JP2013083407A - Cooling device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a cooling device that can effectively utilize electric power during cooling operation or defrosting by arranging a heat storage circuit in a low temperature side circulation circuit.SOLUTION: The cooling device 100 includes: a high temperature side device 10; a low temperature side device 20; a refrigerant-to-refrigerant heat exchanger 30 for performing heat exchange between a high temperature side refrigerant and a low temperature side refrigerant; a means 28 for detecting the suction side pressure of a low temperature side compressor 21; the heat storage circuit 56 arranged on the low temperature side device which performs heat storage; a connection pipe 58 for utilizing stored cold heat for supercooling; and a controller 40 for controlling each equipment of the cooling device.

Description

  TECHNICAL FIELD The present invention relates to a cooling device that can be used for a domestic / commercial refrigerator-freezer, an ultra-low temperature refrigerator, a refrigerator-freezer showcase cooling system, and the like, and more particularly, to a multi-source cooling device having a plurality of refrigerant circulation circuits. is there.

  Conventionally, for example, there is a cooling device configured in multiple stages by forming a high temperature side device that forms a refrigerant circulation circuit on the high temperature side and a low temperature side device that forms a refrigerant circulation circuit on the low temperature side (here, a two-stage configuration) Described as a dual cooling system). In such a binary cooling device, the heat of the refrigerant evaporating in the evaporator of the high temperature side device and the heat of condensation of the refrigerant in the condenser of the low temperature side device are exchanged, and the evaporation of the low temperature side device as the final stage is performed. The cooling operation is performed by exchanging heat with the object to be cooled. Thereby, in the evaporator of the low temperature side apparatus, low temperature evaporation heat of minus several tens of degrees can be efficiently obtained.

JP 2004-190917 A (FIG. 1)

  In the conventional dual cooling system, when normal cooling operation is performed when the cooling load is light, such as at night, driving the compressor of the low-temperature side device with a low output that matches the cooling load is efficient as a compressor. It becomes bad driving. Further, when the compressor is driven with an output that is considered to be efficient, the output becomes unnecessarily large with respect to the cooling load. In addition, when the compressor is driven only when necessary, start and stop are repeated. In either case, the dual cooling device consumes power wastefully.

When defrosting is performed in the evaporator of the low temperature side device, for example, the cooling operation is stopped every predetermined time, and the evaporator of the low temperature side device is heated by a defrost heater or the like to melt the frost. At this time, by operating the heater during defrosting, the ambient temperature rises, the refrigerant temperature rises, and the refrigerant pressure rises. In particular, when carbon dioxide (hereinafter referred to as CO ₂ ) is used as the refrigerant of the low temperature side device as in Patent Document 1, the pressure of the CO ₂ refrigerant increases by stopping the high temperature side circulation circuit during defrosting. The critical pressure may be exceeded. Therefore, the compressor of the high-temperature side refrigerant circulation circuit is operated at the time of defrosting to cool the condenser of the low-temperature side device, thereby preventing an increase in the pressure of the low-temperature side refrigerant.

  Moreover, in a general cooling device, the defrosting time needs about 30-40 minutes per time, for example, and defrosting is performed about 4-5 times per day regularly. Therefore, the compressor of the high temperature side device is driven extra for about 2 to 3 hours per day, and power is consumed wastefully.

  The present invention has been made to solve the above-described problems, and provides a cooling device that can effectively use electric power during cooling operation and defrosting.

The cooling device according to the present invention includes:
A high temperature side apparatus that pipes a high temperature side compressor, a high temperature side condenser, a high temperature side expansion device, and a high temperature side evaporator to form a high temperature side circulation circuit that circulates the high temperature side refrigerant; and
Low-temperature side apparatus for connecting a low-temperature side compressor, a low-temperature side condenser, a receiver, a first opening / closing means, a low-temperature side throttle device, and a low-temperature side evaporator to form a low-temperature side circulation circuit for circulating a low-temperature side refrigerant When,
A refrigerant heat exchanger configured by a high temperature side evaporator and a low temperature side condenser, and performing heat exchange between the high temperature side refrigerant and the low temperature side refrigerant;
The second opening / closing means, the heat storage expansion device, the heat storage evaporator for exchanging heat with the heat storage medium enclosed in the heat storage tank, and the third opening / closing, branched from the pipe connecting the liquid receiver and the first opening / closing means A heat storage circuit that connects the pipes to the pipe that connects the low-temperature side evaporator and the low-temperature side compressor in a sequential pipe connection;
A connecting pipe branched from a pipe connecting the heat storage evaporator and the third opening / closing means and connected to a pipe connecting the first opening / closing means and the low temperature side throttling device via a check valve;
Control at least the high temperature side compressor, the high temperature side expansion device, the low temperature side compressor, the first opening / closing means, the low temperature side expansion device, the second opening / closing means, the heat storage expansion device, the heat storage evaporator, and the third opening / closing means. And a control device.

  According to the cooling device of the present invention, since the heat storage circuit is provided in the low-temperature side circulation circuit, in the cooling operation when the cooling load is light, heat storage is performed while performing the cooling operation using surplus refrigerant, and defrosting is performed. Sometimes heat can be stored while heating the low-temperature side evaporator, and the stored heat can be used for supercooling during the cooling operation. Therefore, the power of the cooling device can be used effectively, and the power of the cooling device can be leveled.

