WO2020115847A1

WO2020115847A1 - Refrigeration cycle device

Info

Publication number: WO2020115847A1
Application number: PCT/JP2018/044774
Authority: WO
Inventors: 昌彦中川; 山下　浩司; 充川島; 千尋江口; 洋一安西; 大林　誠善
Original assignee: 三菱電機株式会社; 三菱電機冷熱応用システム株式会社
Priority date: 2018-12-05
Filing date: 2018-12-05
Publication date: 2020-06-11

Abstract

A refrigeration cycle device (100) comprises a housing (1) and a refrigerant circuit (10). The housing (1) includes a storage chamber (11) and a flow path (12). The refrigerant circuit (10) is housed in the housing (1) and includes a compressor (2), a condenser (3), an expansion device (4), an evaporator (5), and a backflow prevention device (6). The expansion device (4) includes an opening-closing valve (4a) that is configured so as to be capable of opening and closing the refrigerant circuit (10). The refrigerant circuit (10) is configured so as to be capable of executing a pump-down operation in which the compressor (2) is operated while the refrigerant is prevented from flowing backward from the compressor (2) to the evaporator (5) by the backflow prevention device (6) and the refrigerant circuit (10) is closed by the opening-closing valve (4a).

Description

Refrigeration cycle equipment

The present invention relates to a refrigeration cycle device.

Conventionally, a showcase having a storage room for storing food etc. has been used as a refrigeration cycle device. In this showcase, for example, as described in WO 2014/178312 (Patent Document 1), a flow path separated by a partition from a machine room in which a compressor, a condenser and an expansion valve are arranged. The evaporator is located at. The evaporator is arranged above the compressor, the condenser and the expansion valve. The air cooled by exchanging heat with the refrigerant in the evaporator is supplied to the storage chamber through the flow path.

International Publication No. 2014/178312

The refrigerant leak in the above showcase often occurs in the evaporator due to the refrigerant leak from the fin pipe due to the thinness of the fin pipe of the evaporator. When the refrigerant leaks in the evaporator, the refrigerant flows into the storage chamber through the flow path. When the refrigerant has a specific gravity that is heavier than that of air, the leaked refrigerant is much retained in the storage compartment. If this refrigerant is flammable, the refrigerant that has accumulated in the storage compartment may explode.

The present invention has been made in view of the above problems, and an object thereof is to propose a refrigeration cycle device capable of suppressing refrigerant from accumulating in the storage compartment.

The refrigeration cycle device of the present invention includes a housing and a refrigerant circuit. The housing includes a storage chamber and a flow path communicating with the storage chamber. The refrigerant circuit is housed in the housing and includes a compressor, a condenser, an expansion device, an evaporator, and a backflow prevention device. The expansion device includes an on-off valve configured to open and close the refrigerant circuit. The refrigerant circuit is configured such that a refrigerant having a specific gravity heavier than air flows in the order of the compressor, the condenser, the expansion device, and the evaporator. The backflow prevention device is disposed on at least one of the upstream side and the downstream side of the compressor, and is configured to prevent the refrigerant from flowing back from the compressor to the evaporator. The evaporator is housed in the flow path and is located above the compressor, the condenser, the expansion device and the backflow prevention device. The refrigerant circuit prevents the refrigerant from flowing backward from the compressor to the evaporator by the backflow prevention device, and enables the pump down operation in which the compressor is operated with the refrigerant circuit closed by the opening/closing valve. It is configured.

According to the refrigeration cycle apparatus of the present invention, the refrigerant circuit prevents the refrigerant from flowing backward from the compressor to the evaporator by the backflow prevention device, and the compressor is operated in a state where the refrigerant circuit is closed by the opening/closing valve. It is configured to be able to execute the pump down operation to be operated. Therefore, it is possible to confine the refrigerant in the refrigerant circuit from the backflow prevention device to the on-off valve via the condenser. Therefore, it is possible to prevent the refrigerant from leaking from the evaporator. As a result, it is possible to prevent the refrigerant having a specific gravity that is heavier than air from staying in the storage compartment.

It is a schematic sectional drawing of the refrigerating-cycle apparatus which concerns on Embodiment 1 of this invention. It is a functional block diagram of a control device of a refrigerating cycle device concerning Embodiment 1 of the present invention. It is a schematic sectional drawing at the time of pump down operation of the refrigerating cycle device concerning Embodiment 1 of the present invention. 3 is a flowchart showing control for determining whether or not refrigerant leakage has occurred in the refrigeration cycle device according to Embodiment 1 of the present invention. It is a flowchart which shows the continuation of FIG. It is a schematic sectional drawing of the modification 1 of the refrigerating-cycle apparatus which concerns on Embodiment 1 of this invention. It is a schematic sectional drawing of the modification 2 of the refrigerating-cycle apparatus which concerns on Embodiment 1 of this invention. It is a schematic sectional drawing of the modification 3 of the refrigerating-cycle apparatus which concerns on Embodiment 1 of this invention. It is a schematic sectional drawing of the modification 4 of the refrigerating-cycle apparatus which concerns on Embodiment 1 of this invention. It is a schematic sectional drawing of the modification 5 of the refrigerating-cycle apparatus which concerns on Embodiment 1 of this invention. It is a schematic sectional drawing of the refrigerating-cycle apparatus which concerns on Embodiment 2 of this invention. 5 is a flowchart showing control for determining whether or not refrigerant leakage has occurred in the refrigeration cycle device according to Embodiment 2 of the present invention. It is a flowchart which shows the continuation of FIG.

Embodiments of the present invention will be described below with reference to the drawings. In the following, the same or corresponding parts will be denoted by the same reference symbols and description thereof will not be repeated in principle.

Embodiment 1.

The configuration of the refrigeration cycle apparatus 100 according to Embodiment 1 of the present invention will be described with reference to FIG. The refrigeration cycle apparatus 100 according to Embodiment 1 of the present invention is, for example, a showcase. Hereinafter, refrigeration cycle apparatus 100 according to Embodiment 1 of the present invention will be described in a state of being installed on the floor, the ground, or the like. The white arrows in the figure indicate the flow of cooled air.

As shown in FIG. 1, the refrigeration cycle apparatus 100 according to Embodiment 1 of the present invention includes a housing 1, a condenser fan 7, an evaporator fan 8, a refrigerant circuit 10, and a control device 20. I have it.

The refrigerant circuit 10 is housed in the housing 1. The refrigerant circuit 10 includes a compressor 2, a condenser 3, an expansion device 4, an evaporator 5, and a backflow prevention device 6. A refrigerant circuit 10 is configured by connecting the compressor 2, the condenser 3, the expansion device 4, the evaporator 5, and the backflow prevention device 6 by piping. The refrigerant circuit 10 is configured so that the refrigerant flows in the order of the compressor 2, the condenser 3, the expansion device 4, and the evaporator 5. The refrigerant circuit 10 is configured to be able to circulate the refrigerant.

The refrigerant has a heavier specific gravity than air. The refrigerant is, for example, an HC (hydrocarbon) refrigerant. More specifically, the refrigerant is propane (R290), for example, and has a specific gravity of about 1.52. Refrigerants such as propane are flammable. The refrigerant is not limited to this, and may be any refrigerant having a specific gravity heavier than air.

The compressor 2 is configured to compress the sucked refrigerant and discharge it. The compressor 2 has a variable capacity. The compressor 2 is configured so that the capacity is changed by changing the frequency based on an instruction from the control device 20 and adjusting the rotation speed.

