JP2009174769A - Chiller - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent freezing of water at activation of a refrigerator due to a low outside air temperature and to prevent a liquid back to a compressor at this time in a chiller providing cooling of water to a 0°C vicinity. <P>SOLUTION: In the refrigerator 2, a liquid solenoid valve 12 is provided in a primary side of an expansion valve 5. A primary side of a condenser 4 and a secondary side of the expansion valve 5 are connected by a bypass passage 17. An opening-adjustable bypass valve 18 is provided in the bypass passage 17. The water is circulated between an evaporator 6 and a tank 21, and cooling of the circulated water is carried out by heat of vaporization of a refrigerant in the evaporator 6. At activation of the refrigerator 2, if a refrigerant temperature or a refrigerant pressure of a primary side of the liquid solenoid valve 12 is a set value or less, introduction of the water to the evaporator 6 is stopped or limited, the bypass valve 18 is opened in a state of closing the liquid solenoid valve 12, and the refrigerator 2 is activated. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a chiller for cooling a liquid to be cooled such as water. For example, the present invention relates to a chiller for obtaining cold water around 0 ° C. (for example, 0.5 ° C.) while preventing freezing of water for food cooling or air conditioning.

  Conventionally, as disclosed in Patent Document 1 below, in a chilled water apparatus constituted by a refrigerator (1), a heat exchanger (2), and a chilled water tank (3), the refrigerator (1) and the heat exchanger (2 ) Are connected by a refrigerant supply line (4) and a refrigerant reflux line (5), and the refrigerant supply line (4) and the refrigerant reflux line (5) are connected by a bypass line (8). 8) is provided with a flow control valve (9), and the heat exchanger (2) and the cold water tank (3) are connected by a cold water supply line (6) and a cold water reflux line (7). A chilled water device (chiller) is known in which a temperature sensor (10) is provided in (7) and the flow rate control valve (9) is controlled based on a detection value of the temperature sensor (10).

Further, as disclosed in Patent Document 2 below, the refrigerant temperature on the primary side of the heat exchanger (3) is detected by the temperature sensor (15), and the compressor (1) is on / off controlled based on the detected temperature. A chiller for preventing freezing of water circulated and supplied to the heat exchanger (3) is known.
JP-A-9-166339 (Claim 1, FIG. 1, paragraph numbers [0012] and [0013]) JP, 2007-292351, A (Claim 1, FIG. 1, FIG. 2, paragraph number [0032])

  When cooling water to near 0 ° C. using a chiller, it is necessary to take measures to prevent water from freezing in the evaporator (heat exchanger). However, the invention described in Patent Document 1 is to adjust the water temperature by adjusting the flow rate of the refrigerant supplied to the evaporator from the condenser or expansion valve of the refrigerator by adjusting the opening degree of the flow control valve, Sufficient consideration is not given to water freeze prevention.

  Specifically, although the flow rate of the refrigerant can be adjusted, only the refrigerant through the condenser of the refrigerator is supplied to the evaporator. In addition, the flow rate of the refrigerant supplied to the evaporator is adjusted based on the water temperature rather than the refrigerant temperature after the refrigerator is started, not before. Therefore, when the refrigerator is started in a state where the outside air temperature is low, it is inevitable that low-temperature refrigerant enters the evaporator through the expansion valve immediately after the start-up, and there is a risk that water will freeze in the evaporator. is there.

  On the other hand, in the invention described in Patent Document 2, water is prevented from freezing by controlling the compressor on / off based on the refrigerant temperature on the primary side of the evaporator. Similarly, only the refrigerant through the refrigerator condenser is supplied to the evaporator. In addition, as shown in FIG. 2, since the control is not performed before starting the refrigerator but after starting, similar to the invention described in Patent Document 1, when the refrigerator is started in a state where the outside air temperature is low. Immediately after startup, it is inevitable that low-temperature refrigerant enters the evaporator from the condenser via the expansion valve, and water may freeze in the evaporator.

  Such an inconvenience is not limited to a water chiller for cooling water, but is also the case with other chillers in which the liquid to be cooled may be frozen. Further, in the inventions described in the above patent documents, the water is circulated between the chilled water tank and the evaporator. The same applies to the chiller with the specifications.

  By the way, the applicant previously provided a bypass path that connects the primary side of the condenser and the secondary side of the expansion valve, thereby condensing through the bypass path in addition to the refrigerant via the condenser and the expansion valve. A chiller that can supply the refrigerant on the primary side of the evaporator to the evaporator has been proposed, and a patent application has already been filed (Japanese Patent Application No. 2007-178445). According to the invention of this patent application, when the outside air temperature is low and the coolant through the condenser and the expansion valve is used, there is a possibility that the liquid to be cooled will freeze in the evaporator. By using this, it is possible to prevent the liquid to be cooled in the evaporator from freezing. In addition, since the refrigerant supply route to the evaporator is determined before the start-up of the refrigerator, not after the start-up of the refrigerator, it is possible to prevent low-temperature refrigerant from entering the evaporator immediately after the start-up through the condenser and the expansion valve. The freezing of the liquid to be cooled in the evaporator can be reliably prevented.

  However, when such a configuration is adopted, the temperature of the liquid to be cooled supplied to the evaporator for heat exchange with the refrigerant rather than the temperature of the refrigerant supplied from the compressor to the evaporator via the bypass. If the temperature is low, the gas refrigerant from the bypass passage in the evaporator is deprived of heat by the liquid to be cooled and liquefies, and this liquid refrigerant may be sent to the compressor to cause liquid back. In particular, if the bypass valve fails and is kept open, there is a possibility that liquid back cannot be prevented even if an accumulator is provided.

  The problem to be solved by the present invention is that the primary side of the condenser and the secondary side of the expansion valve are connected by a bypass, and refrigerant from the compressor can be supplied to the evaporator via the condenser and the expansion valve. In addition, in the chiller that can be supplied to the evaporator via the bypass path, the liquid back is prevented when the refrigerant is supplied to the evaporator via the bypass path and the cycle is preheated. Specifically, when the outside air temperature is low and the refrigerant through the condenser and the expansion valve is used, in the case where the liquid to be cooled may freeze in the evaporator, by using the refrigerant through the bypass path, When performing control to prevent freezing of the liquid to be cooled in the evaporator, it prevents the relatively high-temperature gas refrigerant supplied to the evaporator via the bypass from being liquefied by the liquid to be cooled and causing liquid back. There is to do.