It is a figure showing the refrigerant circuit at the time of normal cooling driving | operation of the two-way cooling device in Embodiment 1 of this invention. It is a flowchart explaining the operation | movement at the time of the heat storage cooling driving | operation of the two-way cooling device in Embodiment 1 of this invention. It is a figure showing the refrigerant circuit at the time of the heat storage cooling driving | operation of the two-way cooling device in Embodiment 1 of this invention. It is a flowchart explaining the operation | movement at the time of a supercooling driving | operation of the two-way cooling device in Embodiment 1 of this invention. It is a figure showing the refrigerant circuit at the time of a supercooling driving | operation of the two-way cooling device in Embodiment 1 of this invention. It is a table | surface which shows the action | operation of each apparatus by the driving | running state of the two-way cooling device in Embodiment 1 of this invention. It is a ph diagram explaining the transition of the refrigerant state during the normal cooling operation and the supercooling operation of the dual cooling device in Embodiment 1 of the present invention. It is a figure showing the refrigerant circuit at the time of cooling operation stop of the two-way cooling device in Embodiment 1 of this invention. It is a flowchart explaining a series of operation | movement at the time of defrosting of the two-way cooling device in Embodiment 2 of this invention. It is a figure showing the refrigerant circuit at the time of performing pump down driving | operation of the two-way cooling device in Embodiment 2 of this invention. It is a figure showing the refrigerant circuit at the time of the 1st thermal storage defrost operation of the two-way cooling device in Embodiment 2 of this invention. It is a figure showing the refrigerant circuit at the time of the 2nd thermal storage defrost operation of the two-way cooling device in Embodiment 2 of this invention. It is a table | surface which shows the action | operation of each apparatus by the driving | running state of the dual cooling device in Embodiment 2 of this invention. It is a figure showing the refrigerant circuit structure of the two-way cooling device in Embodiment 3 of this invention.

Embodiment 1 FIG.
FIG. 1 is a diagram showing a refrigerant circuit of a dual cooling device in the present embodiment of the present invention. As shown in FIG. 1, the binary cooling device 100 in the present embodiment includes a high temperature side device 10 and a low temperature side device 20, and constitutes a refrigerant circulation circuit that circulates the refrigerant independently of each other. The high temperature side device 10 includes a high temperature side compressor 11, a high temperature side condenser 12, a high temperature side expansion device 13, and a high temperature side evaporator 14 connected in series by a pipe to circulate a refrigerant. Is configured. On the other hand, the low temperature side device 20 includes a low temperature side compressor 21, a low temperature side condenser 22, a receiver 23, a first opening / closing means 24, a low temperature side expansion device 25, and a low temperature side evaporator 26 in series. And a low-temperature circuit 2a that circulates the refrigerant. And in order to make the high temperature side circulation circuit 1a and the low temperature side circulation circuit 2a into a two-stage configuration, heat exchange between the refrigerant passing through the high temperature side evaporator 14 and the low temperature side condenser 22 is made possible. A cascade capacitor 30 is provided as a configured inter-refrigerant heat exchanger. Moreover, it has the control apparatus 40 which performs operation control of the two-way cooling device 100 whole.

  Further, a heat storage tank that is branched from a pipe connecting the liquid receiver 23 and the first opening / closing means 24 and encloses a second opening / closing means 51, a heat storage expansion device 52, and a heat storage medium 55 that stores cold heat. A heat storage circuit 56 is formed in which the heat storage evaporator 53 and the third opening / closing means 54 arranged in the line 50 are connected in series by a pipe and connected to the suction side pipe of the low-temperature compressor 21. Further, a branch is made from a pipe connecting the heat storage tank 50 and the third opening / closing means 54, and a check valve 57 allowing the refrigerant flow only in one direction is passed downstream of the check valve 57 in the refrigerant flow direction. A connecting pipe 58 connected to a pipe connecting the first opening / closing means 24 and the low temperature side expansion device 25 is formed.

In the dual cooling device 100 having such a configuration, for example, R410A, R32, R404A, HFO-1234yf, propane, isobutane, carbon dioxide, ammonia are used as the refrigerant circulating in the high temperature side circulation circuit 1a (hereinafter referred to as high temperature side refrigerant). Etc. are used. Other natural refrigerants that have little influence on global warming, other efficient HFC refrigerants that minimize the amount of refrigerant, and the like may be used. The refrigerant (hereinafter, referred to as the low temperature-side refrigerant) circulating in the low-temperature side circulation circuit 2a may be using the refrigerant as in the present embodiment, carbon dioxide is used influence on global warming is small (CO ₂₎ . In general, CO ₂ has a high saturation pressure and a low critical point (31 ° C.), so it is suitable for a low-temperature side refrigerant in a two-way cooling device, and an extremely low cooling temperature is easily obtained.

  Each component apparatus of the dual cooling device 100 will be described in more detail. The high temperature side compressor 11 sucks and compresses the high temperature side refrigerant and discharges it in a high temperature / high pressure state. For example, the rotation speed is controlled by an inverter or the like, and the discharge amount of the high temperature side refrigerant can be adjusted. It may be configured with a simple compressor. The high temperature side condenser 12 exchanges heat between air supplied from a blower (not shown) and the high temperature side refrigerant, and condenses and liquefies the high temperature side refrigerant.

  The high temperature side expansion device 13 is composed of a flow rate control device whose opening degree is adjusted based on an instruction from the control device 40, and expands and depressurizes the high temperature side refrigerant. For example, an electronic expansion valve or the like is optimal, but a capillary tube (capillary tube), a temperature-sensitive expansion valve, or the like may be used. The high temperature side evaporator 14 is a heat transfer tube or the like through which the high temperature side refrigerant passes in the cascade capacitor 30, and evaporates the high temperature side refrigerant by heat exchange with the low temperature side refrigerant and gasifies it.

