JP7482438B2 - Refrigeration equipment - Google Patents

Description

The present invention relates to a refrigeration device.

Patent Document 1 describes a refrigeration system that performs cooling operation using a refrigerant circuit through which a refrigerant circulates. The refrigeration system performs a defrosting operation to remove frost that has formed on a cooler (evaporator) that cools the inside of a showcase or a refrigerated warehouse installed in a store, for example. While the defrosting operation is being performed, the compressor in the refrigeration system does not operate and the refrigerant does not circulate. Also, if the showcase or refrigerated warehouse has been sufficiently cooled, or if cooling is not required for some reason, the compressor does not operate and the refrigerant does not circulate.

JP 2018-66514 A

In defrosting operations that are performed while cooling operation is stopped, the frost is generally melted by heating the evaporator using an electric heater or hot gas. The heating during defrosting may cause the refrigerant remaining in the evaporator to evaporate, increasing the pressure inside the evaporator. Also, if the outside temperature rises when cooling operation is not performed for a long period of time, the refrigerant remaining in the evaporator may evaporate, increasing the pressure inside the evaporator. If the pressure inside the evaporator becomes relatively high as a result of these factors, problems such as damage to the evaporator may occur.

The present disclosure aims to provide a refrigeration device that can suppress the pressure inside the evaporator when cooling operation is not being performed.

In order to achieve the above-mentioned object, the refrigeration device disclosed herein is a refrigeration device that performs cooling operation using a refrigerant circuit in which a refrigerant circulates through a compressor, a condenser, an expansion device, and an evaporator in that order, and is equipped with a compressor, a condenser, a valve arranged between the condenser and the expansion device and regulating the flow of the refrigerant when in a closed state, a pressure sensor that detects a pressure value of the refrigerant, and a first control device that controls the flow of the refrigerant, wherein the open state of the expansion device that allows the flow of the refrigerant and the closed state of the expansion device that regulates the flow of the refrigerant are controlled by a second control device that is separate from the first control device, and when a cooling operation is not being performed, the first control device closes the valve regardless of the open/closed state of the expansion device, and starts recovering the refrigerant in the evaporator when the pressure value of the refrigerant detected by the pressure sensor becomes equal to or greater than a first predetermined pressure value, and the first predetermined pressure value is set to a value higher than the range of pressure values of the refrigerant detected by the pressure sensor when a cooling operation is being performed.

The refrigeration device disclosed herein can suppress the pressure inside the evaporator when cooling operation is not being performed.

FIG. 1 is a schematic diagram of a refrigeration device according to an embodiment of the present disclosure. 2 is a flowchart of a program executed by the control device shown in FIG. 1 .

The refrigeration device of the present disclosure will be described below with reference to the drawings. Note that, although a preferred embodiment of the refrigeration device of the present disclosure will be described below, the present disclosure is not limited to this embodiment, and various modifications and improvements are possible based on the knowledge of those skilled in the art.

Figure 1 is a schematic diagram of a refrigeration system 1. The refrigeration system 1 performs cooling operation using a refrigerant circuit 50 in which a refrigerant (not shown) circulates through a compressor 10, a gas cooler 20, an electric expansion valve 30, and an evaporator 40 in that order. The gas cooler 20 is an example of a "condenser." The electric expansion valve 30 is an example of an "expansion device."

The refrigerant is carbon dioxide. The lubricating oil used is an existing oil such as mineral oil, alkylbenzene oil, ether oil, ester oil, or PAG (polyalkyl glycol). However, the type of oil is not limited to these.

The refrigeration system 1 includes a compressor 10 and a gas cooler 20. The compressor 10 and the gas cooler 20 are housed in a housing 1a. The compressor 10 and the gas cooler 20 may be disposed in separate housings. The housing 1a also houses an intercooler 52a, an oil separator 53a, three expansion valves 53b, 56a, and 57a, a tank 21, a split heat exchanger 54a, a valve 54b, a pressure sensor 51a, and a control device 60 (each of which will be described later). The valve 54b is a modified version of this embodiment, and will be described later.

