EP3872419A1

EP3872419A1 - Refrigeration apparatus

Info

Publication number: EP3872419A1
Application number: EP21159101.1A
Authority: EP
Inventors: Gaku Shimada; Yuichi Izawa
Original assignee: Panasonic Intellectual Property Management Co Ltd
Current assignee: Panasonic Intellectual Property Management Co Ltd
Priority date: 2020-02-28
Filing date: 2021-02-24
Publication date: 2021-09-01
Also published as: JP2021135020A; JP7482438B2

Abstract

The refrigeration apparatus performs the cooling operation by using a refrigerant circuit in which a refrigerant circulates through a compressor, a condenser, an expansion apparatus, and an evaporator in this order. The refrigeration apparatus includes: a pressure sensor that detects a pressure value of the refrigerant; and a control device that controls a flow of the refrigerant. In a case where the cooling operation is not performed, the control device starts recovery of the refrigerant within the evaporator when the pressure value of the refrigerant detected by the pressure sensor becomes greater than or equal to a first predetermined pressure value. The first predetermined pressure value is set to a value higher than a range of the pressure value detected by the pressure sensor in a case where the cooling operation is performed.

Description

Technical Field

The present invention relates to a refrigeration apparatus.

Background Art

Patent Literature (hereinafter, referred to as "PTL") 1 describes a refrigeration apparatus in which cooling operation is performed using a refrigerant circuit in which a refrigerant circulates. The refrigeration apparatus performs defrosting operation to remove frost generated in a cooler (evaporator) that cools the interior of a showcase or a refrigerated warehouse disposed in a store, for example. While the defrosting operation is performed, a compressor within the refrigeration apparatus does not operate and the refrigerant does not circulate. Further, in a case where the showcase, the refrigerated warehouse or the like is sufficiently cooled or even in a case where cooling is not required for some reason, the compressor does not operate and the refrigerant does not circulate.

Citation List

Patent Literature

PTL 1
Japanese Patent Application Laid-Open No. 2018-66514

Summary of Invention

Technical Problem

In defrosting operation performed while cooling operation stops, frost is generally melted by heating an evaporator by using an electric heater or hot gas. It is conceivable that a refrigerant remaining in the evaporator evaporates by heating during defrosting so that pressure within the evaporator increases. It is also conceivable that even in a case where the outside air temperature rises when the cooling operation has not been performed for a long time, the refrigerant remaining in the evaporator evaporates so that the pressure within the evaporator increases. In a case where the pressure within the evaporator becomes relatively large thereby, it is conceivable that a problem such as breakage of the evaporator occurs.
An object of the present disclosure is to provide a refrigeration apparatus capable of suppressing pressure within an evaporator when cooling operation is not performed.

Solution to Problem

To achieve the object described above, the refrigeration apparatus in the present disclosure is a refrigeration apparatus that performs cooling operation by using a refrigerant circuit in which a refrigerant circulates through a compressor, a condenser, an expansion apparatus, and an evaporator in this order, the refrigeration apparatus including: a pressure sensor that detects a pressure value of the refrigerant; and a control device that controls a flow of the refrigerant, wherein in a case where the cooling operation is not performed, the control device starts recovery of the refrigerant within the evaporator when the pressure value of the refrigerant detected by the pressure sensor becomes greater than or equal to a first predetermined pressure value, wherein the first predetermined pressure value is set to a value higher than a range of the pressure value detected by the pressure sensor in a case where the cooling operation is performed.

Advantageous Effects of Invention

According to the refrigeration apparatus of the present disclosure, it is possible to suppress pressure within an evaporator when cooling operation is not performed.

Brief Description of Drawings

FIG. 1 is a schematic view of a refrigeration apparatus according to an embodiment of the present disclosure; and
FIG. 2 is a flowchart of a program to be executed by a control device illustrated in FIG. 1.

