refrigerant. Note that the intermediate-pressure electronic expansion valve 6 is an example of the "first resistance unit" and the "electronic expansion valve" described in the claims. Also, the low-pressure electronic expansion valve 11 is an example of the "second resistance unit" described in the claims.

[0024] The cooling device 100 is configured to completely condense the non-azeotropic refrigerant mixture in the condenser 2 in order to suppress the generation of flash gas, which is a mixture of the gaseous non-azeotropic refrigerant mixture and the liquid non-azeotropic refrigerant mixture. More specifically, the cooling device 100 is configured to completely liquefy the non-azeotropic refrigerant mixture in the condenser 2.

[0025] The cooling device 100 is configured, via the processing unit 8, to perform a determination process regarding the generation of flash gas based on the correlation between the resistance value of the intermediate pressure electronic expansion valve 6 and the tube temperature, and the measured value Dx of the tube temperature (see Figure 3). In the first embodiment, the resistance value of the intermediate pressure electronic expansion valve 6 is the valve opening. The valve opening used as the resistance value is the initial setting value set when the refrigeration cycle of the cooling device 100 is started. If the valve opening used as the resistance value has been changed from the initial setting value, the changed valve opening is used.

[0026] The pipe temperature is the temperature of the piping that constitutes the intermediate pressure circuit 30 between the intermediate pressure electronic expansion valve 6 and the compressor 1. More specifically, it is the temperature of the fourth pipe 30a that constitutes the intermediate pressure circuit 30 between the intermediate pressure electronic expansion valve 6 and the intermediate heat exchanger 9. The fourth pipe 30a is made of a material with high thermal conductivity. For example, the fourth pipe 30a is made of metal. The pipe temperature is maintained at approximately the same temperature as the non-azeotropic refrigerant mixture circulating inside the fourth pipe 30a.

[0027] The processing unit 8 is configured to perform processing to resolve a malfunction in flash gas generation when it detects such a malfunction. As processing to resolve the flash gas generation malfunction, the processing unit 8 is configured to perform at least one of the following: adjusting the airflow rate of the fan 2a provided on the condenser 2, stopping the compressor 1, and adjusting the valve opening of the intermediate pressure electronic expansion valve 6. A malfunction in flash gas generation refers to a situation where the proportion of non-azeotropic mixed refrigerant in the gas phase of the flash gas is excessively high, which may cause a malfunction in the cooling device 100. Such a malfunction can be caused, for example, by an imbalance in the refrigerant concentration in the gas phase due to the branching of the non-azeotropic mixed refrigerant. The configuration of the cooling device 100 will be described in detail below.

[0028] Non-azeotropic refrigerants are a mixture of low-boiling-point and high-boiling-point refrigerants. Low-boiling-point refrigerants have a low GWP (Global Warming Potential) value and therefore have a small impact on global warming. Furthermore, low-boiling-point refrigerants offer superior cooling performance at low temperatures compared to high-boiling-point refrigerants. However, low-boiling-point refrigerants may undergo self-decomposition (disproportionation) reactions, where they decompose using only their own molecules without the need for other molecules, depending on the composition ratio of the refrigerants in the non-azeotropic mixture, temperature, and external energy. In particular, low-boiling-point refrigerants are prone to self-decomposition at high concentrations. Therefore, non-azeotropic refrigerants are mixed with high-boiling-point refrigerants at concentrations (composition ratios) that prevent self-decomposition. The malfunction of flash gas generation includes cases where self-decomposition is possible due to a high concentration of low-boiling-point refrigerant in the gas phase. For example, the high-boiling point refrigerant is R1234yf (2,3,3,3-tetrafluoropropene). For example, the low-boiling point refrigerant r2 is R1132(E) (trans-1,2-difluoroethylene). The non-azeotropic mixed refrigerant R1 is, for example, refrigerant R474B produced by mixing a high-boiling point refrigerant and a low-boiling point refrigerant in a predetermined mixing ratio. The first mixing ratio is, for example, a mixing ratio of high-boiling point refrigerant (R1234yf):low-boiling point refrigerant (R1132(E)) = 68.5:31.5 (tolerance ±2.0%).

[0029] Based on Figure 1, the details of the cooling device 100 will be described. The high-pressure circuit 20 is a circuit that carries high-pressure refrigerant, which is a non-azeotropic mixed refrigerant that has reached a higher pressure than the non-azeotropic mixed refrigerant evaporated in the evaporator 3 by being compressed by the compressor 1. The high-pressure circuit 20 is configured to supply high-pressure refrigerant from the compressor 1 to the evaporator 3 via the condenser 2. The high-pressure circuit 20 includes a first pipe 20a, a second pipe 20b, and a third pipe 20c. The first pipe 20a, the second pipe 20b, and the third pipe 20c are made of metal.

[0030] The first pipe 20a is configured to connect the compressor 1 and the condenser 2. The first pipe 20a is configured to connect the outlet of the compressor 1 and the inlet of the condenser 2. The second pipe 20b is configured to connect the condenser 2 and the low-pressure electronic expansion valve 11. The second pipe 20b is connected to the first pipe 20a via the condenser 2. The second pipe 20b is configured to connect the outlet of the condenser 2 and the inlet of the low-pressure electronic expansion valve 11 via the inside of the intermediate heat exchanger 9. The second pipe 20b is configured to allow the refrigerant that transfers heat in the intermediate heat exchanger 9 to flow through it. The third pipe 20c branches off from the second pipe 20b at branching point 12 and is configured to connect the condenser 2 and the inlet of the intermediate-pressure electronic expansion valve 6. The third pipe 20c is configured to connect from branching point 12 with the second pipe 20b to the inlet of the intermediate-pressure electronic expansion valve 6. The third pipe 20c is configured to connect the second pipe 20b and the fourth pipe 30a.

[0031] The intermediate pressure circuit 30 is a circuit through which an intermediate pressure refrigerant, which is a non-azeotropic mixed refrigerant whose pressure is lower than that of the high-pressure refrigerant flowing through the high-pressure circuit 20 by passing through the intermediate pressure electronic expansion valve 6, flows. The intermediate pressure circuit 30 is equipped with an intermediate pressure electronic expansion valve 6, a temperature sensing unit 7, and an intermediate heat exchanger 9. The intermediate pressure circuit 30 is configured to evaporate the refrigerant, which has been brought to an intermediate pressure by flowing through the intermediate pressure electronic expansion valve 6, in the intermediate heat exchanger 9, and then supply (return) the non-azeotropic mixed refrigerant to the compressor 1.

[0032] The intermediate pressure circuit 30 includes a fourth pipe 30a. The fourth pipe 30a is configured to connect the outlet of the intermediate pressure electronic expansion valve 6 to the compressor 1. The fourth pipe 30a is configured to connect the outlet of the intermediate pressure electronic expansion valve 6 to the inlet of the compressor 1, passing through the inside of the intermediate heat exchanger 9. The fourth pipe 30a is configured to carry the refrigerant that receives heat in the intermediate heat exchanger 9. The fourth pipe 30a is configured to connect to the third pipe 20c via the intermediate pressure electronic expansion valve 6.

