KR102165353B1 - Refrigerant system - Google Patents

Abstract

A refrigerant system according to an embodiment of the present invention includes a compressor for compressing a refrigerant; A four-way valve disposed on the outlet side of the compressor to control a flow direction of the refrigerant; A first heat exchanger for evaporating the refrigerant in the heating operation mode; A second heat exchanger for condensing the refrigerant passing through the compressor in a heating operation mode; An expansion valve disposed between the first heat exchanger and the second heat exchanger to expand the refrigerant at low temperature and low pressure; An accumulator disposed at the inlet side of the compressor to separate a liquid refrigerant from a gaseous refrigerant; A main pipe connecting the compressor, the four-way valve, the first and second heat exchangers, the expansion valve and the accumulator to circulate a refrigerant; A first bypass pipe branched at a point of the main pipe connecting the second heat exchanger and the expansion valve; A receiver connected to the outlet end of the first bypass pipe; A liquid refrigerant pipe extending from the outlet end of the receiver and connected to a point of the main pipe connecting the first heat exchanger and the expansion valve; A second bypass pipe branched at a point at which the outlet end of the liquid refrigerant pipe is connected and a main pipe connecting the expansion valve to a point at which the first bypass pipe is connected; And a point connecting the second heat exchanger and the four-way valve, and a third bypass pipe connecting a point of the liquid refrigerant pipe.

Description

Refrigerant system

The present invention relates to a refrigerant system.

The refrigerant system is a system that cools and heats a room by performing a refrigerant cycle in which a refrigerant undergoes compression, condensation, expansion, and evaporation processes.

The refrigerant system includes a compressor for compressing a refrigerant to a high temperature and high pressure, a condenser for condensing a gas phase refrigerant of high temperature and high pressure, an expansion valve for expanding a liquid refrigerant of high temperature and high pressure, and an evaporator for evaporating a two-phase refrigerant of low temperature and low pressure.

Here, a system in which water is used as a heat exchange medium for evaporating the refrigerant passing through the evaporator may be specifically defined as a chiller. That is, the water passing through the evaporator is cooled to a temperature lower than room temperature, and the cooled water flows along a pipe extending toward the room and may be used to cool indoor air. In addition, a system in which water is used as a heat exchange medium for condensing the refrigerant passing through the condenser among the chillers may be defined as a water-cooled chiller, and a system in which air is used may be defined as an air-cooled chiller. In addition, the condenser may be disposed outdoors and the evaporator may be disposed indoors. In some cases, the condenser and the evaporator may consist of one module and may be disposed outdoors.

Meanwhile, in the case of an air-cooled chiller, the condenser functions as an evaporator during heating operation, and the evaporator functions as a condenser. In a heat exchanger that functions as a condenser, water is used as a medium for heat exchange with a refrigerant, and water whose temperature is increased through heat exchange is used as indoor heating or hot water.

On the other hand, since the heat exchanger that performs the function of the evaporator is disposed outdoors where the outside temperature is low, implantation proceeds on the surface of the heat exchanger as time passes. In addition, when the degree of implantation increases, heat exchange between air and refrigerant is not performed properly, resulting in poor heating performance. In order to prevent the heat exchange performance from deteriorating, a defrost operation is performed periodically to melt ice on the surface of the heat exchanger.

At this time, while the defrosting operation is being performed, the refrigerant system performs a refrigeration cycle again, and as a result, the heat exchanger that has functioned as a condenser again functions as an evaporator, and the temperature of the water heat-exchanging with the refrigerant drops. That is, the water heated during the heating operation becomes cold due to the defrost operation, and the liquid refrigerant accumulates in the receiver constituting the refrigeration cycle.

In detail, a high-pressure liquid refrigerant flows to the receiver during the heating operation. When the flow of the refrigerant is changed for the defrost operation, the low-pressure refrigerant passing through the expansion valve flows toward the inlet of the receiver. However, the low-pressure refrigerant cannot flow toward the receiver due to a pressure difference between the refrigerant, and eventually, the liquid refrigerant in the receiver cannot circulate during the defrosting operation and is kept in a state. As a result, the amount of refrigerant flowing into the compressor decreases, so that the inlet pressure of the compressor decreases, and as the amount of refrigerant decreases, the compression performance decreases, and the time it takes to rise to the condensing temperature increases.