  This invention was made in order to solve the said subject, The invention of Claim 1 is a refrigerator which performs a refrigerating cycle by circulating a refrigerant | coolant to a compressor, a condenser, an expansion valve, and an evaporator. An introduction path for introducing the liquid to be cooled to be exchanged with the refrigerant in the evaporator into the evaporator, and a lead-out path for deriving the liquid to be cooled having been exchanged with the refrigerant in the evaporator from the evaporator; A liquid electromagnetic valve provided on the primary side of the expansion valve, a bypass path connecting the primary side of the condenser and the secondary side of the expansion valve, and a bypass valve adjustable in opening degree provided in the bypass path; When the refrigerant temperature or refrigerant pressure on the primary side of the liquid electromagnetic valve is equal to or lower than a set value, the introduction of the liquid to be cooled into the evaporator is stopped or limited, and the bypass valve is closed with the liquid electromagnetic valve closed. Open the refrigerator by opening A chiller, characterized by comprising a control vessel.

  According to the first aspect of the present invention, in the evaporator, in addition to the refrigerant via the condenser and the expansion valve, the refrigerant on the primary side of the condenser via the bypass path instead of or in addition to the refrigerant. It can be supplied. Therefore, when the outside air temperature is low and the refrigerant through the condenser and the expansion valve is used, the liquid to be cooled may freeze in the evaporator. Freezing of the liquid to be cooled can be prevented. Moreover, the flow rate adjustment of the refrigerant through the bypass passage is performed by a bypass valve whose opening degree can be adjusted, whereby the refrigerator can be operated in a desired state. Further, when performing such freeze prevention control, if the liquid to be cooled is lower in temperature than the gas refrigerant through the bypass, the gas refrigerant may be liquefied in the evaporator. Therefore, such liquefaction can be prevented by stopping or restricting the introduction of the liquid to be cooled into the evaporator. Accordingly, liquid back to the compressor can be prevented.

  According to a second aspect of the present invention, when the refrigerator is started, the primary side refrigerant temperature or refrigerant pressure of the liquid electromagnetic valve is based on the primary side refrigerant temperature or refrigerant pressure of the liquid electromagnetic valve. In the first case, the liquid to be cooled is introduced into the evaporator, and the refrigerator is started by opening the liquid electromagnetic valve with the bypass valve closed, while the primary of the liquid electromagnetic valve In the second case where the refrigerant temperature or the refrigerant pressure on the side is equal to or lower than the first set value, the liquid to be cooled is not introduced into the evaporator, or the liquid to be cooled is supplied to the evaporator more restrictively than in the first case. And opening the bypass valve with the liquid electromagnetic valve closed, and starting the refrigerator, whereby when the refrigerant temperature or refrigerant pressure on the primary side of the evaporator becomes a second set value or more, Release or stop the introduction of the liquid to be cooled into the evaporator Rutotomoni a chiller of claim 1, characterized in that adjusting the opening of the bypass valve in an open state the liquid solenoid valve.

  According to the second aspect of the present invention, when the refrigerant temperature or the refrigerant pressure on the primary side of the liquid electromagnetic valve is equal to or lower than the first set value, the bypass valve is opened with the liquid electromagnetic valve closed, and the refrigerator is By starting, the refrigerant below the allowable temperature is not supplied to the evaporator. Therefore, even when the outside air temperature is low, freezing of the liquid to be cooled in the evaporator can be prevented. In addition, during such freeze prevention control, introduction of the liquid to be cooled into the evaporator is completely stopped or limited to a flow rate that suppresses liquefaction of the refrigerant. Accordingly, liquid back to the compressor can be prevented. When the refrigerant temperature or refrigerant pressure on the primary side of the evaporator becomes equal to or higher than the second set value, the introduction or stop of the introduction of the liquid to be cooled into the evaporator is released, and the bypass valve is opened with the liquid electromagnetic valve opened. Adjust the opening. In this way, it is possible to operate the chiller while preventing the liquid to be cooled at the time of starting the refrigerator from being frozen and preventing the liquid back at the time of the freeze prevention control. For example, in a water chiller capable of cooling water to around 0 ° C., it is possible to operate the chiller while preventing water freezing in the evaporator and preventing liquid back during the freeze prevention control.

  Further, the invention according to claim 3 is characterized in that the presence or absence of introduction of the liquid to be cooled into the evaporator is switched and controlled depending on whether or not the pump provided in the introduction path is operated. It is a chiller as described in.

  According to the third aspect of the present invention, during the freeze prevention control, by stopping the pump that feeds the liquid to be cooled to the evaporator, the introduction of the liquid to be cooled into the evaporator is stopped, and from the bypass path It is possible to prevent liquefaction of the gas refrigerant. Thus, liquid back can be prevented with a simple configuration and control.

  According to the present invention, when the outside air temperature is low and the refrigerant through the condenser and the expansion valve is used, there is a risk that the liquid to be cooled will freeze in the evaporator. Is supplied to the evaporator, so that the liquid to be cooled in the evaporator can be prevented from freezing. Moreover, at the time of such anti-freezing control, it is possible to prevent the liquid refrigerant from being liquefied by preventing the relatively high temperature gas refrigerant from being liquefied by the liquid to be cooled in the evaporator.

Next, an embodiment of the present invention will be described.
The chiller of the present invention is an apparatus that uses an evaporator of a refrigerator as a heat exchanger between a refrigerant and a liquid to be cooled, and cools the liquid to be cooled by heat of vaporization of the refrigerant in the evaporator. The liquid to be cooled is typically water, but may be another liquid that may freeze. When the liquid to be cooled is water, the chiller can be referred to as a water chiller or a cold water device.

  The chiller of this embodiment includes a compression refrigerator. As is well known, the compression type refrigerator includes a compressor, a condenser, an expansion valve, and an evaporator, and performs a refrigeration cycle of refrigerant compression, condensation, expansion, and evaporation.

  The format of the compressor is not particularly limited. For example, a scroll compressor is used. The condenser is an air-cooled heat exchanger that typically includes a fan. The fan is controlled not to rotate when the refrigerant temperature at a predetermined location is equal to or lower than the set temperature. Further, the expansion valve may be composed of a capillary tube or the like. Further, the evaporator is a heat exchanger that has a refrigerant flow path and a liquid flow path to be cooled, and indirectly exchanges heat without mixing the refrigerant and the liquid to be cooled. The evaporator is typically a plate heat exchanger, but may be a double tube heat exchanger or the like.

