JP6341481B2 - Refrigeration system - Google Patents

Description

  The present invention relates to a refrigeration system, and in particular, even when the load on the refrigerator is small, such as in winter, ensuring a heat source necessary for the hot water supply operation of the supercooled water heater unit, ensuring a sufficient amount of hot water in the hot water storage tank, The present invention relates to a refrigeration system that can improve the reliability of equipment by suppressing the frequency of start and stop of a refrigerator and a supercooled water heater unit.

  Conventionally, stores such as supermarkets and convenience stores often use refrigerators that cool showcases, and in recent years, in order to effectively use the exhaust heat of refrigerators, heat exchange with the refrigerant flowing through these refrigerators is performed. A refrigeration system has been developed that includes a hot water supply unit that heats water in a hot water storage tank to supply hot water.

  As such a refrigeration system, conventionally, for example, the temperature of the hot water supply water can be raised using the exhaust heat of the second refrigerant circuit provided with the refrigerated showcase, and the operation of the second air heat exchanger blower is performed. Has been disclosed to reduce power consumption, improve COP of the entire store including the hot water supply system, and save energy in stores equipped with refrigerated showcases (for example, Patent Document 1).

JP 2007-303698 A

  However, in the invention described in Patent Document 1, the refrigerator is operated with a setting that enables energy-saving operation. When the cooling load of the refrigerator is small, such as in winter, the refrigerator is started and stopped. May increase in frequency. In addition, when the refrigerator is not in operation, the water heater unit is also started and stopped, so the heat source cannot be secured and the hot water supply operation can be maintained by the start and stop of the water heater unit. It has a problem that it cannot be done. As a result, there is a problem in that a sufficient amount of hot water cannot be ensured and the amount of hot water in the hot water storage tank may be insufficient.

  Furthermore, if the frequency of starting and stopping of the refrigerator and the water heater unit is increased, a load is applied to the piping such as the refrigerant piping, which may cause failure of the equipment such as pipe breakage, resulting in a decrease in reliability. have.

  The present invention has been made in view of the above points, and even when the load on the refrigerator is small, such as in winter, the heat source necessary for the hot water supply operation of the supercooled water heater unit is secured, and the amount of hot water in the hot water storage tank is sufficiently increased. An object of the present invention is to provide a refrigeration system that can improve the reliability of equipment by ensuring the frequency of starting and stopping the refrigerator and the supercooled water heater unit.

To achieve the above object, a refrigeration system according to the present invention includes a refrigerator having a supercooling heat exchanger for cooling a showcase, the supercooling heat exchanger, and a gas cooler, and hot water is supplied by the gas cooler. And a supercooling water heater unit that performs a control when the hot water temperature of the hot water storage tank of the supercooling water heater unit is equal to or lower than a certain temperature. An apparatus, and the control device counts the number of starts and stops by the supercooling water heater unit, and controls to perform the defrosting operation of the showcase when the number of starts and stops exceeds a certain value. It is characterized by.

  Further, according to the present invention, in the configuration, the control device counts the number of start / stops by the supercooling water heater unit, and performs the defrosting operation of the showcase when the number of start / stops exceeds a certain value. It controls to perform.

  Further, the present invention is characterized in that, in the configuration, the control device defrosts the number of showcases necessary for increasing the load of the refrigerator during the defrosting operation.

  According to the present invention, when the hot water temperature of the hot water storage tank of the supercooling hot water supply unit becomes equal to or lower than a predetermined temperature, the control device controls the refrigerator to perform the defrosting operation of the showcase. Therefore, even when the outside air temperature is low and the cooling load of the refrigerator is low, such as in winter, the cooling load of the refrigerator can be increased by the defrosting operation, and the operation of the refrigerator and the supercooling water heater unit can be maintained. It becomes possible to secure a heat source necessary for the hot water supply operation of the cooling hot water supply unit. As a result, a sufficient amount of hot water in the hot water storage tank can be secured, and the reliability of the equipment can be improved by suppressing the frequency of starting and stopping the refrigerator and the supercooled water heater unit.