The electric expansion valve 30 and the evaporator 40 are arranged outside the housing 1a. The showcase 2 is arranged outside the housing 1a. The showcase 2 is arranged in a supermarket or other store, and the inside is cooled by the refrigeration device 1. The electric expansion valve 30 is arranged outside the showcase 2. The evaporator 40 is housed in the showcase 2.

The refrigerant circuit 50 includes four main pipes 51-54 and three sub-pipes 55-57. The first main pipe 51 connects the evaporator 40 to the first suction port 10a of the compressor 10. Low-pressure refrigerant flowing out of the evaporator 40 flows into the compressor 10 via the first main pipe 51.

The compressor 10 is an internal intermediate type two-stage compression rotary compressor. The compressor 10 has a first compression section 11 and a second compression section 12. The first compression section 11 and the second compression section 12 are rotary compressors.

The first compression section 11 pressurizes the low-pressure refrigerant drawn in from the first intake port 10a to an intermediate pressure and discharges it from the first discharge port 10b to the second main pipe 52. The second main pipe 52 connects the first discharge port 10b to the second intake port 10c of the compressor 10. An intercooler 52a is arranged in the second main pipe 52.

The intercooler 52a air-cools the refrigerant discharged from the first compression section 11. The intermediate pressure refrigerant air-cooled by the intercooler 52a is sucked into the second compression section 12 from the second intake port 10c via the second main pipe 52.

The second compression section 12 compresses the intermediate pressure refrigerant drawn in from the second intake port 10c to a high temperature and high pressure, and discharges it from the second discharge port 10d to the third main pipe 53. The compressor 10 may be, for example, a reciprocating compressor or a screw compressor. The compressor 10 does not have to be a multi-stage type, in which case the intercooler 52a is not provided.

The third main pipe 53 connects the compressor 10 to the inlet 21a located at the top of the tank 21. The third main pipe 53 is arranged with an oil separator 53a, a gas cooler 20, and a first expansion valve 53b in this order from the compressor 10 side toward the tank 21 side.

The oil separator 53a separates the oil contained in the refrigerant discharged from the compressor 10. The oil separated from the refrigerant is returned from the oil separator 53a to the compressor 10 via the first sub-pipe 55. Note that the refrigeration device 1 does not necessarily have to include the oil separator 53a.

The gas cooler 20 is a condenser that cools and condenses the high-temperature, high-pressure refrigerant that flows out of the compressor 10 and the oil separator 53a. A first blower 20a is disposed near the gas cooler 20. The first blower 20a air-cools the gas cooler 20. The first blower 20a is controlled by the control device 60. In this embodiment, the gas cooler 20 and the intercooler 52a are disposed side by side, and are both air-cooled by the first blower 20a.

The first expansion valve 53b throttles and expands the refrigerant flowing out from the gas cooler 20, and adjusts the pressure of the refrigerant upstream from the first expansion valve 53b. The refrigerant flowing out from the first expansion valve 53b flows into the tank 21 from the inlet 21a.

The tank 21 is a volume body having a space of a specified volume inside. The tank 21 has the role of adjusting the pressure of the refrigerant upstream of the tank 21 and absorbing fluctuations in the flow rate of the refrigerant per unit time. In addition, the refrigerant that flows into the tank 21 is separated into gas and liquid, and the liquid refrigerant is stored at the bottom of the tank 21. The temperature of the gaseous refrigerant that remains at the top of the tank 21 is lower than the temperature of the liquid refrigerant that is stored at the bottom of the tank 21.

The gaseous refrigerant that accumulates in the upper part of the tank 21 flows out from the first outlet 21b to the second sub-pipe 56. The second sub-pipe 56 connects the first outlet 21b to the first connection part 52b provided between the intercooler 52a and the second intake port 10c in the second main pipe 52. In the second sub-pipe 56, a second expansion valve 56a and a split heat exchanger 54a are arranged in this order from the tank 21 side toward the first connection part 52b.

The second expansion valve 56a has the role of throttling the gaseous refrigerant flowing out from the first outlet 21b and of adjusting the pressure inside the tank 21. The refrigerant flowing out from the second expansion valve 56a flows into the split heat exchanger 54a.

