JP2014145565A - Refrigerator and chiller employing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a refrigerator capable of detecting refrigerant leakage caused by damage of an evaporator easily and at low cost, and a chiller.SOLUTION: A pressure sensor 13 is provided in any location from an outlet of an expansion valve 5 to an inlet of a compressor 3 in a vapor compression type refrigerator 1. On the basis of detection output from the pressure sensor 13 during stop of the compressor 3, the presence/absence of refrigerant leakage caused by damage of an evaporator 6 is monitored. Preferably, at an inlet side of the expansion valve 5, a liquid solenoid valve 10 is provided which is opened/closed while interlocked with start/stop of the compressor 3. The presence/absence of refrigerant leakage is monitored by monitoring whether the state where pressure detected by the pressure sensor 13 is equal to or lower than preset pressure is continued for a preset time or longer in the state where the compressor 3 is stopped and the liquid solenoid valve 10 is closed.

Description

  The present invention relates to a vapor compression refrigerator and a chiller using the same.

  Conventionally, as disclosed in Patent Document 1 below, a chiller using a vapor compression refrigerator is known. In this type of chiller, it is desirable that if a refrigerant leak occurs due to the breakage of the evaporator, it can be easily and inexpensively detected. In particular, when producing cold water by exchanging heat between the refrigerant and water in the evaporator, if the refrigerant leaks due to damage to the evaporator, the refrigerant or oil dissolved in it will be mixed in the cold water. Is unfavorable for hygiene, and it is desirable that refrigerant leakage can be easily detected.

JP 2009-14298 A

  The problem to be solved by the present invention is to provide a refrigerator and a chiller that can easily and inexpensively detect refrigerant leakage due to damage to an evaporator.

  The present invention has been made to solve the above-mentioned problems, and the invention according to claim 1 is characterized in that pressure detection is performed at any point between the expansion valve outlet and the compressor inlet of the vapor compression refrigerator. Means for monitoring the presence or absence of refrigerant leakage due to breakage of the evaporator based on the pressure detected by the pressure detection means while the compressor is stopped.

  According to the first aspect of the present invention, by monitoring the pressure while the compressor is stopped between the expansion valve outlet and the compressor inlet, it is possible to easily and inexpensively monitor the presence or absence of refrigerant leakage due to the breakage of the evaporator. can do.

  According to a second aspect of the present invention, a liquid electromagnetic valve that is opened and closed in conjunction with the start and stop of the compressor is provided on the inlet side of the expansion valve, and the monitoring of the presence or absence of the refrigerant leakage stops the compressor. 2. The refrigerator according to claim 1, wherein in a state where the liquid electromagnetic valve is closed, monitoring is performed as to whether or not the pressure detected by the pressure detection unit continues a state equal to or lower than a set pressure for a set time or longer. is there.

  According to the second aspect of the present invention, the liquid electromagnetic valve is closed while the compressor is stopped, so that a closed space is surely formed from the liquid electromagnetic valve to the compressor. Therefore, when the compressor is stopped, the pressure in the closed space is monitored, and it is easy to monitor the presence or absence of refrigerant leakage due to the breakage of the evaporator depending on whether or not the pressure is kept below the set pressure for the set time or longer. It can be done reliably.

  According to a third aspect of the present invention, a suction pressure adjusting valve for adjusting the suction pressure of the compressor is provided on the outlet side of the evaporator, and the pressure detecting means is provided between the expansion valve and the suction pressure adjusting valve. The refrigerator according to claim 1 or 2, wherein the refrigerator is provided.

  According to the third aspect of the present invention, when the suction pressure adjustment valve is provided, the pressure is monitored between the expansion valve and the suction pressure adjustment valve, thereby monitoring the presence or absence of the refrigerant leakage due to the breakage of the evaporator. It can be done easily and reliably.

  A fourth aspect of the invention includes the refrigerator according to any one of the first to third aspects, and the evaporator is supplied with refrigerant from the expansion valve and indirectly exchanges heat with the refrigerant. The chiller is characterized in that the liquid to be cooled is passed through.

  According to the fourth aspect of the present invention, in the chiller, it is possible to easily and reliably monitor the presence or absence of refrigerant leakage due to the breakage of the evaporator.