The condenser 3 is configured to condense the refrigerant compressed by the compressor 2. The condenser 3 is connected to the compressor 2 and the expansion device 4. The condenser 3 is, for example, a fin-and-tube heat exchanger having a plurality of fins and a circular tube or a flat tube heat transfer tube that penetrates the plurality of fins.

The expansion device 4 is configured to expand the refrigerant condensed by the condenser 3 to reduce the pressure. The expansion device 4 is connected to the condenser 3 and the evaporator 5. The expansion device 4 is, for example, an electric valve or the like that can adjust the flow rate of the refrigerant based on an instruction from the control device 20. The expansion device 4 includes an on-off valve 4a. The on-off valve 4a is configured to open and close the refrigerant circuit 10. The on-off valve 4a is configured to be able to fully close the refrigerant circuit 10. The on-off valve 4a is, for example, a solenoid valve. The expansion device 4 and the on-off valve 4a may be integrally configured, or may be a motor-operated valve with a fully closing function. The expansion device 4 is preferably provided in the machine room 13, but may be provided in the storage room 11.

The evaporator 5 is configured to evaporate the refrigerant decompressed by the expansion device 4. In the present embodiment, the evaporator 5 is connected to the expansion device 4 and the compressor 2. The evaporator 5 is, for example, a fin-and-tube heat exchanger having a plurality of fins and a circular tube or a flat tube heat transfer tube that penetrates the plurality of fins.

The backflow prevention device 6 is configured to prevent the backflow of the refrigerant from the compressor 2 toward the evaporator 5. The backflow prevention device 6 is arranged on at least one of the upstream side and the downstream side of the compressor 2. In Embodiment 1 of the present invention, the backflow prevention device 6 is arranged in the refrigerant circuit 10 on the upstream side of the compressor 2. That is, the backflow prevention device 6 is arranged on the suction side of the compressor 2 in the refrigerant circuit 10. In this case, the backflow prevention device 6 is arranged in the refrigerant circuit 10 between the compressor 2 and the evaporator 5.

The backflow prevention device 6 may be arranged on the downstream side of the compressor 2 in the refrigerant circuit 10. That is, the backflow prevention device 6 may be arranged on the discharge side of the compressor 2 in the refrigerant circuit 10. In this case, the backflow prevention device 6 is arranged in the refrigerant circuit 10 between the compressor 2 and the condenser 3.

The check valve 6 is, for example, a check valve. The check valve is configured to allow the refrigerant flow from the evaporator 5 toward the compressor 2 and block the refrigerant flow from the compressor 2 toward the evaporator 5.

The backflow prevention device 6 may be, for example, an on-off valve. This on-off valve is configured to open the refrigerant circuit 10 so that the refrigerant flows from the evaporator 5 toward the compressor 2 and close the refrigerant circuit 10 so that the refrigerant does not flow from the compressor 2 toward the evaporator 5. Has been done.

The condenser fan 7 is attached to the condenser 3 and is configured to supply air as a heat exchange fluid to the condenser 3. The condenser fan 7 adjusts the amount of air flowing around the condenser 3 by adjusting the number of revolutions of the condenser fan 7 based on an instruction from the control device 20, and thus the condenser fan 7 is operated between the air and the refrigerant. It is configured to adjust the amount of heat exchange.

The evaporator fan 8 is attached to the evaporator 5 and is configured to supply air as a heat exchange fluid to the evaporator 5. The evaporator fan 8 adjusts the amount of air flowing around the evaporator 5 by adjusting the number of revolutions of the evaporator fan 8 based on an instruction from the control device 20, and thereby the amount of air flowing between the air and the refrigerant is adjusted. It is configured to adjust the amount of heat exchange.

The control device 20 is housed in the housing 1. The control device 20 is configured to perform calculations, instructions, and the like to control each unit, device, and the like of the refrigeration cycle device 100. The control device 20 is electrically connected to the compressor 2, the expansion device 4, the condenser fan 7, the evaporator fan 8 and the like, and is configured to control the operations of these.

In the refrigeration cycle device 100 according to Embodiment 1 of the present invention, the compressor 2, the condenser 3, the expansion device 4, the evaporator 5, the backflow prevention device 6, and the condensing device are provided in the same housing 1. The container fan 7, the evaporator fan 8, and the control device 20 are housed. That is, the refrigeration cycle apparatus 100 according to Embodiment 1 of the present invention is a built-in showcase.

The housing 1 includes a ceiling part 1a, a bottom part 1b, a front part 1c, a back part 1d, and a side part (not shown). The ceiling portion 1a faces the bottom portion 1b. The direction in which the ceiling portion 1a and the bottom portion 1b face each other is the vertical direction. The front part 1c faces the back part 1d. The front-back direction is the direction in which the front surface portion 1c and the rear surface portion 1d face each other.

In the first embodiment of the present invention, the front portion 1c includes a door 1c1 that can be opened and closed. The housing 1 is provided with an opening OP on the front surface 1c. The opening OP is provided so as to communicate with the storage chamber 11. The door 1c1 is configured to open and close the opening OP. The storage chamber 11 is opened by opening the door 1c1, and the storage chamber 11 is closed by closing the door 1c1. Products and the like are put into and taken out of the storage chamber 11 with the door 1c1 opened. Refrigeration cycle apparatus 100 according to Embodiment 1 of the present invention is a closed type showcase. More specifically, refrigeration cycle apparatus 100 according to Embodiment 1 of the present invention is a reach-in showcase.

Further, the housing 1 includes a storage chamber 11, a flow path 12, a machine room 13, and a partition wall 14. The storage room 11 is for refrigerating or freezing a product or the like. The temperature of the storage chamber 11 is, for example, about 0° C. or higher and 10° C. or lower in the case of refrigeration, and is −20° C. or higher and −10° C. or lower in the case of freezing. A shelf (not shown) may be arranged in the storage chamber 11. In the first embodiment of the present invention, the region surrounded by the door 1c1 and the inner wall 11a of the storage chamber 11 is the storage chamber 11.

The storage chamber 11 and the flow path 12 are separated by the inner wall 11 a of the storage chamber 11. The regions between the inner wall 11a of the storage chamber 11 and the ceiling portion 1a, between the inner wall 11a and the back surface portion 1d, and between the inner wall 11a and the partition wall 14 serve as the flow path 12.

The flow path 12 communicates with the storage room 11. Specifically, the flow path 12 communicates with the storage chamber 11 through the air outlet 11b and the suction port 11c provided on the inner wall 11a of the storage chamber 11. In Embodiment 1 of the present invention, the air outlet 11b is arranged at the upper end of the storage chamber 11, and the suction port 11c is arranged at the lower end of the storage chamber 11.

The evaporator 5 and the evaporator fan 8 are housed in the flow path 12. The evaporator 5 is located above the compressor 2, the condenser 3, the expansion device 4, and the backflow prevention device 6. In the first embodiment of the present invention, the expansion device 4 is housed in the flow path 12. The expansion device 4 is located above the condenser 3. The expansion device 4 is arranged above the condenser 3 in which the refrigerant is confined in the gravity direction. The expansion device 4 is located below the center of the evaporator 5. The expansion device 4 is arranged below the center of the evaporator 5 in the gravity direction.

The flow path 12 is separated from the machine room 13. Specifically, the flow path 12 is separated from the machine room 13 by a partition wall 14. That is, the flow path 12 and the machine room 13 are separated from each other by the partition wall 14. The flow path 12 is arranged above the machine room 13. A compressor 2, a condenser 3, a backflow prevention device 6, a condenser fan 7, and a control device 20 are housed in the machine room 13.

