JP2011080634A - Refrigerating cycle device and hot-water heating device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a refrigerating cycle device, and a hot-water heating device using the same, capable of performing an operation of high efficiency in a high heating load operation such as a heating operation at a low outside air temperature. <P>SOLUTION: This refrigerating cycle device 1 includes a refrigerant circuit 2 provided with a condenser 22 and a supercooling heat exchanger 23, and a bypass passage 3 passing through the supercooling heat exchanger 23. In the bypass passage 3, dryness of the refrigerant flowing out form the supercooling heat exchanger 23 is adjusted. A ratio of a heat exchanging amount between the refrigerant decompressed by the supercooling heat exchanger 23 in the bypass passage 3 and the refrigerant passing through the refrigerant circuit 2 to a heat exchanging amount between the refrigerant flowing into the condenser 22 and a heated fluid in the condenser 22 is kept within a prescribed range by properly configuring the supercooling heat exchanger 23 even in the operation with the adjustment of dryness. As a result, the supercooling effect of the supercooling heat exchanger 23 can be secured. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a refrigeration cycle apparatus for supercooling refrigerant and a hot water heater using the refrigeration cycle apparatus.

  2. Description of the Related Art Conventionally, there has been provided a refrigeration cycle apparatus in which a supercooling heat exchanger is provided on the downstream side of a condenser in a refrigerant circuit, and the refrigerant flowing out of the condenser is supercooled by allowing the expanded refrigerant to flow into the supercooling heat exchanger. Are known. For example, Patent Document 1 discloses a refrigeration cycle apparatus 100 as shown in FIG.

  The refrigeration cycle apparatus 100 includes a refrigerant circuit 110 that circulates refrigerant and a bypass passage 120. The refrigerant circuit 110 is configured by connecting a compressor 111, a condenser 112, a supercooling heat exchanger 113, a main expansion valve 114, and an evaporator 115 in an annular shape by piping. The bypass 120 is branched from the refrigerant circuit 110 between the condenser 112 and the supercooling heat exchanger 113 and connected to the refrigerant circuit 110 between the evaporator 115 and the compressor 111 via the supercooling heat exchanger 113. ing. The bypass passage 120 is provided with a bypass expansion valve 121 upstream of the supercooling heat exchanger 113.

  And in patent document 1, in order to improve a refrigerating capacity, the ratio (bypass ratio) of the bypass refrigerant | coolant flow volume which flows into the bypass path 120 with respect to the total refrigerant | coolant flow volume which flows into the condenser 112 is the range of 1% or more and 25% or less. It is described that the bypass expansion valve 121 is controlled as described above.

Japanese Patent No. 4036288

  By the way, in order to realize high-efficiency operation in the refrigeration cycle apparatus as described above, in the supercooling heat exchanger, the refrigerant flowing in the refrigerant circuit is not overheated (superheated) and the refrigerant flowing in the refrigerant circuit is predetermined. It is preferable to supercool to this state. To achieve this, the subcooling heat exchanger needs to be properly configured. In this regard, Patent Document 1 does not particularly describe the configuration of the supercooling heat exchanger.

  In view of such circumstances, the present invention provides a refrigeration cycle apparatus that includes an appropriately configured supercooling heat exchanger and that can be operated with high efficiency, and a hot water heater using the refrigeration cycle apparatus. With the goal.

  As a result of intensive studies, the inventors of the present invention have a high COP (Coefficient of Performance) if the dryness of the refrigerant flowing out of the supercooling heat exchanger in the bypass passage is kept at 0.8 or more and less than 1.0. It was found that it can be obtained. However, when the dryness is controlled to fall within such a range, depending on the capacity of the supercooling heat exchanger, when the outside air temperature is low and the heating capacity required for the condenser is increased, the refrigerant The supercooling of the refrigerant flowing through the circuit may become insufficient or excessive. The present invention has been made from such a viewpoint.

  That is, the present invention relates to a refrigerant circuit in which a compressor, a condenser, a supercooling heat exchanger, a main expansion means and an evaporator are connected in an annular shape, and between the supercooling heat exchanger and the main expansion means or the condensation. A bypass path that branches from the refrigerant circuit between the evaporator and the supercooling heat exchanger, and connects to the refrigerant circuit between the evaporator and the compressor via the supercooling heat exchanger, and the bypass Bypass expansion means provided on the upstream side of the supercooling heat exchanger of the passage, and the supercooling heat exchanger has a dryness of the refrigerant flowing out of the supercooling heat exchanger in the bypass passage of 0 When the opening degree of the bypass expansion means is adjusted so as to be 0.8 or more and less than 1.0, the excess of the heat exchange amount between the refrigerant flowing into the condenser and the heated fluid in the condenser is determined. The bypass path in the cooling heat exchanger The ratio of the amount of heat exchange between the refrigerant flowing out of the condenser and the decompressed refrigerant is configured such that 0.2 to 0.8, to provide a refrigeration cycle device.

  Moreover, this invention is a hot water heating apparatus which utilizes the warm water produced | generated by the heating means for heating, Comprising: The hot water heating apparatus provided with said refrigeration cycle apparatus as said heating means is provided.