It is a refrigerating cycle figure showing an embodiment of a refrigerating system concerning the present invention. It is a flowchart which shows the control action in embodiment of the refrigerating system which concerns on this invention. It is explanatory drawing which shows the relationship between the hot water temperature of the hot water storage tank and operation | movement of a supercooling water heater unit in embodiment of the refrigerating system which concerns on this invention.

  Embodiments of the present invention will be described below with reference to the drawings.

  FIG. 1 shows an embodiment of a refrigeration system according to the present invention. In this embodiment, an example of a heat pump hot water supply system using supercooled exhaust heat of a refrigerator is shown.

  In the present embodiment, the refrigeration system is installed in a facility having both a cooling facility and a hot water supply facility in a store such as a supermarket or a convenience store, and each showcase 2 installed in the store is installed in the store. A refrigerating machine 10 for cooling and a supercooling water heater unit 20 for heating the hot water using the exhaust heat while supercooling the refrigerant of the refrigerating machine 10 to improve the refrigerating capacity of the refrigerating machine 10 are provided. ing.

  The refrigerator 10 constitutes the system of the showcase 2, and includes a refrigeration compressor 11, a refrigeration condenser 12 including a blower fan 19, a supercooling heat exchanger 13, an on-off valve 14, and a refrigeration expansion valve. 15, the evaporator 16 and the accumulator 17 are sequentially connected by a refrigeration refrigerant pipe 18. In the present embodiment, the refrigeration compressor 11, the refrigeration condenser 12 and the accumulator 17 are arranged outdoors, and the on-off valve 14, the refrigeration expansion valve 15 and the evaporator 16 are installed indoors in the showcase 2. Has been placed.

  The supercooling heat exchanger 13 is a heat exchanger for further cooling the refrigerant of the refrigerator 10 cooled by radiating heat to the atmosphere with the refrigeration condenser 12. The supercooling heat exchanger 13 is electrically connected to the refrigerating refrigerant pipe 18 of the refrigerator 10 and the supercooling refrigerant pipe 24 of the supercooling water heater unit 20 so that the refrigerant flows in opposite directions. The refrigerant flowing through the refrigerant pipe 18 and the refrigerant flowing through the supercooled refrigerant pipe 24 are configured to be able to exchange heat with each other.

  The supercooling water heater unit 20 is configured by connecting a supercooling compressor 21, a gas cooler 22, a supercooling expansion valve 23, and a supercooling heat exchanger 13 through a supercooling refrigerant pipe 24 sequentially. The supercooling compressor 21, the gas cooler 22, the supercooling expansion valve 23, and the supercooling heat exchanger 13 of the supercooling water heater unit 20 are accommodated in the same unit.

  The gas cooler 22 is a heat exchanger for exchanging heat between the refrigerant flowing through the supercooled refrigerant pipe 24 and the water flowing through the water pipe 32 to heat the hot water and boil the hot water. The gas cooler 22 is electrically connected so that the flow directions of the supercooling refrigerant pipe 24 and the water pipe 32 face each other, and the refrigerant flowing through the supercooling refrigerant pipe 24 and the water flowing through the water pipe 32 can exchange heat with each other. It is configured.

  Here, in the supercooled water heater unit 20 in the present embodiment, carbon dioxide is used as a refrigerant. In the refrigeration cycle using carbon dioxide refrigerant, since the high pressure side is a transcritical cycle exceeding the critical pressure of the refrigerant, the refrigerant pressure flowing through the supercooling refrigerant pipe 24 of the gas cooler 22 exceeds the critical pressure. The refrigerant flowing through the cooling refrigerant pipe 24 does not condense, and its temperature decreases as the water flowing opposite the water pipe 32 is heated and cooled. Thereby, the water which flows through the water piping 32 can be heated to high temperature and highly efficient.

  The supercooling water heater unit 20 includes a hot water storage tank 31, a gas cooler 22, and a water pipe 32 that connects the hot water storage tank 31 and the gas cooler 22. The water pipe 32 on the outlet side of the gas cooler 22 is connected to the upper part of the hot water storage tank 31, and the hot water after being heated by the gas cooler 22 is returned to the upper part of the hot water storage tank 31. It is possible to store hot water on the temperature stratification inside.

