JP2015224845A - Refrigeration cycle device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a refrigeration cycle device which secures heating capacity and in which reliability of equipment has improved.SOLUTION: A refrigeration cycle device includes a refrigerant circuit 8. A liquid receiver 5 is provided in the refrigerant circuit 8 between an evaporator 4 and a compressor 1. When temperature of a refrigerant flowing in the evaporator 4 is below a first predetermined temperature, or the outside temperature is below a second predetermined temperature and/or when the temperature of the refrigerant discharged from the compressor 1 is equal to or greater than a third predetermined temperature, the refrigerant staying in the liquid receiver 5 is returned to the refrigerant circuit 8, and the amount of the refrigerant circulating in the refrigerant circuit 8 is increased. Thus, under the condition of low evaporation temperature, heating capacity in a heat radiator 2 is secured, and under the condition of high hot water tapping temperature, excessive increase in discharge temperature is suppressed, and reliability of the equipment can be enhanced.

Description

  The present invention relates to a refrigeration cycle apparatus including a liquid receiver.

  Conventionally, this type of refrigeration cycle apparatus includes a liquid receiver provided between an evaporator and a compressor (see, for example, Patent Document 1).

  FIG. 5 is a schematic configuration diagram of the refrigeration cycle apparatus described in Patent Document 1. This refrigeration cycle apparatus is used as a heat pump water heater. Hot water used for hot water supply is generated by performing a boiling operation in which water is heated by operating the refrigeration cycle apparatus. This refrigeration cycle apparatus includes a refrigerant circuit 108 in which a compressor 101, a radiator 102, an expansion means 103, an evaporator 104, a liquid receiver 105, a superheater 106, and an internal heat exchanger 107 are connected in an annular manner through refrigerant piping in order. Have.

  Carbon dioxide is enclosed in the refrigerant circuit 108 as a refrigerant. When the refrigeration cycle apparatus is in operation, the high pressure side is in a supercritical state.

  When the refrigeration cycle apparatus is operated, the high-pressure refrigerant discharged from the compressor 101 is supplied to the radiator 102 and performs heat exchange with water in the radiator 102 to radiate heat. The refrigerant that has flowed out of the radiator 102 is supplied to the expansion means 103 through the high-pressure channel 171 of the internal heat exchanger 107.

  The low-pressure refrigerant decompressed by the expansion means 3 absorbs heat from the air supplied to the evaporator 104 and blown by the blower 109 and evaporates. Thereafter, the liquid is again sucked into the compressor 101 through the low-pressure channel 172 of the liquid receiver 105, the superheater 106, and the internal heat exchanger 107.

  FIG. 6 is a cross-sectional view showing the internal structure of the liquid receiver 105 of the refrigeration cycle apparatus described in Patent Document 1. The liquid receiver 105 has a function of storing the refrigerant in a liquid state therein. In the liquid receiver 105, the refrigerant is stored particularly under the condition that the outside air temperature and the incoming water temperature change and the refrigerant circulating in the refrigerant circuit 108 becomes excessive. Thereby, the refrigerant quantity circulating through the refrigerant circuit 108 can be adjusted.

  That is, as shown in the Ph diagram (Mollier diagram) in FIG. 7, the refrigerant density on the low pressure side decreases as the outside air temperature decreases, so the amount of refrigerant circulating in the refrigerant circuit 108 decreases. As a result, surplus refrigerant is generated in the refrigerant circuit 108. Since this surplus refrigerant is stored as liquid refrigerant in the liquid receiver 105, the amount of refrigerant circulating in the refrigerant circuit 108 is adjusted.

  The internal heat exchanger 7 is configured such that the refrigerant flowing through the high-pressure channel 171 dissipates heat to the refrigerant flowing through the low-pressure channel 172. This makes it possible to adjust the amount of refrigerant circulating through the refrigerant circuit 108 even under operating conditions where the incoming water temperature is high and the amount of refrigerant is excessive.

JP2013-124802A

  In the conventional configuration, when the outside air temperature decreases, excess refrigerant generated in the refrigerant circuit 108 is stored in the liquid receiver 108. Therefore, as shown in FIG. 8, the amount of liquid refrigerant stored in the liquid receiver 108 increases as the outside air temperature decreases. Therefore, when the outside air temperature is extremely low (for example, outside temperature −10 ° C.) and the evaporation temperature of the refrigerant is extremely low (for example, evaporation temperature −20 ° C.), the refrigerant density on the low pressure side is significantly reduced. Therefore, the amount of refrigerant circulating in the refrigerant circuit 108 is greatly reduced, and the suction density of the refrigerant sucked into the compressor 101 is lowered. As a result, as shown in FIG. 9, there is a problem that the heating capability of the radiator 2 may be insufficient.