  The invention according to claim 5 includes a cold water tank for storing water as the liquid to be cooled, and the water in the cold water tank can be circulated between the evaporator and via a cold water valve. When it is possible to supply to cold water use equipment and the compressor is stopped, if the pressure detected by the pressure detection means continues below the set pressure for a set time or more, it is determined that there is a refrigerant leak due to damage to the evaporator. The chiller according to claim 4, wherein the chiller is informed and the cold water valve is closed.

  According to the fifth aspect of the present invention, in the water chiller, it is possible to easily and reliably monitor the presence or absence of refrigerant leakage due to the breakage of the evaporator. And if the refrigerant | coolant leakage by the failure | damage of an evaporator is detected, it can alert | report that and it can prevent that the cold water mixed with the refrigerant | coolant and oil is used by closing a cold water valve.

  According to a sixth aspect of the present invention, a chilled water passage from the chilled water tank to the chilled water use facility is provided with a chilled water pump instead of or in addition to the chilled water valve. When the detected pressure by the detecting means continues below the set pressure for a set time or longer, it is determined that there is a refrigerant leak due to breakage of the evaporator, and a notification to that effect is made and the cold water pump is stopped. Item 6. The chiller according to Item 5.

  According to the sixth aspect of the present invention, when refrigerant leakage due to the breakage of the evaporator is detected, the fact is notified and the chilled water pump is stopped so that chilled water mixed with refrigerant or oil is used. Can be prevented.

In the invention according to claim 7, the circulation of water between the cold water tank and the evaporator is switched by the start and stop of the circulation pump, and includes at least (b) among the following (a) to (d): The chiller according to claim 5 or 6, wherein in any one or more cases, it is possible to determine the presence or absence of refrigerant leakage due to damage to the evaporator.
(A) While the compressor is stopped, the circulating pump is operating, and within a predetermined time after the compressor is stopped, the pressure detected by the pressure detecting means continues the first set pressure for a specified time or more. When the pressure drops below the first set pressure for more than the first set time.
(B) While the compressor is stopped, the circulating pump is operating, and within a predetermined time after the compressor is stopped, the pressure detected by the pressure detecting means exceeds the first set pressure by a second set time or more. When continuously below.
(C) The compressor is stopped but the circulating pump is operating, and after a predetermined time has elapsed since the compressor was stopped, the pressure detected by the pressure detecting means exceeds the second set pressure by a second set time or more. When continuously below.
(D) When the pressure detected by the pressure detection means continues to fall below the second set pressure for a second set time or more while the compressor and the circulation pump are stopped.

  According to the seventh aspect of the invention, optimum monitoring can be performed according to the degree of breakage of the evaporator, in other words, the degree of refrigerant leakage from the evaporator.

  The invention according to claim 8 is the chiller according to claim 7, wherein the first set pressure is a saturation pressure of 0 ° C. of the refrigerant of the refrigerator.

  According to the eighth aspect of the invention, by using 0 ° C., which is the limit of water freezing, as the reference temperature, it is possible to more easily and reliably determine the refrigerant leakage due to the breakage of the evaporator.

  ADVANTAGE OF THE INVENTION According to this invention, the refrigerator and chiller which can detect the refrigerant | coolant leakage by the damage of an evaporator easily and cheaply are realizable.

It is the schematic which shows one Example of the refrigerator of this invention, and a chiller using the same.

Hereinafter, specific embodiments of the present invention will be described in detail with reference to the drawings.
FIG. 1 is a schematic view showing an embodiment of a refrigerator 1 of the present invention and a chiller 2 using the same. The refrigerator 1 of the present embodiment is a vapor compression refrigerator, and the compressor 3, the condenser 4, the expansion valve 5 and the evaporator 6 are sequentially connected in an annular manner to circulate the refrigerant.

  The compressor 3 compresses the gas refrigerant to high temperature and pressure. The refrigerant from the compressor 3 is preferably sent to the condenser 4 via the oil separator 7. The oil separator 7 separates and removes oil contained in the refrigerant from the compressor 3.

  The condenser 4 condenses and liquefies the refrigerant from the compressor 3. The condenser 4 of this embodiment is an air-cooled heat exchanger that includes a fan 8. The refrigerant from the condenser 4 is preferably sent to the expansion valve 5 via the liquid receiver 9 and the liquid electromagnetic valve 10.