[0033] The low-pressure circuit 40 is a circuit through which low-pressure refrigerant, which is a non-azeotropic mixed refrigerant whose pressure is lower than that of high-pressure and intermediate-pressure refrigerants by passing through the low-pressure electronic expansion valve 11, flows. The low-pressure circuit 40 includes a fifth pipe 40a and a sixth pipe 40b. The fifth pipe 40a and the sixth pipe 40b are made of metal. The fifth pipe 40a connects the outlet of the low-pressure electronic expansion valve 11 to the inlet of the evaporator 3. The fifth pipe 40a is configured to connect to the second pipe 20b via the low-pressure electronic expansion valve 11. The sixth pipe 40b is configured to connect the evaporator 3 to the compressor 1. The sixth pipe 40b is connected to the fifth pipe 40a and is configured to connect from the inlet of the evaporator 3, through the inside of the evaporator 3, to the inlet of the compressor 1. The sixth pipe 40b is connected to the fourth pipe 30a and to another inlet of the compressor 1. The low-pressure circuit 40 is configured to adjust the pressure of the non-azeotropic refrigerant mixture to a low pressure using a low-pressure electronic expansion valve 11.

[0034] Compressor 1 is configured to compress low-pressure, gaseous-phase non-azeotropic refrigerant (R474B) supplied from evaporator 3 via sixth pipe 40b and low-pressure, gaseous-phase non-azeotropic refrigerant (R474B) supplied from intermediate heat exchanger 9 via fourth pipe 30a. Compressor 1 is configured to supply high-temperature, high-pressure non-azeotropic refrigerant to condenser 2 via first pipe 20a. Compressor 1 is configured to compress the low-pressure refrigerant (high-temperature, low-pressure non-azeotropic refrigerant) into high-pressure refrigerant (high-temperature, high-pressure non-azeotropic refrigerant) and then supply the high-pressure refrigerant to condenser 2. Compressor 1 is configured to supply gaseous-phase non-azeotropic refrigerant to condenser 2. Compressor 1 is configured to allow flow rate adjustment by processing unit 8. Compressor 1 is supplied with gaseous-phase non-azeotropic refrigerant with approximately the same concentration of low-boiling-point refrigerant (R1132(E)) from evaporator 3 and intermediate heat exchanger 9. "Approximately the same" includes both cases where they are identical and cases where they differ but within the margin of error. Compressor 1 is configured to mix the non-azeotropic refrigerant mixture supplied from evaporator 3 and the non-azeotropic refrigerant mixture supplied from intermediate heat exchanger 9 and compress them. The arrows in Figure 1 indicate the direction of flow of the non-azeotropic refrigerant mixture. Compressor 1 may be a single-stage compressor or a multi-stage compressor.

[0035] The condenser 2 has an internal flow path connecting the first pipe 20a and the second pipe 20b. The condenser 2 is configured to condense the non-azeotropic mixed refrigerant (R474B) compressed in the compressor 1. The condenser 2 is configured to cool the heat of the high-temperature, high-pressure non-azeotropic mixed refrigerant supplied from the compressor 1 via the first pipe 20a with air or the like to convert it into a low-temperature, high-pressure non-azeotropic mixed refrigerant. In other words, the condenser 2 is configured to condense the high-temperature, high-pressure refrigerant supplied from the compressor 1 into a low-temperature, high-pressure refrigerant. The condenser 2 is configured to supply the low-temperature, high-pressure non-azeotropic mixed refrigerant to the intermediate heat exchanger 9 via the second pipe 20b. The condenser 2 is configured to perform heat exchange between the supplied non-azeotropic mixed refrigerant and the object to be heated. The object to be heated is air. The condenser 2 includes a fan 2a. Fan 2a is configured to cool the non-azeotropic refrigerant mixture by blowing air, which is the object to be heated, onto the surface of the piping through which the non-azeotropic refrigerant mixture flows, thereby cooling the internal flow path through which the high-temperature, high-pressure refrigerant flows. In condenser 2, if all of the low-boiling point refrigerant (R1132(E)) has liquefied, then all of the high-boiling point refrigerant (R1234yf) has also liquefied, resulting in a completely liquefied liquid-phase non-azeotropic refrigerant mixture. In this case, condenser 2 is configured to supply the liquid-phase non-azeotropic refrigerant mixture to the intermediate heat exchanger 9. In condenser 2, if some of the low-boiling point refrigerant remains in the gas phase, a flash gas is generated, which is a mixture of the gas-phase non-azeotropic refrigerant mixture and the liquid-phase non-azeotropic refrigerant mixture.

[0036] The evaporator 3 has an internal flow path connecting the fifth pipe 40a and the sixth pipe 40b. The evaporator 3 is configured to perform heat exchange between the object to be cooled and the non-azeotropic refrigerant mixture flowing through the internal flow path. The object to be cooled is, for example, air or water. The evaporator 3 is configured to supply heat from the object to be cooled to the liquid-phase non-azeotropic refrigerant mixture flowing through the internal flow path. This cools the object to be cooled. The evaporator 3 is configured to supply the non-azeotropic refrigerant mixture, which has been heated by the object to be cooled and turned into a gas phase, to the compressor 1 via the sixth pipe 40b. The evaporator 3 is supplied with the non-azeotropic refrigerant mixture from the condenser 2 via the intermediate heat exchanger 9 and the low-pressure electronic expansion valve 11. The evaporator 3 is configured to evaporate the low-pressure refrigerant, which has been reduced to a low temperature and low pressure by the low-pressure electronic expansion valve 11, to obtain a high-temperature low-pressure refrigerant.

[0037] The intermediate pressure electronic expansion valve 6 is installed between the branching point 12 of the second pipe 20b and the third pipe 20c and the inlet 9a of the intermediate heat exchanger 9 connected to the fourth pipe 30a. The intermediate pressure electronic expansion valve 6 is configured to expand the non-azeotropic refrigerant mixture flowing through the intermediate pressure circuit 30 (fourth pipe 30a). The intermediate pressure electronic expansion valve 6 is configured to reduce the pressure of the non-azeotropic refrigerant mixture and lower its temperature when the valve opening is reduced (throttled). The intermediate pressure electronic expansion valve 6 is also configured to increase the flow rate and the amount of non-azeotropic refrigerant mixture supplied to the intermediate heat exchanger 9 when the valve opening is increased. The resistance value of the intermediate pressure electronic expansion valve 6 is the valve opening of the intermediate pressure electronic expansion valve 6.

[0038] The temperature sensing unit 7 is located in the fourth pipe 30a of the intermediate pressure circuit 30. The temperature sensing unit 7 is located between the intermediate pressure electronic expansion valve 6 and the compressor 1. More specifically, the temperature sensing unit 7 is provided between the intermediate pressure electronic expansion valve 6 and the inlet 9a of the intermediate heat exchanger 9 connected to the fourth pipe 30a. The temperature sensing unit 7 is configured to detect the pipe temperature, which is the temperature of the fourth pipe 30a between the intermediate pressure electronic expansion valve 6 and the compressor 1. More specifically, the temperature sensing unit 7 is configured to detect the pipe temperature of the fourth pipe 30a between the intermediate pressure electronic expansion valve 6 and the inlet 9a of the intermediate heat exchanger 9 connected to the fourth pipe 30a. The temperature sensing unit 7 is configured to measure the surface temperature of the pipe. The temperature sensing unit 7 may be contact type or non-contact type.