Further, as the time taken to rise to the condensation temperature increases, the defrost operation time increases, and conversely, the temperature of water for heating decreases more and more, thereby causing a problem in that heating cannot be performed smoothly.

The present invention has been proposed to improve the above problems.

A refrigerant system according to an embodiment of the present invention having the above configuration includes: a compressor for compressing a refrigerant; A four-way valve disposed on the outlet side of the compressor to control a flow direction of the refrigerant; A first heat exchanger for evaporating the refrigerant in the heating operation mode; A second heat exchanger for condensing the refrigerant passing through the compressor in a heating operation mode; An expansion valve disposed between the first heat exchanger and the second heat exchanger to expand the refrigerant at low temperature and low pressure; An accumulator disposed at the inlet side of the compressor to separate a liquid refrigerant from a gaseous refrigerant; A main pipe connecting the compressor, the four-way valve, the first and second heat exchangers, the expansion valve and the accumulator to circulate a refrigerant; A first bypass pipe branched at a point of the main pipe connecting the second heat exchanger and the expansion valve; A receiver connected to the outlet end of the first bypass pipe; A liquid refrigerant pipe extending from the outlet end of the receiver and connected to a point of the main pipe connecting the first heat exchanger and the expansion valve; A second bypass pipe branched at a point at which the outlet end of the liquid refrigerant pipe is connected and a main pipe connecting the expansion valve to a point at which the first bypass pipe is connected; And a point connecting the second heat exchanger and the four-way valve, and a third bypass pipe connecting a point of the liquid refrigerant pipe.

The refrigerant system may further include a first on-off valve installed in the second bypass pipe and a second on-off valve installed in the third bypass pipe.

The first and second on-off valves are valves capable of adjusting an opening degree.

The refrigerant system may further include a check valve installed at a point in the liquid refrigerant pipe and controlling the refrigerant to flow in only one direction.

The receiver is characterized in that it is installed to be in contact with the accumulator.

The second heat exchanger may include a plate heat exchanger in which refrigerant and water exchange heat.

The first heat exchanger may include a fin-tube type heat exchanger.

The refrigerant system configured as described above has the following effects.

First, in an air-cooled chiller serving as both cooling and heating, there is an effect of shortening the defrost time by rapidly increasing the condensation temperature by preventing the refrigerant from accumulating in the receiver during the defrost operation.

Second, by shortening the defrosting time, the time for the low-temperature refrigerant to flow toward the plate heat exchanger in which the low-temperature refrigerant and water for heating exchange heat during the defrosting process is shortened. In addition, the amount of low-temperature refrigerant flowing toward the plate heat exchanger is reduced, so that the width of the water temperature decrease is reduced. As a result, there is an advantage of minimizing deterioration in heating performance.

In detail, according to the refrigerant system according to the embodiment of the present invention, second and third bypass pipes are additionally installed, so that even when the cycle is switched from the heating mode to the defrost mode, the liquid refrigerant does not accumulate in the receiver and flows continuously. By doing so, it is possible to minimize deterioration of compression performance, and, during defrosting operation, since the amount of low-temperature, low-pressure two-phase refrigerant flowing to the second heat exchanger that heats up heat with water for cooling and heating can be controlled, deterioration in heating performance can be minimized.

1 is a refrigerant system according to an embodiment of the present invention.
2 is a refrigerant flow chart showing a state in which the refrigerant system is operated in a heating mode according to an embodiment of the present invention.
3 is a refrigerant flow chart showing a state in which a defrost operation is performed in a refrigerant system according to an embodiment of the present invention.

Hereinafter, a refrigerant system according to an embodiment of the present invention will be described in detail with reference to the drawings.

1 shows a refrigerant system according to an embodiment of the present invention.