  The liquid receiver 9 temporarily stores the refrigerant liquefied by the condenser 4. The liquid electromagnetic valve 10 is a valve that is opened and closed in conjunction with the start and stop of the compressor 3, and switches whether the refrigerant is supplied to the expansion valve 5. During operation of the compressor 3, the liquid electromagnetic valve 10 is opened, and while the compressor 3 is stopped, the liquid electromagnetic valve 10 is closed. The liquid electromagnetic valve 10 is not limited to a literal electromagnetic valve, and may be constituted by an electric valve depending on circumstances.

  The expansion valve 5 reduces the pressure and temperature of the refrigerant by allowing the refrigerant from the condenser 4 to pass therethrough.

  The evaporator 6 is a heat exchanger that takes heat from the surroundings by evaporation of the refrigerant. As will be described later, the refrigerator 1 is used in the chiller 2 in this embodiment. In this case, the evaporator 6 is an indirect heat exchanger between the refrigerant and the liquid to be cooled (for example, water or brine). That is, the evaporator 6 is a heat exchanger that exchanges heat without mixing the refrigerant and the liquid to be cooled, and is configured by, for example, a plate heat exchanger.

  The refrigerant vaporized in the evaporator 6 is preferably returned to the compressor 3 via the accumulator 11. A suction pressure adjusting valve (SPR valve) 12 that adjusts the suction pressure of the compressor 3 is preferably provided between the evaporator 6 and the accumulator 11.

  Now, in order to monitor the presence or absence of refrigerant leakage due to breakage of the evaporator 6, pressure detection means (13) for detecting the refrigerant pressure is provided at any location between the expansion valve 5 outlet and the compressor 3 inlet. Provided. The pressure detecting means is the pressure sensor 13 in this embodiment, but may be a pressure switch depending on circumstances. When the suction pressure adjustment valve 12 is provided between the evaporator 6 and the compressor 3, the pressure sensor 13 is provided between the expansion valve 5 and the suction pressure adjustment valve 12, more preferably the evaporator 6 and the suction pressure adjustment. It is provided between the valve 12.

  While the compressor 3 is stopped, a controller (not shown) monitors the presence or absence of refrigerant leakage due to breakage of the evaporator 6 based on the pressure detected by the pressure sensor 13. If there is a refrigerant leak due to breakage of the evaporator 6, the detected pressure of the pressure sensor 13 is lowered, so that the refrigerant leak due to breakage of the evaporator 6 can be detected.

  In particular, when the refrigerator 1 includes the liquid electromagnetic valve 10 and the liquid electromagnetic valve 10 is closed while the compressor 3 is stopped, the section from the liquid electromagnetic valve 10 to the compressor 3 is surely a closed space. The pressure in the enclosed space is monitored, and whether or not the refrigerant leaks due to breakage of the evaporator 6 can be easily and reliably detected depending on whether or not the pressure is kept below the set pressure for a set time. .

  When the compressor 3 is stopped, if the pressure detected by the pressure sensor 13 continues below the set pressure for a set time or longer, the controller informs the user that there is a refrigerant leak due to breakage of the evaporator 6. Good. For example, the user may be notified by sounding a buzzer or displaying it on the screen.

  The refrigerator 1 having the above configuration is used for various applications, but is used for the chiller 2 in this embodiment. The chiller 2 of the present embodiment is a water chiller that cools water in the evaporator 6. That is, the liquid to be cooled in the evaporator 6 is water, and the evaporator 6 is an indirect heat exchanger in which the refrigerant flow path 14 and the water flow path 15 are formed. The refrigerant from the expansion valve 5 is passed through the refrigerant flow path 14, while the water from the cold water tank 16 is passed through the water flow path 15. For this purpose, the water flow path 15 of the evaporator 6 is connected to the cold water tank 16 via a water supply path 17 and a return path 18. The capacity of the cold water tank 16 is, for example, a relatively large capacity of 10 tons or more.

  A circulation pump 19 is provided in the water supply path 17. Therefore, by operating this circulation pump 19, the water from the cold water tank 16 is supplied to the evaporator 6 through the water supply path 17, passes through the water flow path 15 in the evaporator 6, and then returns to the return path 18. To the cold water tank 16. In this way, the water in the cold water tank 16 can circulate between the evaporator 6. The circulating water can be cooled by utilizing the heat of vaporization when the refrigerant evaporates in the evaporator 6.