  A hot water supply pipe 33 for supplying hot water from the hot water storage tank 31 is connected to the upper part of the hot water storage tank 31, for example, to a hot water supply load facility of the same facility of the store where the refrigeration system is installed. A water supply pipe (not shown) for supplying water from the water pipe is connected to the lower part of the pipe. Then, hot water is supplied from the upper part of the hot water storage tank 31 to the hot water supply load facility via the hot water supply pipe 33, and accordingly, the cold water is supplied to the lower part of the hot water storage tank 31 through the water supply pipe. It is configured.

Next, the control device for the refrigeration system in the present embodiment will be described.
The control device 40 is configured by, for example, a general microcomputer, and the control device 40 is configured to be able to control operations of the refrigerator 10 and the supercooling water heater unit 20, respectively.

Moreover, in this embodiment, as shown in FIG. 1, the refrigerant | coolant pressure sensor 41 which detects the refrigerant | coolant pressure of the inlet side of the refrigerator 10 is provided. The hot water storage tank 31 has a hot water temperature sensor 42 for detecting the temperature of hot water stored in the lower part of the hot water storage tank 31 and a pipe temperature sensor 43 for detecting the temperature of the water pipe 32 on the outlet side of the hot water storage tank 31. Each is provided. Further, although not shown, an outside air temperature sensor for detecting the outside air temperature, an inside temperature sensor for detecting the temperature of the showcase 2, and the like are provided. The detection results detected by these sensors are configured to be sent to the control device 40, and the control device 40 performs coordinated control of the operation of the refrigerator 10 and the operation of the supercooling water heater unit 20. It is configured.
Note that the internal temperature setting of the showcase 2 may be performed from a control unit provided in the showcase 2 without using the control device 40. Similarly, when adjusting the rotation speed of the blower fan 19 of the refrigerator 10 and the opening degree of the expansion valve 15 by the outside air temperature sensor, the adjustment is performed from the control unit provided in the refrigerator 10 without using the control device 40. Also good.

In this embodiment, the control device 40 monitors the pressure of the refrigerant sent to the refrigerator 10 detected by the refrigerant pressure sensor 41, and when the pressure of the refrigerant becomes equal to or lower than a certain pressure, Control by the low pressure cut which stops the operation of the machine 10 is performed. As a threshold value for such low pressure cut control of the refrigerant pressure, for example, when the refrigerant pressure becomes 4 MPa or less, the operation of the refrigerator 10 is stopped.
On the other hand, the control device 40 monitors the temperature of the hot water in the hot water storage tank 31 detected by the hot water temperature sensor 42, and when the temperature of the hot water in the hot water storage tank 31 falls below a certain temperature, When the operation is performed and the temperature becomes equal to or higher than a certain temperature, the supercooling water heater unit 20 is controlled to stop the operation.

Further, the control device 40 monitors the temperature of the hot water in the hot water storage tank 31 detected by the hot water temperature sensor 42, and when the temperature of the hot water in the hot water storage tank 31 falls below a certain temperature, the refrigerator 10 shows the showcase 2. Is configured to perform the defrosting operation. By performing the defrosting operation of the showcase 2 in this manner, the internal temperature of the showcase 2 temporarily rises, so that the cooling load of the refrigerator 10 increases. And since a cooling load increases, by performing pull-down operation after that, while being able to continue operation of refrigerator 10, operation of supercooling hot water supply unit 20 can also be continued. . Thereby, it becomes possible to maintain the operation of the refrigerator 10 and the supercooled water heater unit 20 and to secure a heat source necessary for the hot water supply operation of the supercooled water heater unit 20.
The defrosting operation of the showcase 2 may be performed for all the showcases 2 or may be performed for the number of showcases 2 necessary to increase the cooling load of the refrigerator 10.

  Moreover, in this embodiment, the control apparatus 40 counts the frequency | count of operation | movement and a stop (start / stop) of the supercooling water heater unit 20, and when the frequency | count of start / stop becomes more than a fixed number within the fixed time, The defrosting operation of the showcase 2 is performed by the refrigerator 10. Since the outside air temperature is low in winter and the like, the refrigerator 10 often stops its operation. When hot water is supplied by the supercooling hot water supply unit 20, the number of times the refrigerator 10 and the supercooling hot water supply unit 20 are started and stopped. It will increase. Therefore, when the number of start / stop is more than a certain value, by performing the defrosting operation of the showcase 2, the cooling load of the refrigerator 10 is increased to maintain the operation of the refrigerator 10 and the supercooled water heater unit 20, A heat source necessary for the hot water supply operation of the supercooling water heater unit 20 can be secured.