  In the refrigerator provided in the chiller of this embodiment, a liquid electromagnetic valve is provided on the primary side (inlet side) of the expansion valve. In other words, the liquid electromagnetic valve is provided between the condenser and the expansion valve, and switches whether the refrigerant is supplied to the expansion valve.

  The primary side (inlet side) of the condenser and the secondary side (outlet side) of the expansion valve are connected by a bypass. Therefore, the refrigerant from the compressor can be supplied to the evaporator through the condenser and the expansion valve as usual, and can be supplied to the evaporator through the bypass.

  The flow rate of the refrigerant supplied to the evaporator via the bypass path can be adjusted by a bypass valve provided in the bypass path. The bypass valve is composed of an electric valve whose opening degree can be adjusted. Specifically, the bypass valve is composed of a motor valve or a proportional control valve. However, a plurality of pipe lines having different pipe diameters may be provided in parallel as bypass paths, and the electromagnetic valves provided in the respective pipe lines may be individually opened and closed. In this case, the plurality of electromagnetic valves function as bypass valves, and substantially adjust the opening of the bypass passage.

  As described above, the heat exchanger constituting the evaporator has a refrigerant flow path through which the refrigerant passes and a liquid flow path to be cooled through which the liquid to be cooled passes. The evaporator is provided with an introduction path for introducing the liquid to be cooled into the liquid flow path to be cooled and an outlet path for deriving the liquid to be cooled from the liquid flow path to be cooled. The introduction path is provided with a pump for feeding the liquid to be cooled to the evaporator. Therefore, by operating the pump, the liquid to be cooled flows from the introduction path through the evaporator to the outlet path, and is cooled by the heat of vaporization of the refrigerant while passing through the evaporator.

  The flow path of the liquid to be cooled is not particularly limited as long as it passes through the evaporator. Further, the use of the liquid to be cooled which is cooled by the evaporator is not particularly limited. For example, the liquid to be cooled is passed through an evaporator and cooled, and then used for heat exchange with a load (for example, cooling of food) and is disposable (flowing water specifications). In addition, a tank for storing the liquid to be cooled is provided, and the liquid to be cooled is supplied from the tank to the evaporator via the introduction path, cooled by the evaporator, and then returned to the tank via the outlet path. Also good (circulation specification). That is, the liquid to be cooled may be circulated between the evaporator and the tank via the introduction path and the outlet path.

  In the case of the circulation specification, heat exchange with the load may be achieved in the lead-out path from the evaporator to the tank, or heat exchange with the load may be achieved in the tank. For example, using a tank as a cooling tank, the packed food can be immersed in a liquid to be cooled in the tank for cooling. Further, the liquid to be cooled may be circulated between the evaporator and the tank to cool the liquid to be cooled in the tank, and the cooled liquid to be cooled may be supplied to another device for use.

  In addition to a refrigerator (particularly a compressor and a condenser fan), a liquid electromagnetic valve and a bypass valve attached thereto, a pump and the like are controlled by a controller. This control is performed based on the refrigerant temperature or refrigerant pressure on the primary side of the liquid electromagnetic valve, the refrigerant temperature or refrigerant pressure on the primary side of the evaporator, the liquid temperature of the liquid to be cooled, and the like. For this purpose, a temperature sensor or a pressure sensor is provided on the primary side of the liquid electromagnetic valve and the primary side of the evaporator, respectively, and a liquid for detecting the temperature of the liquid to be cooled is provided on the outlet path of the liquid to be cooled from the evaporator. A temperature sensor is provided. Based on the detection signals of these sensors, the controller executes activation of the compressor, rotation of the condenser fan, opening and closing of the liquid electromagnetic valve, opening and closing of the bypass valve, and adjustment of the opening degree.

  When the outside air temperature is low in a cold district or the like, the condenser is cooled, so that the refrigerant temperature or refrigerant pressure on the primary side of the liquid electromagnetic valve is low, and such low-temperature refrigerant is supplied to the evaporator via the expansion valve. Then, the liquid to be cooled may be frozen in the evaporator. Therefore, in the chiller of the present embodiment, the refrigerant temperature or refrigerant pressure on the primary side of the liquid electromagnetic valve is confirmed when the refrigerator is started (including when it is restarted).

  When the refrigerant temperature or refrigerant pressure on the primary side of the liquid electromagnetic valve exceeds the first set value (first case), the liquid electromagnetic valve is opened with the bypass valve closed, and the refrigerator is started. On the other hand, when the refrigerant temperature or refrigerant pressure on the primary side of the liquid electromagnetic valve is equal to or lower than the first set value (second case), the bypass valve is opened with the liquid electromagnetic valve closed, and the refrigerator is started.

  The first set value is set based on whether or not there is a possibility of freezing the liquid to be cooled in the evaporator when a refrigerant having a temperature or pressure lower than that is supplied to the evaporator through the expansion valve. When the refrigerant temperature or refrigerant pressure on the primary side of the liquid electromagnetic valve is equal to or lower than the first set value, the refrigerant to be cooled in the evaporator is prevented from freezing by using the refrigerant via the bypass. On the other hand, when the refrigerant temperature or refrigerant pressure on the primary side of the liquid electromagnetic valve exceeds the first set value, a normal refrigeration cycle is executed.

  When the bypass valve is opened and the refrigerator is started with the liquid electromagnetic valve closed, the refrigerant is supplied to the evaporator via the bypass path. Since the refrigerant passing through the bypass passage is relatively hot, when the temperature of the liquid to be cooled is lower than that of the refrigerant, the refrigerant passing through the bypass passage is deprived of heat by the liquid to be cooled in the evaporator. The liquid refrigerant may be liquefied and sent to the compressor. In order to prevent such liquid back into the compressor, introduction of the liquid to be cooled into the evaporator may be stopped or restricted when the temperature of the liquid to be cooled is lower or lower than the refrigerant. . For example, when only the refrigerant through the bypass is supplied to the evaporator, the introduction of the liquid to be cooled into the evaporator is stopped or restricted. As the means, the following four embodiments can be mentioned.

  In the first embodiment, the pump provided in the introduction path is on / off controlled. When the temperature of the liquid to be cooled is lower or lower than that of the refrigerant, the introduction of the liquid to be cooled to the evaporator is stopped by stopping the pump. Therefore, in the evaporator, liquefaction of the refrigerant through the bypass path can be prevented, and liquid back to the compressor can be prevented.