The split heat exchanger 54a is a heat exchanger that uses the refrigerant that flows in through the second sub-pipe 56 to cool the refrigerant flowing in the other pipe (the fourth main pipe 54 described below). The refrigerant that flows out of the split heat exchanger 54a through the second sub-pipe 56 flows into the second main pipe 52 from the first connection part 52b.

Meanwhile, the liquid refrigerant stored at the bottom of the tank 21 flows out from the second outlet 21c and the third outlet 21d.

The refrigerant flowing out from the second outlet 21c flows through the third sub-pipe 57. The third sub-pipe 57 connects the second outlet 21c to a second connection part 56b provided between the second expansion valve 56a and the split heat exchanger 54a in the second sub-pipe 56. A third expansion valve 57a is disposed in the third sub-pipe 57. The refrigerant flowing out from the second outlet 21c is throttled by the third expansion valve 57a and flows from the second connection part 56b into the second sub-pipe 56 and evaporates.

Meanwhile, the refrigerant flowing out from the third outlet 21d flows through the fourth main pipe 54. The fourth main pipe 54 connects the second outlet 21c and the evaporator 40. In the fourth main pipe 54, a split heat exchanger 54a and an electric expansion valve 30 are arranged in this order from the tank 21 side toward the evaporator 40 side.

The refrigerant that flows into the split heat exchanger 54a through the fourth main pipe 54 is cooled by the refrigerant flowing through the other pipe (the above-mentioned second sub-pipe 56) and flows out toward the electric expansion valve 30. The refrigeration device 1 may not include the split heat exchanger 54a. In this case, the refrigeration device 1 may not include the tank 21, the three expansion valves 53b, 56a, 57a, and the fourth main pipe 54. In this case, the third main pipe 53 connects the compressor 10 and the evaporator 40, and the oil separator 53a, the gas cooler 20, and the electric expansion valve 30 are arranged in this order from the compressor 10 side toward the evaporator 40 side.

The electric expansion valve 30 throttles the refrigerant flowing out of the split heat exchanger 54a. The opening degree of the electric expansion valve 30 is controlled by a control device (not shown) separate from the control device 60 so that the degree of superheat of the refrigerant in the evaporator 40 is an appropriate value. This separate control device controls the temperature inside the showcase 2.

The evaporator 40 cools the inside of the showcase 2. The evaporator 40 is a plate fin tube type, and includes a tube (not shown) through which the refrigerant flows and fins (not shown) that release the heat of the refrigerant. A second blower 41 is disposed near the evaporator 40 to blow air inside the showcase 2 to the fins and tubes. The second blower 41 is controlled by another control device described above. The refrigerant that flows into the evaporator 40 evaporates, thereby cooling the air blown by the second blower 41 and thus the inside of the showcase 2.

The refrigerant flowing out from the evaporator 40 is sucked into the compressor 10 via the first main pipe 51. A pressure sensor 51a is arranged in the first main pipe 51.

The pressure sensor 51a detects the pressure value of the refrigerant. The pressure sensor 51a is disposed between the evaporator 40 and the compressor 10 in the refrigerant circuit 50. In this case, the pressure sensor 51a detects the pressure value in the first main pipe 51. The detection result of the pressure sensor 51a is output to the control device 60.

The evaporator 40 is also provided with a defroster 42. The defroster 42 performs defrosting inside the evaporator 40. The defroster 42 is controlled by another control device described above. The defroster 42 is of an electric heater type. The defroster 42 is equipped with an electric heater (not shown) and a temperature sensor (not shown).

The electric heater generates heat when electricity is applied. The electric heater is a sheath heater. The electric heater is disposed near the tube of the evaporator 40. The temperature sensor detects the temperature inside the evaporator 40. The detection result of the temperature sensor is output to the separate control device described above.

The control device 60 provides overall control of the refrigeration device 1. The control device 60 controls the flow of the refrigerant to perform cooling operation. When cooling operation is performed, the compressor 10 is operated and the refrigerant circulates through the refrigerant circuit 50. Furthermore, when cooling operation is performed, the opening of the electric expansion valve 30 and the second blower 41 are controlled by the separate control device described above to cool the inside of the showcase 2.