Referring to FIG. 1, a refrigerant system 10 according to an exemplary embodiment of the present invention will be described using an air-cooled chiller as an example. That is, in the cooling process, a water refrigerant heat exchanger for exchanging water and refrigerant is used as a heat exchanger corresponding to an indoor unit, and a fin-tube heat exchanger for exchanging air and refrigerant is used as a heat exchanger corresponding to the outdoor unit. In addition, a plate heat exchanger may be applied as the water refrigerant heat exchanger.

In detail, the refrigerant system 10 according to the embodiment of the present invention includes a compressor 11, an oil separator 12, a four way valve 13, a first heat exchanger 14, and an expansion valve 15. , A second heat exchanger 16, an accumulator 18, and a receiver 19 may be included. In addition, the components may be connected in series by the main pipe 101.

In addition, the compressor 11 may be a single constant-speed compressor, and a plurality of compressors 111 and 112 may be connected in parallel. The plurality of compressors 111 and 112 may be composed of an inverter compressor and a constant speed compressor, or may be composed of a plurality of inverter compressors, which may be defined as a first compressor 111 and a second compressor 112. In addition, when a plurality of compressors are provided, oil separators 121 and 122 may be respectively installed at the outlets of each compressor, and these may be defined as a first oil separator 121 and a second oil separator 122.

In addition, since the first heat exchanger 14 functions to condense the refrigerant in the cooling mode, it can be defined as a condenser in the cooling mode, and the first heat exchanger 14 functions as an evaporator in the heating mode because it functions to evaporate the refrigerant in the heating mode. Can be. In addition, the first heat exchanger 14 may be a fin-tube type air-cooled heat exchanger so that the refrigerant heats the air with air. In addition, the first heat exchanger 14 is disposed outdoors to exchange heat with outdoor air, and a heat exchange fan 141 is provided near the first heat exchanger 14 to facilitate heat exchange with outdoor air. I can.

In addition, the expansion valve 15 is disposed at any point of the main pipe 101 connecting the first heat exchanger 14 and the second heat exchanger 16, and a high-temperature high-pressure liquid refrigerant is 2 It expands with the phase refrigerant. In addition, the expansion valve 15 may be a capillary tube or an electronic expansion valve capable of adjusting the opening degree.

In addition, the second heat exchanger 16 may be defined as an evaporator in the cooling mode because it functions to evaporate the refrigerant in the cooling mode, and may be defined as a condenser because it functions to condense the refrigerant in the heating mode. . In addition, the second heat exchanger 16 may be a water-cooled heat exchanger in which refrigerant and water exchange heat. In this embodiment, the second heat exchanger 16 may be a plate-type heat exchanger that exchanges heat without mixing the refrigerant passing through the expansion valve 15 or the compressor 11 and water introduced from the outside.

In detail, in order to heat exchange between the refrigerant and water in the second heat exchanger 16, the inlet pipe 31 and the outlet pipe 32 are connected to the second heat exchanger 16. That is, water flowing from an external water supply source along the intake pipe 31 passes through the second heat exchanger 16 and draws heat toward the refrigerant to become cold water at low temperature, or absorbs heat from the refrigerant to generate hot water. do. In addition, the cold water or hot water discharged through the water outlet pipe 32 may flow into the room to cool the floor of the room to perform cooling, or to warm it to perform heating. In addition, cold water or hot water discharged along the water outlet pipe 32 may flow to a heat exchanger such as a radiator to cool or warm indoor air. Alternatively, it may be used as hot water for a shower or cold water for drinking.

In addition, the refrigerant that has passed through the expansion valve 15 flows into the accumulator 17 to separate a liquid refrigerant and a gaseous refrigerant. Then, only the separated gaseous refrigerant flows into the inlet of the compressor 11 along the main pipe 101.

In addition, a part of the liquid refrigerant that has passed through the expansion valve 15 in the cooling mode or a part of the liquid refrigerant that has passed through the second heat exchanger in the heating mode is introduced into the receiver 18. The receiver 18 is a device for storing excess liquid refrigerant remaining according to the required cooling power of the heat exchangers 14 and 16.