  On the other hand, when the target value of the boiling operation is high (for example, the tapping temperature 90 ° C.), the opening degree of the expansion means 3 of the refrigeration cycle apparatus is reduced. Thereby, since the superheat degree of the refrigerant | coolant suck | inhaled by the compressor 101 can be increased and the temperature (discharge temperature) of the refrigerant | coolant discharged from the compressor 101 can be raised, high hot-water temperature can be implement | achieved. However, if sufficient heating capacity is secured by narrowing the expansion means 3, the discharge temperature rises excessively, and there is a problem that the reliability of components such as the compressor 101 and lubricating oil is impaired. It was.

  This invention solves the said conventional subject, and it aims at providing the refrigerating-cycle apparatus which can respond also to the case where the low outdoor temperature and the tapping temperature of the to-be-heated fluid are high.

  In order to achieve the above object, the present invention comprises a refrigerant circuit in which a compressor, a radiator, expansion means, and an evaporator are annularly connected by a refrigerant pipe and in which a refrigerant circulates, and the evaporator and the compressor The refrigerant circuit is provided with a liquid receiver, and the refrigerant flowing through the evaporator is discharged from the compressor when the temperature of the refrigerant flowing below the first predetermined temperature or the outside air temperature is lower than the second predetermined temperature. When the temperature of the refrigerant is equal to or higher than a third predetermined temperature, the refrigerant staying in the receiver is returned to the refrigerant circuit to increase the amount of refrigerant circulating in the refrigerant circuit. The refrigeration cycle apparatus.

  Thereby, the fall of the heating capability resulting from the excessive fall of the suction density at the time of low outside air temperature, and the reliability fall of the compressor resulting from the excessive raise of the discharge temperature at the time of high hot water temperature can be suppressed.

  ADVANTAGE OF THE INVENTION According to this invention, the refrigerating cycle apparatus which exhibits required heating capability and has high reliability can be provided.

Schematic configuration diagram of a refrigeration cycle apparatus according to Embodiment 1 of the present invention. Schematic configuration diagram showing the internal structure of the receiver of the refrigeration cycle apparatus Ph diagram (Mollier diagram) showing different operating points according to the outside air temperature of the refrigeration cycle apparatus Ph diagram (Mollier diagram) showing different operating points according to the tapping temperature of the refrigeration cycle apparatus Schematic configuration diagram of a conventional refrigeration cycle apparatus Schematic configuration diagram showing the internal structure of the receiver of the refrigeration cycle apparatus Ph diagram (Mollier diagram) showing different operating points according to the outside air temperature in the refrigeration cycle apparatus The conceptual diagram which shows the relationship between the quantity of the liquid refrigerant stored in the liquid receiver of the same refrigeration cycle apparatus, and external temperature Graph showing the heating capacity of each refrigeration cycle device for each outside temperature

  A first invention includes a refrigerant circuit in which a compressor, a radiator, expansion means, and an evaporator are annularly connected by a refrigerant pipe, and the refrigerant circulates therein, and the refrigerant between the evaporator and the compressor A liquid receiver is provided in the circuit, and the temperature of the refrigerant flowing through the evaporator is lower than the first predetermined temperature or the outside air temperature is lower than the second predetermined temperature, and / or the temperature of the refrigerant discharged from the compressor is the first temperature. 3. A refrigeration cycle apparatus characterized in that when the temperature is equal to or higher than a predetermined temperature, the refrigerant staying in the receiver is returned to the refrigerant circuit to increase the amount of refrigerant circulating in the refrigerant circuit. .

  Accordingly, when the outside air temperature or the evaporation temperature of the refrigerant becomes lower than a predetermined temperature (low evaporation temperature condition), the liquid refrigerant staying in the liquid receiver flows into the refrigerant circuit, and thus circulates through the refrigerant circuit. The amount of refrigerant increases. As a result, the heating capability of the radiator can be maintained at a predetermined value or more. Therefore, an excessive decrease in the suction density of the compressor can be suppressed, and the heating capability of the radiator can be ensured. In particular, when heating or hot water supply is performed using a non-heated fluid of a refrigeration cycle device under conditions of a low outside air temperature, a large amount of heat is required, and thus it is necessary to increase the heating capacity of the radiator. Therefore, it is particularly effective to increase the amount of refrigerant circulating in the refrigerant circuit under the low evaporation temperature condition.