[0039] The processing unit 8 includes a determination processing unit 8a and an operation processing unit 8b. The processing unit 8 is, for example, a microcontroller. The processing unit 8 also includes, for example, a CPU (Central Processing Unit). The determination processing unit 8a of the processing unit 8 performs a determination process regarding the generation of flash gas, which is a mixture of gas-phase non-azeotropic mixed refrigerant and liquid-phase non-azeotropic mixed refrigerant, based on the resistance-temperature correlation between the valve opening of the intermediate-pressure electronic expansion valve 6 and the pipe temperature, and the measured value Dx of the pipe temperature. The pipe temperature is the temperature of the fourth pipe 30a measured by the temperature detection unit 7. The determination processing unit 8a is configured to perform a determination process regarding the generation of flash gas, based on the target value of the pipe temperature and the measured value Dx of the pipe temperature, which is set by the resistance-temperature correlation between the valve opening of the intermediate-pressure electronic expansion valve 6 and the pipe temperature, and is estimated to be the pipe temperature at which the non-azeotropic mixed refrigerant has completely condensed in the condenser 2, and the measured value Dx of the pipe temperature detected by the temperature detection unit 7, to determine whether the difference between the target value of the pipe temperature and the measured value Dx of the pipe temperature is within an acceptable range. The acceptable range includes the range of tube temperatures in which the difference between the target tube temperature and the measured tube temperature Dx is expected to result in complete condensation of the non-azeotropic refrigerant mixture in condenser 2, and the range of tube temperatures in which flash gas is thought to be generated, but the proportion of the gas phase is quite low, making it extremely unlikely that a self-decomposition reaction will occur. Details of the processing of the judgment processing unit 8a will be described later.

[0040] The operation processing unit 8b is configured to control the operation of the cooling device 100. The operation processing unit 8b is configured to perform a process to resolve a malfunction in which flash gas is generated when it detects such a malfunction. As a process to resolve the malfunction, the operation processing unit 8b is configured to perform at least one of the following: adjusting the airflow rate of the fan 2a provided in the condenser 2, stopping the compressor 1, and adjusting the valve opening of the intermediate pressure electronic expansion valve 6. In the first embodiment, the operation processing unit 8b is configured to adjust the airflow rate of the fan 2a provided in the condenser 2. Specifically, the operation processing unit 8b is configured to increase the airflow rate of the fan 2a provided in the condenser 2 to increase the cooling degree of the non-azeotropic mixed refrigerant flowing through the second pipe 20b inside the condenser 2. If the operation processing unit 8b detects a malfunction in which flash gas is generated after adjusting the airflow rate of the fan 2a provided in the condenser 2, it adjusts the valve opening of the intermediate pressure electronic expansion valve 6. In this case, the operation processing unit 8b is configured to completely close the intermediate pressure electronic expansion valve 6. Furthermore, the operation processing unit 8b is configured to stop the compressor 1 if it detects a malfunction in the generation of flash gas after adjusting the valve opening of the intermediate pressure electronic expansion valve 6.

[0041] The intermediate heat exchanger 9 is located in the second piping 20b between the condenser 2 and the low-pressure electronic expansion valve 11. The intermediate heat exchanger 9 is also located in the fourth piping 30a between the intermediate-pressure electronic expansion valve 6 and the inlet of the compressor 1. The intermediate heat exchanger 9 is configured to perform heat exchange between the high-pressure refrigerant flowing through the second piping 20b and the intermediate-pressure refrigerant flowing through the fourth piping 30a via the third piping 20c. The intermediate heat exchanger 9 is configured to cool the high-pressure non-azeotropic mixed refrigerant (high-pressure refrigerant) supplied from the condenser 2 flowing through the second piping 20b with the intermediate-pressure non-azeotropic mixed refrigerant (intermediate-pressure refrigerant) flowing through the fourth piping 30a, which has been expanded by the intermediate-pressure electronic expansion valve 6. As a result, the non-azeotropic mixed refrigerant flowing through the fourth piping 30a evaporates and becomes the gaseous intermediate-pressure refrigerant. The non-azeotropic mixed refrigerant flowing through the second piping 20b remains the liquid-phase high-pressure refrigerant.

[0042] The memory unit 10 stores correlation information 10a, which is information on the resistance-temperature correlation between the intermediate pressure electronic expansion valve 6 and the pipe temperature of the fourth pipe 30a. The memory unit 10 is, for example, the memory unit of the microcontroller that constitutes the processing unit 8, and is provided integrally with the processing unit 8.

[0043] The correlation information 10a includes the temperature of the non-azeotropic refrigerant mixture when it is completely condensed in the condenser 2 for each valve opening of the intermediate-pressure electronic expansion valve 6, and the valve opening of the intermediate-pressure electronic expansion valve 6. The correlation information 10a stores the temperature of the non-azeotropic refrigerant mixture when it is completely condensed in the condenser 2 in association with each valve opening (n, n1) of the intermediate-pressure electronic expansion valve 6. The correlation information 10a includes, for example, a table or graph showing the correlation between the valve opening of the intermediate-pressure electronic expansion valve 6 and the temperature of the non-azeotropic refrigerant mixture when it is completely condensed in the condenser 2.

[0044] The memory unit 10 is configured to update correlation information 10a based on information obtained from the server 50. The cooling device 100 is configured to communicate with the server 50 via the network N. The server 50 obtains information about the operation of the cooling device 100, including the valve opening of the intermediate pressure electronic expansion valve 6 and the measured value Dx of the pipe temperature, from the cooling device 100, and creates corrected correlation information 10a. The server 50 performs principle analysis or statistical analysis of the conditions under which flash gas is generated from the information about the operation of the cooling device 100, and creates corrected correlation information 10a suitable for performing judgment processing regarding the generation of flash gas. Based on the acquisition of the corrected correlation information 10a from the server 50, the memory unit 10 is configured to update correlation information 10a.

[0045] As shown in Figures 1 and 3, the memory unit 10 stores a temperature change threshold D1, which is the upper limit of the acceptable range of difference between the target value of the pipe temperature of the fourth pipe 30a and the measured value Dx of the pipe temperature. The temperature change threshold D1 is constant regardless of the valve opening of the intermediate pressure electronic expansion valve 6.

[0046] The low-pressure electronic expansion valve 11 is located between the outlet of the intermediate heat exchanger 9, which is connected to the second piping 20b, and the inlet of the evaporator 3. The low-pressure electronic expansion valve 11 is configured to reduce the pressure of the non-azeotropic refrigerant mixture cooled in the intermediate heat exchanger 9, thereby further lowering the temperature of the non-azeotropic refrigerant mixture.

[0047] The branching point 12 is located between the condenser 2 and the inlet 9a of the intermediate heat exchanger 9.

[0048] The processing performed by the determination processing unit 8a will be explained in detail.

[0049] Figure 2 shows the correlation between the valve opening of the intermediate-pressure electronic expansion valve 6 and the pipe temperature of the fourth pipe 30a when no flash gas is generated, with a solid line, and the correlation between the valve opening of the intermediate-pressure electronic expansion valve 6 and the pipe temperature when flash gas is generated, with a dashed line. As shown in Figure 2, even if the valve opening of the intermediate-pressure electronic expansion valve 6 is the same, the pipe temperature when flash gas is generated (represented by a circle) is significantly lower than the pipe temperature when flash gas is not generated (represented by a square). Therefore, by setting the pipe temperature when flash gas is not generated at the valve opening of the intermediate-pressure electronic expansion valve 6 set in the cooling device 100 as the target value, and obtaining the difference D (the length from the center of the square to the center of the circle in Figure 2) between this and the measured pipe temperature Dx, the processing unit 8 can accurately detect the presence or absence of flash gas generation. For example, the difference D will be 10K (10℃) or more.

