JP-2026075027-A - Cooling system using non-azeotropic refrigerant mixture

Abstract

[Problem] To provide a cooling device using a non-azeotropic refrigerant mixture that can identify the composition of the non-azeotropic refrigerant mixture while suppressing the increase in size and complexity of the device. [Solution] The cooling device 100 using this azeotropic mixed refrigerant includes a compressor 1 for compressing a non-azeotropic mixed refrigerant 20, a cooling circuit 101 including a heat exchanger for heat exchange of the non-azeotropic mixed refrigerant 20, a pressure sensor 6 placed in the piping 101b of the cooling circuit 101 connecting the compressor 1 or the compressor 1 and the evaporator 2 for measuring the pressure of the non-azeotropic mixed refrigerant 20, a temperature sensor 7 for measuring the temperature of the non-azeotropic mixed refrigerant 20, and a control unit 10 that determines the concentration of low-boiling point gaseous refrigerant 22a in the cooling circuit 101 based on the pressure of the non-azeotropic mixed refrigerant 20 flowing into the condenser 2 measured by the pressure sensor 6, and the temperature of the non-azeotropic mixed refrigerant 20 near the condenser 2 measured by the temperature sensor 7. [Selection Diagram] Figure 1

Inventors

• 中村 新吾
• 伊豆野 優作
• 滝口 浩司
• 水澤 竜也
• 田村　嘉忠

Assignees

• 富士電機株式会社

Dates

Publication Date

20260507

Application Date

20250128

Priority Date

20241021

Claims (19)