  In addition, the refrigeration cycle apparatus causes the liquid refrigerant staying in the liquid receiver to flow into the refrigerant circuit when the discharge temperature becomes equal to or higher than a predetermined temperature (high discharge temperature condition). The amount of increases. Therefore, since the refrigerant suction density increases, an excessive increase in the discharge temperature can be suppressed. Therefore, under high discharge temperature conditions, the heating capacity of the radiator is sufficiently secured to achieve a high hot water temperature, but the reliability of the compressor and its lubricating oil is not impaired.

  In a second aspect of the invention, particularly in the first aspect of the invention, the liquid receiver includes a container, a refrigerant inlet into which the refrigerant flows into the container, a first refrigerant outlet provided at a predetermined height in the container, A second refrigerant outlet provided at a position lower than the first outlet in the container, and a flow rate adjusting means for adjusting the amount of refrigerant flowing out of the second refrigerant outlet. It is.

  As a result, when the low evaporation temperature condition and / or the high discharge temperature condition are reached, the flow rate adjusting means is operated to cause the refrigerant to flow into the refrigerant circuit via the second refrigerant outlet. Therefore, it is possible to suppress a decrease in heating capability due to an excessive decrease in the suction density at a low outside air temperature and a decrease in reliability of the compressor due to an excessive increase in the discharge temperature at a high tapping temperature.

  Moreover, since the liquid receiver arrange | positions the 2nd refrigerant | coolant outflow port in the position used as predetermined | prescribed height L2 in a container, it utilizes the positional energy of the refrigerant | coolant which has accumulated above the 2nd refrigerant | coolant outflow port. The liquid refrigerant can be returned to the refrigerant circuit. That is, since the refrigerant can be returned to the refrigerant circuit without using power such as a pump, energy saving can be maintained high.

  In addition, a control device that controls the operation of the refrigeration cycle apparatus is provided, and the control device is configured to execute a heating operation for heating the fluid to be heated and a defrosting operation for removing frost attached to the evaporator. Also good. The fluid to be heated becomes water when the refrigeration cycle apparatus is used as an application for a water heater, and becomes air when the refrigeration cycle apparatus is used as an application for an air conditioner.

  Further, the control device operates the flow rate adjusting means during execution of the defrosting operation so that the liquid refrigerant staying in the liquid receiver flows into the refrigerant circuit via the second refrigerant outlet. May be.

As a result, the liquid refrigerant staying in the liquid receiver flows into the refrigerant circuit, and the amount of refrigerant circulating in the refrigerant circuit increases. Therefore, the time taken for the defrosting of the evaporator can be reduced.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. Note that the present invention is not limited to the embodiments.

(Embodiment 1)
FIG. 1 is a schematic configuration diagram of the refrigeration cycle apparatus of the present embodiment. In the present embodiment, a case where the refrigeration cycle apparatus is used for a heat pump water heater will be described as an example. By using this refrigeration cycle apparatus, a boiling operation for heating water to generate hot water is performed.

  The refrigeration cycle apparatus includes a compressor 1, a radiator 2, an expansion means (expansion valve) 3, an evaporator 4, a liquid receiver 5, a superheater 6, and an internal heat exchanger 7. These are connected in an annular shape in order by a refrigerant pipe, and constitute a refrigerant circuit 8. In the present embodiment, carbon dioxide is used as the refrigerant. Thereby, hot water (for example, 80 degreeC or more) can be produced | generated. As the refrigerant, in addition to carbon dioxide, a fluorocarbon refrigerant such as R410A, R407C, R134a, and R32 can be used. When carbon dioxide is used as the refrigerant, the high-pressure side pressure when the refrigeration cycle apparatus is operating is a supercritical pressure. On the other hand, when a chlorofluorocarbon refrigerant is used, the high-pressure side pressure when the refrigeration cycle apparatus is operating is a subcritical pressure. Therefore, when a fluorocarbon refrigerant is used, the radiator 2 functions as a refrigerant condenser.