Description of Embodiments

Hereinafter, the refrigeration apparatus of the present disclosure will be described with reference to the accompanying drawings. Note that, although a preferred embodiment of the refrigeration apparatus of the present disclosure will be described below, the refrigeration apparatus of the present disclosure is not limited thereto and various changes and improvements can be made based on the knowledge of those skilled in the art.
FIG. 1 is a schematic view of refrigeration apparatus 1. Refrigeration apparatus 1 is configured to perform cooling operation by using refrigerant circuit 50 in which a refrigerant (not illustrated) circulates through compressor 10, gas cooler 20, electric expansion valve 30, and evaporator 40 in this order. Gas cooler 20 is an example of "condenser". Electric expansion valve 30 is an example of "expansion apparatus".
The refrigerant is carbon dioxide. Note that, as an oil as a lubricant, an existing oil such as a mineral oil, an alkylbenzene oil, an ether oil, an ester oil, and PAG (polyalkyl glycol) is used, for example. However, the type of the oil is not limited thereto.
Refrigerator 1 includes compressor 10 and gas cooler 20. Compressor 10 and gas cooler 20 are housed in housing 1a. Note that, compressor 10 and gas cooler 20 may be disposed in separate housings. Further, housing 1a houses intercooler 52a, oil separator 53a, three expansion valves 53b, 56a and 57a, tank 21, split heat exchanger 54a, valve 54b, pressure sensor 51a, and control device 60 (each of which will be described later). Note that, valve 54b is included in a configuration of a variation of the present embodiment and therefore will be described later.
Electric expansion valve 30 and evaporator 40 are disposed outside housing 1a. Showcase 2 is disposed outside housing 1a. Showcase 2 is configured to be disposed at a store of a supermarket or the like, and the interior thereof is configured to be cooled by refrigeration apparatus 1. Electric expansion valve 30 is disposed outside showcase 2. Evaporator 40 is stored in showcase 2.
Refrigerant circuit 50 includes four main pipes 51 to 54 and three sub pipes 55 to 57. First main pipe 51 is configured to connect between evaporator 40 and first suction port 10a of compressor 10. A low-pressure refrigerant flowing out of evaporator 40 flows into compressor 10 via first main pipe 51.
Compressor 10 is an internal intermediate type two-stage compression type rotary compressor. Compressor 10 includes first compression section 11 and second compression section 12. First compression section 11 and second compression section 12 are rotary compressors.
First compression section 11 is configured to boost a low-pressure refrigerant sucked through first suction port 10a up to an intermediate pressure, and to discharge the refrigerant from first discharge port 10b into second main pipe 52. Second main pipe 52 is configured to connect between first discharge port 10b and second suction port 10c of compressor 10. Intercooler 52a is disposed in second main pipe 52.
Intercooler 52a is configured to air-cool a refrigerant discharged from first compression section 11. An intermediate-pressure refrigerant air-cooled by intercooler 52a is sucked through second suction port 10c into second compression section 12 via second main pipe 52.
Second compression section 12 is configured to compress an intermediate-pressure refrigerant sucked through second suction port 10c up to a high temperature and a high pressure, and to discharge the refrigerant from second discharge port 10d into third main pipe 53. Note that, compressor 10 may be, for example, a reciprocating compressor or a screw compressor. Further, compressor 10 may not be of a multi-stage type. In this case, intercooler 52a is not configured.
Third main pipe 53 is configured to connect between compressor 10 and inlet 21a disposed in an upper part of tank 21. In third main pipe 53, oil separator 53a, gas cooler 20, and first expansion valve 53b are disposed in this order from a side of compressor 10 toward a side of tank 21.
Oil separator 53a is configured to separate an oil included in a refrigerant discharged from compressor 10. An oil separated from a refrigerant is returned from oil separator 53a to compressor 10 via first sub pipe 55. Note that, refrigeration apparatus 1 may not include oil separator 53a.
Gas cooler 20 is a condenser that cools and condenses a high-temperature and high-pressure refrigerant flowing out of compressor 10 and further oil separator 53a. First blower 20a is disposed near gas cooler 20. First blower 20a is configured to air-cool gas cooler 20. First blower 20a is controlled by control device 60. In the present embodiment, gas cooler 20 and intercooler 52a are arranged side by side, and both are air-cooled by first blower 20a.
First expansion valve 53b is configured to throttle and expand a refrigerant flowing out of gas cooler 20, and to adjust pressure of a refrigerant on an upstream side from first expansion valve 53b. A refrigerant flowing out of first expansion valve 53b flows into tank 21 through inlet 21a.
Tank 21 is a volume body including a space of a predetermined volume therein. Tank 21 has a role of adjusting pressure of a refrigerant on an upstream side from tank 21, and a role of absorbing a fluctuation in a flow rate per unit time of a refrigerant. Further, a refrigerant that has flown into tank 21 is separated into a gas and a liquid, and the liquid refrigerant is stored in a bottom part of tank 21. The gaseous refrigerant staying in an upper part of tank 21 has a temperature lower than a temperature of the liquid refrigerant stored in the bottom part of tank 21.
The gaseous refrigerant staying in the upper part of tank 21 flows out into second sub pipe 56 through first outlet 21b. Second sub pipe 56 is configured to connect between first outlet 21b and first connection part 52b provided between intercooler 52a in second main pipe 52 and second suction port 10c. In second sub pipe 56, second expansion valve 56a and split heat exchanger 54a are disposed in this order from a side of tank 21 toward first connection part 52b.
Second expansion valve 56a has a role of throttling a gaseous refrigerant flowing out of first outlet 21b, and has a role of adjusting pressure within tank 21. A refrigerant flowing out of second expansion valve 56a flows into split heat exchanger 54a.