  In the second embodiment, inverter control is performed on a pump provided in the introduction path. When the temperature of the liquid to be cooled is lower or lower than that of the refrigerant, the pump is controlled by an inverter to limit the introduction of the liquid to be cooled into the evaporator as compared with the first case. Specifically, the flow rate of the liquid to be cooled supplied to the evaporator is extremely reduced. Therefore, liquefaction of the refrigerant through the bypass path can be suppressed in the evaporator, and liquid back to the compressor can be prevented.

  In the third embodiment, the presence or absence of introduction of the liquid to be cooled into the evaporator is switched by the secondary water supply adjustment valve of the pump provided in the introduction path, or the introduction restriction and the release thereof are switched and controlled. Specifically, a water supply adjustment valve is further provided on the pump secondary side of the introduction path, and when the temperature of the liquid to be cooled is lower or lower than the refrigerant, the supply water adjustment valve is controlled to control the supply to the evaporator. Stop or limit the introduction of the liquid to be cooled. The water supply adjustment valve is configured by an electromagnetic valve that can only be opened and closed, or an electric valve that can be adjusted in opening. When the water supply adjustment valve is an electromagnetic valve, the control is performed by switching whether or not the liquid to be cooled is introduced into the evaporator. For example, when only the refrigerant through the bypass passage is supplied to the evaporator, the introduction of the liquid to be cooled into the evaporator is stopped by closing the water supply adjustment valve. On the other hand, when the water supply adjustment valve is an electric valve, the control is performed by switching between the restriction of the introduction of the liquid to be cooled into the evaporator and the release thereof. For example, when only the refrigerant via the bypass passage is supplied to the evaporator, the introduction of the liquid to be cooled into the evaporator is limited by reducing the opening of the water supply adjustment valve. By controlling the water supply adjustment valve in this way, liquefaction of the refrigerant through the bypass path can be prevented or suppressed in the evaporator, and liquid back to the compressor can be prevented.

  In the fourth embodiment, in the above-described circulation specification, the supply destination of the liquid to be cooled discharged from the pump is selectively switched to an evaporator, a lead-out path, or a tank. When the temperature of the liquid to be cooled is lower or lower than that of the refrigerant, the introduction of the liquid to be cooled to the evaporator is prevented without stopping the pump. Specifically, by providing a connection path between the pump secondary side of the introduction path and the outlet path, the liquid to be cooled from the pump is guided to the outlet path without passing through the evaporator. Alternatively, by providing a return path between the pump secondary side of the introduction path and the tank, the liquid to be cooled from the pump may be returned directly to the tank. In either case, the refrigerant can be prevented from being liquefied through the bypass in the evaporator, and liquid back to the compressor can be prevented.

  After the bypass valve is opened and the refrigerator is started with the liquid electromagnetic valve closed, the refrigerant temperature or refrigerant pressure on the primary side of the evaporator rises. When the refrigerant temperature or refrigerant pressure on the primary side of the evaporator becomes equal to or higher than the second set value, the liquid electromagnetic valve is opened in addition to the bypass valve. As a result, the high-temperature refrigerant (gas phase) via the bypass passage and the low-temperature refrigerant (gas-liquid two-phase) via the condenser and the expansion valve are supplied to the evaporator to operate the refrigerator.

  At this time, typically, the stop or restriction of the introduction of the liquid to be cooled into the evaporator is released. That is, when the introduction of the liquid to be cooled to the evaporator is stopped, the introduction of the liquid to be cooled to the evaporator is started. In addition, when the introduction of the liquid to be cooled into the evaporator is restricted, the flow rate is increased. When the introduction restriction of the liquid to be cooled to the evaporator is released and the flow rate is returned to a desired flow rate, it may be returned at once or may be gradually returned.

  Further, the opening degree of the bypass valve is adjusted after the liquid electromagnetic valve is opened because the refrigerant temperature or refrigerant pressure on the primary side of the evaporator becomes equal to or higher than the second set value. During supply of the refrigerant to the evaporator via the bypass, the refrigerant temperature or refrigerant pressure on the primary side of the liquid electromagnetic valve is constantly monitored. When the temperature or pressure exceeds the first set value, it is determined that there is no risk of freezing of the liquid to be cooled in the evaporator, and the bypass valve is fully closed.

  When configured as a circulating water chiller, the cold water obtained in the evaporator is used for cooling food after cooking, for example. In order to maintain food safety, texture, and freshness, it is preferable to quickly cool to a low temperature of 5 ° C. or less after cooking. Therefore, for example, in a water chiller with a circulation specification, it is preferable to cool the circulating water to a temperature around 0 ° C. (usually 0.5 to 1.5 ° C.) rather than a level of several degrees C. In this case, the water is circulated between the cold water tank and the evaporator, and at that time, the water is cooled by the evaporator. The temperature of the chilled water returned from the evaporator to the chilled water tank while preventing the liquid back to the compressor and water freezing by controlling the refrigerator based on the refrigerant temperature and controlling the introduction of water to the evaporator. Or the temperature of the cold water in the cold water tank can be kept at the desired temperature.

  Hereinafter, specific embodiments of the present invention will be described in detail with reference to the drawings. Here, a circulating water chiller will be described.

  FIG. 1 is a schematic configuration diagram illustrating a chiller according to a first embodiment of the present invention. The chiller 1 according to the first embodiment includes a refrigerator 2, and the refrigerator 2 is a compression refrigerator. As is well known, the compression refrigerator includes a compressor 3, a condenser 4, an expansion valve 5, and an evaporator 6, and performs a refrigerant compression, condensation, expansion, and evaporation refrigeration cycle.

  The compressor 3 compresses the refrigerant into a high-temperature and high-pressure gas. The gas from the compressor 3 is sent to the condenser 4 via the oil separator 7. The oil separator 7 separates and removes the oil contained in the gas from the compressor 3. The format of the compressor 3 is not particularly limited. For example, a scroll compressor is used. In this case, it is preferable to provide a KVR valve (high pressure control valve) 8 on the primary side of the condenser 4.