Next, the operation of the refrigeration system in the present embodiment will be described.
First, in the first refrigeration cycle circuit 10, when the refrigeration compressor 11 is operated, the high-temperature refrigerant discharged from the refrigeration compressor 11 flows into the condenser 12 and is cooled by exchanging heat with the atmosphere. Is done. The refrigerant air-cooled by the condenser 12 flows into the supercooling heat exchanger 13 and is supercooled by the evaporating action of the refrigerant flowing through the supercooling refrigerant pipe 24.

  The high-pressure and low-temperature liquid refrigerant that has flowed out of the supercooling heat exchanger 13 is decompressed by the freezing expansion valve 15 and then flows into the evaporator 16 to evaporate. Cooled to temperature. Then, the refrigerant that has flowed out of the evaporator 16 of the showcase 2 is returned to the refrigeration compressor 11.

  When the supercooling water heater unit 20 is operated, the high temperature refrigerant discharged from the supercooling compressor 21 flows into the gas cooler 22 by operating the supercooling compressor 21, and the water pipe 32. It is cooled by exchanging heat with hot water flowing through. In the gas cooler 22, since the carbon dioxide refrigerant is in a supercritical state, its temperature decreases as it is cooled by heat exchange with water without condensing. Here, since the supercooled refrigerant pipe 24 and the water pipe 32 are provided so as to face each other, efficient heat exchange between the supercritical refrigerant having a temperature gradient accompanying heat exchange and water is possible. Become. Thereby, hot water can be boiled with high efficiency.

  The refrigerant cooled in the gas cooler 22 is decompressed by the supercooling expansion valve 23 and then flows into the supercooling heat exchanger 13. In the supercooling heat exchanger 13, the refrigerant flowing through the supercooling refrigerant pipe 24 exchanges heat with the refrigerant flowing through the refrigeration refrigerant pipe 18, and the refrigerant in the refrigerator 10 evaporates the refrigerant in the supercooling water heater unit 20. Is supercooled.

  Then, the refrigerant that has flowed out of the supercooling heat exchanger 13 is returned to the supercooling compressor 21. As described above, the supercooling water heater unit 20 continuously operates, so that the refrigerant of the refrigerator 10 is supercooled by the supercooling water heater unit 20 and the hot water is heated using the exhaust heat. It becomes possible.

  Further, the low-temperature water taken out from the hot water storage tank 31 flows into the gas cooler 22 where it is heated by exchanging heat with the high-temperature refrigerant flowing through the supercooled refrigerant pipe 24, and the hot water storage tank is connected via the water pipe 32. It flows into the hot water storage tank 31 from the upper part of 31. When the hot water stored in the hot water storage tank 31 reaches a predetermined amount, the hot water storage operation is stopped by the control device 40.

Next, the control operation in this embodiment will be described with reference to the flowchart shown in FIG.
In the present embodiment, the control device 40 monitors the refrigerant pressure by the refrigerant pressure sensor 41 and the hot water temperature by the hot water temperature sensor 42, and determines whether or not the refrigerant pressure has become below a certain pressure (ST1). Then, the control device 40 starts the operation of the refrigerator 10 (ST2) when the refrigerant pressure is not below a certain pressure (ST1: NO), and when the refrigerant pressure is not below the certain pressure (ST1: YES). ), The operation of the refrigerator 10 is stopped (ST8).

  When the operation of the refrigerator 10 is started, the hot water temperature of the lower hot water in the hot water storage tank 31 is detected by the hot water temperature sensor 42. If the hot water temperature is 50 ° C. or higher (ST3: YES), the supercooling hot water heater unit 20 is It is determined whether or not it is in a stopped state (ST9). If it is in a stopped state (ST9: YES), the supercooling water heater unit 20 is stopped (ST11). Similarly, when the supercooling water heater unit 20 is not in a stopped state (ST9: NO), and the piping temperature on the outlet side of the hot water storage tank 31 is 50 ° C. or higher (ST10: YES), the cooling water heater unit 20 is similarly set. Stop (ST11).