The refrigerant circuit 10 is configured to be able to execute a cooling operation in which the refrigerant flows in the order of the compressor 2, the condenser 3, the expansion device 4, and the evaporator 5. Further, the refrigerant circuit 10 is configured to be able to perform a defrost (defrost) operation for removing frost formation on the evaporator 5. Further, in the refrigerant circuit 10, the backflow prevention device 6 prevents the refrigerant from flowing back from the compressor 2 toward the evaporator 5, and the compressor 2 operates with the on-off valve 4a closing the refrigerant circuit 10. It is configured to be able to execute the pump down operation.

The control device 20 according to the first embodiment of the present invention will be described in detail with reference to FIGS. 1 and 2. The control device 20 includes a control unit 21, a compressor drive unit 22, an expansion device drive unit 23, a condenser fan drive unit 24, an evaporator fan drive unit 25, a timer 26, and a storage unit 27. ing.

The control unit 21 controls the compressor drive unit 22, the expansion device drive unit 23, and the condensing unit based on signals from the timer 26, the storage unit 27, the pressure measuring device (not shown), the temperature measuring device (not shown), and the like. The controller fan drive unit 24 and the evaporator fan drive unit 25 are configured to be controlled.

The compressor drive unit 22 is configured to drive the compressor 2 based on an instruction from the control unit 21. Specifically, the compressor drive unit 22 is configured to control the rotation speed of the motor of the compressor 2 by controlling the frequency of the alternating current flowing through the motor (not shown) of the compressor 2. ..

The expansion device drive unit 23 is configured to drive the expansion device 4 based on an instruction from the control unit 21. Specifically, the expansion device drive unit 23 is configured to control the opening degree of the on-off valve 4a of the expansion device 4 by controlling a drive source such as a motor (not shown) attached to the expansion device 4. Has been done.

The condenser fan drive unit 24 is configured to drive the condenser fan 7 based on an instruction from the control unit 21. Specifically, the rotation speed of the condenser fan 7 is controlled by controlling a drive source such as a motor (not shown) attached to the condenser fan 7.

The evaporator fan drive unit 25 is configured to drive the evaporator fan 8 based on an instruction from the control unit 21. Specifically, the rotation speed of the evaporator fan 8 is controlled by controlling a drive source such as a motor (not shown) attached to the evaporator fan 8.

The timer 26 is configured to measure time and send a signal based on the time to the control unit 21. The storage unit 27 is configured to store signals from the timer 26, a pressure measuring device (not shown), a temperature measuring device (not shown), and the like.

A pressure measuring device (not shown) is attached to the refrigerant circuit 10, and is configured to measure the pressure of the refrigerant and send a signal based on the pressure to the control unit 21. The temperature measuring device (not shown) is attached to the refrigerant circuit 10, and is configured to measure the temperatures of the refrigerant and the air and send a signal based on the temperature to the control unit 21.

The control device 20 calculates the refrigerant leakage amount of the refrigerant leaked from the refrigerant circuit 10 based on the refrigerant flowing through the refrigerant circuit 10, and the refrigerant leakage amount indicates the flammable region formation limit concentration of the refrigerant in the internal volume of the storage chamber 11. The refrigerant circuit 10 is configured to execute the pump-down operation before the multiplied calculated value is exceeded.

The control device 20 calculates the refrigerant leakage amount from the difference between the initial refrigerant charging amount charged in the refrigerant circuit 10 and the refrigerant amount in the refrigerant circuit calculated based on the refrigerant flowing in the refrigerant circuit 10, and the refrigerant leakage amount is An alarm is output when the calculated value is equal to or more than the allowable value obtained by multiplying the allowable coefficient.

The control device 20 calculates the refrigerant leakage amount from the difference between the initial refrigerant charging amount charged in the refrigerant circuit 10 and the refrigerant amount in the refrigerant circuit calculated based on the refrigerant flowing in the refrigerant circuit 10, and the refrigerant leakage amount is It is configured to output an abnormality when the calculated value is equal to or more than the dangerous value obtained by multiplying the dangerous coefficient.

Next, the operation of the refrigeration cycle apparatus 100 according to Embodiment 1 of the present invention will be described.

First, the cooling operation of the refrigeration cycle apparatus 100 according to Embodiment 1 of the present invention will be described with reference to FIGS. 1 and 2.

In the refrigerant circuit 10 shown in FIG. 1, in the cooling operation, the refrigerant circulates in the order of the compressor 2, the condenser 3, the expansion device 4, the evaporator 5, and the backflow prevention device 6. In this cooling operation, the expansion device 4 is opened by controlling a drive source such as a motor attached to the expansion device 4 based on an instruction from the control unit 21 of the control device 20. As a result, the on-off valve 4a included in the expansion device 4 opens the refrigerant circuit 10.

The refrigerant is compressed by the compressor 2. The refrigerant compressed by the compressor 2 becomes a high-temperature and high-pressure gas refrigerant and is discharged from the compressor 2. The high-temperature and high-pressure gas refrigerant discharged from the compressor 2 flows into the condenser 3. The high-temperature and high-pressure gas refrigerant flowing into the condenser 3 is condensed by heat exchange with the air blown by the condenser fan 7 in the condenser 3 to become a low-temperature and high-pressure liquid refrigerant. The low-temperature high-pressure liquid refrigerant flows into the expansion device 4. The low-temperature high-pressure liquid refrigerant that has flowed into the expansion device 4 is expanded in the expansion device 4 and is decompressed to become a low-temperature low-pressure gas-liquid two-phase refrigerant.

The low-temperature low-pressure gas-liquid two-phase refrigerant flows into the evaporator 5. The low-temperature low-pressure gas-liquid two-phase refrigerant that has flowed into the evaporator 5 evaporates due to heat exchange with the air blown by the evaporator fan 8 in the evaporator 5 to become a low-temperature low-pressure gas refrigerant. ..

The air cooled by heat exchange with the gas-liquid two-phase refrigerant in the evaporator 5 is supplied from the air outlet 11b to the storage chamber 11 by the evaporator fan 8. The cooled air chills or freezes the food or the like stored in the storage chamber 11. The air supplied to the storage chamber 11 from the air outlet 11b is sent to the flow path 12 from the suction port 11c.

The low-temperature low-pressure gas refrigerant flows into the compressor 2 via the backflow prevention device 6. The low-temperature low-pressure gas refrigerant flowing into the compressor 2 is compressed and discharged. In this way, the refrigerant circulates in the refrigerant circuit 10 while changing its phase.

Subsequently, the defrosting operation of the refrigeration cycle apparatus 100 according to Embodiment 1 of the present invention will be described with reference to FIGS. 1 and 2.

In the evaporator 5, since the temperature of the refrigerant is low, the temperature of the air passing through the evaporator 5 may be below the dew point, so that the evaporator 5 may be frosted. When frost is formed on the evaporator 5, a defrost operation is performed to remove the frost. The defrost operation in refrigeration cycle apparatus 100 according to Embodiment 1 of the present invention is a so-called off-cycle operation. That is, the frost on the evaporator 5 is warmed by the air blown from the evaporator fan 8 while the drive of the compressor 2 is stopped. As a result, the frost on the evaporator 5 is melted and removed from the evaporator 5.

Next, the pump down operation of the refrigeration cycle apparatus 100 according to Embodiment 1 of the present invention will be described with reference to FIGS. 2 and 3.

The pump down operation is for confining the refrigerant in the condenser 3 or the like in the refrigerant circuit 10. In FIG. 3, the pipe in which the refrigerant is confined during the pump-down operation is shown in bold. In the refrigerant circuit 10 shown in FIG. 3, in the pump down operation, the expansion device 4 controls the drive source such as a motor attached to the expansion device 4 based on an instruction from the control unit 21 of the control device 20. To be closed. As a result, the refrigerant circuit 10 is closed by the opening/closing valve 4a included in the expansion device 4.