1. A cooling circuit including 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, and a heat exchanger for performing heat exchange of the non-azeotropic mixed refrigerant, A pressure sensor is placed in the compressor or in the piping of the cooling circuit connecting the compressor and the heat exchanger, and measures the pressure of the non-azeotropic refrigerant mixture. A temperature sensor for measuring the temperature of the non-azeotropic refrigerant mixture, A cooling device using a non-azeotropic mixed refrigerant, comprising: a control unit that determines the concentration of the low-boiling-point refrigerant in the cooling circuit based on the pressure of the non-azeotropic mixed refrigerant flowing into the heat exchanger, measured by the pressure sensor arranged in the cooling circuit, and the temperature of the non-azeotropic mixed refrigerant near the heat exchanger, measured by the temperature sensor.
2. The control unit, The system stores relationship information showing the correspondence between the pressure of the non-azeotropic refrigerant mixture flowing into the heat exchanger, measured by the pressure sensor, the temperature of the non-azeotropic refrigerant mixture near the heat exchanger, measured by the temperature sensor, and the concentration of the low-boiling point refrigerant in the cooling circuit. A cooling device using a non-azeotropic mixed refrigerant according to claim 1, configured to perform control to determine the concentration of the low-boiling point refrigerant in the cooling circuit based on the aforementioned related information.
3. The heat exchanger includes a condenser that condenses the non-azeotropic refrigerant mixture discharged by the compressor. The cooling apparatus using a non-azeotropic refrigerant mixture according to claim 2, wherein the control unit is configured to determine the concentration of the low-boiling-point refrigerant in the cooling circuit based on the pressure of the non-azeotropic refrigerant mixture flowing into the compressor or the condenser measured by the pressure sensor, the saturation temperature of the non-azeotropic refrigerant mixture in the condenser, and the related information.
4. The cooling apparatus using a non-azeotropic mixed refrigerant according to claim 3, wherein the control unit is configured to perform concentration reduction operation control such that the concentration of the low-boiling point refrigerant in the cooling circuit is reduced when a state value determined from the pressure of the non-azeotropic mixed refrigerant flowing into the condenser and the housing temperature of the compressor exceeds a concentration threshold set according to the concentration of the low-boiling point refrigerant in the cooling circuit.
5. The cooling apparatus using a non-azeotropic mixed refrigerant according to claim 4, wherein the control unit is configured to perform control to increase the superheating degree of the non-azeotropic mixed refrigerant flowing into the compressor as a concentration reduction operation control when the state value exceeds the concentration threshold.
6. The cooling device using a non-azeotropic refrigerant mixture according to claim 5, wherein the control unit is configured to reduce the rotational speed of the compressor if the state value exceeds the concentration threshold even after controlling the superheating of the non-azeotropic refrigerant mixture flowing into the compressor.
7. The cooling apparatus using a non-azeotropic mixed refrigerant according to claim 4, wherein the control unit is configured to control the degree of superheating of the non-azeotropic mixed refrigerant flowing into the compressor, or the rotational speed of the compressor, so as to bring the concentration of the low-boiling-point refrigerant in the cooling circuit closer to the concentration threshold, but within a range that does not exceed the concentration threshold.
8. The condenser is further equipped with a fan for blowing air, The cooling apparatus using a non-azeotropic mixed refrigerant according to claim 3, wherein the control unit is configured to increase the rotation speed of the fan in order to increase the amount of heat dissipated by the condenser when the temperature of the non-azeotropic mixed refrigerant near the inlet side of the condenser is not at the saturation temperature.
9. The cooling apparatus using a non-azeotropic refrigerant mixture according to claim 2, wherein the aforementioned relationship information includes table data showing the correspondence between the pressure of the non-azeotropic refrigerant mixture flowing into the heat exchanger, measured by the pressure sensor, the temperature of the non-azeotropic refrigerant mixture near the heat exchanger, measured by the temperature sensor, and the concentration of the low-boiling-point refrigerant in the cooling circuit.
10. The heat exchanger includes an evaporator for evaporating the non-azeotropic refrigerant mixture, An accumulator for temporarily storing the non-azeotropic refrigerant mixture discharged from the evaporator, The accumulator further comprises a liquid level gauge for measuring the liquid level of the non-azeotropic mixed refrigerant stored in liquid state, The cooling apparatus using a non-azeotropic mixed refrigerant according to claim 1, wherein the control unit is configured to perform control to determine the concentration of the low-boiling-point refrigerant in the cooling circuit based on relational information indicating the correspondence between the liquid level height of the non-azeotropic mixed refrigerant in the accumulator arranged in the cooling circuit, measured by the liquid level gauge, and the concentration of the low-boiling-point refrigerant in the cooling circuit.
11. The cooling apparatus using a non-azeotropic mixed refrigerant according to claim 10, wherein the control unit is configured to perform a concentration reduction operation control such that the concentration of the low-boiling-point refrigerant in the cooling circuit is reduced when the liquid level of the non-azeotropic mixed refrigerant in the accumulator arranged in the cooling circuit, as measured by the liquid level gauge, exceeds a predetermined liquid level threshold.
12. The system further includes a bypass pipe that draws in the liquid state of the non-azeotropic refrigerant mixture stored in the accumulator, converts it to a gaseous state, and draws it into the compressor. The cooling device using a non-azeotropic refrigerant mixture according to claim 11, wherein the control unit is configured to perform at least one of the following controls as the concentration reduction operation control when the liquid level measured by the liquid level gauge exceeds the liquid level threshold: control to increase the degree of superheating of the non-azeotropic refrigerant mixture flowing into the compressor, control to decrease the rotational speed of the compressor, or control to draw the liquid stored in the accumulator into the compressor via the bypass piping.
13. The temperature sensor includes a plurality of inlet-side temperature sensors arranged on the inlet side of the condenser and a plurality of outlet-side temperature sensors arranged on the outlet side of the condenser. The cooling apparatus using a non-azeotropic refrigerant mixture according to claim 3, wherein the control unit is configured to determine the saturation temperature of the non-azeotropic refrigerant mixture in the condenser based on a plurality of temperatures of the non-azeotropic refrigerant mixture in the condenser measured by a plurality of inlet-side temperature sensors and a plurality of temperatures of the non-azeotropic refrigerant mixture in the condenser measured by a plurality of outlet-side temperature sensors.
14. The control unit, The difference in the position of each of the two inlet-side temperature sensors, and the difference in the temperature of the non-azeotropic refrigerant mixture in the condenser measured by each of the two inlet-side temperature sensors, A cooling device using a non-azeotropic refrigerant according to claim 13, configured to determine the saturation temperature of the non-azeotropic refrigerant in the condenser based on the difference in the positions of the two outlet-side temperature sensors and the difference in the temperature of the non-azeotropic refrigerant in the condenser measured by each of the two outlet-side temperature sensors.
15. The condenser is equipped with an ambient temperature sensor that measures the temperature of the surrounding environment of the condenser. The cooling device using a non-azeotropic mixed refrigerant according to claim 13, wherein the ambient temperature sensor also serves as the outlet temperature sensor.
16. The cooling apparatus using a non-azeotropic refrigerant mixture according to claim 13, wherein the control unit is configured to determine, when the temperature difference between the temperatures of the non-azeotropic refrigerant mixture measured by two of the plurality of inlet-side temperature sensors is less than a predetermined threshold, the temperature of the non-azeotropic refrigerant mixture measured by the inlet-side temperature sensor closer to the inlet side of the condenser is the saturation temperature of the non-azeotropic refrigerant mixture in the condenser.
17. The temperature sensor includes a thermograph, The cooling apparatus using a non-azeotropic refrigerant according to claim 3, wherein the control unit is configured to determine the saturation temperature of the non-azeotropic refrigerant in the condenser based on the temperatures of the non-azeotropic refrigerant at each of the multiple points on the inlet side of the condenser measured by the thermography and the temperatures of the non-azeotropic refrigerant at each of the multiple points on the outlet side of the condenser measured by the thermography.
18. A cooling circuit including 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, and a heat exchanger for performing heat exchange of the non-azeotropic mixed refrigerant, A temperature sensor for measuring the temperature of the non-azeotropic refrigerant mixture, A cooling device using a non-azeotropic mixed refrigerant, comprising: a control unit that determines the concentration of the low-boiling-point refrigerant in the cooling circuit based on the saturation temperature of the non-azeotropic mixed refrigerant in the heat exchanger measured by the temperature sensor, the liquid saturation temperature of the non-azeotropic mixed refrigerant in the heat exchanger, and relational information showing the correspondence between the saturation temperature and the liquid saturation temperature and the concentration of the low-boiling-point refrigerant in the cooling circuit.
19. A compressor for compressing a non-azeotropic refrigerant mixture, which is a mixture of low-boiling point and high-boiling point refrigerants, An evaporator for evaporating the aforementioned non-azeotropic refrigerant mixture, An accumulator for temporarily storing the non-azeotropic refrigerant mixture discharged from the evaporator, A cooling circuit including a liquid level gauge for measuring the liquid level of the non-azeotropic refrigerant mixture stored in the accumulator, A cooling device using a non-azeotropic mixed refrigerant, comprising: a control unit that determines the concentration of the low-boiling point refrigerant in the cooling circuit based on relational information showing the correspondence between the liquid level height of the non-azeotropic mixed refrigerant in the accumulator arranged in the cooling circuit, measured by the liquid level gauge, and the concentration of the low-boiling point refrigerant in the cooling circuit.