  The condenser 4 condenses and liquefies the gas from the compressor 3. The condenser 4 of the present embodiment is an air-cooled heat exchanger that includes a fan 9. The fan 9 is rotated by a motor 10. However, when the refrigerant temperature at a predetermined location is equal to or lower than the set temperature, control is performed so as not to rotate. The refrigerant from the condenser 4 is sent to the expansion valve 5 via the liquid receiver 11 and the liquid electromagnetic valve 12. The liquid receiver 11 temporarily stores the refrigerant liquefied by the condenser 4. The liquid electromagnetic valve 12 switches whether the refrigerant is supplied from the condenser 4 and the liquid receiver 11 to the expansion valve 5.

  The expansion valve 5 allows the liquefied refrigerant from the condenser 4 to pass therethrough, thereby reducing the pressure and temperature of the refrigerant. The evaporator 6 is a heat exchanger that takes heat away from the surroundings by evaporation of the refrigerant. The evaporator 6 is a heat exchanger that has a refrigerant flow path 13 and a water flow path 14 and exchanges heat between the refrigerant and water without mixing the refrigerant and water. The evaporator 6 of the present embodiment is a plate heat exchanger.

  The refrigerant evaporated in the evaporator 6 is returned to the compressor 3 through the accumulator 15. An SPR valve (suction pressure adjusting valve) 16 is preferably provided between the evaporator 6 and the accumulator 15. The refrigerator 2 is configured as described above, so that the refrigeration cycle can be executed.

  In the refrigerator 2 of this embodiment, the primary side of the condenser 4 and the secondary side of the expansion valve 5 are further connected by a bypass path 17. Is the bypass passage 17 equivalent to a main pipe (such as a pipe connecting the oil separator 7 and the condenser 4) constituting the refrigeration cycle so that the refrigerator 2 does not become abnormal when the refrigerant passes through the bypass passage 17? It is preferable to form from a larger diameter. For the same purpose, it is preferable to provide the KVR valve 8 on the secondary side of the oil separator 7 as described above.

  By providing the bypass passage 17 branched from the main pipe, the refrigerant from the compressor 3 can be supplied to the evaporator 6 through the condenser 4 and the expansion valve 5 as usual, and also via the bypass passage 17. Thus, it can be supplied to the evaporator 6. The bypass passage 17 is provided with a bypass valve 18 whose opening degree can be adjusted. The bypass valve 18 of the present embodiment is composed of a motor valve. The motor valve is a valve whose opening degree can be adjusted by rotating the motor forward or backward.

  The refrigerator 2 of the present embodiment is provided with a first temperature sensor 19 and a second temperature sensor 20. The first temperature sensor 19 is provided between the liquid receiver 11 and the liquid electromagnetic valve 12 and detects the refrigerant temperature on the primary side of the liquid electromagnetic valve 12. The second temperature sensor 20 is provided between the expansion valve 5 and the evaporator 6 and detects the refrigerant temperature on the primary side of the evaporator 6. At this time, the main pipe connecting the expansion valve 5 and the evaporator 6 and the bypass passage 17 are provided on the downstream side. Thereby, the temperature of the refrigerant | coolant via the liquid solenoid valve 12, the temperature of the refrigerant | coolant via the bypass valve 18, and the temperature of the refrigerant | coolant in the state in which these were mixed are detectable.

  In the plate heat exchanger constituting the evaporator 6, the refrigerant from the expansion valve 5 and / or the refrigerant from the bypass path 17 is passed through the refrigerant flow path 13. On the other hand, water from the cold water tank 21 is supplied to and discharged from the water channel 14. Specifically, the water flow path 14 of the evaporator 6 is connected to the cold water tank 21 via the introduction path 22 and the outlet path 23. A pump 24 is provided in the introduction path 22. Therefore, by operating this pump 24, the water from the cold water tank 21 is supplied to the evaporator 6 through the introduction path 22, passes through the water flow path 14 in the evaporator 6, and then passes through the outlet path 23. And returned to the cold water tank 21. In this way, the water in the cold water tank 21 is circulated between the cold water tank 21 and the evaporator 6. The circulating water can be cooled by utilizing the heat of vaporization when the refrigerant evaporates in the evaporator 6.

  By the way, in the evaporator 6, the refrigerant flowing through the refrigerant flow path 13 and the circulating water flowing through the water flow path 14 are normally opposed to each other, but may be parallel flow depending on circumstances. Further, in this embodiment, a water temperature sensor 25 is provided in the outlet path 23 in the vicinity of the outlet of the evaporator 6 in order to detect the temperature of the circulating water.

  The chiller 1 of this embodiment is controlled by the controller 26. Therefore, the controller 26 is connected to the refrigerator 2 and the pump 24. More specifically, the controller 26 is connected to a pump 24 and the like in addition to the compressor 3, the motor 10 of the fan 9 of the condenser 4, the liquid electromagnetic valve 12 and the bypass valve 18. Further, the controller 26 is connected to the first temperature sensor 19, the second temperature sensor 20, and the water temperature sensor 25. The controller 26 controls the compressor 3, the motor 10 of the fan 9 of the condenser 4, the liquid electromagnetic valve 12 and the bypass valve 18 as well as the pump 24 based on the detection signals of these sensors 19, 20 and 25. Control. In the illustrated example, the controller 26 controls a refrigerator main body unit 27 surrounded by a two-dot chain line, and the refrigerator main body unit 27 connects the compressor 3 and the motor 10 of the fan 9 of the condenser 4. Although it is configured to control, the controller 26 may directly control the compressor 3 and the motor 10 of the fan 9 of the condenser 4.

  By operating the pump 24 during the operation of the chiller 1, water can be circulated between the evaporator 6 and the cold water tank 21. The chiller 1 of the present embodiment is typically operated so that the temperature of the circulating water returned to the cold water tank 21 via the outlet path 23 is around 0 ° C. (for example, 0.5 ° C.). At this time, the compressor 3 of the refrigerator 2 may be activated (including restart) or stopped, but at the time of activation, control is performed so that the circulating water is not frozen by the low-temperature refrigerant.

  That is, in a state where the compressor 3 is stopped and there is no refrigerant circulation, the condenser 4 is cooled when the outside air temperature is low, so that the refrigerant temperature on the primary side of the liquid electromagnetic valve 12 is lowered. Therefore, when such a low-temperature refrigerant is supplied to the evaporator 6 via the expansion valve 5, the circulating water may be frozen in the evaporator 6. Therefore, in the chiller 1 of the present embodiment, when the refrigerator 2 is started (which can be said to be the start of the compressor 3), the control as described later based on FIGS. Prevention is achieved.