  On the other hand, in the low temperature side device 20, the low temperature side compressor 21 sucks and compresses the low temperature side refrigerant and discharges it in a high temperature / high pressure state. It is good to comprise with the compressor which can adjust the discharge amount of a side refrigerant | coolant. The suction side pipe of the low temperature side compressor 21 is provided with a suction side pressure sensor 28 as pressure detection means for detecting the pressure of the low temperature side refrigerant.

  The low temperature side condenser 22 is a heat transfer tube or the like through which the low temperature side refrigerant passes in the cascade capacitor 30, and condenses and liquefies the low temperature side refrigerant by heat exchange with the high temperature side refrigerant.

  The liquid receiver 23 is for storing surplus refrigerant and has a capacity capable of recovering all the refrigerant in the low-temperature side circulation circuit 2a. The first opening / closing means 24 controls the flow of the low-temperature side refrigerant in the low-temperature side circulation circuit 2a by opening and closing, and an electromagnetic valve or the like is used.

  The low temperature side expansion device 25 is configured by a flow rate control device whose opening degree is adjusted based on an instruction from the control device 40, and expands and depressurizes the low temperature side refrigerant. For example, an electronic expansion valve or the like is optimal, but a capillary tube (capillary tube), a temperature-sensitive expansion valve, or the like may be used.

  The low temperature side evaporator 26 performs heat exchange between the load side air supplied from a blower (not shown) and the low temperature side refrigerant, and evaporates and gasifies the low temperature side refrigerant. Cool the object (load) to be cooled, such as inside the showcase. Further, the defrosting heater 27 as a heating means is attached directly to the low temperature side evaporator 26 or in a peripheral part such as a drain pan, and generates heat by being energized at the time of defrosting, and the low temperature side evaporator 26 and its surroundings. Melt the frost on the parts.

  The cascade condenser 30 has a high temperature side evaporator 14 and a low temperature side condenser 22, and enables heat exchange between the high temperature side refrigerant and the low temperature side refrigerant. For example, a plate heat exchanger or a double tube heat Consists of exchangers and the like.

  The second opening / closing means 51 and the third opening / closing means 54 control the flow of the low-temperature side refrigerant in the heat storage circuit 56 by opening and closing, and an electromagnetic valve or the like is used. The heat storage expansion device 52 is composed of a flow rate control device that adjusts the opening degree based on an instruction from the control device 40, and expands and decompresses the low-temperature side refrigerant. For example, an electronic expansion valve or the like is optimal, but a capillary tube (capillary tube), a temperature-sensitive expansion valve, or the like may be used.

  The heat storage evaporator 53 is disposed in the heat storage tank 50 and exchanges heat with the heat storage medium 55 enclosed in the heat storage tank 50 to evaporate the low-temperature refrigerant. One heat storage medium 55 stores cold by exchanging heat with the low-temperature side refrigerant. In this embodiment, water is used as the heat storage medium 55 in the heat storage tank 50, but brine or the like may be used.

  As the heat storage evaporator 53, it is desirable not to use a distributor having a large pressure loss, a shunt pipe, or the like. This is because when water is used as the heat storage medium 55, ice with low thermal conductivity is generated on the heat transfer surface, the amount of ice accretion increases, and the ice itself acts as a heat resistor. This is because the characteristics deteriorate and the operation efficiency of the apparatus decreases.

  The control device 40 controls the operation of each device in the binary cooling device 100. Here, each device includes the high temperature side compressor 11, the high temperature side expansion device 13, the low temperature side compressor 21, the first opening / closing means 24, the low temperature side expansion device 25, the defrosting heater 27, the suction side pressure sensor 28, the first. A second opening / closing means 51, a heat storage expansion device 52, a heat storage evaporator 53, a third opening / closing means 54, and the like. The control device 40 may be configured by two control devices that respectively control the high temperature side device 10 and the low temperature side device 20, or may be controlled by communication from the outside of the dual cooling device 100. Anyway.

  Next, the operation | movement at the time of the normal cooling operation of the two-way cooling device 100 is demonstrated. In the normal cooling operation, in the high temperature side circulation circuit 1a and the low temperature side circulation circuit 2a, the refrigerant flows as shown by arrows in FIG. 1 and the load is cooled by the evaporation heat of the low temperature side evaporator 26. In the high temperature side circulation circuit 1 a, the high temperature side refrigerant is discharged from the high temperature side compressor 11 in a high temperature and high pressure state, and is condensed and liquefied by the high temperature side condenser 12. Furthermore, the refrigerant is expanded and depressurized by the high-temperature side expansion device 13, and is evaporated and gasified by exchanging heat with the low-temperature side refrigerant flowing in the low-temperature side condenser 22 by the high-temperature side evaporator 14, and is sucked back to the high-temperature side compressor 11. The

  On the other hand, in the low temperature side circulation circuit 2a, the low temperature side refrigerant is discharged from the low temperature side compressor 21 in a high temperature and high pressure state, flows into the low temperature side condenser 22, and exchanges heat with the high temperature side refrigerant flowing in the high temperature side evaporator 14. The liquid is condensed and stored in the liquid receiver 23. The liquid refrigerant that has exited the liquid receiver 23 passes through the opened first opening / closing means 24, is decompressed by the low-temperature side expansion device 25, is then evaporated and gasified by the low-temperature side evaporator 26, and then the low-temperature side compressor 21. Returned to and inhaled. During the normal cooling operation, the second opening / closing means 51 is closed, and the low temperature side refrigerant does not flow through the heat storage circuit 56 and the connecting pipe 58. At this time, the third opening / closing means 54 may be closed. However, if the third opening / closing means 54 is left open, the third opening / closing means 54 is opened in the present embodiment because unnecessary opening / closing operations can be avoided. Keep it.