In this state, when the compressor 2 is driven, the refrigerant flows from the evaporator 5 into the compressor 2 and the condenser 3 via the backflow prevention device 6. At this time, the backflow prevention device 6 prevents the refrigerant from backflowing from the compressor 2 to the evaporator 5. On the other hand, the refrigerant circuit 10 is closed by the opening/closing valve 4a included in the expansion device 4, so that the refrigerant does not flow from the expansion device 4 into the evaporator 5. Therefore, the refrigerant is trapped in the refrigerant circuit 10 that reaches the expansion device 4 from the backflow prevention device 6 via the compressor 2 and the condenser 3.

Further, the driving of the compressor 2 may be stopped after the pump down operation is completed. The refrigerant circuit 10 may be closed by the opening/closing valve 4a included in the expansion device 4 even after the driving of the compressor 2 is stopped. As a result, the refrigerant does not flow into the evaporator 5 from the expansion device 4 even after the driving of the compressor 2 is stopped. Further, the backflow prevention device 6 prevents the refrigerant from backflowing from the compressor 2 to the evaporator 5. Therefore, even after the driving of the compressor 2 is stopped, the refrigerant is confined in the refrigerant circuit 10 from the backflow prevention device 6 to the expansion device 4 via the compressor 2 and the condenser 3.

With reference to FIGS. 1 to 5, in refrigeration cycle apparatus 100 according to Embodiment 1 of the present invention, it is determined whether or not refrigerant leakage has occurred as follows. First, the determination is started in a state where there is no disturbance element such as after the defrost operation is completed (S1).

The output of the condenser fan 7 is 100% (condenser fan output=100%), the output of the evaporator fan 8 is 100% (evaporator fan output=100%), and the frequency of the compressor 2 is 60 Hz( Frequency=60 Hz) (S2). Subsequently, the condensation temperature CT(i) is measured every 5 seconds, and the data for the latest 3 minutes are stored (S3). The condensation temperature CT(i) is the temperature of the refrigerant inside the condenser 3 measured by a temperature measuring device (not shown). The most recent 3 minutes are measured by the timer 26. The data of the measured condensation temperature CT(i) is stored in the storage unit 27.

The temperature difference between the maximum value CT(i)MAX of the condensation temperature CT(i) and the minimum value CT(i)MIN of the condensation temperature CT(i) in the data of the condensation temperature CT(i) measured in the last 3 minutes is It is determined whether it is 0.5 Kelvin (K) or less (S4). This determination is made by the control unit 21 based on signals from the timer 26 and the storage unit 27. As a result, it is determined whether the high pressure is stable. When the temperature difference exceeds 0.5K, determination is performed again until the temperature difference becomes 0.5K or less (S4).

When the temperature difference is 0.5 K or less, the output of the condenser fan 7 (condenser fan output with the opening/closing valve 4a and the frequency of the compressor 2 fixed (opening/closing valve opening/frequency fixed) ) Is reduced by 5% (S5). Subsequently, it is determined whether or not the degree of superheat of the refrigerant at the outlet of the evaporator 5 (evaporator outlet SH) is 4.0 K or less (S6). The superheat degree of the refrigerant at the outlet of the evaporator 5 is the superheat degree of the refrigerant at the outlet of the evaporator 5 measured by a temperature measuring device (not shown). This determination is performed by the controller 21 based on a signal from a temperature measuring device (not shown). When the degree of superheat exceeds 4.0K, it is determined again until the degree of superheat becomes 4.0K or less (S6).

When the degree of superheat is 4.0 K or less, the current condensation temperature (CT1) and current evaporation temperature (ET1) are measured (S7). The current condensation temperature (CT1) is the temperature of the refrigerant inside the condenser 3 measured by a temperature measuring device (not shown). The current evaporator temperature (ET1) is the temperature of the refrigerant inside the evaporator 5 measured by a temperature measuring device (not shown).

Subsequently, CT0, s, k, ET0, ss, kk stored in advance in the storage unit 27 are read (S8). CT0 is the high-pressure saturation temperature when stable under rated conditions. s is the average high-pressure side wetness at CT0. k is the high-pressure-side average dryness at CT0 (=1-s). ET0 is the low pressure saturation temperature when stable under rated conditions. ss is the low-pressure side average wetness at ET0. kk is the low-pressure side average dryness at ET0 (=1-ss).

Then, the refrigerant amount W is calculated based on the following equations (1) to (3) (S9). This calculation is performed by the control unit 21 based on the signal from the storage unit 27. The refrigerant amount W1 of the condenser 3 is calculated by the equation (1). The refrigerant amount W2 in the liquid pipe is calculated by the equation (2). The liquid pipe is a pipe that connects the condenser 3 and the evaporator 5 via the expansion device 4. The liquid pipe internal volume in Expression (2) is stored in the storage unit 27 in advance. The refrigerant amount W3 of the evaporator 5 is calculated by the equation (3). In the following, ρL is the saturated liquid density (kg/m ³ ) and ρG is the saturated gas density (kg/m ³ ).

W1=ρL(CT1)×s+ρG(CT1)×k (1)

W2 = ρL (CT1) x internal volume of liquid tube (2)

W3=ρL(ET1)×ss+ρG(ET1)×kk (3)

Based on the following equation (4), it is determined whether the refrigerant leakage amount is equal to or more than the allowable value (S10). This determination is performed by the control unit 21 based on the signal from the storage unit 27. In the following, W0 is obtained by multiplying the amount of initially filled refrigerant by the refrigerant distribution coefficient (W0=amount of initially filled refrigerant×refrigerant distribution coefficient). The refrigerant distribution coefficient is obtained by dividing the amount of refrigerant in the condenser 3, liquid pipe, and evaporator 5 when operating under rated conditions by the total amount of refrigerant (number of refrigerant distribution = condenser/liquid when operating under rated conditions). The amount of refrigerant in the pipe/evaporator/total amount of refrigerant). The amount of refrigerant in the condenser 3, the liquid pipe, and the evaporator 5 accounts for about 90% of the refrigerant distribution during operation.

The refrigerant leakage amount is calculated by W0-(W1+W2+W3). The allowable value is obtained by multiplying the flammable region formation limit concentration (LFL) (kg/m ³ ), the internal volume, and the allowable coefficient 0.1. The flammable zone formation limit concentration (LFL), the internal volume, and the tolerance coefficient 0.1 are stored in the storage unit 27 in advance.

W0-(W1+W2+W3)≧0.1×LFL×internal volume (4)

The flammable region formation limit concentration (LFL) of propane (R290) as a refrigerant is 0.038 kg/m ³ .

If the refrigerant leakage amount is less than the allowable value, determination is made until the refrigerant leakage amount becomes equal to or more than the allowable value (S10). When the refrigerant leakage amount is equal to or more than the allowable value, the refrigerant leakage alarm is output via the connector A (S11). In this case, the cooling operation is maintained. The refrigerant leak alarm is output by an alarm device (not shown) such as a display device or a speaker.

Subsequently, based on the following equation (5), it is determined whether the refrigerant leakage amount is equal to or more than the dangerous value (S12). This determination is performed by the control unit 21 based on the signal from the storage unit 27. The dangerous value is obtained by multiplying the flammable zone formation limit concentration (LFL), the internal volume, and the risk factor 0.25. The flammable zone formation limit concentration (LFL), the internal volume, and the risk factor 0.25 are stored in the storage unit 27 in advance.