Description

This invention relates to a cooling device using a non-azeotropic refrigerant mixture. Conventionally, refrigeration and air conditioning systems (cooling systems) using non-azeotropic refrigerants, which are mixtures of low-boiling-point and high-boiling-point refrigerants, are known (see, for example, Patent Document 1). Patent Document 1 discloses a refrigeration and air conditioning system that, in addition to a refrigeration cycle using a non-azeotropic mixed refrigerant (a mixture of low-boiling-point and high-boiling-point refrigerants), includes bypass piping, capillary tubes, a double-walled heat exchanger, and a composition calculator. In the refrigeration and air conditioning system of Patent Document 1, a portion of the non-azeotropic mixed refrigerant discharged from the compressor in the refrigeration cycle flows into the bypass piping, condenses and liquefies in the double-walled heat exchanger, and is depressurized by the capillary tubes. In Patent Document 1, the composition calculator receives the temperature and pressure of the non-azeotropic mixed refrigerant, which is in a low-pressure and saturated state, as detected by a temperature detector and a pressure detector. The composition calculator in Patent Document 1 stores the relationship between the temperature and pressure of the non-azeotropic mixed refrigerant and the circulating composition of the non-azeotropic mixed refrigerant in the refrigeration cycle (the concentration ratio of each refrigerant being mixed). Based on this, the composition calculator in Patent Document 1 identifies the circulating composition of the non-azeotropic mixed refrigerant flowing through the bypass piping and other components added to the refrigeration cycle, based on the temperature and pressure of the non-azeotropic mixed refrigerant it receives. Japanese Patent Publication No. Hei 8-75280 Specification This is a block diagram of a cooling device according to the first embodiment of the present invention.This figure shows the cooling circuit of a cooling device according to the first embodiment of the present invention.This is a diagram illustrating the accumulator of a cooling device according to a first embodiment of the present invention.This is a diagram illustrating the condenser of a cooling device according to a first embodiment of the present invention.This figure illustrates a method for obtaining the saturation temperature of a non-azeotropic refrigerant mixture in a cooling circuit in a cooling device according to a first embodiment of the present invention.This figure illustrates a table of relational information stored in the control unit of a cooling device according to the first embodiment of the present invention.This figure illustrates the state values acquired by the control unit of the cooling device according to the first embodiment of the present invention.This is a block diagram of a cooling device according to a second embodiment of the present invention.This is a diagram illustrating the cooling circuit of a cooling device according to a second embodiment of the present invention.This figure illustrates a method for calculating the low-boiling point refrigerant concentration of a cooling device according to a second embodiment of the present invention.This figure illustrates a method for calculating the refrigerant ratio of the stored liquid in a cooling device according to a second embodiment of the present invention.This is a diagram illustrating the arrangement relationship between a condenser and a temperature sensor according to a third embodiment of the present invention.This figure illustrates a method for calculating the saturation temperature of a non-azeotropic refrigerant mixture in a condenser when the ambient temperature is relatively high, according to a third embodiment of the present invention.This figure illustrates a method for calculating the saturation temperature of a non-azeotropic refrigerant mixture in a condenser when the ambient temperature is relatively low, according to a third embodiment of the present invention.This diagram illustrates the arrangement relationship between the condenser and the temperature sensor according to the fourth embodiment of the present invention.This figure illustrates a method for calculating the saturation temperature of a non-azeotropic mixed refrigerant in a condenser according to a fourth embodiment of the present invention.This is a block diagram of a cooling device according to a fifth embodiment of the present invention.This figure illustrates the temperature distribution of the non-azeotropic refrigerant in a condenser according to a fifth embodiment of the present invention.This figure illustrates a method for calculating the saturation temperature of a non-azeotropic mixed refrigerant in a condenser according to a fifth embodiment of the present invention.This is a block diagram of a cooling device according to a sixth embodiment of the present invention.This