  Next, when the cooling load is light or at night (from 10:00 am to 8:00 am) that each electric power company is set to be cheap, the remaining refrigerant is used to store the cold energy while storing the cold energy. Operation | movement at the time of performing the thermal storage cooling operation which performs cooling is demonstrated. Generally, since the cooling load is lighter at night than in the daytime, it is not necessary to use 100% of the refrigeration capacity of the dual cooling device 100, and surplus refrigerant is often generated.

  The operation of the two-way cooling device 100 will be described using the flowchart of FIG. 2 representing the operation during the heat storage and cooling operation of the present embodiment. Further, the flow of the refrigerant in the high temperature side circulation circuit 1a and the low temperature side circulation circuit 2a at this time is indicated by arrows in FIG. FIG. 6 is a table showing the operation of each device in the binary cooling device 100 for each operating state.

  In the high temperature side circulation circuit 1a, the high temperature side refrigerant discharged from the high temperature side compressor 11 is condensed and liquefied by the high temperature side condenser 12 and decompressed by the high temperature side expansion device 13, as in the normal cooling operation. The gas is evaporated by the high temperature side evaporator 14 and returns to the high temperature side compressor 11.

  First, the suction side pressure sensor 28 detects the suction side pressure (low pressure) Ps of the low temperature side compressor 21 (S1). Then, the control device 40 compares the reference pressure Pn calculated in advance and necessary for maintaining the load side temperature (surface temperature of the low temperature side evaporator 26) with the detected suction side pressure Ps, and the suction side pressure Ps. Is less than the reference pressure Pn, it is determined that there is excess refrigerant (S2). When the suction side pressure Ps is equal to or higher than the reference pressure Pn, the normal cooling operation is continued.

  At this time, the second opening / closing means 51 is opened, the opening degree of the heat storage expansion device 52 is adjusted, and the heat storage cooling operation is performed (S3). At this time, in the low temperature side circulation circuit 2 a, the low temperature side refrigerant discharged from the low temperature side compressor 21 is condensed and liquefied by the low temperature side condenser 22 and is divided after passing through the liquid receiver 23. One of the divided low-temperature side refrigerants passes through the first opening / closing means 24, is decompressed by the low-temperature side expansion device 25, is evaporated and gasified by the low-temperature side evaporator 26, and then returns to the low-temperature side compressor 21. The other of the divided low-temperature side refrigerant flows into the heat storage circuit 56, passes through the second opening / closing means 51, is depressurized by the heat storage expansion device 52, and is evaporated and gasified by the heat storage evaporator 53. Then, after passing through the third opening / closing means 54, it joins with the low-temperature side refrigerant evaporated by the low-temperature side evaporator 26 and returns to the low-temperature side compressor 21. Since the connection pipe 58 includes the check valve 57, the low temperature side refrigerant does not flow due to the pressure difference.

  Further, the opening degree of the heat storage expansion device 52 may be adjusted according to the surplus refrigerant amount. And if the heat storage amount Ts detected in the heat storage amount sensor (not shown) which is installed in the heat storage tank 50 and detects the heat storage amount of the heat storage medium reaches a preset limit heat storage amount Tn (S4). The control device 40 determines that the cold energy is sufficiently stored in the heat storage tank 50, ends the heat storage cooling operation, and returns to the normal cooling operation. If the heat storage amount detection sensor uses water for the heat storage medium 55, for example, a water level sensor that detects the water level may be used.

  Next, the operation of performing the supercooling operation using the stored cold energy during the daytime or when the cooling load is high will be described with reference to the flowchart of FIG. Moreover, the flow of the refrigerant in the high temperature side circulation circuit 1a and the low temperature side circulation circuit 2a at this time is indicated by arrows in FIG. At this time, in the high temperature side circulation circuit 1a, the high temperature side refrigerant discharged from the high temperature side compressor 11 is condensed and liquefied by the high temperature side condenser 12 and depressurized by the high temperature side expansion device 13 as in the normal cooling operation. After that, the gas is evaporated by the high temperature side evaporator 14 and returns to the high temperature side compressor 11.

  In the low temperature side circulation circuit 2a, first, the suction side pressure Ps of the low temperature side compressor 21 is detected by the suction side pressure sensor 28 (S11). Then, the control device 40 compares the predetermined pressure Pm larger than the reference pressure Pn with the detected suction side pressure Ps, and determines that the cooling load is high when the suction side pressure Ps is equal to or higher than the predetermined pressure Pm. (S12).

  Next, the control device 40 performs the supercooling operation when the heat storage amount Ts detected by a heat storage amount detection sensor (not shown) installed in the heat storage tank 50 is equal to or greater than a preset reference heat storage amount Th. It is determined that sufficient cold energy is stored in the heat storage tank 50 (S13), the first opening / closing means 24 and the third opening / closing means 54 are closed, the second opening / closing means 51 is opened, and the heat storage throttle device is opened. 52 is opened and a supercooling operation is performed (S14). At this time, the heat storage evaporator 53 functions not as an evaporator but as a heat exchanger.

  At this time, in the low temperature side circulation circuit 2 a, the low temperature side refrigerant discharged from the low temperature side compressor 21 is condensed and liquefied by the low temperature side condenser 22 and passes through the liquid receiver 23. Then, the low-temperature side refrigerant passes through the opened second opening / closing means 51 and the heat storage expansion device 52, flows into the heat storage tank 50, and is supercooled by the stored cold heat. Then, after passing through the reverse support valve 57 provided in the connecting pipe 58, the low-temperature side expansion device 25 decompresses and expands, evaporates and gasifies in the low-temperature side evaporator 26, and returns to the low-temperature side compressor 21.