  The refrigerant circuit 8 is provided with a discharge temperature detecting means 10 for detecting the temperature of the refrigerant discharged from the compressor 1 in a refrigerant pipe between the compressor 1 and the radiator 2. The refrigerant circuit 8 is provided with an evaporation temperature detecting means (evaporator inlet temperature sensor) 11 for detecting the temperature of the refrigerant flowing through the evaporator 4. The evaporating temperature detecting means 11 can detect the evaporating temperature of the refrigerant in the evaporator 4. In the present embodiment, the evaporation temperature detecting means 11 is provided on the inlet side of the evaporator 4, that is, on the refrigerant pipe between the expansion valve 3 and the evaporator 4, but provided at a position where the evaporation temperature can be detected. The position is not particularly limited as long as it is. For example, the evaporating temperature detecting means 11 may be provided in the refrigerant pipe constituting the evaporator 4. Further, the refrigerant circuit 8 between the evaporator 4 and the liquid receiver 5 is provided with an evaporator outlet temperature detecting means (evaporator outlet temperature sensor) 12 for detecting the temperature of the refrigerant flowing out of the evaporator 4. . The degree of superheat of the refrigerant flowing out of the evaporator 4 can be calculated from the temperature difference between the detected temperature of the evaporation temperature detecting means 11 and the detected temperature of the evaporator outlet temperature detecting means 12.

  The radiator 2 in the present embodiment heats water by exchanging heat between the water and the refrigerant. The radiator 2 is connected to a water inlet pipe 13 through which water flowing out from below a hot water storage tank (not shown) for storing water flows. The water inlet pipe 13 is provided with a pump (not shown) for flowing water. Water flows into the radiator 2 through the water inlet pipe 13. The radiator 2 is connected to the other end of a hot water supply pipe 14 having one end connected above the hot water storage tank. Hot water that has flowed out of the radiator 2 returns to the hot water storage tank via the hot water supply pipe 14. Thereby, hot water is stored in the hot water storage tank in order from above.

  As the expansion means 3, an electromagnetic expansion valve whose opening degree can be freely adjusted, or a capillary tube can be used. In this embodiment, an electromagnetic expansion valve whose opening degree can be adjusted is used.

  The evaporator 4 is an air heat exchanger that performs heat exchange between the refrigerant and the air. The evaporator 4 is a finned tube heat exchanger having a refrigerant pipe made of copper or aluminum (including an aluminum alloy) and aluminum fins. A blower 9 that blows air to the evaporator 4 is provided in the vicinity of the evaporator 4.

The internal heat exchanger 7 has a high-pressure channel 71 through which the refrigerant flowing out of the radiator 2 flows and a low-pressure channel 72 through which the refrigerant flowing into the compressor 1 flows. And the refrigerant flowing through the low-pressure channel 72 exchanges heat. This prevents the high-pressure side pressure of the refrigeration cycle apparatus from becoming excessive.

  That is, in the boiling operation, when the temperature of the water flowing into the radiator 2 is low, the refrigerant sufficiently dissipates heat to the water in the radiator 2 and the temperature is lowered. Therefore, the heat exchange amount in the internal heat exchanger 7 Is not too big.

  On the other hand, when the boiling operation proceeds, hot water is distributed to the lower part of the hot water storage tank, the temperature of the hot water flowing into the radiator 2 is rapidly increased, and the high-pressure side pressure is increased to near the design pressure. However, as the high pressure side pressure rises, the temperature of the refrigerant flowing into the high pressure side flow channel 71 of the internal heat exchanger 7 also rises. Therefore, the refrigerant flowing through the high pressure side flow channel 71 and the refrigerant flowing through the low pressure side flow channel 72. And the temperature difference increases, the amount of heat exchange increases. Therefore, the low pressure side flow path 72 is further cooled, and the density of the high pressure side refrigerant is increased. Therefore, even if the hold amount of the high pressure side refrigerant is the same, the high pressure side pressure can be reduced.

  The superheater 6 is provided in the refrigerant circuit 8 downstream of the liquid receiver 5 and upstream of the low-pressure channel 72 of the internal heat exchanger 7. Similar to the evaporator 4, the superheater 6 is an air heat exchanger that exchanges heat between the refrigerant and the air. Similarly to the evaporator 4, the superheater 6 is a finned tube heat exchanger having a copper or aluminum refrigerant pipe and aluminum fins. The superheater 6 is preferably configured integrally with the evaporator 4. That is, a part of the fin tube heat exchanger becomes the evaporator 4 and the other part of the fin tube heat exchanger becomes the superheater 6. However, the heat transfer area of the fins constituting the evaporator 4 is larger than the heat transfer area of the fins constituting the superheater 6. Thereby, the evaporator 4 and the superheater 6 can share the air blower 9, and size reduction of a refrigerating cycle apparatus can be achieved. In addition, if the superheater 6 is a structure which can heat a refrigerant | coolant, it will not be specifically limited to a finned-tube heat exchanger.