Split heat exchanger 54a is a heat exchanger that uses a refrigerant flowing through second sub pipe 56 into split heat exchanger 54a and thereby cools a refrigerant flowing through another pipe (fourth main pipe 54 to be described later). A refrigerant flowing through second sub pipe 56 from split heat exchanger 54a flows from first connection part 52b into second main pipe 52.
On the other hand, a liquid refrigerant stored in the bottom part of tank 21 flows out of second outlet 21c and third outlet 21d.
A refrigerant flowing out of second outlet 21c flows through third sub pipe 57. Third sub pipe 57 is configured to connect between second outlet 21c and second connection part 56b provided between second expansion valve 56a in second sub pipe 56 and split heat exchanger 54a. Third expansion valve 57a is disposed in third sub pipe 57. A refrigerant flowing out of second outlet 21c is throttled by third expansion valve 57a, flows from second connection part 56b into second sub pipe 56, and evaporates.
On the other hand, a refrigerant flowing out of third outlet 21d flows through fourth main pipe 54. Fourth main pipe 54 is configured to connect between third outlet 21d and evaporator 40. In fourth main pipe 54, split heat exchanger 54a and electric expansion valve 30 are disposed in this order from a side of tank 21 toward a side of evaporator 40.
A refrigerant flowing through fourth main pipe 54 into split heat exchanger 54a is cooled by a refrigerant flowing through another pipe (second sub pipe 56 described above), and flows out toward electric expansion valve 30. Note that, refrigeration apparatus 1 may not include split heat exchanger 54a. In this case, refrigeration apparatus 1 may not include tank 21, three expansion valves 53b, 56a and 57a, and fourth main pipe 54. Further, in this case, third main pipe 53 connects between compressor 10 and evaporator 40, and oil separator 53a, gas cooler 20, and electric expansion valve 30 are disposed in this order from a side of compressor 10 toward a side of evaporator 40.
Electric expansion valve 30 is configured to throttle a refrigerant flowing out of split heat exchanger 54a. Electric expansion valve 30 has an opening controlled by a control device (not illustrated) other than control device 60 such that the degree of superheat of a refrigerant in evaporator 40 becomes an appropriate value. The other control device is configured to control a temperature inside showcase 2.
Evaporator 40 is configured to cool the interior of showcase 2. Evaporator 40 is of a plate fin tube type, and includes a tube (not illustrated) through which a refrigerant flows, and a fin (not illustrated) which releases heat of a refrigerant. Second blower 41 that blows air within showcase 2 into the fin and the tube is disposed near evaporator 40. Second blower 41 is controlled by the other control device described above. A refrigerant that has flown into evaporator 40 evaporates, and thereby the air blown by second blower 41 and further the interior of showcase 2 are cooled.
A refrigerant flowing out of evaporator 40 is sucked into compressor 10 via first main pipe 51. Pressure sensor 51a is disposed in first main pipe 51.
Pressure sensor 51a is configured to detect a pressure value of a refrigerant. Pressure sensor 51a is disposed between evaporator 40 and compressor 10 in refrigerant circuit 50. In this case, pressure sensor 51a detects a pressure value within first main pipe 51. A result detected by pressure sensor 51a is output to control device 60.
Further, defrosting apparatus 42 is disposed in evaporator 40. Defrosting apparatus 42 is configured to perform defrosting within evaporator 40. Defrosting apparatus 42 is controlled by the other control device described above. Defrosting apparatus 42 is of an electric heater system. Defrosting apparatus 42 includes an electric heater (not illustrated) and a temperature sensor (not illustrated).
The electric heater is configured to generate heat by being energized. The electric heater is a sheathed heater. The electric heater is disposed near the tube of evaporator 40. The temperature sensor is configured to detect a temperature within evaporator 40. A result detected by the temperature sensor is output to the other control device described above.
Control device 60 is configured to collectively control refrigeration apparatus 1. Control device 60 performs cooling operation by controlling a flow of a refrigerant. In a case where the cooling operation is performed, operation of compressor 10 is performed and a refrigerant circulates through refrigerant circuit 50. Furthermore, in a case where the cooling operation is performed, the other control device described above controls the opening of electric expansion valve 30 and second blower 41 and the interior of showcase 2 is cooled.
Further, control device 60 performs refrigerant recovery control in which a refrigerant within evaporator 40 is recovered.
Hereinafter, the refrigerant recovery control performed by control device 60 will be described with reference to a flowchart illustrated in FIG. 2. The refrigerant recovery control is performed in a case where the cooling operation is not performed. In a case where the cooling operation is not performed, the operation of compressor 10 is stopped by control device 60. Thus, the circulation of refrigerant in refrigerant circuit 50 stops. Further, in a case where the cooling operation is not performed, the other control device described above closes electric expansion valve 30 and stops driving of second blower 41.
In S10, control device 60 determines whether a pressure value detected by pressure sensor 51a (hereinafter, referred to as "detected pressure value") is greater than or equal to a first predetermined pressure value.
The first predetermined pressure value is set to a value higher than a range of the detected pressure value in a case where the cooling operation is performed. Specifically, the first predetermined pressure value is set to a pressure value higher than the detected pressure value in a case where a refrigerant circulates through refrigerant circuit 50 and the interior of showcase 2 is normally cooled. Furthermore, the first predetermined pressure value is set to a pressure value lower than a pressure value at which evaporator 40 may fail.
In a case where the detected pressure value is lower than the first predetermined pressure value, control device 60 determines NO in S10, and repeatedly executes S10. In this case, a state in which the operation of compressor 10 stops is continued.