For example, when an attempt is made to increase the room temperature in the cooling mode or when the room temperature is lowered in the heating mode, the amount of refrigerant required to perform the refrigerant cycle is reduced. Then, the liquid refrigerant remaining in the total refrigerant in the receiver 18 is temporarily stored and stored. In addition, as for the liquid refrigerant stored in the receiver 18, only the liquid refrigerant exceeding the set water level is discharged from the receiver 18 to participate in the refrigeration cycle.

In addition, the receiver 18 may be separated from the accumulator 17 and may be independently disposed, and as shown, attached to the outer circumferential surface of the accumulator 17, specifically on the bottom surface, and the accumulator 17 and one It can also be installed in the form of a module. When the receiver 18 is disposed in contact with the accumulator 17, it is transferred from the receiver 18 to the accumulator 17, so that the liquid refrigerant in the accumulator 17 can be evaporated into a gaseous refrigerant. There is an advantage. Then, the amount of gaseous refrigerant flowing into the compressor 11 is increased, thereby improving compression capacity.

In addition, in the refrigerant system 10 according to an embodiment of the present invention, since heat is always transferred from the receiver 18 to the accumulator 17 regardless of a heating mode and a cooling mode, compression performance compared to a conventional refrigerant cycle This has the advantage of getting better.

Meanwhile, the refrigerant pipes constituting the refrigerant system 10 according to the embodiment of the present invention include a compressor 11, an oil separator 12, a four-way valve 13, a first heat exchanger 14, and an expansion valve 15. , And a main pipe 101 connecting the second heat exchanger 16, the four-way valve 13, and the accumulator 17 in series.

In addition, the refrigerant pipe is a first bypass pipe 102 connecting the inlet end of the receiver 18 to a point of the main pipe 101 connecting the expansion valve 15 and the second heat exchanger 16 ) May be further included.

In addition, the refrigerant pipe is a second connecting point of the main pipe 101 connecting the first heat exchanger 14 and the expansion valve 15 and a point of the first bypass pipe 102 A bypass pipe 103 may be further included. In addition, an on-off valve 19 is installed in the second bypass pipe 103.

In addition, the refrigerant pipe may include a point of the main pipe 101 corresponding to a point between the outlet end of the first heat exchanger 14 and a branch point of the second bypass pipe 103, and the receiver 18 ) May further include a liquid refrigerant pipe 105 connecting the outlet end. In addition, a check valve 19 for allowing the refrigerant to flow in only one direction is installed at a point in the liquid refrigerant pipe 105 to block the reverse flow of the refrigerant toward the outlet of the receiver 18.

In addition, the refrigerant pipe is a third via connecting a point of the main pipe 101 connecting the four-way valve 13 and the second heat exchanger 16 and a point of the liquid refrigerant pipe 105 A pass pipe 104 may be further included. In addition, an on-off valve 20 is also installed in the third bypass pipe 104. The opening/closing valves 10 and 20 are valves capable of adjusting an opening degree, and may be valves that perform the function of an expansion valve to some extent.

In the refrigerant system 10 according to the embodiment of the present invention, the second and third bypass pipes 103 and 104 are installed so that the liquid refrigerant is supplied to the receiver 18 when the cycle is switched from the heating mode to the defrost mode. It is characterized by minimizing deterioration of compression performance by allowing it to flow continuously without standing still, and minimizing deterioration of heating performance by adjusting the amount of low-temperature, low-pressure two-phase refrigerant flowing into the second heat exchanger 16 in the defrost mode.

2 is a refrigerant flow chart showing a state in which the refrigerant system is operated in a heating mode according to an embodiment of the present invention.

2, when the refrigerant system 10 according to the embodiment of the present invention is operated in the heating mode, the opening/closing valves 19 and 20 are closed, so that the second bypass pipe 103 and the second 3 The refrigerant does not flow through the bypass pipe 104.

In detail, the compressor 11 compresses a low-temperature, low-pressure gaseous refrigerant into a high-temperature, high-pressure gaseous refrigerant. In addition, the refrigerant passing through the compressor 11 passes through the oil separator 12 to separate the oil and the refrigerant, and the separated oil is recovered to the compressor 11.