  FIG. 2 is a schematic configuration diagram showing the internal structure of the liquid receiver 5. The liquid receiver 5 stores liquid refrigerant in a container 50 having a cylindrical central portion and hemispherical upper and lower portions. A refrigerant inlet 51 is provided in the upper part of the container 50. The refrigerant flows into the container 50 from the uppermost part of the container 50 through the refrigerant inlet 51.

  Inside the container 50, a plurality of refrigerant outlets (52a, 52b) are provided at different heights. The refrigerant outlet 52a is provided at a height L1 from the bottom of the container 50. The refrigerant outlet 52b is provided at a height L2 (<L1) from the bottom of the container 50. The refrigerant outlet 52b is provided at a position lower than the refrigerant outlet 52a, and is for allowing the refrigerant staying in the liquid receiver 5 to flow into the refrigerant circuit 8 under a predetermined condition described later.

  A junction portion 54 is provided outside the container 50 to join the refrigerant flowing out from the refrigerant outlet 52a and the refrigerant flowing out from the refrigerant outlet 52b. Note that the merging portion 54 may be provided inside the container 50.

  Between the junction part 54 and the refrigerant | coolant outflow port 52b, the flow volume adjustment means 53 which adjusts the quantity of the refrigerant | coolant which flows out out of the refrigerant | coolant outflow port 52b is provided. The flow rate adjusting means 53 may be a two-way valve that opens and closes the flow path. That is, it is only necessary to have a function of causing the liquid refrigerant inside the liquid receiver 5 to flow into the refrigerant circuit 8.

The control device 30 performs a plurality of operations. The plurality of operations includes a heating operation for heating the fluid to be heated by the radiator 2 and a defrosting operation for melting the frost attached to the evaporator 4. In the present embodiment, the refrigeration cycle apparatus is used as a heat pump water heater, and water that is a fluid to be heated is heated by the radiator 2. That is, in the present embodiment, the heating operation is a water boiling operation. The control device 30 controls the rotational speed of the compressor 1, the opening degree of the expansion valve 3, and the rotational speed of the blower 9 during execution of the operation. Further, the control device 30 operates the flow rate adjusting means 53 under a predetermined condition to cause the liquid refrigerant in the liquid receiver 5 to flow into the refrigerant circuit 8.

  About the refrigerating-cycle apparatus comprised as mentioned above, the operation | movement and an effect | action are demonstrated below.

  The control device 30 operates the compressor 1 in the boiling operation. The refrigerant that has been compressed by the compressor 1 and has become high temperature and pressure is discharged from the compressor 1 and sent to the radiator 2. On the other hand, water is sent to the radiator 2 by a circulation pump provided in the water inlet pipe 13. In the radiator 2, the refrigerant dissipates heat to the water and exchanges heat. Thereby, hot water is produced | generated. The generated hot water flows into the hot water storage tank from the upper part of the hot water storage tank through the hot water piping.

  The refrigerant that has radiated water to the radiator 2 flows through the expansion valve 3 via the high-pressure channel 71 of the internal heat exchanger 7. The refrigerant is decompressed by the expansion valve 3 and sent to the evaporator 4. In the evaporator 4, the refrigerant absorbs heat from the air blown by the blower 9, and part or all of the refrigerant evaporates. The refrigerant is sent from the refrigerant outlet 52a of the liquid receiver 5 to the superheater 6 in a saturated gas state. At this time, the flow rate adjusting means 53 is in a closed state so that the refrigerant does not flow out from the refrigerant outlet 52b. In the superheater 6, the refrigerant absorbs heat from the air sent by the blower 9 and enters a superheated state. Thereafter, the refrigerant further absorbs heat from the refrigerant flowing through the high-pressure channel 71 in the internal heat exchanger 7 and is sucked into the compressor 1.

  Next, an operation of returning the liquid refrigerant staying in the liquid receiver 5 to the refrigerant circuit 8 in the present embodiment will be described.