W0-(W1+W2+W3)≧0.25×LFL×internal volume (5)

If the refrigerant leakage amount is less than the dangerous value, it is judged until the refrigerant leakage amount becomes the dangerous value or more (S12). When the refrigerant leakage amount is equal to or more than the dangerous value, the refrigerant leakage abnormality is output (S13). As a result, the cooling operation is stopped and the pump down operation is performed. The refrigerant leakage abnormality is output by an alarm device (not shown) such as a display device or a speaker. When the refrigerant leakage abnormality is output, the determination as to whether or not refrigerant leakage has occurred is stopped (S14).

Note that the pump down operation is continued until the refrigerant leakage detection state is released. Further, the condenser fan 7 may be continuously operated even after the pump down operation is completed. Further, regardless of whether or not the refrigerant leakage is detected, the control may be performed such that when the housing is stopped, the pump down operation is performed to confine the refrigerant and then the compressor, the fan, and the like are stopped. This makes it possible to always keep the refrigerant in the refrigerant circuit other than the evaporator when the housing is stopped.

Next, operation effects of the refrigeration cycle apparatus 100 according to the present embodiment will be described.

With reference to FIG. 1 and FIG. 3, according to refrigeration cycle apparatus 100 in accordance with the present embodiment, refrigerant circuit 10 can cause refrigerant to flow backward from compressor 2 to evaporator 5 by backflow prevention device 6. A pump down operation is performed in which the compressor 2 is operated while being prevented and the refrigerant circuit 10 is closed by the opening/closing valve 4a. For this reason, the refrigerant can be confined in the refrigerant circuit 10 from the backflow prevention device 6 to the on-off valve 4a via the condenser 3. Therefore, it is possible to prevent the refrigerant from leaking from the evaporator 5. The compressor 2 and the condenser 3 are located below the evaporator 5. For this reason, the refrigerant trapped in the condenser 3 is unlikely to flow into the storage chamber 11. As a result, the refrigerant R having a specific gravity heavier than air can be prevented from staying in the storage chamber 11. The greater the specific gravity of the refrigerant, the greater the effect, and the greater the specific gravity, the more effective it is.

According to the refrigeration cycle device 100 according to the present embodiment, the expansion device 4 is located above the condenser 3. Therefore, the refrigerant trapped in the condenser 3 does not easily flow into the storage chamber 11 beyond the expansion device 4. Therefore, it is possible to prevent the leaked refrigerant R from staying in the storage chamber 11. The greater the specific gravity of the refrigerant, the greater the effect, and the greater the specific gravity, the more effective it is.

According to the refrigeration cycle apparatus 100 according to the present embodiment, the expansion device 4 is located below the center of the evaporator 5. Therefore, the refrigerant trapped in the refrigerant circuit 10 is unlikely to flow from the expansion device 4 into the evaporator 5. Therefore, it is possible to prevent the leaked refrigerant R from staying in the storage chamber 11.

According to the refrigeration cycle apparatus 100 according to the present embodiment, the flow path 12 is separated from the machine room 13 and arranged above the machine room 13. Therefore, the leaked refrigerant R can be suppressed from flowing into the machine chamber 13 from the flow path 12.

According to refrigeration cycle apparatus 100 according to the present embodiment, control device 20 calculates the refrigerant leakage amount of the refrigerant leaked from refrigerant circuit 10 based on the refrigerant flowing in refrigerant circuit 10, and the refrigerant leakage amount is the storage chamber. It is configured to cause the refrigerant circuit 10 to execute the pump-down operation before the calculated value obtained by multiplying the internal volume of 11 by the flammable region formation limit concentration of the refrigerant is exceeded. Therefore, when the refrigerant leaks, the pump down operation can be executed without using the refrigerant leak detection device such as the gas sensor.

According to refrigeration cycle apparatus 100 in accordance with the present embodiment, control device 20 sets the amount of the initial refrigerant filled in refrigerant circuit 10 and the amount of refrigerant in the refrigerant circuit calculated based on the refrigerant flowing in refrigerant circuit 10. The refrigerant leakage amount is calculated from the difference, and an alarm is output when the refrigerant leakage amount reaches a concentration equal to or higher than an allowable value obtained by multiplying the calculated value by an allowable coefficient. Therefore, it can be notified by outputting an alarm that the refrigerant leakage amount has exceeded the allowable value.

According to the refrigeration cycle apparatus 100 according to the present embodiment, the control device 20 controls the amount of the initial refrigerant filled in the refrigerant circuit 10 and the amount of refrigerant in the refrigerant circuit calculated based on the refrigerant flowing in the refrigerant circuit 10. The refrigerant leakage amount is calculated from the difference, and an abnormality is output when the refrigerant leakage amount reaches a concentration equal to or higher than the dangerous value obtained by multiplying the calculated value by the risk coefficient. For this reason, it is possible to notify that the refrigerant leakage amount has exceeded the dangerous value by outputting an abnormality.

Here, the method of obtaining the allowable value or the dangerous value by multiplying the LFL (kg/m ³ ) by the internal volume and the allowable coefficient or the dangerous coefficient has been described, but the present invention is not limited to this. The allowable value or the dangerous value may be obtained by multiplying the LFL (vol%), the internal volume, and the allowable coefficient or the dangerous coefficient. The LFL of propane (R290) as a refrigerant is 2.1 vol%.

Next, each modified example of the refrigeration cycle apparatus 100 according to Embodiment 1 of the present invention will be described. Each modification of the refrigeration cycle apparatus 100 according to Embodiment 1 of the present invention has the same configuration, operation, and effect as the refrigeration cycle apparatus 100 according to Embodiment 1 of the present invention, unless otherwise specified. ..

The configuration of Modification 1 of refrigeration cycle apparatus 100 according to Embodiment 1 of the present invention will be described with reference to FIG. 6. In the first modification of the refrigeration cycle apparatus 100 according to Embodiment 1 of the present invention, the expansion device 4 includes an opening/closing valve 4a and a solenoid valve 4b. The solenoid valve 4b is connected to the opening/closing valve 4a. The solenoid valve 4b is configured to be able to fully close the refrigerant circuit 10. The on-off valve 4a is housed in the flow path 12. The solenoid valve 4b is housed in the machine room 13.

According to the first modification of the refrigeration cycle apparatus 100 according to Embodiment 1 of the present invention, the expansion device 4 includes the electromagnetic valve 4b capable of fully closing the refrigerant circuit 10, so that the electromagnetic valve 4b serves to close the refrigerant circuit 10. Can be fully closed. Therefore, the solenoid valve 4b can prevent the refrigerant from flowing into the evaporator 5. Further, since the electromagnetic valve 4b is housed in the machine room 13, it is possible to prevent the refrigerant trapped in the refrigerant circuit 10 in the machine room 13 from flowing over the electromagnetic valve 4b into the flow path 12.

The configuration of Modification 2 of refrigeration cycle apparatus 100 according to Embodiment 1 of the present invention will be described with reference to FIG. 7. The second modification of the refrigeration cycle apparatus 100 according to the first embodiment of the present invention includes the refrigerant leakage detection device 9. The refrigerant leakage detection device 9 is housed in the housing 1. The refrigerant leak detection device 9 is configured to be able to detect the refrigerant leaked from the evaporator 5 in the housing 1. The coolant leakage detection device 9 is, for example, a gas sensor. The refrigerant circuit 10 is configured to execute the pump-down operation when the refrigerant leakage detection device 9 detects the refrigerant.