The flow direction of the refrigerant passing through the oil separator 12 is determined by the four-way valve 13, and the opening and closing of the valve is controlled so that the refrigerant flows toward the second heat exchanger 16 in the heating mode.

The refrigerant introduced into the second heat exchanger (16) exchanges heat with water introduced into the second heat exchanger through the inlet pipe (31), and the heat exchanged water is discharged through the outlet pipe (32) to Used for heating or hot water.

In addition, a part of the refrigerant condensed into a liquid refrigerant while passing through the second heat exchanger 16 expands into a low-temperature, low-pressure two-phase refrigerant while passing through the expansion valve 15, and the rest of the refrigerant at a certain point b It is branched into the first bypass pipe 102 and introduced into the receiver 18.

In addition, the refrigerant passing through the expansion valve 15 flows into the first heat exchanger 14 along the main pipe 101. Here, the high-temperature and high-pressure liquid refrigerant flowing into the receiver 18 is filled in the receiver 18, and the liquid refrigerant exceeding the set level is discharged to the liquid refrigerant pipe 105. In addition, the refrigerant flowing along the liquid refrigerant pipe 105 is combined with a low-temperature, low-pressure two-phase refrigerant that has passed through the expansion valve 15 at a point (a) of the main pipe 101. The point where the refrigerant is combined is a point (a) at which the outlet end of the liquid refrigerant pipe 105 is connected, and one of the main pipe 101 connecting the first heat exchanger 14 and the expansion valve 15 It corresponds to the branch. In addition, as the refrigerant is combined, the temperature and pressure decrease, and the pressure when the refrigerant is combined becomes the evaporation pressure introduced into the compressor 11.

Then, the liquid refrigerant flowing along the liquid refrigerant pipe 105 and the two-phase refrigerant passing through the expansion valve 15 are combined and then introduced into the first heat exchanger 14. In addition, the refrigerant introduced into the first heat exchanger 14 undergoes a process of evaporating into a gaseous refrigerant by exchanging heat with air.

Further, the refrigerant that has passed through the first heat exchanger 14 is introduced into the accumulator 17 under the control of the four-way valve 13. The refrigerant introduced into the accumulator 17 is classified into a liquid refrigerant and a gaseous refrigerant, and only gaseous refrigerant is re-introduced into the compressor 11. In addition, a part of the liquid refrigerant separated in the accumulator 17 is evaporated by heat transferred from the receiver 18 and introduced into the compressor 11.

According to the refrigerant system 10 of the present invention, the refrigerant flowing into the receiver 18 in the heating mode has a higher temperature than the refrigerant flowing into the accumulator 17. Accordingly, heat is transferred from the receiver 18 to the accumulator 17, and a part of the liquid refrigerant inside the accumulator 17 is evaporated by the transferred heat. As a result, there is an advantage that the amount of gaseous refrigerant flowing into the compressor 11 increases, and as the amount of gaseous refrigerant increases, the time taken to compress the gaseous refrigerant to a condensing pressure is shortened.

Meanwhile, while the heating operation is in progress, freezing occurs on the surface of the first heat exchanger 14 installed outdoors. In addition, when freezing is accumulated, the contact area with air decreases, resulting in poor heat exchange performance. To prevent this, it is necessary to periodically perform the defrost operation.

3 is a refrigerant flow chart showing a state in which a defrost operation is performed in a refrigerant system according to an embodiment of the present invention.

Referring to FIG. 3, when the defrost operation starts, the four-way valve 13 switches the flow direction of the refrigerant. That is, the opening degree of the valve is adjusted so that the refrigerant discharged from the compressor 11 flows toward the first heat exchanger 14.

In addition, when the defrost operation starts, the on-off valves 19 and 20 are opened.