In a case where the outside air temperature rises when the cooling operation is stopped, the temperature within evaporator 40 rises. Further, since the electric heater is energized in a case where the cooling operation is stopped and the defrosting operation is performed, the temperature within evaporator 40 rises. Since the refrigerant evaporates by the temperature rise, the pressure of the refrigerant and further the detected pressure value rise.
Thus, in a case where the detected pressure value becomes greater than or equal to the first predetermined pressure value, control device 60 determines YES in S10, and starts the operation of compressor 10 in S11. When the operation of compressor 10 is started, the refrigerant within evaporator 40 flows out into first main pipe 51. At this time, as described above, electric expansion valve 30 is closed so that the refrigerant does not flow into evaporator 40. Accordingly, the refrigerant within evaporator 40 is recovered onto a side of compressor 10 (downstream side) from evaporator 40 in refrigerant circuit 50. Thus, the refrigerant within evaporator 40 is recovered by the operation of compressor 10.
Subsequently, in S12, control device 60 determines whether the detected pressure value is less than or equal to a second predetermined pressure value. The second predetermined pressure value is set to a pressure value lower than the first predetermined pressure value. Further, the second predetermined pressure value is set to a value higher than the range of the detected pressure value in a case where the cooling operation is performed.
In a case where the detected pressure value is higher than the second predetermined pressure value, control device 60 determines NO in S12, and repeatedly executes S12. In this case, the operation of compressor 10 is continued.
The refrigerant within evaporator 40 is recovered by the operation of compressor 10, and thereby the amount of the refrigerant within evaporator 40 decreases. Accordingly, the pressure of the refrigerant and further the detected pressure value decrease. Thus, in a case where the detected pressure value becomes less than or equal to the second predetermined pressure value, control device 60 determines YES in S12, and stops the operation of compressor 10 in S13. When the operation of compressor 10 is stopped, the recovery of the refrigerant within evaporator 40 is stopped. Subsequently, control device 60 returns the program to S10.
As seen above, in a case where the cooling operation is not performed, control device 60 controls the operation of compressor 10 based on the detected pressure value, and starts or stops the recovery of the refrigerant within evaporator 40.
Refrigeration apparatus 1 of the embodiment described above is a refrigeration apparatus that performs cooling operation by using refrigerant circuit 50 in which a refrigerant circulates through compressor 10, gas cooler 20, electric expansion valve 30, and evaporator 40 in this order. Refrigeration apparatus 1 includes pressure sensor 51a that detects a pressure value of the refrigerant, and control device 60 that controls a flow of the refrigerant. In a case where the cooling operation is not performed, control device 60 starts recovery of the refrigerant within evaporator 40 when the pressure value of the refrigerant detected by pressure sensor 51a becomes greater than or equal to a first predetermined pressure value. The first predetermined pressure value is set to a value higher than a range of the pressure value detected by pressure sensor 51a in a case where the cooling operation is performed.
Thus, in a case where the cooling operation is not performed, refrigeration apparatus 1 is capable of suppressing pressure within evaporator 40. Further, since the recovery of the refrigerant does not start in a case where the pressure value of the refrigerant is lower than the first predetermined pressure value, it is possible to suppress energy and time for driving compressor 10.
Further, in a case where the recovery of the refrigerant within evaporator 40 is executed, control device 60 stops the recovery of the refrigerant within evaporator 40 when the pressure value of the refrigerant detected by pressure sensor 51a becomes less than or equal to a second predetermined pressure value that is lower than the first predetermined pressure value.
Thus, the operation of compressor 10 is stopped when the pressure value of the refrigerant becomes less than or equal to the second predetermined pressure value after the recovery of the refrigerant is started. Accordingly, it is possible to further suppress the energy and time for driving compressor 10.
Although refrigeration apparatus 1 according to one or more aspects has been described thus far based on the embodiment, the present disclosure is not limited to this embodiment. The present embodiment to which various modifications conceived by those skilled in the art are applied or forms constructed by combining constituent elements in different embodiments may also be within the scope of the one or more aspects as long as they do not depart from the gist of the present disclosure.
In the embodiment described above, refrigeration apparatus 1 may be configured to include valve 54b. Valve 54b is configured to be disposed between gas cooler 20 and evaporator 40 in refrigerant circuit 50, to allow the flow of the refrigerant in a case where valve 54b is in an open state, and to regulate the flow of the refrigerant in a case where valve 54b is in a closed state. Specifically, valve 54b is disposed between split heat exchanger 54a and electric expansion valve 30 in refrigerant circuit 50. Control device 60 brings valve 54b into the closed state in a case where the cooling operation is stopped.
Thus, valve 54b is brought into the closed state, and thereby flowing of the refrigerant into evaporator 40 from a side of gas cooler 20 is surely regulated. Accordingly, in the refrigerant recovery control, the refrigerant within evaporator 40 is surely recovered by the operation of compressor 10.
Further, electric expansion valve 30 of the embodiment described above may be changed to a capillary tube.
Further, in the embodiment described above, pressure sensor 51a is disposed between evaporator 40 and compressor 10 in refrigerant circuit 50, but may also be disposed at another site in refrigerant circuit 50 instead thereof. Further, pressure sensor 51a may also be disposed within evaporator 40.