[0050] The determination processing unit 8a is configured to perform a process to determine whether the difference between the target value of the pipe temperature and the measured value of the pipe temperature Dx of the fourth pipe 30a is within an acceptable range, based on a temperature change threshold D1, which is the upper limit of the acceptable range of the difference between the target value of the pipe temperature and the measured value of the pipe temperature Dx.

[0051] Based on Figure 3, the process of determining whether the difference between the target value and the measured value Dx of the fourth pipe 30a is within an acceptable range will be explained, based on the temperature change threshold D1, which is the lower limit of the acceptable range for the difference between the target value and the measured value Dx of the pipe temperature. For example, the temperature change threshold D1 is set within the range of 0.5K (0.5℃) to 20K (20℃). The temperature change threshold D1 is set based on the maximum acceptable decrease in the measured value Dx of the pipe temperature. In Figure 3, the target value is shown by a square, and the measured value Dx of the pipe temperature is shown by a circle. Also in Figure 3, the dashed line shows the pipe temperature when the acceptable decrease in the measured value Dx of the pipe temperature is at its maximum. Note that the dashed line shows the pipe temperature when the valve opening of the intermediate pressure electronic expansion valve 6 is n, and the maximum acceptable decrease in the measured value Dx of the pipe temperature is set by the target value and the temperature change threshold D1. Therefore, the position of the dashed line will be different when the valve opening is n1.

[0052] The determination processing unit 8a is configured to acquire the valve opening of the intermediate pressure electronic expansion valve 6. If there is no change from the valve opening of the intermediate pressure electronic expansion valve 6 (initial setting value) at the start of operation of the cooling device 100, the determination processing unit 8a is configured to acquire the initial setting value as the valve opening of the intermediate pressure electronic expansion valve 6. If the valve opening of the intermediate pressure electronic expansion valve 6 has been changed from the initial setting value, the determination processing unit 8a is configured to acquire the changed valve opening of the intermediate pressure electronic expansion valve 6. Based on the correlation information 10a stored in the memory unit 10, the determination processing unit 8a sets the tube temperature at the time of complete condensation, which is stored in correspondence with the acquired valve opening of the intermediate pressure electronic expansion valve 6, as the target tube temperature. In the case of Figure 3, the case where the valve opening is n is shown. The processing unit 8 is also configured to acquire the measured value Dx of the tube temperature from the temperature detection unit 7.

[0053] The judgment processing unit 8a determines that the value obtained by subtracting the measured value Dx of the pipe temperature from the acquired target value of the pipe temperature exceeds the acceptable range if it is greater than the temperature change threshold D1, and detects a malfunction in the generation of flash gas. If a malfunction in the generation of flash gas is detected, the judgment processing unit 8a is configured to perform processing to resolve the malfunction in the generation of flash gas. Also, if the value obtained by subtracting the measured value Dx of the pipe temperature from the acquired target value of the pipe temperature is less than or equal to the temperature change threshold D1, the judgment processing unit 8a does not perform processing to resolve the malfunction in the generation of flash gas and continues to operate the refrigeration cycle. In the case of Figure 3, the magnitude of the difference D2 between the target value and the measured value Dx (in Figure 3, the length from the center of the square to the center of the circle) is greater than the temperature change threshold D1 (in Figure 3, the length from the center of the square to the dashed line), so the judgment processing unit 8a is configured to determine that the value obtained by subtracting the measured value Dx of the pipe temperature from the acquired target value of the pipe temperature exceeds the acceptable range and detects the generation of flash gas. The operation processing unit 8b is configured to perform a process to resolve the malfunction when the determination processing unit 8a determines that the value obtained by subtracting the measured value Dx of the tube temperature from the target value of the tube temperature exceeds the acceptable range.

[0054] (Effects of the first embodiment) The effects of the first embodiment will be described.

[0055] In the first embodiment, as described above, the system includes a processing unit 8 that performs a determination process regarding the generation of flash gas, which is a mixture of gas-phase non-azeotropic refrigerant and liquid-phase non-azeotropic refrigerant, based on the resistance-temperature correlation between the resistance value (valve opening) of the intermediate-pressure electronic expansion valve 6 and the pipe temperature, and the measured value Dx of the pipe temperature. As a result, the gas-phase non-azeotropic refrigerant has a larger pressure loss in the intermediate-pressure electronic expansion valve 6 compared to the liquid-phase non-azeotropic refrigerant. Therefore, when flash gas is generated, the pressure of the non-azeotropic refrigerant in the intermediate-pressure electronic expansion valve 6 drops significantly compared to when flash gas is not generated, and the temperature of the piping between the intermediate-pressure electronic expansion valve 6 and the compressor 1 becomes significantly lower. For this reason, the generation of flash gas can be clearly detected by obtaining the pipe temperature when flash gas is not generated based on the resistance-temperature correlation between the resistance value (valve opening) of the intermediate-pressure electronic expansion valve 6 and the pipe temperature, and comparing it with the measured value Dx of the pipe temperature. Furthermore, because the generation of flash gas can be clearly detected, the condenser 2 can be controlled to eliminate the flash gas, making it possible to keep the concentrations of the low-boiling point refrigerant supplied to the intermediate pressure circuit 30 and the low-pressure circuit 40 approximately the same. This suppresses an increase in the concentration of the low-boiling point refrigerant supplied to the compressor 1, thereby suppressing the occurrence of self-decomposition (disproportionation). In addition, because the occurrence of self-decomposition (disproportionation) is suppressed, there is no need to rapidly increase the flow rate of the refrigerant supplied to the compressor 1, and the occurrence of liquid compression can be suppressed. As a result, by improving the accuracy of the judgment process regarding the generation of flash gas, it is possible to prevent self-decomposition (disproportionation) and suppress the occurrence of liquid compression.

[0056] Furthermore, in the first embodiment, as described above, an intermediate heat exchanger 9 is provided in the second pipe 20b between the condenser 2 and the low-pressure electronic expansion valve 11, and performs heat exchange between the high-pressure refrigerant flowing through the second pipe 20b and the intermediate-pressure refrigerant flowing through the fourth pipe 30a via the third pipe 20c. The intermediate-pressure electronic expansion valve 6 is provided between the branching point 12 between the second pipe 20b and the third pipe 20c and the inlet 9a of the intermediate heat exchanger 9 connected to the fourth pipe 30a. The temperature detection unit 7 is provided between the intermediate-pressure electronic expansion valve 6 and the inlet of the intermediate heat exchanger 9 connected to the fourth pipe 30a. The processing unit 8 is configured to perform determination processing regarding the generation of flash gas based on the resistance-temperature correlation and the measured value of the pipe temperature of the fourth pipe 30a that supplies non-azeotropic mixed refrigerant from the intermediate-pressure electronic expansion valve 6 to the intermediate heat exchanger 9. This allows us to determine whether or not flash gas is being generated in the non-azeotropic refrigerant mixture supplied to the intermediate heat exchanger 9 by obtaining the pipe temperature between the intermediate pressure electronic expansion valve 6 and the inlet 9a of the intermediate heat exchanger 9 connected to the fourth pipe 30a. Furthermore, when flash gas is supplied to the intermediate heat exchanger 9, the ability of the intermediate heat exchanger 9 to cool the non-azeotropic refrigerant flowing through the second pipe 20b is reduced compared to when liquid-phase non-azeotropic refrigerant mixture is supplied, resulting in a decrease in heat exchange efficiency. Therefore, by detecting the generation of flash gas in the non-azeotropic refrigerant mixture supplied to the intermediate heat exchanger 9, the non-azeotropic refrigerant mixture can be processed to be completely condensed in the condenser 2, thereby suppressing the decrease in the heat exchange efficiency of the intermediate heat exchanger 9.