  A water temperature sensor 20 is provided to detect the temperature of the circulating water. In the present embodiment, the water temperature sensor 20 is provided on the return path 18 from the evaporator 6 to the cold water tank 16.

  The water in the cold water tank 16 can be supplied to various cold water use facilities (cold water use points) via the cold water channel 21. The chilled water passage 21 is provided with a chilled water pump 22 and a chilled water valve 23 from the chilled water tank 16 side. When the chilled water valve 23 is opened while the chilled water pump 22 is operated, the chilled water in the chilled water tank 16 is taken out. be able to. The cold water pump 22 of this embodiment has a built-in pressure switch. When the cold water valve 23 is closed, the cold water pump 22 is stopped accordingly. When the cold water valve 23 is opened, the cold water pump 22 is operated accordingly. Further, as the water in the cold water tank 16 is used, water is appropriately supplied into the cold water tank 16 using a ball tap (not shown) or the like, and the water level in the cold water tank 16 is maintained as desired.

  Now, the chiller 2 having the above-described configuration is controlled as follows by a controller (not shown). That is, the controller is connected to the pressure sensor 13 and the water temperature sensor 20 in addition to the compressor 3, the liquid electromagnetic valve 10, the circulation pump 19, the cold water valve 23, and the like based on the detection signals of these sensors 13 and 20. The compressor 3, the liquid electromagnetic valve 10, the circulation pump 19, the cold water valve 23, and the like are controlled.

  In order to manufacture cold water, the liquid electromagnetic valve 10 may be opened and the compressor 3 may be operated. During this time, the circulation pump 19 is operated to circulate water between the evaporator 6 and the cold water tank 16. At this time, the water in the cold water tank 16 is maintained at a desired temperature based on the temperature detected by the water temperature sensor 20. For example, when the detected temperature of the water temperature sensor 20 reaches a target temperature (for example, 1 ° C.), the compressor 3 is stopped, and when the detected temperature reaches an upper limit temperature (for example, 3 ° C.), the compressor 3 is restarted. The circulation pump 19 is normally operated regardless of whether the compressor 3 is started or stopped, but may be stopped for energy saving while the compressor 3 is stopped.

  While the compressor 3 is stopped, if the pressure detected by the pressure sensor 13 continues below the set pressure for a set time or longer, it is determined that there is a refrigerant leak due to breakage of the evaporator 6, and this is notified and the chilled water valve 23 Close. Thereby, it can prevent beforehand that the cold water which the refrigerant | coolant and the oil contained in it mixed is used. In particular, when the chilled water tank 16 has a relatively large capacity, it is possible to prevent the contaminated water from being used outside even if it takes some time to determine the refrigerant leakage.

  More specifically, the chiller 2 of the present embodiment is configured to be able to determine the presence or absence of refrigerant leakage due to breakage of the evaporator 6 in at least one of the following (a) to (d). Has been. In this case, it is particularly preferable to include (b).

  (A) While the compressor 3 is stopped but the circulating pump 19 is operating and the compressor 3 is stopped, the pressure detected by the pressure sensor 13 exceeds the first set pressure within a predetermined time. When continuously exceeding this first set pressure for more than the first set time after exceeding.

  (B) While the compressor 3 is stopped, the circulating pump 19 is in operation, and within a predetermined time after the compressor 3 is stopped, the pressure detected by the pressure sensor 13 is set to the first set pressure. When continuously below the hour.

  (C) The compressor 3 is stopped but the circulating pump 19 is operating, and after a predetermined time has elapsed since the compressor 3 was stopped, the pressure detected by the pressure sensor 13 is set to the second set pressure. When continuously below the hour.

  (D) When the pressure detected by the pressure sensor 13 continues below the second set pressure for a second set time or more while the compressor 3 and the circulation pump 19 are stopped.

  Here, the predetermined time, the specified time, the first set time, and the second set time in each condition are appropriately set. In this embodiment, for example, the predetermined time is 2 hours and the specified time is 30. Second, the first set time is 60 seconds, and the second set time is 30 minutes.