The second modification of the refrigeration cycle apparatus 100 according to the first embodiment of the present invention includes the shelves 15 arranged in the storage chamber 11. Since the cool air is supplied to each of the shelves 15, a plurality of air passages are formed. The air flowing through the plurality of air passages joins at the suction port 11c. The refrigerant leakage detection device 9 is arranged downstream of the suction port 11c in the flow of air and upstream of the expansion device 4 and the evaporator 5. Therefore, the flow of air is concentrated at the position where the refrigerant leakage detection device 9 is arranged. Therefore, when the evaporator fan 8 is in operation, the flow of air concentrated at the suction port 11c hits the refrigerant leakage detection device 9, so that the refrigerant leakage detection device 9 can accurately detect the leakage of the refrigerant.

In the second modification of the refrigeration cycle device 100 according to the first embodiment of the present invention, the refrigerant leakage detection device 9 is arranged at the bottom of the flow path 12. For this reason, the refrigerant having a specific gravity heavier than air is likely to accumulate at the position where the refrigerant leakage detection device 9 is arranged. Therefore, while the evaporator fan 8 is stopped, the refrigerant leakage detection device 9 can accurately detect the refrigerant leakage at a position where the refrigerant having a specific gravity heavier than air is likely to accumulate.

According to the second modification of the refrigeration cycle device 100 according to the first embodiment of the present invention, the refrigerant circuit 10 can execute the pump-down operation when the refrigerant leakage detection device 9 detects the refrigerant.

In the second modification of the refrigeration cycle apparatus 100 according to Embodiment 1 of the present invention, the refrigerant leakage detection device 9 is downstream of the suction port 11c in the flow of air and upstream of the expansion device 4 and the evaporator 5. It is located in. Therefore, when the evaporator fan 8 is operating, the flow of air concentrated at the suction port 11c hits the refrigerant leakage detection device 9, so that the refrigerant leakage detection device 9 can accurately detect the leakage of the refrigerant.

In the second modification of the refrigeration cycle device 100 according to the first embodiment of the present invention, the refrigerant leakage detection device 9 is arranged at the bottom of the flow path 12. Therefore, while the evaporator fan 8 is stopped, the refrigerant leakage detection device 9 can accurately detect the leakage of the refrigerant at a position where the refrigerant having a specific gravity heavier than air is likely to accumulate.

The configuration of Modification 3 of refrigeration cycle apparatus 100 according to Embodiment 1 of the present invention will be described with reference to FIG. 8. The third modification of the refrigeration cycle apparatus 100 according to the first embodiment of the present invention is different from the second modification of the refrigeration cycle apparatus 100 according to the present embodiment in the position of the refrigerant leakage detection device 9.

In the third modification of the refrigeration cycle apparatus 100 according to the first embodiment of the present invention, the refrigerant leakage detection device 9 is located at the bottom of the storage chamber 11 and below the center of the evaporator 5. Therefore, the flow of air is likely to stagnant at the position where the refrigerant leakage detection device 9 is arranged, and the refrigerant having a specific gravity heavier than that of air is likely to accumulate. Therefore, during operation and stoppage of the evaporator fan 8, the refrigerant leakage detection device 9 can accurately detect the leakage of the refrigerant at a position where the air flow is likely to stagnant and the refrigerant having a specific gravity heavier than the air is likely to accumulate. You can

The configuration of Modification 4 of refrigeration cycle apparatus 100 according to Embodiment 1 of the present invention will be described with reference to FIG. 9. Modification 4 of refrigeration cycle apparatus 100 according to Embodiment 1 of the present invention differs from refrigeration cycle apparatus 100 according to Embodiment 1 of the present invention in that housing 1 does not include a door. That is, the modification 4 of the refrigeration cycle apparatus 100 according to Embodiment 1 of the present invention is an open type showcase. The modification 4 of the refrigeration cycle apparatus 100 according to Embodiment 1 of the present invention is more specifically a pre-checkout showcase.

In the fourth modification of the refrigeration cycle apparatus 100 according to the first embodiment of the present invention, the housing 1 has an opening OP communicating with the storage chamber 11 on the front surface 1c. A part of the air leaks from the front portion 1c to the outside of the storage chamber 11 as indicated by the white and dotted broken arrow in FIG. However, since most of the air remains in the storage chamber 11, when the refrigerant leaks from the evaporator 5, the leaked refrigerant R is collected at the bottom of the storage chamber 11.

According to the modified example 4 of the refrigeration cycle apparatus 100 according to Embodiment 1 of the present invention, the refrigerant can be confined in the refrigerant circuit 10 from the backflow prevention device 6 to the on-off valve 4a via the condenser 3, so that the evaporation It is possible to prevent the refrigerant from leaking from the container 5. As a result, the refrigerant R having a specific gravity heavier than air can be prevented from staying in the storage chamber 11.

The configuration of Modification 5 of refrigeration cycle apparatus 100 according to Embodiment 1 of the present invention will be described with reference to FIG. 10. Modification 5 of refrigeration cycle apparatus 100 according to Embodiment 1 of the present invention has a point that housing 1 does not include a door and that housing 1 has an opening OP that communicates with storage chamber 11 in ceiling portion 1a. The difference from the refrigeration cycle apparatus 100 according to Embodiment 1 of the present invention lies in that. That is, the modification 5 of the refrigeration cycle apparatus 100 according to Embodiment 1 of the present invention is an open type showcase. More specifically, refrigeration cycle apparatus 100 according to Embodiment 1 of the present invention is a flat showcase.

In the fifth modified example of the refrigeration cycle apparatus 100 according to the first embodiment of the present invention, air leaks from the ceiling portion 1a to the outside of the storage chamber 11 as indicated by the white dashed arrow in FIG. However, since most of the air remains in the storage chamber 11, when the refrigerant leaks from the evaporator 5, the leaked refrigerant R is collected at the bottom of the storage chamber 11.

According to the modified example 5 of the refrigeration cycle apparatus 100 according to Embodiment 1 of the present invention, the refrigerant can be confined in the refrigerant circuit 10 from the backflow prevention device 6 through the condenser 3 to the on-off valve 4a, so that evaporation It is possible to prevent the refrigerant from leaking from the container 5. As a result, the refrigerant R having a specific gravity heavier than air can be prevented from staying in the storage chamber 11.

Embodiment 2.

The refrigeration cycle apparatus 100 according to Embodiment 2 of the present invention has the same configuration, operation, and effect as those of the refrigeration cycle apparatus 100 according to Embodiment 1 of the present invention and the modifications thereof, unless otherwise specified. ing.

The configuration of the refrigeration cycle apparatus 100 according to Embodiment 2 of the present invention will be described with reference to FIG. 11. The refrigeration cycle apparatus 100 according to Embodiment 2 of the present invention differs from the refrigeration cycle apparatus 100 according to Embodiment 1 of the present invention in the configuration of the expansion device 4.

In the refrigeration cycle apparatus 100 according to Embodiment 2 of the present invention, the expansion device 4 includes an opening/closing valve 4a and an expansion valve 4c. The expansion valve 4c is, for example, a capillary tube. The expansion valve 4c is housed in the flow path 12. The on-off valve 4a is housed in the machine room 13.

The control device 20 is configured to stop the drive of the compressor 2 after causing the refrigerant circuit 10 to perform the pump-down operation.

The control device 20 calculates the refrigerant leakage amount of the refrigerant leaked from the refrigerant circuit 10 based on the refrigerant flowing through the refrigerant circuit 10, and the refrigerant leakage amount indicates the combustible zone formation limit concentration of the refrigerant in the internal volume of the storage chamber 11. It is configured to output an alarm when the calculated value obtained by multiplying is equal to or larger than the allowable value obtained by multiplying the allowable coefficient.