Industrial Applicability

The present disclosure can be widely utilized for refrigeration apparatuses.

Reference Signs List

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

Claims

A refrigeration apparatus that performs cooling operation by using a refrigerant circuit in which a refrigerant circulates through a compressor, a condenser, an expansion apparatus, and an evaporator in this order, the refrigeration apparatus comprising:
a pressure sensor that detects a pressure value of the refrigerant; and

a control device that controls a flow of the refrigerant, wherein

in a case where the cooling operation is not performed, the control device starts recovery of the refrigerant within the evaporator when the pressure value of the refrigerant detected by the pressure sensor becomes greater than or equal to a first predetermined pressure value, wherein
the first predetermined pressure value is set to a value higher than a range of the pressure value detected by the pressure sensor in a case where the cooling operation is performed.
The refrigeration apparatus according to claim 1, wherein in a case where the recovery of the refrigerant within the evaporator is executed, the control device stops the recovery of the refrigerant within the evaporator when the pressure value of the refrigerant detected by the pressure sensor becomes less than or equal to a second predetermined pressure value that is lower than the first predetermined pressure value.
The refrigeration apparatus according to claim 1 or 2, further comprising a valve disposed between the condenser and the evaporator in the refrigerant circuit, the valve allowing the flow of the refrigerant in a case where the valve is in an open state, and regulating the flow of the refrigerant in a case where the valve is in a closed state, wherein
the control device executes the recovery of the refrigerant within the evaporator by bringing the valve into the closed state and driving the compressor.