[0057] Furthermore, in the first embodiment, as described above, the resistance unit is an intermediate-pressure electronic expansion valve 6, and the processing unit 8 is configured to perform a determination process regarding the generation of flash gas based on the resistance-temperature correlation between the valve opening of the intermediate-pressure electronic expansion valve 6 (which is the resistance value of the intermediate-pressure electronic expansion valve 6) and the pipe temperature, and the measured value Dx of the pipe temperature. As a result, since the pipe temperature differs depending on the valve opening of the intermediate-pressure electronic expansion valve 6, a determination process regarding the generation of flash gas according to the valve opening of the intermediate-pressure electronic expansion valve 6 can be performed based on the resistance-temperature correlation between the valve opening of the intermediate-pressure electronic expansion valve 6 (which is the resistance value of the intermediate-pressure electronic expansion valve 6) and the pipe temperature, and the measured value Dx of the pipe temperature. As a result, the accuracy of the determination process regarding the generation of flash gas can be further improved.

[0058] Furthermore, in the first embodiment, as described above, the processing unit 8 is configured to perform a process to determine whether the difference between the target value of the pipe temperature and the actual value of the pipe temperature Dx is within an acceptable range, based on the target value of the pipe temperature estimated to be the point at which the non-azeotropic mixed refrigerant has completely condensed in the condenser 2, which is set by the resistance-temperature correlation, and the actual value of the pipe temperature Dx. By setting an acceptable range for the difference between the target value of the pipe temperature and the actual value of the pipe temperature Dx, the difference between the target value of the pipe temperature and the actual value of the pipe temperature Dx where no flash gas has been generated, and the difference between the target value of the pipe temperature and the actual value of the pipe temperature Dx where it is determined that flash gas has been generated but does not affect the cooling device 100, can be included in the acceptable range. As a result, when it is estimated that flash gas has been generated, the processing unit 8 can determine whether it is acceptable or not, and thus the accuracy of the flash gas generation determination process can be further improved.

[0059] Furthermore, in the first embodiment, as described above, the processing unit 8 is configured to perform a process to determine whether the difference between the target value of the pipe temperature and the measured value of the pipe temperature Dx is within an acceptable range, based on a temperature change threshold D1, which is the upper limit of the acceptable range of the difference between the target value of the pipe temperature and the measured value of the pipe temperature Dx. As a result, the processing unit 8 can easily perform a determination process regarding the generation of flash gas by comparing the temperature change threshold D1 with the difference between the target value of the pipe temperature and the measured value of the pipe temperature Dx.

[0060] Furthermore, in the first embodiment, as described above, the system further includes a storage unit 10 that stores correlation information 10a, which is information on the resistance-temperature correlation, and the processing unit 8 is configured to perform a process to determine whether the difference between the target value of the tube temperature set based on the correlation information 10a stored in the storage unit 10 and the measured value Dx of the tube temperature is within an acceptable range. As a result, the processing unit 8 can easily perform a determination process regarding the generation of flash gas based on the correlation information 10a stored in the storage unit 10.

[0061] Furthermore, in the first embodiment, as described above, the storage unit 10 is configured to update the correlation information 10a based on information acquired from the server 50, and the processing unit 8 is configured to perform a process to determine whether the difference between the target value of the tube temperature set based on the updated correlation information 10a and the measured value Dx of the tube temperature is within an acceptable range. This allows the correlation information 10a stored in the storage unit 10 to be updated and made new, so that, for example, the target value used to determine whether the difference between the actual measured value Dx of the tube temperature and the target value is within an acceptable range can be set to a more appropriate value based on information acquired by actually using the cooling device 100.

[0062] Furthermore, in the first embodiment, as described above, the low-boiling-point refrigerant includes a refrigerant that is prone to self-decomposition at high concentrations, and the processing unit 8 is configured to perform at least one of the following actions when it detects a malfunction in the generation of flash gas: adjusting the airflow of the fan 2a provided in the condenser 2, stopping the compressor 1, and adjusting the valve opening of the intermediate pressure electronic expansion valve 6 which acts as a resistance unit. This makes it possible to perform a determination process regarding the generation of flash gas in a cooling device 100 that uses a non-azeotropic mixed refrigerant that is prone to self-decomposition at high concentrations of the low-boiling-point refrigerant, thus enabling processing to be performed to prevent the generation of flash gas and the occurrence of a self-decomposition reaction. In addition, by adjusting the airflow of the fan 2a provided in the condenser 2, the processing unit 8 can promote further cooling and condensation of the non-azeotropic mixed refrigerant in the condenser 2, thereby suppressing the generation of flash gas. Furthermore, by stopping the compressor 1, the processing unit 8 can prevent the cooling device 100 from being affected by malfunctions caused by the generation of flash gas. Furthermore, the processing unit 8 can adjust the flow rate of the non-azeotropic refrigerant mixture by adjusting the valve opening of the intermediate pressure electronic expansion valve 6, which acts as a resistance unit, and can also prevent flash gas from flowing through the fourth pipe 30a by closing the electronic expansion valve. As a result, malfunctions caused by the generation of flash gas can be addressed.

[0063] Furthermore, in the first embodiment, as described above, a processing unit 8 is provided that performs a determination process regarding the generation of flash gas, which is a mixture of gas-phase non-azeotropic refrigerant and liquid-phase non-azeotropic refrigerant, based on the resistance-temperature correlation between the resistance value of the intermediate-pressure electronic expansion valve 6 and the pipe temperature, and the measured value of the pipe temperature. As a result, because the pressure loss in the intermediate-pressure electronic expansion valve 6 is greater for gas-phase non-azeotropic refrigerant than for liquid-phase non-azeotropic refrigerant, when flash gas is generated, the pressure of the non-azeotropic refrigerant in the intermediate-pressure electronic expansion valve 6 drops significantly compared to when flash gas is not generated, and the temperature of the piping between the intermediate-pressure electronic expansion valve 6 and the compressor 1 becomes significantly lower. Therefore, by obtaining the pipe temperature when flash gas is not generated based on the resistance-temperature correlation between the resistance value of the intermediate-pressure electronic expansion valve 6 and the pipe temperature, and comparing it with the measured value of the pipe temperature, the generation of flash gas can be clearly detected. Furthermore, because the generation of flash gas can be clearly detected, the condenser 2 can be controlled to eliminate the flash gas, making it possible to keep the concentration of R1132(E), a low-boiling point refrigerant supplied to the intermediate pressure circuit 30 and the low-pressure circuit 40, approximately the same. This suppresses an increase in the concentration of R1132(E), a low-boiling point refrigerant supplied to the compressor 1, thereby suppressing the occurrence of self-decomposition (disproportionation). In addition, because the occurrence of self-decomposition (disproportionation) is suppressed, there is no need to rapidly increase the flow rate of the refrigerant supplied to the compressor 1, thereby suppressing the occurrence of liquid compression. As a result, by improving the accuracy of the judgment process regarding the generation of flash gas, it is possible to prevent self-decomposition (disproportionation) and suppress the occurrence of liquid compression.