  When the outside air temperature is relatively low, the control device 30 throttles the opening of the expansion valve 3 so that the evaporator 4 can absorb heat even from low temperature air. Further, the control device 30 increases the rotation frequency of the compressor 1 in order to ensure the heating capability in the radiator 2. At this time, as shown in the Ph diagram (Mollier diagram) of FIG. 3, the suction density of the refrigerant sucked into the compressor 1 decreases, and the circulation amount of the refrigerant flowing through the refrigerant circuit 8 decreases. The surplus refrigerant generated in the refrigerant circuit 8 is stored in the liquid receiver 5.

  Here, under a low evaporation temperature condition in which the outside air temperature is further lowered (for example, the outside air temperature −10 ° C.) and the evaporation temperature of the refrigerant flowing through the evaporator 4 is lowered (for example, the evaporation temperature −20 ° C.), Even if the refrigerant density decreases excessively and the rotational frequency of the compressor 1 is increased, the heating capability of the radiator 2 may be insufficient.

  Therefore, when the control device 30 detects that the predetermined low evaporation temperature condition has been reached by the evaporation temperature detection means 11, the opening degree of the flow rate adjustment means 53 is adjusted (opened) and stored in the liquid receiver 5. The liquid refrigerant is returned to the refrigerant circuit 8. Thereby, the density of the refrigerant sucked into the compressor 1 is increased, and the amount of the refrigerant circulating in the refrigerant circuit 8 is increased, so that the heating capacity in the radiator 2 can be sufficiently ensured.

  In the present embodiment, whether or not the low evaporation temperature condition is satisfied is determined by the evaporation temperature detection means 11, but the low evaporation temperature condition is also determined by the temperature of the refrigerant flowing through the evaporator 4 and the outside air temperature. It is possible to determine whether this is the case.

Further, the control device 30 performs normal boiling (for example, the tapping temperature is 65 ° C.) when the temperature of the hot water flowing out of the radiator 2 or the target temperature is high (for example, the tapping temperature is 90 ° C.).
The evaporating temperature of the refrigerant is lowered by restricting the expansion valve 3 to less than (° C.), thereby increasing the refrigerant superheating degree. Thereby, the discharge temperature of the refrigerant | coolant discharged from the compressor 1 is raised, and high temperature boiling is performed.

  At the time of high-temperature boiling, as shown in the Ph diagram (Mollier diagram) in FIG. 4, the suction pressure of the compressor 1 decreases and the density of the refrigerant sucked into the compressor 1 decreases. Therefore, excess refrigerant generated in the refrigerant circuit 8 is stored in the liquid receiver 5.

  And the control apparatus 30 adjusts the opening degree of the flow volume adjustment means 53, when the discharge temperature detected by the discharge temperature detection means 10 exceeds predetermined temperature (for example, discharge temperature 120 degreeC) (high discharge temperature conditions). Then, the liquid refrigerant stored in the liquid receiver 5 is returned to the refrigerant circuit 8.

  For this reason, the quantity of the refrigerant | coolant which circulates through the refrigerant circuit 8 increases, and since the density of the refrigerant | coolant suck | inhaled by the compressor 1 increases, the excessive raise of discharge temperature can be suppressed. Therefore, the heating capability in the radiator 2 can be sufficiently ensured without impairing the reliability of the component parts of the compressor 1 and the lubricating oil used in the compressor 1.

  Further, since the liquid receiver 5 is provided with a plurality of refrigerant outlets (52a, 52b) at different heights, and further provided with a flow rate adjusting means 53 for adjusting the amount of refrigerant flowing out of the refrigerant outlet 52b. The liquid refrigerant can be easily caused to flow into the refrigerant circuit 8 by using the potential energy of the liquid refrigerant staying above the refrigerant outlet 52b having a relatively low height. That is, the liquid refrigerant can be returned to the refrigerant circuit 8 without using extra power such as a pump, and energy efficiency can be maintained high.

  Next, the defrosting operation of the refrigeration cycle apparatus will be described.

  When the boiling operation is performed in a state where the outside air temperature is low, frost adheres to the periphery of the evaporator 4 to inhibit heat exchange between the air and the refrigerant, and the heat exchange amount of the evaporator 4 is significantly reduced. Then, the defrost operation which melt | dissolves the frost adhering to the evaporator 4 and recovers the heat exchange amount of the evaporator 4 is performed.