  When the heat storage amount Ts detected by a heat storage amount detection sensor (not shown) installed in the heat storage tank 50 becomes less than a preset reference heat storage amount Th, the control device 40 It is determined that all the cooling heat has been consumed (S15), the first opening / closing means 24 and the third opening / closing means 54 are opened, the second opening / closing means 51 is closed, and the normal cooling operation is resumed (S16). It should be noted that when the suction side pressure Ps rises during the normal cooling operation without performing the supercooling operation and exceeds a limit pressure Pmax that is set in advance and larger than the predetermined pressure Pm, the two-way cooling device 100 is caused to stop abnormally. ing. Pmax is a value (for example, 4 MPa) set in advance to such an extent that the piping is not destroyed by the increase in internal pressure in the low temperature side circulation circuit 2a.

  According to the present embodiment, the heat storage cooling operation is performed by using surplus refrigerant at night or when the cooling load is light, and can be used as supercooling when the cooling load is high such as in the daytime. In addition, a cooling system capable of leveling the load of electric power can be obtained.

  Since the low temperature side circulation circuit 2a includes the heat storage evaporator 53, when the object to be cooled is a refrigeration application such as daily delivery or fresh food, the evaporation temperature of the low temperature side evaporator 26 is minus 10 ° C. Therefore, it is easy to produce ice and is effective for storing ice. At this time, since the evaporation temperature of the high-temperature side evaporator 14 is about 5 to 15 ° C., it is not an appropriate temperature for generating ice, and even if the heat storage evaporator is arranged in the high-temperature side circulation circuit 1a, the effect is not much Absent. Further, even in a refrigeration application used in a temperature range of minus 40 ° C. or lower, ice storage can be effectively performed by providing an adjustment valve or the like for adjusting the evaporation pressure on the outlet side of the heat storage evaporator 53. it can.

  The transition of the refrigerant state during the normal cooling operation and the supercooling operation will be described with reference to the ph diagram of FIG. 7 showing the relationship between the phase change of the refrigerant and the pressure. During the normal cooling operation, the low temperature side refrigerant is compressed by the low temperature side compressor 21 from the state of A1 sucked into the low temperature side compressor 21 to be in the state of A2, and is condensed and liquefied by the low temperature side condenser 22. It becomes a state. Furthermore, it passes through the liquid receiver 23 and is decompressed and expanded by the low temperature side expansion device 25 to be in the A4 state, and is evaporated and gasified by the low temperature side evaporator 26 to return to the A1 state. At this time, the freezing effect as the two-way cooling device 100 is the difference q1 in the enthalpy (heat content) between A1 and A4 (A3).

  On the other hand, at the time of supercooling operation, the low temperature side refrigerant is compressed by the low temperature side compressor 21 from the state of A1 sucked into the low temperature side compressor 21 to become the state of A2, and is condensed and liquefied by the low temperature side condenser 22. It will be in the state of A3. Then, after passing through the liquid receiver 23, it passes through the heat storage evaporator 53 via the second opening / closing means 51 and the heat storage expansion device 52. At this time, the heat storage medium 55 in the heat storage tank 50 is cooled by the cold energy stored in the heat storage medium 55 to be in the state of B3. That is, it is supercooled. The supercooled low-temperature side refrigerant is decompressed and expanded by the low-temperature side expansion device 25 to be in the state of B4, is evaporated and gasified by the low-temperature side evaporator 26, and returns to the state of A1. At this time, the refrigeration effect as the two-way cooling device 100 is the difference q2 in enthalpy between A1 and B4 (B3).

  Thus, by providing the heat storage circuit 56 in the low temperature side circulation circuit 2a, heat can be stored while suppressing an increase in the pressure of the low temperature side refrigerant during defrosting, and the stored cold can be used for the supercooling operation. Compared with the normal cooling operation, in the supercooling operation of the present invention, the refrigeration effect can be improved by the difference between q1 and q2 (q2-q1). As a result, the cooling capacity (general About 20%).

  Here, the heat storage tank 50 in the present embodiment will be described. Here, water is used as the heat storage medium 55. Moreover, the capacity | capacitance of the two-way cooling device 100 shall be about 15 kW (20 horsepower) of the cooling machine capacity generally used well. In the case where the load to be cooled is used for refrigeration applications such as fresh or daily distribution, the average temperature of the low-temperature evaporator 26 is about minus 10 degrees, so that the cooling of the binary cooling device 100 is frozen. The capacity is about 40 kW. The night load is generally about 60%. At this time, the two-stage cooling device 100 needs about 24 kW of refrigerating capacity. Therefore, the remaining refrigerating capacity of about 16 kW should be used for the regenerative cooling operation. Can do.

  If the refrigerating capacity is 16 kW and the heat storage and cooling operation is continued for 10 hours at night, a heat quantity of 16 (kW) × 10 (hours) × 3600 (seconds) = 576 MJ is obtained. Accordingly, since the latent heat of melting of ice is 333.55 (kJ / kg), ice of 576 (MJ) /333.55 (MJ / kg) = 1727 (kg) can be generated. That is, if 1727 kg of water is sealed in the heat storage tank 50, the heat storage cooling operation can be continued throughout the night.