  FIG. 2 is a flowchart showing control of the chiller 1 when the refrigerator 2 is started, more specifically, when the compressor 3 is started (including when it is restarted). FIG. 3 is a flowchart showing details of the freeze prevention control in FIG.

  Assume that the chiller 1 is in a stopped state. In this state, the compressor 3 is stopped, the liquid electromagnetic valve 12 is closed, the bypass valve 18 is fully closed, and the pump 24 is stopped. When starting the refrigerator 2 from that state, first, whether or not the refrigerant temperature on the primary side of the liquid electromagnetic valve 12 based on the first temperature sensor 19 is equal to or lower than the freeze prevention control start temperature (first set value). Is confirmed (S11). If the refrigerant temperature on the primary side of the liquid electromagnetic valve 12 is equal to or lower than the anti-freezing control start temperature, the refrigerator 2 is activated by the anti-freezing control shown in FIG. 3 (S12). On the other hand, when the refrigerant temperature on the primary side of the liquid electromagnetic valve 12 exceeds the freeze prevention control start temperature, the liquid electromagnetic valve 12 is opened to start the refrigerator 2 and the pump 24 is operated as usual (S13). ).

  Next, freezing prevention control will be described based on FIG. When the primary side refrigerant temperature of the liquid electromagnetic valve 12 is equal to or lower than the anti-freezing control start temperature, when the control is shifted to the anti-freezing control, the bypass valve 18 is first fully opened or opened to the set opening degree to start the refrigerator 2 (S21). Thereby, a comparatively high-temperature refrigerant is supplied to the evaporator 6 via the bypass passage 17, and the cycle is preheated. By the way, when antifreezing control is performed, the fan 9 of the condenser 4 is normally stopped because the refrigerant temperature is low.

  In this way, when the compressor 3 is started with the liquid electromagnetic valve 12 closed and the bypass valve 18 opened, the refrigerant temperature detected by the second temperature sensor 20 increases. When the refrigerant temperature on the primary side of the evaporator 6 based on the second temperature sensor 20 becomes equal to or higher than the liquid electromagnetic valve opening temperature (second set value), the liquid electromagnetic valve 12 is opened and the pump 24 is operated (S22, S23). ). By opening the liquid electromagnetic valve 12, the high-temperature refrigerant (gas phase) via the bypass path 17 and the low-temperature refrigerant (gas-liquid two-phase) via the condenser 4 and the expansion valve 5 are mixed to form the evaporator 6. The refrigerator 2 is operated while being supplied to the motor. Moreover, the circulating water is introduced into the evaporator 6 by operating the pump 24. The refrigerant temperature on the primary side of the evaporator 6 based on the second temperature sensor 20 once decreases immediately after the liquid electromagnetic valve 12 is opened, but then increases.

  When the refrigerant temperature on the primary side of the evaporator 6 based on the second temperature sensor 20 becomes equal to or higher than the opening adjustment transition temperature or when a set time has elapsed since the liquid electromagnetic valve 12 was opened, the bypass valve 18 starts to close gradually ( S24, S25). That is, the bypass valve 18 is controlled to be gradually closed at a predetermined speed. Then, before the bypass valve 18 is fully closed, the refrigerant temperature on the primary side of the evaporator 6 reaches the opening fixed transition temperature (third set value) (S26).

  If the refrigerant temperature on the primary side of the evaporator 6 reaches the opening fixed transition temperature, the opening of the bypass valve 18 is fixed to the opening at that time (S27). Thereafter, the refrigerator 2 is operated in that state. However, if the refrigerant temperature on the primary side of the evaporator 6 rises and becomes higher than the opening degree readjustment transition temperature, the process returns to step S25 again. Then, the opening degree of the bypass valve 18 is adjusted (S28).

  In this way, finally, the temperature of the refrigerant supplied to the evaporator 6 is controlled to a desired temperature at which the circulating water is not frozen below the water temperature supplied to the evaporator 6. During such anti-freezing control, the primary side refrigerant temperature of the liquid electromagnetic valve 12 is monitored based on the first temperature sensor 19, and if the temperature exceeds the anti-freezing control start temperature, there is no fear of freezing of the circulating water. Therefore, the bypass valve 18 is fully closed and the operation is performed in the normal refrigeration cycle.

  The chiller 1 having such a configuration may exchange heat with the load in the outlet path 23 from the evaporator 6 to the cold water tank 21, or may exchange heat with the load in the cold water tank 21. . For example, using the cold water tank 21 as a cooling tank, the packed food can be immersed in the cold water in the cold water tank 21 for cooling. In addition, water is circulated between the evaporator 6 and the cold water tank 21 to cool the water in the cold water tank 21, and the cooled water is transferred to another device (for example, an ice storage type cold water device). You may supply and use.

  According to the chiller 1 of the present embodiment, the evaporator 6 includes, in addition to or in addition to the refrigerant via the condenser 4 and the expansion valve 5, the condenser 4 via the bypass path 17. The primary-side refrigerant can be supplied. And, when the outside air temperature is low and the refrigerant through the condenser 4 and the expansion valve 5 is used, if there is a risk of water freezing in the evaporator 6, by using the refrigerant through the bypass path 17, Freezing of water in the evaporator 6 can be prevented.

  At this time, when the temperature of the circulating water is lower than that of the refrigerant passing through the bypass passage 17, the refrigerant passing through the bypass passage 17 in the evaporator 6 is deprived of heat by the circulating water and liquefied. May be sent to the compressor 3. That is, there is a possibility of causing liquid back to the compressor 3. However, according to the chiller 1 of the present embodiment, the introduction of the circulating water to the evaporator 6 is stopped while only the refrigerant via the bypass path 17 is supplied to the evaporator 6. Therefore, when the temperature of the circulating water is lower than that of the refrigerant via the bypass path 17, it is possible to prevent the refrigerant from being liquefied by the circulating water in the evaporator 6. Thereby, the liquid back to the compressor 3 can be prevented.

  Next, a second embodiment of the chiller of the present invention will be described. The chiller 1 of the second embodiment is basically the same configuration as the first embodiment. Therefore, the following description will focus on the differences between the two.

  In the first embodiment, the pump 24 is on / off controlled. In the second embodiment, the pump 24 is inverter-controlled. Thereby, the restriction | limiting of the introduction of circulating water to the evaporator 6 and its cancellation | release can be switched.