The control device 60 also performs refrigerant recovery control to recover the refrigerant in the evaporator 40.

The refrigerant recovery control performed by the control device 60 will be described below with reference to the flowchart shown in FIG. 2. The refrigerant recovery control is executed when cooling operation is not being performed. When cooling operation is not being performed, the control device 60 stops the operation of the compressor 10. This stops the circulation of the refrigerant in the refrigerant circuit 50. Furthermore, when cooling operation is not being performed, the separate control device described above closes the electric expansion valve 30 and stops driving the second blower 41.

In S10, the control device 60 determines whether the pressure value detected by the pressure sensor 51a (hereinafter referred to as the detected pressure value) is equal to or greater than the first predetermined pressure value.

The first predetermined pressure value is set to a value higher than the range of detected pressure values when the cooling operation is being performed. Specifically, the first predetermined pressure value is set to a pressure value higher than the detected pressure value when the refrigerant is circulating through the refrigerant circuit 50 and the inside of the showcase 2 is being cooled normally. Furthermore, the first predetermined pressure value is set to a pressure value lower than the pressure value at which the evaporator 40 may break down.

If the detected pressure value is lower than the first predetermined pressure value, the control device 60 judges NO in S10 and repeats S10. In this case, the compressor 10 continues to be stopped.

If the outside air temperature rises while the cooling operation is stopped, the temperature inside the evaporator 40 rises. Also, when the cooling operation is stopped and the defrosting operation is performed, the electric heater is energized, and the temperature inside the evaporator 40 rises. This temperature rise causes the refrigerant to evaporate, and the refrigerant pressure and therefore the detected pressure value rise.

As a result, when the detected pressure value becomes equal to or greater than the first predetermined pressure value, the control device 60 judges YES in S10 and starts operation of the compressor 10 in S11. When operation of the compressor 10 starts, the refrigerant in the evaporator 40 flows out to the first main pipe 51. At this time, as described above, the electric expansion valve 30 is closed, so the refrigerant does not flow into the evaporator 40. Therefore, the refrigerant in the evaporator 40 is recovered on the compressor 10 side (downstream side) of the evaporator 40 in the refrigerant circuit 50. In this way, the refrigerant in the evaporator 40 is recovered by operation of the compressor 10.

The control device 60 then determines in S12 whether the detected pressure value is equal to or less than a second predetermined pressure value. The second predetermined pressure value is set to a pressure value lower than the first predetermined pressure value. The second predetermined pressure value is also set to a value higher than the range of detected pressure values when cooling operation is being performed.

If the detected pressure value is higher than the second predetermined pressure value, the control device 60 judges NO in S12 and repeats S12. In this case, the operation of the compressor 10 continues.

The amount of refrigerant in the evaporator 40 decreases as the compressor 10 is operated to recover the refrigerant in the evaporator 40. This causes the refrigerant pressure, and therefore the detected pressure value, to decrease. When the detected pressure value becomes equal to or lower than the second predetermined pressure value, the control device 60 judges YES in S12 and stops the operation of the compressor 10 in S13. When the operation of the compressor 10 is stopped, the recovery of the refrigerant in the evaporator 40 is stopped. The control device 60 then returns the program to S10.

In this way, when cooling operation is not being performed, the control device 60 controls the operation of the compressor 10 based on the detected pressure value to start or stop the recovery of the refrigerant in the evaporator 40.

The refrigeration device 1 of the above-described embodiment is a refrigeration device that performs cooling operation using a refrigerant circuit 50 in which the refrigerant circulates through the compressor 10, gas cooler 20, motorized expansion valve 30, and evaporator 40 in that order. It is equipped with a pressure sensor 51a that detects the pressure value of the refrigerant, and a control device 60 that controls the flow of the refrigerant. When the pressure value of the refrigerant detected by the pressure sensor 51a becomes equal to or greater than a first predetermined pressure value when the cooling operation is not being performed, the control device 60 starts recovering the refrigerant in the evaporator 40, and the first predetermined pressure value is set to a value higher than the range of pressure values detected by the pressure sensor 51a when the cooling operation is being performed.