In detail, when the high-temperature, high-pressure gaseous refrigerant discharged from the compressor 11 flows to the first heat exchanger 14, ice adhering to the surface of the first heat exchanger 14 is melted down. In addition, a part of the refrigerant passing through the first heat exchanger 14 flows into the expansion valve 15 and the remaining part flows into the second bypass pipe 103. At this time, the amount of the refrigerant passing through the expansion valve 15 is adjusted by adjusting the opening degree of the opening/closing valve 19 mounted in the second bypass pipe 103.

In addition, the refrigerant expanded into the low-temperature, low-pressure two-phase refrigerant while passing through the expansion valve 15 flows into the second heat exchanger 16. During the defrosting operation, the water flowing into the inlet pipe 31 is deprived of heat by the refrigerant flowing into the second heat exchanger 16 and the temperature is lowered.

Meanwhile, the refrigerant introduced into the second bypass pipe 103 flows into the receiver 18 along the first bypass pipe 102. In addition, among the refrigerants flowing into the receiver 18, the refrigerant exceeding the set water level is discharged to the liquid refrigerant pipe 105. The refrigerant discharged through the liquid refrigerant pipe 105 flows through the third bypass pipe 104 and is combined with the refrigerant discharged from the second heat exchanger 16.

Here, a part of the liquid refrigerant may flow from the point (c) where the third bypass pipe 104 is branched to the point a along the liquid refrigerant pipe 105, but the amount is very small and most of the liquid refrigerant It flows through the third bypass pipe 104. This is, at the point a, the pressure of the refrigerant passing through the first heat exchanger 14 is relatively higher than the pressure of the refrigerant flowing along the liquid refrigerant pipe 105. This is because the pressure drops while the refrigerant branched into the second bypass pipe 103 passes through the on-off valve 19. Therefore, the amount of the liquid refrigerant flowing toward the expansion valve 15 after being combined with the refrigerant flowing along the liquid refrigerant pipe 105 and passing through the first heat exchanger 14 is very small.

Meanwhile, the low-temperature refrigerant that has passed through the second heat exchanger 16 and the liquid refrigerant flowing through the third bypass pipe 104 meet and are adjusted to the evaporation pressure. In addition, the temperature of the refrigerant is also lower than the internal temperature of the receiver 18. In addition, the combined refrigerant is introduced into the accumulator 17 by the four-way valve 13.

Here, since the refrigerant flowing into the receiver 18 is part of the refrigerant that has passed through the first heat exchanger 14, the temperature is relatively higher than that of the refrigerant flowing into the accumulator 17. Accordingly, heat is transferred from the receiver 18 to the accumulator 17, and a part of the liquid refrigerant flowing into the accumulator 17 is evaporated by the transferred heat.

In addition, the gaseous refrigerant flowing into the accumulator 17 and the gaseous refrigerant evaporating by the heat transferred from the receiver 18 are introduced into the compressor 11. Here, since the receiver 18 is installed in contact with the accumulator 17 to enable heat exchange, the amount of gaseous refrigerant flowing into the compressor 11 increases. In addition, as the amount of gaseous refrigerant flowing into the compressor 11 increases, the time required to compress it to a condensing pressure is shortened. In addition, by shortening the time required for compression by the condensing pressure, the defrost time is shortened, and as the defrost time is shortened, it is possible to minimize a decrease in the temperature of water for heating.

In the case of the conventional refrigerant system 10 in which the second and third bypass pipes 103 and 104 are not provided, when the heating operation mode is changed to the defrost operation mode, the liquid refrigerant accumulated in the receiver 18 during the heating operation is During the defrosting operation, it does not flow to the main pipe 101 and remains in a standing state.

In detail, during the heating operation, a high-pressure liquid refrigerant flows through the first bypass pipe 103. When switching to the defrost operation in this state, the low pressure refrigerant that has passed through the expansion valve 15 flows toward the first bypass pipe 103 and the second heat exchanger 16. However, since the pressure of the first bypass pipe 103 is higher than the pressure of the refrigerant branched at the outlet of the expansion valve 15, the refrigerant cannot flow toward the receiver 18. On the other hand, when the defrost operation is performed, the liquid refrigerant remaining in the first bypass pipe 103 flows into the second heat exchanger 16 due to a pressure difference.