  The first set pressure and the second set pressure are also set as appropriate, but the second set pressure is set lower than the first set pressure. The first set pressure is higher than the refrigerant evaporation pressure during operation of the refrigerator 1 (saturation pressure corresponding to the evaporator 6 refrigerant temperature (for example, −3 ° C.)) and the refrigerant saturation corresponding to the water temperature target temperature (for example, 1 ° C.). It is lower than the pressure (saturation pressure when the evaporator 6 refrigerant temperature is raised to the water temperature target temperature (for example, 1 ° C.) by stopping the refrigerator 1). Further, the second set pressure is lower than the refrigerant evaporation pressure during operation of the refrigerator 1 (saturation pressure corresponding to the evaporator 6 refrigerant temperature (for example, −3 ° C.)) (for example, refrigerant saturation pressure corresponding to −15 ° C.).

  During the operation of the refrigerator 1, the refrigerant temperature in the evaporator 6 is lower (for example, −3 ° C.) than the water temperature target temperature (for example, 1 ° C.) because water is cooled by the refrigerant. When the temperature detected by the water temperature sensor 20 reaches the target water temperature, the compressor 3 is stopped, and when the temperature detected by the water temperature sensor 20 reaches the upper limit temperature (for example, 3 ° C.), the compressor 3 is operated again.

  Now, when the evaporator 6 is not damaged and there is no refrigerant leakage, when the compressor 3 is stopped when the detected temperature of the water temperature sensor 20 reaches the water temperature target temperature, during this stop, the refrigerant is heated in reverse by water, The detection pressure of the pressure sensor 13 rises above the first set pressure.

  However, if there is a refrigerant leak due to breakage of the evaporator 6, the pressure detected by the pressure sensor 13 will decrease even if it once increases. Therefore, as shown in the above (a), after the detected pressure by the pressure sensor 13 has continuously exceeded the first set pressure for a predetermined time or more, the first set pressure has continuously dropped below the first set time. In this case, it is determined that there is a refrigerant leak due to breakage of the evaporator 6. In addition, since the water temperature does not fall below 0 ° C. (freezes below 0 ° C.), in the chiller 2 of this embodiment, setting the saturation pressure at 0 ° C. of the refrigerant as the first set pressure is the easiest and most reliable. Breakage of the evaporator 6 can be detected.

  When the refrigerant leaks from the evaporator 6 is relatively large, the detected pressure of the pressure sensor 13 decreases without increasing to the first set pressure after the compressor 3 is stopped. Therefore, as shown in the above (b), when the pressure detected by the pressure sensor 13 is continuously lower than the first set pressure for the second set time or more, it is determined that there is a refrigerant leak due to breakage of the evaporator 6. To do.

  Moreover, when the refrigerant | coolant leakage from the evaporator 6 is minute, the detection may require time. Therefore, as shown in (c) above, when the pressure detected by the pressure sensor 13 continues to fall below the second set pressure for a second set time after a predetermined time has elapsed since the compressor 3 was stopped. Then, it is determined that there is a refrigerant leak due to breakage of the evaporator 6.

  Further, when the compressor 3 and the circulation pump 19 are stopped, the pressure detected by the pressure sensor 13 continues to fall below the second set pressure for the second set time or longer, similarly to the above (c). It is determined that there is a refrigerant leak from 6.

  According to such control, optimal monitoring can be performed in accordance with the degree of breakage of the evaporator 6, in other words, the degree of refrigerant leakage from the evaporator 6.

  The refrigerator 1 and the chiller 2 using the same according to the present invention are not limited to the configuration of the above-described embodiment, and can be appropriately changed. In particular, as long as the pressure detection means (13) is provided on the low pressure side of the refrigeration cycle and the pressure drop while the refrigerator 1 is stopped is detected, other configurations can be changed as appropriate.

  For example, in the above-described embodiment, the water chiller that exchanges heat between the refrigerant and the water is used in the evaporator 6. However, in some cases, the refrigerant and the brine may be exchanged in the evaporator 6. Moreover, the use of the refrigerator 1 is not limited to the chiller 2 but can be applied to other uses, for example, a heat pump. In any case, similarly to the above embodiment, the pressure sensor 13 is provided at any location between the outlet of the expansion valve 5 and the inlet of the compressor 3, and based on the detected pressure of the pressure sensor 13 when the compressor 3 is stopped. The presence or absence of refrigerant leakage due to damage to the evaporator 6 can be detected.