  The control device 30 estimates that frost has adhered to the evaporator 4 based on the detected temperature of the evaporator outlet temperature detecting means 12, and starts the defrosting operation. Specifically, the defrosting operation is started when the detected temperature of the evaporator outlet temperature detecting means 12 becomes lower than a predetermined temperature. The control device 30 stops the circulation pump and the blower 9 in the defrosting operation. Next, the opening degree of the expansion valve 3 is set to a predetermined opening degree, preferably fully opened. When the compressor 1 is operated in this state, the high-temperature and high-pressure refrigerant compressed by the compressor 1 flows through the radiator 2 and the internal heat exchanger 7 and is not decompressed by the expansion valve 3, that is, the temperature is high. As it is, it flows into the evaporator 4. The refrigerant flowing into the evaporator 4 melts frost attached to the fins and the like of the evaporator 4 by the heat. The refrigerant is then sucked into the compressor 1. When the temperature detected by the evaporator outlet temperature detection means 12 is equal to or higher than the predetermined temperature, the control device 30 ends the defrosting operation and shifts to the boiling operation.

  In the defrosting operation, the refrigerant that has flowed out of the evaporator 4 absorbs heat from the refrigerant that passes through the high-pressure side passage 71 while flowing through the low-pressure side passage 72 of the internal heat exchanger 7, and most or all of the refrigerant is discharged. Evaporate. Therefore, a large amount of liquid refrigerant flows into the compressor 1 and the compressor 1 is not damaged.

Here, the control device 30 performs an operation of causing the liquid refrigerant staying in the liquid receiver 5 to flow into the refrigerant circuit 8 during the defrosting operation. The control device 30 operates the flow rate adjusting means 53 during the defrosting operation so that the liquid refrigerant staying in the liquid receiver 5 flows into the refrigerant circuit 8. Thereby, since the quantity of the refrigerant | coolant which circulates through the refrigerant circuit 8 increases, more heat can be supplied to the evaporator 4 and defrosting can be performed. Therefore, the defrosting of the evaporator 4 can be performed in a short time, and energy saving performance can be maintained high.

  As described above, the refrigeration cycle apparatus causes the liquid refrigerant stored in the liquid receiver 5 to flow into the refrigerant circuit 8 and circulates through the refrigerant circuit 8 under predetermined low evaporation temperature conditions and / or high discharge temperature conditions. Increase the amount of refrigerant. Thereby, while ensuring the heating capability in the heat radiator 2, the reliability of an apparatus improves.

  According to the present invention, the heating capability of the radiator is sufficiently ensured, and the reliability of the device is improved, so that it can be used for applications such as a water heater and an air conditioner.

DESCRIPTION OF SYMBOLS 1 Compressor 2 Radiator 3 Expansion means (expansion valve)
DESCRIPTION OF SYMBOLS 4 Evaporator 5 Liquid receiver 6 Superheater 7 Internal heat exchanger 8 Refrigerant circuit 9 Blower 10 Discharge temperature detection means 11 Evaporation temperature detection means 12 Evaporator outlet temperature detection means 13 Inlet piping 14 Hot water piping 30 Control device 50 Container 51 Refrigerant Inlet 52a, 52b Refrigerant outlet 53 Flow rate adjusting means 54 Junction portion 71 High-pressure side channel 72 Low-pressure side channel

Claims (2)

A compressor, a radiator, an expansion means, and an evaporator are connected in a ring shape with a refrigerant pipe, and a refrigerant circuit in which the refrigerant circulates is provided.
A liquid receiver is provided in the refrigerant circuit between the evaporator and the compressor;
When the temperature of the refrigerant flowing through the evaporator is lower than a first predetermined temperature or the outside air temperature is lower than a second predetermined temperature, and / or when the temperature of the refrigerant discharged from the compressor is equal to or higher than a third predetermined temperature, A refrigeration cycle apparatus characterized in that the refrigerant staying in the liquid receiver is returned to the refrigerant circuit to increase the amount of refrigerant circulating in the refrigerant circuit. The receiver is
A container,
A refrigerant inlet through which refrigerant flows into the container;
A first refrigerant outlet provided at a predetermined height in the container;
A second refrigerant outlet provided in a position lower than the first outlet in the container;
2. The refrigeration cycle apparatus according to claim 1, further comprising: a flow rate adjusting unit that adjusts an amount of the refrigerant flowing out from the second refrigerant outlet.