In addition, a high-pressure liquid refrigerant remains in the liquid refrigerant pipe 105, and the refrigerant flowing to the point a along the main pipe 101 during the defrosting operation is higher than the pressure of the liquid refrigerant pipe 105. Therefore, the refrigerant in the liquid refrigerant pipe 105 does not flow to the main pipe 101 and is accumulated.

For this reason, the amount of refrigerant flowing along the main pipe 101 during the defrosting operation is reduced, so that the time taken to compress the refrigerant to the condensing pressure is lengthened, and the refrigerant cannot be compressed to the set pressure. As a result, there is a disadvantage in that the time taken to release the frozen state of the first heat exchanger 14 is lengthened, the temperature of the heating water is further reduced, and the overall heating efficiency is lowered.

On the other hand, as in the present invention, the second and third bypass pipes 103 and 104 are provided, so that the refrigerant that has passed through the first heat exchanger 14 passes through the receiver 18 and flows into the accumulator 17 even during the defrosting operation. Since the refrigerant circulation passage (dotted line) is formed, the problems of the conventional refrigerant system can be solved.

In addition, during the defrosting operation, the amount of refrigerant flowing into the expansion valve 15 can be adjusted through the opening of the opening/closing valve 19, thereby minimizing a decrease in the temperature of the heating water received through the inlet pipe 31. I can.

Claims (7)

A compressor for compressing a refrigerant;
A four-way valve disposed on the outlet side of the compressor to control a flow direction of the refrigerant;
A first heat exchanger for evaporating the refrigerant in the heating operation mode;
A second heat exchanger for condensing the refrigerant passing through the compressor in a heating operation mode;
An expansion valve disposed between the first heat exchanger and the second heat exchanger to expand the refrigerant at low temperature and low pressure;
An accumulator disposed at the inlet side of the compressor to separate a liquid refrigerant from a gaseous refrigerant;
A main pipe connecting the compressor, the four-way valve, the first and second heat exchangers, the expansion valve and the accumulator to circulate a refrigerant;
A first bypass pipe branched at a point of the main pipe connecting the second heat exchanger and the expansion valve;
A receiver connected to the outlet end of the first bypass pipe;
A liquid refrigerant pipe extending from the outlet end of the receiver and connected to a point of the main pipe connecting the first heat exchanger and the expansion valve;
A second bypass pipe branched at a point at which the outlet end of the liquid refrigerant pipe is connected and between the first heat exchanger and the expansion valve among the main pipes and connected to a point of the first bypass pipe;
A third bypass pipe connecting a point connecting the second heat exchanger and the four-way valve and a point of the liquid refrigerant pipe;
A first on-off valve installed in the second bypass pipe; And
Including a second on-off valve installed in the third bypass pipe,
In the heating mode, the four-way valve is adjusted so that the refrigerant compressed by the compressor flows into the second heat exchanger, and some of the refrigerant that has passed through the second heat exchanger passes through the expansion valve and the rest of the refrigerant passes through the first bypass pipe. The first and second opening and closing valves are closed so as to pass through and flow into the receiver,
In the defrost mode, the four-way valve is adjusted so that the refrigerant compressed by the compressor flows into the first heat exchanger, and some of the refrigerant that has passed through the first heat exchanger passes through the expansion valve and the remaining part is the second bypass pipe. After passing, the first and second opening and closing valves are opened so as to pass through the first bypass pipe and flow into the receiver,
The receiver is a refrigerant system installed to be in contact with the accumulator. delete The method of claim 2,
The first and second on-off valves are refrigerant systems, characterized in that the opening is adjustable valve. The method of claim 1,
A refrigerant system further comprising a check valve installed at any point in the liquid refrigerant pipe and controlling the refrigerant to flow in only one direction. delete The method of claim 1,
The second heat exchanger is a refrigerant system including a plate heat exchanger in which the refrigerant and water exchange heat. The method of claim 1,
The first heat exchanger is a refrigerant system including a fin-tube type heat exchanger.

Images