  Therefore, if 1727 kg of water is sealed in the heat storage tank 50, the housing of the heat storage tank 50 has a height of 1.727 m if the width and depth are 1 m. Since the size of a general two-way cooling device is about 1 to 2 m in width and about 1.5 m in height, the heat storage tank 50 is installed side by side close to the two-way cooling device 100, or the heat storage tank 50 is installed. It is preferable to place the two-way cooling device 100 on the installation, and the installation space can be used effectively. Of course, it goes without saying that the capacity of the heat storage tank 50 may be changed according to the required amount of heat storage, and the same applies to Embodiments 2 and 3 described later.

  When there is no need to operate the dual cooling device 100, it is preferable to close the first opening / closing means 24 and the second opening / closing means 51 and leave the third opening / closing means 54 open. FIG. 8 shows a refrigerant circuit of the dual cooling device 100 when the cooling operation is stopped. This is because the low-temperature side refrigerant is cooled by the stored cold heat if the temperature or pressure of the low-temperature side refrigerant of the heat storage evaporator 53 is detected even when the two-way cooling device 100 is stopped. This is because an increase in pressure in the circuit 2a can be prevented. Also, if the pump-down operation described later is performed before stopping the two-way cooling device 100, the low-temperature side refrigerant is recovered and then stopped, so that an increase in the pressure of the low-temperature side refrigerant can be suppressed, Can be stopped for a long time.

Embodiment 2. FIG.
In the first embodiment described above, when the cooling load is light or at night when each electric power company is set to be cheap, the heat storage cooling operation is performed using the heat storage circuit 56, and the heat storage is performed when the cooling load is high or in the daytime. The case where the cold energy stored in the cooling operation is used as supercooling is described. In the present embodiment, a heat storage defrosting operation for storing cold energy while defrosting the low temperature side evaporator 26 will be described. In addition, the same code | symbol is attached | subjected about the same thing as Embodiment 1. FIG.

  The operation of the dual cooling device 100 in the present embodiment will be described using the flowchart of FIG. 9 representing a series of operation operations of the defrosting operation. Moreover, the flow of the refrigerant in the high temperature side circulation circuit 1a and the low temperature side circulation circuit 2a at this time is indicated by arrows in FIGS. 10, 11, and 12. FIG. FIG. 13 is a table showing the operation of each device in the binary cooling device 100 for each operating state.

  First, when the start of the defrosting operation is instructed from the control device 40, a so-called pump-down operation is performed in which the liquid refrigerant remaining in the low-temperature evaporator 26 and the piping is collected in the liquid receiver 23. When the control device 40 determines that, for example, the operation integration time from the start of the cooling operation in the low temperature side compressor 21 has passed a predetermined time (for example, 4 hours) (S21), the high temperature side compressor 11 is stopped, The first opening / closing means 24 is closed so that the low-temperature side refrigerant from the liquid receiver 23 does not flow into the low-temperature side evaporator 26 (S22).

  Then, the low temperature side compressor 21 is driven until it is determined that the suction side pressure Ps detected by the suction side pressure sensor 28 is equal to or lower than a preset specified pressure Pe (for example, 1 to 2 MPa) (S23). Thereby, the low temperature side refrigerant is evaporated in the low temperature side evaporator 26, and the low temperature side refrigerant is caused to flow out as much as possible. The low-temperature side refrigerant that has flowed out is discharged from the low-temperature side compressor 21, flows into the low-temperature side condenser 22, is condensed, and is collected by the liquid receiver 23.

  By performing the pump-down operation before defrosting, the low-temperature side evaporator 26 is heated in a state in which the low-temperature side refrigerant in the low-temperature side evaporator 26 is reduced. Can do. Further, since the amount of the low temperature side refrigerant in the low temperature side evaporator 26 at the time of defrosting can be reduced, the amount of heat of the defrost heater 27 taken away by the low temperature side refrigerant is small, and the defrost heater 27 is operated with a small amount of heat. Power consumption can be reduced.

  When the suction side pressure Ps becomes equal to or lower than the specified pressure Pe, the control device 40 determines that the low temperature side refrigerant has been properly recovered in the receiver 23, stops the low temperature side compressor 21, and the low temperature side expansion device 25. Is closed, the defrosting heater 27 is energized to heat the low temperature side evaporator 26, and defrosting is performed (S24). At this time, although the temperature of the low-temperature side refrigerant remaining in the low-temperature side evaporator 26 and the surrounding piping rises due to the heating of the defrost heater 27, it flows into the heat storage tank 50 via the third opening / closing means 54 and stores the heat. Heat exchange with the medium 55 is performed to store cold energy. Thereby, even if the high temperature side compressor 11 and the low temperature side compressor 21 are stopped, the electric power generated by the defrost heater 27 is effectively used to store the cold while preventing the pressure increase of the low temperature side refrigerant during defrosting. can do.

  Next, the control device 40 compares the predetermined pressure Pm set in advance with the suction side pressure Ps, and determines that the pressure Ps is equal to or higher than the predetermined pressure Pm (S25), opens the second opening / closing means 51. The opening degree of the thermal storage expansion device 52 is adjusted, the low temperature side compressor 21 is driven, and the first thermal storage defrosting operation is performed (S26). The predetermined pressure Pm is assumed to be a value when, for example, all the cold energy stored in the heat storage tank 50 is consumed and the suction side pressure of the low temperature side compressor 21 starts to rise.