  Specifically, when the refrigerant temperature on the primary side of the liquid electromagnetic valve 12 is equal to or lower than the freeze prevention control start temperature, the pump 24 is controlled by an inverter so that introduction of circulating water to the evaporator 6 is restricted more than usual. The That is, while only the refrigerant through the bypass 17 is supplied to the evaporator 6, the flow rate of the circulating water to the evaporator 6 is extremely reduced. Therefore, when the temperature of the circulating water is lower than that of the refrigerant via the bypass passage 17, liquefaction of the refrigerant in the evaporator 6 by the circulating water can be suppressed, and liquid back to the compressor 3 can be prevented. it can. When the refrigerant temperature on the primary side of the evaporator 6 is equal to or higher than the liquid solenoid valve opening temperature, it is determined that the refrigerant does not liquefy in the evaporator 6, and the above-described restriction is released. Thereby, the circulating water to the evaporator 6 is returned to the normal flow rate. Other configurations and controls are the same as those in the first embodiment, and a description thereof will be omitted.

  FIG. 4 is a schematic diagram showing a third embodiment of the chiller according to the present invention, which is a modification of the flow path of the circulating water in FIG. The chiller 1 of the third embodiment is basically the same configuration as that of the first embodiment. Therefore, in the following description, differences between the two will be mainly described, and corresponding portions will be described with the same reference numerals.

  In the first embodiment, the pump 24 is controlled to be turned on / off, but in the third embodiment, the water supply adjustment valve 28 is provided on the secondary side of the pump 24 and the opening degree of the water supply adjustment valve 28 is controlled. By controlling the opening degree of the water supply adjustment valve 28, it is possible to switch between the restriction of the introduction of circulating water to the evaporator 6 and the release thereof. The water supply adjustment valve 28 of the present embodiment is composed of a motor valve that is an electric valve whose opening degree can be adjusted.

  When the refrigerant temperature on the primary side of the liquid electromagnetic valve 12 is equal to or lower than the anti-freezing control start temperature, the circulating water to the evaporator 6 is reduced by reducing the opening of the water supply adjustment valve 28 while the pump 24 is operated. Introduction is more limited than usual. That is, while only the refrigerant through the bypass 17 is being supplied to the evaporator 6, the opening of the water supply adjustment valve 28 is narrowed to extremely reduce the flow rate of the circulating water to the evaporator 6. Therefore, when the temperature of the circulating water is lower than that of the refrigerant via the bypass passage 17, liquefaction of the refrigerant in the evaporator 6 by the circulating water can be suppressed, and liquid back to the compressor 3 can be prevented. it can. When the refrigerant temperature on the primary side of the evaporator 6 is equal to or higher than the liquid solenoid valve opening temperature, it is determined that the refrigerant does not liquefy in the evaporator 6, and the above-described restriction is released. Thereby, the circulating water to the evaporator 6 is returned to the normal flow rate. Other configurations and controls are the same as those in the first embodiment, and a description thereof will be omitted.

  In the present embodiment, the water supply adjustment valve 28 is constituted by a motor valve, but may be constituted by a proportional control valve which is an electric valve capable of adjusting the opening degree. Further, the water supply adjustment valve 28 of this embodiment may be an electromagnetic valve that can only be opened and closed, instead of an electric valve such as a motor valve or a proportional control valve. In this case, the presence / absence of introduction of circulating water to the evaporator 6 can be switched. By closing the water supply adjustment valve 28, the introduction of the circulating water to the evaporator 6 is stopped while only the refrigerant via the bypass path 17 is supplied to the evaporator 6. When it is determined that the refrigerant is not liquefied in the evaporator 6, the water supply adjustment valve 28 is opened and circulating water is introduced into the evaporator 6.

  FIG. 5 is a schematic view showing Embodiment 4 of the chiller of the present invention, which is a modified example of the flow path of the circulating water in FIG. The chiller 1 of the fourth embodiment is basically the same configuration as that of the first embodiment. Therefore, in the following description, differences between the two will be mainly described, and corresponding portions will be described with the same reference numerals.

  In the first embodiment, the pump 24 is controlled to be turned on / off, but in the fourth embodiment, the circulating water from the pump 24 is directly led to the outlet path 23 without going through the evaporator 6 when desired.

  That is, the connection path 29 is provided between the secondary side of the pump 24 of the introduction path 22 and the middle of the outlet path 23. Three-way valves (three-way switching motor valves) 30 and 30 are provided at a connection portion between the connection passage 29 and the introduction passage 22 and a connection portion between the connection passage 29 and the lead-out passage 23, respectively. By controlling each three-way valve 30, the supply destination of the water discharged from the pump 24 is selectively switched to the evaporator 6 or the outlet path 23.

  When the refrigerator 2 is started, if the refrigerant temperature on the primary side of the liquid electromagnetic valve 12 is equal to or lower than the anti-freezing control start temperature, each three-way valve 30 is switched so that the supply destination of the circulating water is the outlet path 23. Thereby, while only the refrigerant through the bypass path 17 is supplied to the evaporator 6, the circulating water from the cold water tank 21 flows from the introduction path 22 to the outlet path 23 via the connection path 29, and the cold water tank 21 is returned. Therefore, when the temperature of the circulating water is lower than that of the refrigerant passing through the bypass path 17, liquefaction of the refrigerant in the evaporator 6 by the circulating water can be prevented, and liquid back to the compressor 3 can be prevented. it can. When the refrigerant temperature on the primary side of the evaporator 6 becomes equal to or higher than the liquid solenoid valve opening temperature, it is determined that the refrigerant does not liquefy in the evaporator 6, and the supply destination of the circulating water is switched to the evaporator 6. Thus, the circulating water from the cold water tank 21 is introduced into the evaporator 6 from the introduction path 22, cooled by the evaporator 6, and then returned to the cold water tank 21 through the outlet path 23.

  By the way, FIG. 6 is a figure which shows the modification of Example 4 of the chiller of this invention. In this modification, the circulating water from the pump 24 is directly returned to the cold water tank 21 without going through the evaporator 6 when desired.

  Specifically, a return path 31 is provided between the secondary side of the pump 24 of the introduction path 22 and the cold water tank 21, and a three-way valve 32 is provided at a connection portion between the return path 31 and the introduction path 22. By controlling the three-way valve 32, the supply destination of the water discharged from the pump 24 is selectively switched to the evaporator 6 or the cold water tank 21.