  Moreover, in the said Example, when it determines with the cold water pump 22 and the cold water valve 23 being provided in the cold water channel 21 from the cold water tank 16 and there exists a refrigerant | coolant leak by the failure | damage of the evaporator 6, the cold water valve 23 will be closed (according to this) Although the cold water pump 22 is stopped), installation of one of the cold water pump 22 and the cold water valve 23 may be omitted. When only the cold water pump 22 is installed in the cold water channel 21 (when the installation of the cold water valve 23 is omitted), if it is determined that there is a refrigerant leak due to damage to the evaporator 6, the cold water pump 22 may be stopped.

DESCRIPTION OF SYMBOLS 1 Refrigerator 2 Chiller 3 Compressor 4 Condenser 5 Expansion valve 6 Evaporator 7 Oil separator 8 Fan 9 Liquid receiver 10 Liquid electromagnetic valve 11 Accumulator 12 Suction pressure adjustment valve (SPR valve)
13 Pressure sensor (pressure detection means)
DESCRIPTION OF SYMBOLS 14 Refrigerant flow path 15 Water flow path 16 Chilled water tank 17 Water supply path 18 Return path 19 Circulation pump 20 Water temperature sensor 21 Cold water path 22 Chilled water pump 23 Chilled water valve

Claims (8)

Pressure detection means is provided at any point between the expansion valve outlet of the vapor compression refrigerator and the compressor inlet,
A refrigerator that monitors the presence or absence of refrigerant leakage due to breakage of an evaporator based on the pressure detected by the pressure detection means while the compressor is stopped. On the inlet side of the expansion valve, a liquid electromagnetic valve that is opened and closed in conjunction with the start and stop of the compressor is provided.
Whether or not the refrigerant leaks is monitored by monitoring whether or not the pressure detected by the pressure detecting means continues for a set time or longer in a state where the compressor is stopped and the liquid electromagnetic valve is closed. The refrigerator according to claim 1, wherein the refrigerator is provided. A suction pressure adjusting valve for adjusting the suction pressure of the compressor is provided on the outlet side of the evaporator,
The refrigerator according to claim 1 or 2, wherein the pressure detection means is provided between an expansion valve and a suction pressure adjustment valve. Comprising the refrigerator according to any one of claims 1 to 3,
A chiller characterized in that a refrigerant from an expansion valve is passed through the evaporator, and a liquid to be cooled that is cooled by indirect heat exchange with the refrigerant. A cold water tank for storing water as the liquid to be cooled;
The water in the cold water tank can be circulated with the evaporator and can be supplied to the cold water use facility through the cold water valve.
While the compressor is stopped, if the pressure detected by the pressure detecting means continues below the set pressure for a set time or longer, it is determined that there is a refrigerant leak due to damage to the evaporator, and this is notified and the chilled water valve is closed. The chiller according to claim 4, wherein: In the cold water path from the cold water tank to the cold water use facility, a cold water pump is provided instead of or in addition to the cold water valve,
While the compressor is stopped, if the pressure detected by the pressure detection means continues below the set pressure for a set time or longer, it is determined that there is a refrigerant leak due to the evaporator being broken, and that is notified and the cold water pump is stopped The chiller according to claim 5, wherein: The circulation of water between the cold water tank and the evaporator is switched by the on / off of the circulation pump,
6. The presence or absence of refrigerant leakage due to damage to an evaporator can be determined when at least one of the following (a) to (d) includes at least (b): The chiller according to claim 6.
(A) While the compressor is stopped, the circulating pump is operating, and within a predetermined time after the compressor is stopped, the pressure detected by the pressure detecting means continues the first set pressure for a specified time or more. When the pressure drops below the first set pressure for more than the first set time.
(B) While the compressor is stopped, the circulating pump is operating, and within a predetermined time after the compressor is stopped, the pressure detected by the pressure detecting means exceeds the first set pressure by a second set time or more. When continuously below.
(C) The compressor is stopped but the circulating pump is operating, and after a predetermined time has elapsed since the compressor was stopped, the pressure detected by the pressure detecting means exceeds the second set pressure by a second set time or more. When continuously below.
(D) When the pressure detected by the pressure detection means continues to fall below the second set pressure for a second set time or more while the compressor and the circulation pump are stopped. The chiller according to claim 7, wherein the first set pressure is a saturation pressure of 0 ° C. of the refrigerant of the refrigerator.

Images