  At this time, the low-temperature-side refrigerant flows into the heat storage evaporator 53 disposed in the heat storage tank 50 by the liquid refrigerant in the liquid receiver 23 flowing into the heat storage expansion device 52 via the second opening / closing means 51 and being decompressed and expanded. Inflow. The low-temperature side refrigerant that has flowed into the heat storage evaporator 53 is heat-exchanged with the heat storage medium 55 sealed in the heat storage tank 50 to be evaporated and gasified, and returns to the low-temperature side compressor 21 via the third opening / closing means 54. At this time, since the high temperature side compressor 11 is stopped, the low temperature side compressor 21 is driven at a frequency at which the condensation temperature does not increase rapidly. Thereby, it is possible to perform defrosting while performing heat storage without driving the high temperature side compressor 11, and it is not necessary to consume unnecessary power.

  Further, the control device 40 compares the preset limit pressure Pmax with the suction side pressure Ps, and if it is determined that the suction side pressure Ps is equal to or higher than the limit pressure Pmax (S27), the high temperature side compressor 11 is driven. Then, the second heat storage defrosting operation is performed (S28). Thereby, heat storage can be performed with the maximum output while defrosting while cooling the low-temperature side refrigerant by the high-temperature side evaporator 14 and suppressing the pressure rise.

  As described above, the high temperature side compressor 11 and the low temperature side compressor 21 are appropriately driven according to the detected pressure of the suction side pressure sensor 28 at the time of defrosting after the pump down operation, so that an increase in the pressure of the low temperature side refrigerant is prevented. Thus, wasteful power consumption due to driving of the compressor can be prevented, and power can be used effectively.

  In the present embodiment, the drive of the high temperature side compressor 11 and the low temperature side compressor 21 is controlled stepwise based on the detected pressure of the suction side pressure sensor 28, but is controlled based on a single predetermined pressure value. Of course. When the cold energy is sufficiently stored in the heat storage tank 50, it is not necessary to store more heat, so the operation of the high temperature side compressor 11 and the low temperature side compressor 21 may be stopped. Even if it does, it can suppress the pressure rise of a low temperature side refrigerant | coolant with the cold energy stored in the thermal storage medium 55. FIG.

  For example, when a temperature sensor (not shown) for detecting the surface temperature of the low-temperature side evaporator 26 detects a predetermined temperature or higher (S29), the control device 40 determines that the defrosting is completed, and the defrost heater 27 Is stopped (S30). And it returns to normal cooling driving | operation. In addition, the predetermined temperature of the surface of the low temperature side evaporator 26 which judges that defrosting was complete | finished is 10 degreeC or more, for example. This is because even if the surface of the low temperature side evaporator 26 becomes 0 ° C. or more and frost is melted, for example, frost remains around the drain pan (not shown) or the remaining water does not freeze again. In addition, the defrosting heater 27 is heated for a while to surely melt the frost.

  Note that after S24 and S26, if the defrosting of the low-temperature side evaporator 26 is completed, it goes without saying that the normal cooling operation is resumed, and a temperature sensor (not shown) for detecting the surface temperature of the low-temperature side evaporator 26. Judged by the detected temperature. When defrosting is completed, the normal cooling operation is resumed. Alternatively, when it is determined that the cooling load is high, the supercooling operation may be performed immediately after defrosting. The supercooling operation is the same as in the first embodiment.

  As described above, in the dual cooling device 100 according to the present embodiment, the low-temperature side evaporator 26 is heated and defrosted while the low-temperature side circulation circuit 2a is provided with the heat storage circuit to perform the heat storage defrosting operation. By performing the cooling operation, the cold energy stored in the heat storage tank 50 can be used for the supercooling operation of the low-temperature side circulation circuit 2a, so that the power can be effectively used as the two-way cooling device 100.

Further, since the cold energy is stored while monitoring the pressure increase during defrosting of the low temperature side evaporator 26, the critical pressure of the CO ₂ refrigerant is not exceeded. That is, even at the time of defrosting, the refrigerant pressure in the low temperature side circulation circuit 2a can be suppressed to, for example, a pressure (for example, 4 MPa) or less that is about the same as that of the HFC refrigerant that has been conventionally used. Therefore, in the design, the pressure resistance of the low-temperature side refrigerant of the low-temperature side evaporator 26 can be estimated to be low, and the thickness of the copper pipe used as the heat transfer pipe of the low-temperature side evaporator 26 can be halved, for example. It is possible to provide a dual cooling device that is inexpensive and easy to construct on-site refrigerant.

  In addition, conventionally, as another method for preventing the refrigerant pressure of the low temperature side device from increasing during defrosting, a safety valve is provided in the low temperature side device to release the air when the pressure increases, or an expansion tank is installed in the vicinity of the cooling device. Measures such as installing a separate cooler as an application to maintain temperature in the low-temperature side device have been considered, but in this embodiment, it is possible to suppress an increase in refrigerant pressure during defrosting with a simple configuration. it can.

  In the present embodiment, when the low temperature side evaporator 26 is defrosted, the defrost heater 27 is heated by being energized to melt the frost. For example, it is discharged from the low temperature side compressor 21. The low temperature side evaporator 26 may act as a condenser by flowing a high temperature and high pressure low temperature side refrigerant to the low temperature side evaporator 26, and the frost may be melted by the heat of condensation (hot gas defrost).

Embodiment 3 FIG.
FIG. 14 shows the dual cooling device 200 according to the present embodiment, in which a supercooling coil 60 is provided in the heat storage tank 50, and one end of the supercooling coil 60 is connected to the refrigerant outflow side of the high-temperature side condenser 12. The other end is connected to the refrigerant inflow side piping of the high temperature side expansion device 13. In addition, the same code | symbol is attached | subjected about the same thing as Embodiment 1,2.