[0064] [Second Embodiment] Next, the cooling device 200 according to the second embodiment will be described with reference to Figures 2 to 4. Note that components similar to those in the first embodiment are denoted by the same reference numerals, and detailed explanations are omitted.

[0065] In the second embodiment, the position of branch point 22 is different from the position of branch point 12 in the first embodiment.

[0066] As shown in Figure 4, the branching point 22 is located in the second pipe 20b on the outlet side of the intermediate heat exchanger 9. Therefore, the non-azeotropic refrigerant mixture cooled in the intermediate heat exchanger 9 is supplied to the third pipe 20c and the fourth pipe 30a.

[0067] The intermediate heat exchanger 9 is located in the second piping 20b, between the condenser 2 and the evaporator 3. The intermediate heat exchanger 9 is also located in the fourth piping 30a. The intermediate heat exchanger 9 is configured to perform heat exchange between the non-azeotropic refrigerant mixture (high-pressure refrigerant) flowing through the second piping 20b and the non-azeotropic refrigerant mixture (intermediate-pressure refrigerant) flowing through the fourth piping 30a. The intermediate heat exchanger 9 is configured to further cool a portion of the non-azeotropic refrigerant mixture flowing through the second piping 20b, which has been cooled in the intermediate heat exchanger 9, by branching it to the third piping 20c and expanding it using the intermediate-pressure electronic expansion valve 6. This cools the non-azeotropic refrigerant mixture flowing through the second piping 20b, which is supplied from the condenser 2. As a result, the non-azeotropic refrigerant mixture flowing through the fourth piping 30a easily absorbs heat and evaporates into the gas phase. The non-azeotropic refrigerant mixture flowing through the second piping 20b remains in the liquid phase.

[0068] Furthermore, the other configurations of the second embodiment are the same as those of the first embodiment described above.

[0069] (Effects of the second embodiment) The effects of the second embodiment will now be described.

[0070] In the second embodiment, as described above, a processing unit 8 is provided that performs a determination process regarding the generation of flash gas, which is a mixture of gas-phase non-azeotropic refrigerant and liquid-phase non-azeotropic refrigerant, based on the resistance-temperature correlation between the resistance value (valve opening) of the intermediate-pressure electronic expansion valve 6 and the pipe temperature, and the measured value Dx of the pipe temperature. As a result, the gas-phase non-azeotropic refrigerant has a larger pressure loss in the intermediate-pressure electronic expansion valve 6 compared to the liquid-phase non-azeotropic refrigerant. Therefore, when flash gas is generated, the pressure of the non-azeotropic refrigerant in the intermediate-pressure electronic expansion valve 6 drops significantly compared to when flash gas is not generated, and the temperature of the piping between the intermediate-pressure electronic expansion valve 6 and the compressor 1 becomes significantly lower. For this reason, the generation of flash gas can be clearly detected by obtaining the pipe temperature when flash gas is not generated based on the resistance-temperature correlation between the resistance value (valve opening) of the intermediate-pressure electronic expansion valve 6 and the pipe temperature, and comparing it with the measured value Dx of the pipe temperature. Furthermore, because the generation of flash gas can be clearly detected, the condenser 2 can be controlled to eliminate the flash gas, making it possible to keep the concentrations of the low-boiling point refrigerant supplied to the intermediate pressure circuit 30 and the low-pressure circuit 40 approximately the same. This suppresses an increase in the concentration of the low-boiling point refrigerant supplied to the compressor 1, thereby suppressing the occurrence of self-decomposition (disproportionation). In addition, because the occurrence of self-decomposition (disproportionation) is suppressed, there is no need to rapidly increase the flow rate of the refrigerant supplied to the compressor 1, and the occurrence of liquid compression can be suppressed. As a result, by improving the accuracy of the judgment process regarding the generation of flash gas, it is possible to prevent self-decomposition (disproportionation) and suppress the occurrence of liquid compression.

[0071] Furthermore, in the second embodiment, the refrigerant from the second pipe 20b, which has been cooled in the intermediate heat exchanger 9, is supplied to the fourth pipe 30a of the intermediate heat exchanger 9. In this case, where the refrigerant cooled by the intermediate heat exchanger 9 after the condenser 2 is branched at the branching point 22, and then reduced to low pressure and low temperature by the intermediate pressure electronic expansion valve 6 before being supplied to the fourth pipe 30a of the intermediate heat exchanger 9, the flash gas may be eliminated by the intermediate heat exchanger 9. Therefore, by having the processing unit 8 perform a determination process regarding the generation of flash gas based on the measured value Dx of the pipe temperature of the fourth pipe 30a between the intermediate pressure electronic expansion valve 6 and the inlet 9a of the intermediate heat exchanger 9, it is also possible to determine whether the generation of flash gas was suppressed by flowing through the intermediate heat exchanger 9 before branching. In other words, if flash gas is generated beyond the allowable range, it can be considered that the refrigerant flowing through the second pipe 20b is not being sufficiently cooled in the intermediate heat exchanger 9, and therefore, processing can be performed to improve the cooling efficiency of the intermediate heat exchanger 9.

[0072] Furthermore, the other effects of the second embodiment are the same as those of the first embodiment described above.

[0073] [First variation] A cooling device 300 according to the first modified example will be described with reference to Figures 1 and 5. Note that components similar to those in the first embodiment are denoted by the same reference numerals, and detailed descriptions are omitted.

[0074] In the first modified example, the determination processing unit 8a is configured to perform a process to determine whether the difference between the target value of the pipe temperature of the fourth pipe 30a and the measured value D4 of the pipe temperature of the fourth pipe 30a is within an acceptable range, based on a temperature threshold D3, which is the lower limit of the measured value of the acceptable pipe temperature of the fourth pipe 30a. The temperature threshold D3 is constant regardless of the valve opening of the intermediate pressure electronic expansion valve 6.

[0075] The memory unit 10 stores a temperature threshold D3, which is the lower limit of the acceptable measured tube temperature, set so that the difference between the target tube temperature and the measured tube temperature is within an acceptable range.

[0076] Based on Figure 5, the process of determining whether the difference between the target pipe temperature and the measured pipe temperature is within an acceptable range will be explained, based on the temperature threshold D3, which is the lower limit of the acceptable measured pipe temperature. For example, the temperature threshold D3 is set within the range of 0°C to 5°C. In Figure 5, the target value is shown by a square, and the measured pipe temperature D4 is shown by a circle. Figure 5 shows the case where the valve opening of the intermediate pressure electronic expansion valve 6 is n.

[0077] The judgment processing unit 8a is configured to acquire the measured value D4 of the pipe temperature from the temperature detection unit 7. The judgment processing unit 8a acquires the temperature threshold D3 from the correlation information 10a and compares the measured value D4 with the temperature threshold D3. If the measured value D4 of the pipe temperature is below the temperature threshold D3, the judgment processing unit 8a determines that it exceeds the acceptable range and detects a malfunction in the generation of flash gas. If a malfunction in the generation of flash gas is detected, the judgment processing unit 8a is configured to perform processing to resolve the malfunction in the generation of flash gas. Furthermore, if the measured value D4 of the pipe temperature is above the temperature threshold D3, the judgment processing unit 8a does not perform processing to resolve the malfunction in the generation of flash gas, as it is within the acceptable range, and continues to operate the refrigeration cycle. In the case of Figure 5, since the measured value D4 is below the temperature threshold D3, the judgment processing unit 8a is configured to determine that the measured value D4 of the pipe temperature exceeds the acceptable range and detect the generation of flash gas. The operation processing unit 8b is configured to perform a process to resolve the malfunction when the determination processing unit 8a determines that the measured value D4 of the tube temperature exceeds the acceptable range.