As a result, the refrigeration device 1 can suppress the pressure in the evaporator 40 when cooling operation is not being performed. In addition, when the refrigerant pressure value is lower than the first predetermined pressure value, refrigerant recovery is not started, so the energy and time required to drive the compressor 10 can be suppressed.

In addition, when recovery of refrigerant in the evaporator 40 is being performed, the control device 60 stops recovery of the refrigerant in the evaporator 40 when the refrigerant pressure value detected by the pressure sensor 51a becomes equal to or lower than a second predetermined pressure value that is lower than the first predetermined pressure value.

According to this, after refrigerant recovery has started, operation of the compressor 10 is stopped when the refrigerant pressure value falls below the second predetermined pressure value. This further reduces the energy and time required to drive the compressor 10.

The refrigeration device 1 according to one or more aspects has been described above based on the embodiment, but the present invention is not limited to this embodiment. As long as it does not deviate from the gist of the present invention, various modifications conceivable by a person skilled in the art to this embodiment, or a form constructed by combining components in different embodiments, may also be included within the scope of one or more aspects.

In the above-described embodiment, the refrigeration device 1 may be configured to include a valve 54b. The valve 54b is disposed between the gas cooler 20 and the evaporator 40 in the refrigerant circuit 50, and allows the flow of refrigerant when in an open state and restricts the flow of refrigerant when in a closed state. Specifically, the valve 54b is disposed between the split heat exchanger 54a and the electric expansion valve 30 in the refrigerant circuit 50. The control device 60 closes the valve 54b when the cooling operation is stopped.

By closing the valve 54b, the flow of refrigerant from the gas cooler 20 side into the evaporator 40 is reliably restricted. Therefore, in the refrigerant recovery control, the refrigerant in the evaporator 40 is reliably recovered by operating the compressor 10.

The electric expansion valve 30 in the above-described embodiment may also be changed to a capillary tube.

In addition, in the above-described embodiment, the pressure sensor 51a is disposed between the evaporator 40 and the compressor 10 in the refrigerant circuit 50, but instead, the pressure sensor 51a may be disposed at another location in the refrigerant circuit 50. The pressure sensor 51a may also be disposed within the evaporator 40.

This invention can be widely used in refrigeration equipment.

1 Refrigeration device 10 Compressor 20 Gas cooler (condenser)
30 Electric expansion valve (expansion device)
40 Evaporator 42 Defroster 50 Refrigerant circuit 51a Pressure sensor 54b Valve 60 Control device

Claims (2)

A refrigeration apparatus that performs a cooling operation using a refrigerant circuit in which a refrigerant circulates through a compressor, a condenser, an expansion device, and an evaporator in this order,
The compressor;
The condenser;
a valve disposed between the condenser and the expansion device, the valve restricting the flow of the refrigerant when in a closed state;
a pressure sensor for detecting a pressure value of the refrigerant;
A first control device that controls the flow of the refrigerant,
an open state of the expansion device that allows the flow of the refrigerant and a closed state of the expansion device that restricts the flow of the refrigerant are controlled by a second control device that is separate from the first control device;
The first control device is
When the cooling operation is not being performed, regardless of whether the expansion device is open or closed, the valve is closed, and when the pressure value of the refrigerant detected by the pressure sensor becomes equal to or higher than a first predetermined pressure value, recovery of the refrigerant in the evaporator is started;
The refrigeration apparatus, wherein the first predetermined pressure value is set to a value higher than a range of pressure values of the refrigerant detected by the pressure sensor while the cooling operation is being performed. The first control device is
2. The refrigeration device according to claim 1, wherein when recovery of the refrigerant in the evaporator is being performed, recovery of the refrigerant in the evaporator is stopped when the pressure value of the refrigerant detected by the pressure sensor becomes equal to or lower than a second predetermined pressure value that is lower than the first predetermined pressure value.

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