  When the refrigerator 2 is started, if the refrigerant temperature on the primary side of the liquid electromagnetic valve 12 is equal to or lower than the freeze prevention control start temperature, the three-way valve 32 is switched so that the supply destination of the circulating water is the cold water tank 21. Thereby, while only the refrigerant through the bypass path 17 is supplied to the evaporator 6, the circulating water from the cold water tank 21 is returned from the introduction path 22 to the cold water tank 21 via the return path 31. Therefore, when the temperature of the circulating water is lower than that of the refrigerant passing through the bypass path 17, liquefaction of the refrigerant in the evaporator 6 by the circulating water can be prevented, and liquid back to the compressor 3 can be prevented. it can. When the refrigerant temperature on the primary side of the evaporator 6 becomes equal to or higher than the liquid solenoid valve opening temperature, it is determined that the refrigerant does not liquefy in the evaporator 6, and the supply destination of the circulating water is switched to the evaporator 6. Thus, the circulating water from the cold water tank 21 is introduced into the evaporator 6 from the introduction path 22, cooled by the evaporator 6, and then returned to the cold water tank 21 through the outlet path 23.

  The chiller of the present invention is not limited to the configuration of each of the above embodiments, and can be changed as appropriate. For example, in each of the above embodiments, the temperature sensors 19 and 20 are used to control based on the temperature of the refrigerant. However, the pressure sensors may be used to control based on the refrigerant pressure. In each of the above embodiments, step S24 can be omitted.

  Moreover, in each said Example, although the bypass valve 18 was comprised from the motor valve, you may use a proportional control valve instead of a motor valve. In this case, steps S25 to S28 in FIG. 3 are based on the second temperature sensor (pressure sensor) 20 so that the refrigerant temperature (refrigerant pressure) on the primary side of the evaporator 6 becomes the third set value. More precise control can be performed by increasing or decreasing the opening degree.

  Further, in each of the above embodiments, a plurality of pipelines having different pipe diameters are provided in parallel as the bypass passage 17, and the solenoid valves provided in the respective pipelines can be individually opened and closed. The flow rate of the refrigerant supplied to the evaporator 6 may be adjusted. In this case, the plurality of solenoid valves function as the bypass valve 18. In each of the above-described embodiments, as the name suggests, the liquid electromagnetic valve 12 is normally composed of an electromagnetic valve that can only be opened and closed. However, the opening degree may be adjusted by using a motor valve or the like depending on circumstances.

  In each of the above embodiments, the water chiller has been described. However, the present invention can be similarly applied to other chillers. In other words, the liquid to be cooled that exchanges heat with the refrigerant in the evaporator 6 is not limited to water, but may be other liquids that may freeze.

  Moreover, in each said Example, although it was set as the circulation specification by which a to-be-cooled liquid circulates between the tank 21 and the evaporator 6, the to-be-cooled liquid supplied to the evaporator 6 is heat-exchanged with load (of foodstuffs). After use for cooling, etc., it may be a disposable running water specification.

  Moreover, in the said Example 2 and the said Example 3, when introduction | transduction of the circulating water to the evaporator 6 is restrict | limited, the cancellation | release of the restriction | limiting may be performed at a stretch or may be performed gradually.

  Further, in each of the above embodiments, while only the refrigerant via the bypass path 17 is supplied to the evaporator 6, the introduction of water to the evaporator 6 is stopped or restricted. When the water temperature is low, it is sufficient to stop or limit the supply of water into the evaporator 6, and the configuration and control for achieving this can be changed as appropriate.

It is a schematic block diagram which shows Example 1 of the chiller of this invention. It is a flowchart which shows the control at the time of starting of the refrigerator of the chiller of FIG. It is a flowchart which shows the detail of the freeze prevention control in FIG. It is the schematic which shows Example 3 of the chiller of this invention, and is a modification of the flow path of the circulating water in FIG. It is the schematic which shows Example 4 of the chiller of this invention, and is a modification of the flow path of the circulating water in FIG. It is a figure which shows the modification of FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Chiller 2 Refrigerator 3 Compressor 4 Condenser 5 Expansion valve 6 Evaporator 12 Liquid solenoid valve 17 Bypass path 18 Bypass valve 22 Introduction path 23 Derivation path 24 Pump 26 Controller 28 Water supply adjustment valve 29 Connection path 30 Three-way valve 31 Return Road 32 Three-way valve

Claims (3)

A refrigerator that performs a refrigeration cycle by circulating refrigerant through a compressor, a condenser, an expansion valve, and an evaporator;
An introduction path for introducing a liquid to be cooled to be exchanged with a refrigerant in the evaporator to the evaporator;
A lead-out path for deriving the liquid to be cooled, heat-exchanged with the refrigerant in the evaporator, from the evaporator;
A liquid solenoid valve provided on the primary side of the expansion valve;
A bypass path connecting a primary side of the condenser and a secondary side of the expansion valve;
A bypass valve with an adjustable opening degree provided in the bypass passage;
When the refrigerant temperature or refrigerant pressure on the primary side of the liquid electromagnetic valve is equal to or lower than a set value, the introduction of the liquid to be cooled into the evaporator is stopped or restricted, and the bypass valve is closed with the liquid electromagnetic valve closed. And a controller for opening and starting the refrigerator. When starting the refrigerator, based on the refrigerant temperature or refrigerant pressure on the primary side of the liquid electromagnetic valve,
In the first case where the refrigerant temperature or refrigerant pressure on the primary side of the liquid electromagnetic valve exceeds a first set value, the liquid electromagnetic is introduced into the evaporator while the bypass valve is closed. While opening the valve to start the refrigerator,
In the second case where the refrigerant temperature or the refrigerant pressure on the primary side of the liquid electromagnetic valve is equal to or lower than the first set value, the liquid to be cooled is not introduced into the evaporator, or more limited than in the first case. The liquid to be cooled is introduced into the evaporator, and the bypass valve is opened with the liquid electromagnetic valve closed to start the refrigerator, whereby the refrigerant temperature or refrigerant pressure on the primary side of the evaporator is increased to the second level. When the value exceeds a set value, the stop or restriction of the introduction of the liquid to be cooled into the evaporator is released, and the opening degree of the bypass valve is adjusted with the liquid electromagnetic valve opened. The chiller according to 1. The chiller according to claim 2, wherein the presence or absence of introduction of the liquid to be cooled to the evaporator is switched and controlled depending on whether or not a pump provided in the introduction path is operated.

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