The control device 20 calculates the refrigerant leakage amount of the refrigerant leaked from the refrigerant circuit 10 based on the refrigerant flowing through the refrigerant circuit 10, and the refrigerant leakage amount indicates the combustible zone formation limit concentration of the refrigerant in the internal volume of the storage chamber 11. It is configured to output an abnormality when the calculated value obtained by multiplication is equal to or higher than the dangerous value obtained by multiplying the dangerous coefficient.

With reference to FIGS. 11 to 13, in refrigeration cycle device 100 according to the second embodiment of the present invention, it is determined whether or not refrigerant leakage has occurred as follows. The configuration of control device 20 in the second embodiment of the present invention is similar to the configuration of control device 20 in the first embodiment shown in FIG. First, the determination starts by starting the defrost operation (S21).

It is determined whether or not the condition for starting the defrost operation (defrost start condition) is satisfied (S22). This determination is performed by the control unit 21 based on a signal from the storage unit 27 in which the defrost start condition is stored in advance. If the defrost start condition is not satisfied, the determination is made until the defrost start condition is satisfied (S22). When the defrost disclosure condition is satisfied, the open/close valve 4a is closed (open/close valve=OFF) (S23). As a result, the pump down operation is performed. At this time, the drive of the evaporator fan 8 is maintained due to the defrosting in the off cycle.

Subsequently, it is determined whether the temperature of the refrigerant at the inlet of the evaporator 5 (evaporator inlet temperature) is -20°C or lower (S24). The temperature of the refrigerant at the inlet of the evaporator 5 is the temperature of the refrigerant at the inlet of the evaporator 5 measured by a temperature measuring device (not shown). This determination is performed by the controller 21 based on a signal from a temperature measuring device (not shown). When the evaporator inlet temperature exceeds −20° C., the determination is repeated until the evaporator inlet temperature becomes −20° C. or lower (S24).

When the evaporator inlet temperature is -20°C or lower, the compressor 2 is stopped (S25). Subsequently, the condensation temperature CT(i) is measured every 5 seconds, and the data for the latest 3 minutes is stored (S26). The condensation temperature CT(i) is the temperature of the refrigerant inside the condenser 3 measured by a temperature measuring device (not shown). The most recent 3 minutes are measured by the timer 26. The data of the measured condensation temperature CT(i) is stored in the storage unit 27.

The temperature difference between the maximum value CT(i)MAX of the condensation temperature CT(i) and the minimum value CT(i)MIN of the condensation temperature CT(i) in the data of the condensation temperature CT(i) measured in the last 3 minutes is It is determined whether it is 0.5 Kelvin (K) or less (S27). This determination is made by the control unit 21 based on signals from the timer 26 and the storage unit 27. As a result, it is determined whether the high pressure is stable. If the temperature difference exceeds 0.5K, it is determined again until the temperature difference becomes 0.5K or less (S27).

If the temperature difference is 0.5 K or less, the current condensation temperature (CT1) is measured (S28). The current condensation temperature (CT1) is the temperature of the refrigerant inside the condenser 3 measured by a temperature measuring device (not shown). The current condensing temperature (CT1) is the balanced condensing temperature when the high pressure is considered stable.

Subsequently, CT0, s, and k stored in advance in the storage unit 27 are read (S29). CT0 is a balanced high-pressure saturation temperature when pumping down with the refrigerant amount at the time of shipment. s is the average high-pressure side wetness at CT0. k is the high-pressure-side average dryness at CT0 (=1-s).

Subsequently, the refrigerant amount W is calculated based on the following equations (6) and (7) (S30). This calculation is performed by the control unit 21 based on the signal from the storage unit 27. The high-pressure-side refrigerant amount W(CT0) is calculated by the equation (6). The high-pressure side refrigerant amount W(CT0) is the high-pressure side refrigerant amount based on the balanced high-pressure saturation temperature when pumping down with the shipping refrigerant amount. The high-pressure side refrigerant amount W(CT1) is calculated by the equation (7). The high-pressure side refrigerant amount W (CT1) is the high-pressure side refrigerant amount based on the current condensation temperature (CT1). As described above, ρL is the saturated liquid density (kg/m ³ ) and ρG is the saturated gas density (kg/m ³ ).

W(CT0)=ρL(CT0)×s+ρG(CT0)×k (6)

W(CT1)=ρL(CT1)×s+ρG(CT1)×k (7)

Based on the following equation (8), it is determined whether the refrigerant leakage amount is equal to or more than the allowable value (S31). This determination is performed by the control unit 21 based on the signal from the storage unit 27. The refrigerant leakage amount is calculated by subtracting W(CT1) from W(CT0). The permissible value is obtained by multiplying the flammable zone formation limit concentration (LFL) (kg/m ³ ), the internal volume, and the permissible coefficient (for example, 0.1). The flammable zone formation limit concentration (LFL), the internal volume, and the tolerance coefficient 0.1 are stored in the storage unit 27 in advance. Alternatively, a value corresponding to an allowable value obtained by multiplying LFL (kg/m ³ ) by the internal volume and the allowable coefficient is stored in advance in the storage unit 27 as a constant.

W (CT0)-W (CT1) ≧ 0.1 x LFL x internal volume (8)

If the refrigerant leakage amount is less than the allowable value, determination is made until the refrigerant leakage amount becomes equal to or more than the allowable value (S31). When the refrigerant leakage amount is equal to or more than the allowable value, the refrigerant leakage alarm is output via the connector A (S32). In this case, the operation of the evaporator fan is maintained. The refrigerant leak alarm is output by an alarm device (not shown) such as a display device or a speaker.

Then, it is determined based on the following equation (9) whether or not the refrigerant leakage amount is equal to or more than the dangerous value (S33). This determination is performed by the control unit 21 based on the signal from the storage unit 27. The dangerous value is obtained by multiplying the flammable zone formation limit concentration (LFL), the internal volume and the risk factor (for example, 0.25). The flammable zone formation limit concentration (LFL), the internal volume, and the risk factor 0.25 are stored in the storage unit 27 in advance. Alternatively, a value corresponding to a dangerous value obtained by multiplying LFL (kg/m ³ ) by the internal volume and the dangerous coefficient is stored in advance in the storage unit 27 as a constant.

W (CT0)-W (CT1) ≧0.25 × LFL × internal volume (9)

If the refrigerant leakage amount is less than the dangerous value, determination is made until the refrigerant leakage amount becomes equal to or higher than the dangerous value (S33). When the refrigerant leakage amount is equal to or more than the dangerous value, the refrigerant leakage abnormality is output (S33). Then, the pump down operation is performed. Abnormal refrigerant leakage is output by an alarm device (not shown) such as a display device or a speaker. In this case, the drive of the evaporator fan 8 is maintained. When the refrigerant leakage abnormality is output, the determination as to whether or not refrigerant leakage has occurred is stopped (S35).

Next, the operation and effect of the refrigeration cycle apparatus 100 according to the second embodiment of the present invention will be described.

According to the refrigeration cycle apparatus 100 according to Embodiment 2 of the present invention, the expansion device 4 includes the on-off valve 4a and the expansion valve 4c, so that the on-off valve 4a closes the refrigerant circuit 10 to generate the refrigerant. The refrigerant can be prevented from flowing into the evaporator 5, and the expansion valve 4c can expand the refrigerant. Further, since the opening/closing valve 4a is housed in the machine chamber 13, it is possible to prevent the refrigerant trapped in the refrigerant circuit 10 in the machine chamber 13 from flowing over the opening/closing valve 4a into the flow path 12.