By comprising in this way, since the cold stored in the low temperature side circulation circuit 2a at the time of defrosting or when the cooling load is light such as at night can be used for the supercooling of the high temperature side circulation circuit 1b, The side compressor 11 can be covered with a small capacity, and electric power can be used effectively. Moreover, since the refrigerant filling amount circulated to the high-temperature side circulation circuit 1b can be reduced, the HFC system is efficient but has a relatively high global warming potential (GWP) compared to natural refrigerants such as CO ₂ and ammonia. Even if a refrigerant is used, the environmental load can be reduced.

  The supercooling coil 60 only needs to be configured to exchange heat with the cold stored in the heat storage tank 50, and may not be installed in the heat storage tank 50. The length of the pipe connected from the high temperature side circulation circuit 1b to the supercooling coil 60 should be as short as possible, and it is better to arrange the high temperature side condenser 12 and the heat storage tank 50 close to each other. That is, it is preferable to arrange the heat storage tank 50 close to the two-way cooling device 200, for example.

  Although the above-mentioned embodiment explained individually the form which performs heat storage at the time of defrosting and when the cooling load is light at night, etc., each operation (normal cooling operation, heat storage cooling operation, defrosting heat storage operation) , Operation stop, and supercooling operation) may be combined to operate the cooling device, thereby preventing more wasteful power consumption and effectively using power. Moreover, although the above-mentioned embodiment was demonstrated with the two-way cooling device, it is applicable also to the multi-way cooling device of a multistage structure.

  DESCRIPTION OF SYMBOLS 10 High temperature side apparatus, 11 High temperature side compressor, 12 High temperature side condenser, 13 High temperature side expansion apparatus, 14 High temperature side evaporator, 20 Low temperature side apparatus, 21 Low temperature side compressor, 22 Low temperature side condenser, 23 Receiver 24 first opening / closing means, 25 low temperature side expansion device, 26 low temperature side evaporator, 27 defrost heater, 28 suction side pressure sensor, 30 cascade condenser, 50 heat storage tank, 51 second opening / closing means, 52 heat storage expansion device, 53 heat storage evaporator, 54 third opening / closing means, 55 heat storage medium, 56 heat storage circuit, 57 check valve, 58 connecting pipe, 60 supercooling coil.

Claims (9)

A high temperature side apparatus that pipes a high temperature side compressor, a high temperature side condenser, a high temperature side expansion device, and a high temperature side evaporator to form a high temperature side circulation circuit that circulates the high temperature side refrigerant; and
Low-temperature side apparatus for connecting a low-temperature side compressor, a low-temperature side condenser, a receiver, a first opening / closing means, a low-temperature side throttle device, and a low-temperature side evaporator to form a low-temperature side circulation circuit for circulating a low-temperature side refrigerant When,
An inter-refrigerant heat exchanger configured by the high-temperature side evaporator and the low-temperature side condenser, and performing heat exchange between the high-temperature side refrigerant and the low-temperature side refrigerant,
A heat storage evaporator that branches off from a pipe connecting the liquid receiver and the first opening / closing means and that exchanges heat with a second storage means, a heat storage expansion device, a heat storage medium enclosed in a heat storage tank; A heat storage circuit connected to a pipe connecting the low-temperature side evaporator and the low-temperature side compressor by sequentially connecting three open / close means to the pipe;
A connection pipe branched from a pipe connecting the heat storage evaporator and the third opening / closing means, and connected to a pipe connecting the first opening / closing means and the low temperature side throttle device via a check valve;
At least the high temperature side compressor, the high temperature side expansion device, the low temperature side compressor, the first opening / closing means, the low temperature side expansion device, the second opening / closing means, the heat storage expansion device, the heat storage evaporator, And a control device for controlling the third opening / closing means. Heating means for heating the low-temperature side evaporator,
The control device closes the first opening / closing means, opens the second opening / closing means and the third opening / closing means, heats the low-temperature side evaporator by the heating means, and controls the low-temperature side compressor. The cooling device according to claim 1 to be driven. Pressure detecting means for detecting the pressure of the low-temperature side refrigerant on the low-temperature side compressor suction side,
The cooling device according to claim 2, wherein the control device controls driving of the low temperature side compressor and the high temperature side compressor according to the pressure detected by the pressure detection means. 2. The cooling device according to claim 1, wherein when the cooling device is stopped, the control device closes the first opening and closing means and the second opening and closing means and opens the third opening and closing means. Heating means for heating the low-temperature evaporator;
Pressure detecting means for detecting the pressure of the low-temperature side refrigerant on the low-temperature side compressor suction side,
The cooling device according to claim 4, wherein the control device heats the low-temperature side evaporator by the heating means when the pressure detected by the pressure detection means is less than a preset specified pressure. Pressure detecting means for detecting the pressure of the low-temperature side refrigerant on the low-temperature side compressor suction side,
When the cooling device is operating to cool the load,
When the pressure detected by the pressure detection means is less than the pressure necessary for maintaining the evaporation temperature of the low temperature side evaporator, the control device is configured to provide the first opening / closing means, the second opening / closing means, and the first 3. The cooling device according to claim 1, wherein the opening / closing means is opened. A supercooling coil that performs heat exchange with the cold energy stored in the heat storage medium,
The cooling device according to claim 1, wherein one end of the supercooling coil is connected to a refrigerant outflow side pipe of the high temperature side condenser, and the other end is connected to a refrigerant inflow side pipe of the high temperature side expansion device. When the cooling device performs an operation of cooling the load in a state where cold heat is stored in the heat storage medium,
The cooling device according to claim 1, wherein the control device closes the first opening / closing means and the third opening / closing means and opens the second opening / closing means. The cooling device according to any one of claims 1 to 7, wherein the low-temperature side refrigerant is carbon dioxide.

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