  On the other hand, when the hot water temperature of the lower hot water in the hot water storage tank 31 is not 50 ° C. or higher (ST3: NO) and when the outlet side piping temperature of the hot water storage tank 31 is not higher than 50 ° C. (ST 10: NO), the supercooling hot water heater The unit 20 is operated (ST4).

  The control device 40 counts the number of times the supercooled water heater unit 20 starts and stops. And when the frequency | count of start / stop of the supercooling water heater unit 20 becomes more than a certain number within a certain time (ST5: YES), it is determined whether or not the defrosting operation of the showcase 2 has been performed a certain time ago. (ST6) If the defrosting operation is not performed (ST6: NO), a predetermined number of showcases 2 are defrosted (ST7). On the other hand, when the defrosting operation of the showcase 2 is performed before a certain time (ST6: YES), the defrosting operation is not performed and the normal control is repeatedly performed. In addition, even when the number of start / stop times of the supercooling water heater unit 20 does not exceed a certain number within a certain time (ST5: NO), the defrosting operation is not performed and the normal control is repeated. ing.

  Since the cooling load of the refrigerator 10 increases by performing the defrosting operation in this way, the operation of the refrigerator 10 is continuously performed by the pull-down operation after the defrosting operation, and the supercooling water heater unit 20 is also performed. Thus, it becomes possible to secure a heat source necessary for the hot water supply operation of the supercooling hot water supply unit 20.

  By controlling in this way, as shown in FIG. 3, the cooling load of the refrigerator 10 is increased by the defrosting operation, and then the pull-down operation is performed. Therefore, the refrigerator 10 and the supercooled water heater unit The number of start / stop times of 20 can be reduced, and even when the number of start / stop times is reduced, the hot water temperature in the hot water storage tank 31 can be secured.

  As described above, in the present embodiment, the control device 40 causes the hot water temperature of the hot water storage tank of the supercooling water heater unit 20 to become a certain temperature or less, and the number of times of starting and stopping the supercooling water heater unit 20 becomes a certain value or more. In such a case, the refrigerator 10 is controlled so that the defrosting operation of the showcase 2 is performed. Therefore, even if the outside air temperature is low such as in winter and the cooling load of the refrigerator 10 is small, the refrigerator 10 can be frozen by the defrosting operation. The cooling load of the machine 10 can be increased, the operation of the refrigerator 10 and the supercooled water heater unit 20 can be maintained, and a heat source necessary for the hot water supply operation of the supercooled water heater unit 20 can be secured. As a result, a sufficient amount of hot water in the hot water storage tank 31 can be secured, and the reliability of the equipment can be improved by suppressing the frequency of starting and stopping of the refrigerator 10 and the supercooled water heater unit 20.

  In addition, this invention is not limited to the said embodiment, A various deformation | transformation is possible based on the meaning of this invention.

2 Showcase 10 Refrigerator 11 Compressor for refrigeration 12 Supercooling condenser 13 Supercooling heat exchanger 14 On-off valve 15 Expansion valve for refrigeration 16 Evaporator 17 Accumulator 18 Refrigerant piping for refrigeration 19 Blower fan 20 Supercooling water heater unit 21 Supercooled compressor 22 Gas cooler 23 Supercooled expansion valve 24 Supercooled refrigerant pipe 31 Hot water storage tank 32 Water pipe 33 Hot water supply pipe 40 Controller 41 Refrigerant pressure sensor 42 Hot water temperature sensor

Claims (2)

In a refrigeration system comprising: a refrigerator having a supercooling heat exchanger for cooling a showcase; and a supercooling water heater unit that includes the supercooling heat exchanger and a gas cooler and supplies hot water by the gas cooler. ,
When the hot water temperature of the hot water storage tank of the supercooling water heater unit is equal to or lower than a certain temperature, a control device is provided for controlling the defrosting operation of the showcase ,
The control device counts the number of times of start / stop by the supercooling hot water supply unit, and controls to perform the defrosting operation of the showcase when the number of start / stop becomes equal to or greater than a certain value. Refrigeration system. 2. The refrigeration system according to claim 1, wherein the control device performs defrosting of the number of the showcases necessary for increasing a load on the refrigerator during the defrosting operation .

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