[0078] The other components of the first modified example are the same as those of the first embodiment described above.

[0079] (Effects of the first modified example) The effects of the first modified example will be explained.

[0080] In the first modified example, as described above, a processing unit 8 is provided that performs a determination process regarding the generation of flash gas, which is a mixture of gas-phase non-azeotropic refrigerant and liquid-phase non-azeotropic refrigerant, based on the resistance-temperature correlation between the resistance value (valve opening) of the intermediate-pressure electronic expansion valve 6 and the pipe temperature, and the measured value D4 of the pipe temperature. As a result, the gas-phase non-azeotropic refrigerant has a larger pressure loss in the intermediate-pressure electronic expansion valve 6 compared to the liquid-phase non-azeotropic refrigerant. Therefore, when flash gas is generated, the pressure of the non-azeotropic refrigerant in the intermediate-pressure electronic expansion valve 6 drops significantly compared to when flash gas is not generated, and the temperature of the piping between the intermediate-pressure electronic expansion valve 6 and the compressor 1 becomes significantly lower. For this reason, by obtaining the pipe temperature when flash gas is not generated based on the resistance-temperature correlation between the resistance value (valve opening) of the intermediate-pressure electronic expansion valve 6 and the pipe temperature, and comparing it with the measured value D4 of the pipe temperature, the generation of flash gas can be clearly detected. As a result, the accuracy of the determination process regarding the generation of flash gas can be improved.

[0081] In the first modified example, the processing unit 8 is configured to perform a process to determine whether the difference between the target value of the pipe temperature and the measured value of the pipe temperature D4 is within an acceptable range, based on the temperature threshold D3, which is the lower limit of the acceptable measured pipe temperature, and the measured pipe temperature D4, which is set so that the difference between the target value of the pipe temperature of the fourth pipe 30a and the measured pipe temperature of the fourth pipe 30a is within an acceptable range. As a result, by comparing the measured pipe temperature D4 with the temperature threshold D3, if the measured pipe temperature D4 is lower than the temperature threshold D3, it can be determined that the difference between the target value of the pipe temperature and the measured pipe temperature D4 exceeds the acceptable range, so the processing unit 8 can easily perform a determination process regarding the generation of flash gas based on the measured pipe temperature D4.

[0082] Furthermore, the first modification and other effects are the same as those of the first embodiment described above.

[0083] [Other variations] It should be noted that the embodiments and first modifications disclosed herein are illustrative and not restrictive in all respects. The scope of the present invention is indicated by the claims rather than by the above-described embodiments and first modifications, and further includes all modifications within the same meaning and scope as the claims.

[0084] For example, the first embodiment, the second embodiment, and the first modification described above show examples using low-boiling-point refrigerants that are prone to self-decomposition reactions at high concentrations, but the present invention is not limited thereto. For example, in the present invention, a non-azeotropic mixed refrigerant that does not undergo self-decomposition reactions may be used as the low-boiling-point refrigerant.

[0085] Furthermore, in the first embodiment, the second embodiment, and the first modified example described above, the cooling device 100 (200, 300) is shown to include an intermediate heat exchanger 9 and the first resistance section is an intermediate pressure electronic expansion valve 6, but the present invention is not limited thereto. For example, in the present invention, the cooling device may not include an intermediate heat exchanger and the first resistance section may be a capillary tube. In this case, the intermediate pressure circuit becomes an injection circuit. The processing unit also obtains the correlation between the set resistance value of the capillary tube and the tube temperature.

[0086] Furthermore, while the first embodiment, second embodiment, and first modification described above show an example where the first resistance section is an intermediate pressure electronic expansion valve 6, the present invention is not limited thereto. For example, in the present invention, the first resistance section may be an expansion valve other than an electronic expansion valve, or a pressure-adjustable member other than an expansion valve.

[0087] Furthermore, while the first embodiment, the second embodiment, and the first modification described above show an example in which the storage unit 10 is provided integrally with the processing unit 8, the present invention is not limited thereto. For example, in the present invention, the storage unit may be separate from the processing unit. In this case, the storage unit may be a different microcontroller from the processing unit, or it may be an external storage device.

[0088] Furthermore, while the first embodiment, the second embodiment, and the first modified example described above show the storage unit 10 configured to update correlation information 10a based on information acquired from the server 50, the present invention is not limited thereto. For example, in the present invention, the storage unit does not need to update the correlation information. Also, in the present invention, the storage unit may be configured to update the correlation information based on information acquired from a device other than the server, such as a processing unit.

[0089] Furthermore, in the first and second embodiments described above, the temperature change threshold D1 is constant regardless of the valve opening of the intermediate pressure electronic expansion valve 6, and in the first modified example described above, the temperature threshold D3 is constant regardless of the valve opening of the intermediate pressure electronic expansion valve 6. However, the present invention is not limited thereto. For example, in the present invention, the temperature change threshold and the temperature threshold may be changed according to the valve opening (resistance value) of the intermediate pressure electronic expansion valve (resistance part).

[0090] Furthermore, while the first embodiment, the second embodiment, and the first modified example described above show examples in which a determination processing unit 8a and an operation processing unit 8b are provided, the present invention is not limited thereto. For example, in the present invention, the determination processing unit and the operation processing unit may be the same.

[0091] Furthermore, while the first embodiment, second embodiment, and first modification described above show examples where the high-boiling-point refrigerant is R1234yf, the low-boiling-point refrigerant is R1132(E), and the non-azeotropic mixed refrigerant is R474B, the present invention is not limited thereto. In the present invention, any combination of refrigerants can be used as long as the low-boiling-point refrigerant has a greater cooling capacity than the high-boiling-point refrigerant. Also, the non-azeotropic mixed refrigerant may be appropriately changed depending on the types of high-boiling-point and low-boiling-point refrigerants.

[0092] Furthermore, the first modified example described above may have the configuration of the second embodiment instead of the configuration of the first embodiment. [Explanation of Symbols]

[0093] 1. Compressor 2. Condenser 2a Fan 3. Evaporator 6. Electronic expansion valve for intermediate pressure (first resistance section) 7. Temperature detection unit 8 Processing Unit 9 Intermediate heat exchanger 10 Storage section 10a Correlation Information 11. Low-pressure electronic expansion valve (second resistance section) 12, 22 Branching point 20 High-voltage circuits 20a First piping 20b 2nd piping 20c 3rd pipe 30 Intermediate pressure circuit 30a Fourth pipe 40 Low-voltage circuits 40a Fifth pipe 40b Piping No. 6 50 servers 100, 200, 300 chillers