According to the refrigeration cycle device 100 according to the second embodiment of the present invention, the control device 20 is configured to stop the drive of the compressor 2 after causing the refrigerant circuit 10 to execute the pump down operation. Therefore, it is possible to confine the refrigerant in the refrigerant circuit 10 from the backflow prevention device 6 to the on-off valve 4a via the condenser 3 while the drive of the compressor 2 is stopped after the pump down operation.

According to the refrigeration cycle device 100 according to Embodiment 2 of the present invention, the control device 20 calculates the refrigerant leakage amount of the refrigerant leaked from the refrigerant circuit 10 based on the refrigerant flowing in the refrigerant circuit 10, and the refrigerant leakage amount. Is configured to output an alarm when the value exceeds a permissible value obtained by multiplying a calculated value obtained by multiplying the internal volume of the storage chamber 11 by the flammable region formation limit concentration of the refrigerant by a permissible coefficient. Therefore, it can be notified by outputting an alarm that the refrigerant leakage amount has exceeded the allowable value.

According to the refrigeration cycle device 100 according to Embodiment 2 of the present invention, the control device 20 calculates the refrigerant leakage amount of the refrigerant leaked from the refrigerant circuit 10 based on the refrigerant flowing in the refrigerant circuit 10, and the refrigerant leakage amount. Is configured to output an abnormality when the calculated value obtained by multiplying the internal volume of the storage chamber 11 by the flammable region formation limit concentration of the refrigerant is multiplied by the risk factor. For this reason, it is possible to notify that the refrigerant leakage amount has exceeded the dangerous value by outputting an abnormality.

The above embodiments can be combined as appropriate.

The embodiments disclosed this time are to be considered as illustrative in all points and not restrictive. The scope of the present invention is shown not by the above description but by the scope of the claims, and is intended to include meanings equivalent to the scope of the claims and all modifications within the scope.

1 case, 2 compressor, 3 condenser, 4 expansion device, 4a open/close valve, 4b solenoid valve, 4c expansion valve, 5 evaporator, 6 backflow prevention device, 7 condenser fan, 8 evaporator fan, 9 refrigerant leakage Detection device, 10 refrigerant circuit, 11 storage chamber, 11a inner wall, 11b outlet, 11c suction port, 12 flow path, 13 machine room, 14 partition wall, 15 shelves, 20 control device, 21 control unit, 100 refrigeration cycle device.

Claims

A housing including a storage chamber and a flow path communicating with the storage chamber;
A refrigerant circuit that is housed in the housing and that includes a compressor, a condenser, an expansion device, an evaporator, and a backflow prevention device;
The expansion device includes an on-off valve configured to open and close the refrigerant circuit,
The refrigerant circuit is configured such that a refrigerant having a specific gravity heavier than air flows in the order of the compressor, the condenser, the expansion device, and the evaporator,
The backflow prevention device is disposed on at least one of the upstream side and the downstream side of the compressor, and is configured to prevent the refrigerant from flowing back from the compressor toward the evaporator. ,
The evaporator is housed in the flow path, and is located above the compressor, the condenser, the expansion device and the backflow prevention device,
The refrigerant circuit prevents the refrigerant from flowing backward from the compressor toward the evaporator by the backflow prevention device, and the compressor is operated in a state in which the refrigerant circuit is closed by the opening/closing valve. A refrigeration cycle device configured to be capable of executing pump down operation.
The refrigeration cycle apparatus according to claim 1, wherein the expansion device is located above the condenser.
The refrigeration cycle apparatus according to claim 2, wherein the expansion device is located below the center of the evaporator.
The housing includes a machine room in which the compressor and the condenser are housed,
The refrigeration cycle apparatus according to any one of claims 1 to 3, wherein the flow path is separated from the machine room and is arranged above the machine room.
The expansion device includes an electromagnetic valve that is connected to the on-off valve and is capable of fully closing the refrigerant circuit,
The on-off valve is housed in the flow path,
The refrigeration cycle apparatus according to claim 4, wherein the electromagnetic valve is housed in the machine room.
The expansion device includes an expansion valve connected to the on-off valve,
The expansion valve is housed in the flow path,
The refrigeration cycle apparatus according to claim 4, wherein the opening/closing valve is housed in the machine room.
A refrigerant leakage detection device housed in the housing and configured to be able to detect the refrigerant leaked from the evaporator in the housing,
7. The refrigeration cycle apparatus according to claim 1, wherein the refrigerant circuit is configured to perform the pump down operation when the refrigerant leakage detection device detects the refrigerant.
The refrigeration cycle apparatus according to claim 7, wherein the refrigerant leakage detection device is installed in the flow path below the evaporator and upstream from the evaporator.
The refrigeration cycle device according to claim 7, wherein the refrigerant leakage detection device is installed in the storage chamber at a position lower than the center of the evaporator.
Further comprising a control device housed in the housing,
The refrigerant has flammability,
The control device calculates a refrigerant leakage amount of the refrigerant leaked from the refrigerant circuit based on the refrigerant flowing in the refrigerant circuit, and the refrigerant leakage amount is a combustible region of the refrigerant in a storage volume of the storage chamber. The refrigeration cycle apparatus according to any one of claims 1 to 9, which is configured to cause the refrigerant circuit to perform the pump-down operation before the calculated value obtained by multiplying the formation limit concentration is exceeded.
The control device calculates the refrigerant leakage amount from the difference between the initial refrigerant charging amount charged in the refrigerant circuit and the refrigerant amount in the refrigerant circuit calculated based on the refrigerant flowing in the refrigerant circuit, and the refrigerant. The refrigeration cycle according to claim 10, which is configured to output an alarm when the amount of leakage is equal to or larger than an allowable value obtained by multiplying the calculated value by an allowable coefficient or a value corresponding to a previously stored allowable value. apparatus.
The control device calculates the refrigerant leakage amount from the difference between the initial refrigerant charging amount charged in the refrigerant circuit and the refrigerant amount in the refrigerant circuit calculated based on the refrigerant flowing in the refrigerant circuit, and the refrigerant. The refrigeration cycle according to claim 10, wherein an abnormality is output when the amount of leakage is equal to or greater than a dangerous value obtained by multiplying the calculated value by a dangerous coefficient or a value corresponding to a previously stored dangerous value. apparatus.
Further comprising a control device housed in the housing,
The refrigerant has flammability,
The refrigeration cycle apparatus according to any one of claims 1 to 9, wherein the control device is configured to stop driving of the compressor after causing the refrigerant circuit to perform the pump down operation. ..
The control device calculates a refrigerant leakage amount of the refrigerant leaked from the refrigerant circuit based on the refrigerant flowing in the refrigerant circuit, and the refrigerant leakage amount is a combustible region of the refrigerant in a storage volume of the storage chamber. 14. The alarm according to claim 13, which is configured to output an alarm when the calculated value obtained by multiplying the formation limit concentration is equal to or higher than an allowable value obtained by multiplying the allowable coefficient or a value corresponding to a previously stored allowable value or more. Refrigeration cycle device.
The control device calculates a refrigerant leakage amount of the refrigerant leaked from the refrigerant circuit based on the refrigerant flowing in the refrigerant circuit, and the refrigerant leakage amount is a combustible region of the refrigerant in a storage volume of the storage chamber. 14. The abnormality according to claim 13, which is configured to output an abnormality when the calculated value obtained by multiplying the formation limit concentration is equal to or higher than a dangerous value obtained by multiplying the dangerous coefficient or a value corresponding to a previously stored dangerous value or more. Refrigeration cycle device.
The refrigeration cycle device according to any one of claims 1 to 15, wherein the specific gravity of the refrigerant is 1.5 or more.
The refrigeration cycle apparatus according to any one of claims 1 to 16, wherein when the casing is stopped, a stop operation is performed after a pump down operation.