Claims

1. A compressor for compressing a non-azeotropic refrigerant mixture, which is a mixture of low-boiling point and high-boiling point refrigerants, A condenser for condensing the non-azeotropic refrigerant mixture compressed in the compressor, An evaporator for evaporating the non-azeotropic mixed refrigerant condensed in the condenser, A first resistor that adjusts the pressure of the non-azeotropic refrigerant mixture supplied from the condenser to the compressor, A second resistor adjusts the pressure of the non-azeotropic refrigerant mixture supplied from the condenser to the evaporator, A high-pressure circuit through which a high-pressure refrigerant, which is a non-azeotropic mixed refrigerant that has reached a pressure higher than the non-azeotropic mixed refrigerant evaporated in the evaporator by being compressed by the compressor, flows, including a first pipe connecting the compressor and the condenser, a second pipe connecting the condenser and the second resistor, and a third pipe branching off from the second pipe and connecting the condenser and the first resistor. An intermediate pressure circuit includes a fourth pipe connecting the first resistor and the compressor, through which an intermediate pressure refrigerant, which is a non-azeotropic mixed refrigerant whose pressure is lower than that of the high-pressure refrigerant flowing through the high-pressure circuit by passing through the first resistor, A low-pressure circuit includes a fifth pipe connecting the second resistance section and the evaporator, and a sixth pipe connecting the evaporator and the compressor, through which a low-pressure refrigerant, which is a non-azeotropic mixed refrigerant whose pressure is lower than that of the high-pressure refrigerant and the intermediate-pressure refrigerant, flows after passing through the second resistance section. A temperature detection unit is provided in the fourth pipe of the intermediate pressure circuit to detect the pipe temperature, which is the temperature of the fourth pipe. A cooling device using a non-azeotropic mixed refrigerant, comprising a processing unit that performs determination processing regarding the generation of a flash gas, which is a mixture of a gaseous non-azeotropic mixed refrigerant and a liquid non-azeotropic mixed refrigerant, based on the resistance-temperature correlation between the resistance value of the first resistance section and the tube temperature, and the measured value of the tube temperature.

2. The second piping further comprises an intermediate heat exchanger provided between the condenser and the second resistance section, which performs heat exchange between the high-pressure refrigerant flowing through the second piping and the intermediate-pressure refrigerant flowing through the fourth piping. The first resistance section is provided between the branching point of the second pipe and the third pipe and the inlet of the intermediate heat exchanger connected to the fourth pipe. The temperature sensing unit is provided between the first resistance unit and the inlet of the intermediate heat exchanger connected to the third piping. The cooling apparatus using a non-azeotropic mixed refrigerant according to claim 1, wherein the processing unit is configured to perform a determination process regarding the generation of flash gas based on the resistance-temperature correlation and the measured value of the pipe temperature of the fourth pipe that supplies the non-azeotropic mixed refrigerant from the first resistance unit to the intermediate heat exchanger.

3. The first resistor is an electronic expansion valve, The cooling device using a non-azeotropic mixed refrigerant according to claim 1, wherein the processing unit is configured to perform a determination process regarding the generation of flash gas based on the resistance-temperature correlation between the valve opening of the electronic expansion valve, which is the resistance value of the first resistance unit, and the tube temperature, and the measured value of the tube temperature.

4. The cooling apparatus using a non-azeotropic mixed refrigerant according to claim 1, wherein the processing unit is configured to perform a process to determine whether the difference between the target value of the pipe temperature and the actual value of the pipe temperature is within an acceptable range, as a determination process regarding the generation of flash gas, based on the target value of the pipe temperature, which is estimated to be the value at which the non-azeotropic mixed refrigerant has been completely condensed in the condenser, set by the resistance-temperature correlation, and the actual value of the pipe temperature.

5. The cooling device using a non-azeotropic mixed refrigerant according to claim 4, wherein the processing unit is configured to perform a process to determine whether the difference between the target value of the pipe temperature and the measured value of the pipe temperature is within an acceptable range, based on a temperature change threshold which is the upper limit of the acceptable range of the difference between the target value of the pipe temperature and the measured value of the pipe temperature.

6. The cooling device using a non-azeotropic mixed refrigerant according to claim 4, wherein the processing unit is configured to perform a process to determine whether the difference between the target value of the pipe temperature and the measured value of the pipe temperature is within an acceptable range, based on a temperature threshold value which is the lower limit of the measured value of the pipe temperature, set so that the difference between the target value of the pipe temperature and the measured value of the pipe temperature is within an acceptable range, and the measured value of the pipe temperature.

7. The system further includes a memory unit that stores correlation information, which is information regarding the resistance-temperature correlation. The cooling device using a non-azeotropic mixed refrigerant according to claim 4, wherein the processing unit is configured to perform a process to determine whether the difference between the target value of the tube temperature set based on the correlation information stored in the storage unit and the measured value of the tube temperature is within an acceptable range.

8. The storage unit is configured to update the correlation information based on information obtained from the server. The cooling device using a non-azeotropic mixed refrigerant according to claim 7, wherein the processing unit is configured to perform a process to determine whether the difference between the target value of the tube temperature set based on the updated correlation information and the measured value of the tube temperature is within an acceptable range.

9. The low boiling point refrigerant includes a refrigerant that is prone to self-decomposition reactions at high concentrations. The cooling device using a non-azeotropic refrigerant mixture according to claim 1, wherein the processing unit is configured to perform at least one of the following actions when it detects a malfunction in the generation of flash gas: adjust the airflow of a fan provided in the condenser, stop the compressor, and adjust the valve opening of the electronic expansion valve which serves as the first resistance unit.

10. A compressor for compressing a non-azeotropic refrigerant mixture, which is a mixture of at least R1132(E) as a low-boiling point refrigerant and R1234yf as a high-boiling point refrigerant, A condenser for condensing the non-azeotropic refrigerant mixture compressed in the compressor, An evaporator for evaporating the non-azeotropic refrigerant mixture condensed in the condenser, A first resistor that adjusts the pressure of the non-azeotropic refrigerant mixture supplied from the condenser to the compressor, A second resistor for adjusting the pressure of the non-azeotropic refrigerant mixture supplied from the condenser to the evaporator, The system includes a first pipe connecting the compressor and the condenser, a second pipe connecting the condenser and the second resistance unit, and a third pipe branching off from the second pipe and connecting the condenser and the first resistance unit. A high-pressure refrigerant, which is the non-azeotropic refrigerant mixture, flows through a high-pressure circuit through which the pressure of the non-azeotropic refrigerant mixture has become higher than the pressure of the non-azeotropic refrigerant mixture evaporated in the evaporator by being compressed by the compressor. An intermediate pressure circuit includes a fourth pipe connecting the first resistor and the compressor, through which an intermediate pressure refrigerant, which is a non-azeotropic mixed refrigerant, flows, having a lower pressure than the high-pressure refrigerant flowing through the high-pressure circuit by passing through the first resistor; A low-pressure circuit includes a fifth pipe connecting the second resistance section and the evaporator, and a sixth pipe connecting the evaporator and the compressor, through which the low-pressure refrigerant, which is a non-azeotropic mixed refrigerant whose pressure is lower than that of the high-pressure refrigerant and the intermediate-pressure refrigerant, flows after passing through the second resistance section. A temperature detection unit is provided in the fourth pipe of the intermediate pressure circuit to detect the pipe temperature, which is the temperature of the fourth pipe. A cooling device using a non-azeotropic mixed refrigerant, comprising a processing unit that performs a determination process regarding the generation of a flash gas, which is a mixture of the gaseous non-azeotropic mixed refrigerant and the liquid non-azeotropic mixed refrigerant, based on the resistance-temperature correlation between the resistance value of the first resistance section and the tube temperature, and the measured value of the tube temperature.

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