  According to the above, since the supercooling heat exchanger is appropriately configured, when the dryness of the refrigerant flowing out from the supercooling heat exchanger in the bypass passage is kept at 0.8 or more and less than 1.0, the outside air Even if the temperature is low and the heating capacity required for the condenser is increased, the refrigerant flowing through the refrigerant circuit can be supercooled to an appropriate state. Therefore, according to the present invention, highly efficient operation can be realized.

1 is a schematic configuration diagram of a refrigeration cycle apparatus according to an embodiment of the present invention. It is a correlation diagram of the dryness of the refrigerant | coolant in an evaporator inlet, and a heat exchange ratio, (a) shows the time of using R407C as a refrigerant | coolant, (b) shows the time of using R410A as a refrigerant | coolant. It is a Mollier diagram of the refrigeration cycle apparatus when R407C is used as a refrigerant, (a) shows when the dryness of the refrigerant at the inlet of the evaporator is 0.55, (b) shows at the inlet of the evaporator. When the dryness of the refrigerant is zero. It is a Mollier diagram of a refrigeration cycle apparatus when using R410A as a refrigerant, (a) shows when the dryness of the refrigerant at the inlet of the evaporator is 0.45, (b) is at the inlet of the evaporator. When the dryness of the refrigerant is zero. Correlation diagram of ambient temperature and heat exchange ratio for each refrigerant condensation temperature in the condenser Schematic configuration diagram of a conventional refrigeration cycle apparatus

  FIG. 1 shows a refrigeration cycle apparatus 1 according to an embodiment of the present invention. The refrigeration cycle apparatus 1 includes a refrigerant circuit 2 that circulates refrigerant, a bypass path 3, and a control device 4. As the refrigerant, for example, a non-azeotropic refrigerant mixture such as R407C, a pseudo-azeotropic refrigerant mixture such as R410A, or a single refrigerant can be used.

  The refrigerant circuit 2 is configured by connecting a compressor 21, a condenser 22, a supercooling heat exchanger 23, a main expansion valve 24, and an evaporator 25 in a ring shape by piping. In the present embodiment, a sub-accumulator 26 and a main accumulator 27 that perform gas-liquid separation are provided between the evaporator 25 and the compressor 21. The refrigerant circuit 2 is provided with a four-way valve 28 for switching between normal operation and defrost operation.

  In the present embodiment, the refrigeration cycle apparatus 1 constitutes heating means of a hot water heating apparatus that uses hot water generated by the heating means for heating, and the condenser 22 exchanges heat between the refrigerant and water. It is a heat exchanger that heats water. Specifically, a supply pipe 71 and a recovery pipe 72 are connected to the condenser 22. Water is supplied to the condenser 22 through the supply pipe 71, and water (hot water) heated by the condenser 22 is recovered in the recovery pipe 72. It has come to be collected through. The water (warm water) recovered by the recovery pipe 72 is sent directly or via a hot water storage tank to a heater such as a radiator, for example, thereby heating.

  The bypass path 3 branches from the refrigerant circuit 2 between the supercooling heat exchanger 23 and the main expansion valve 24, and enters the refrigerant circuit 2 between the evaporator 25 and the compressor 21 via the supercooling heat exchanger 23. linked. In the present embodiment, the bypass 3 is connected to the refrigerant circuit 2 between the sub accumulator 26 and the main accumulator 27. The bypass passage 3 is provided with a bypass expansion valve 31 on the upstream side of the supercooling heat exchanger 23.

  In the normal operation, the refrigerant discharged from the compressor 21 is sent to the condenser 22 via the four-way valve 28, and in the defrost operation, the refrigerant discharged from the compressor 21 is sent to the evaporator 25 via the four-way valve 28. It is done. In FIG. 1, the direction of refrigerant flow during normal operation is indicated by arrows. Hereinafter, the state change of the refrigerant in the normal operation will be described.

  The high-pressure refrigerant discharged from the compressor 21 flows into the condenser 22 and radiates heat to the water passing through the condenser 22. The high-pressure refrigerant flowing out of the condenser 22 flows into the supercooling heat exchanger 23 and is supercooled by the low-pressure refrigerant decompressed by the bypass expansion valve 31. The high-pressure refrigerant that has flowed out of the supercooling heat exchanger 23 is divided into the main expansion valve 24 side and the bypass expansion valve 31 side.

  The high-pressure refrigerant branched to the main expansion valve 24 side is decompressed and expanded by the main expansion valve 24 and then flows into the evaporator 25. Here, the low-pressure refrigerant flowing into the evaporator 25 absorbs heat from the air. On the other hand, the high-pressure refrigerant branched to the bypass expansion valve 31 side is decompressed and expanded by the bypass expansion valve 31 and then flows into the supercooling heat exchanger 23. The low-pressure refrigerant that has flowed into the supercooling heat exchanger 23 is heated by the high-pressure refrigerant that has flowed out of the condenser 22. Thereafter, the low-pressure refrigerant that has flowed out of the supercooling heat exchanger 23 merges with the low-pressure refrigerant that has flowed out of the evaporator 25, and is sucked into the compressor 21 again.

  The configuration of the refrigeration cycle apparatus 1 of the present embodiment is that the pressure of the refrigerant sucked into the compressor 21 at the low outside air temperature decreases and the refrigerant circulation amount decreases, thereby reducing the heating capacity of the condenser 22. It is for preventing. In order to realize this, the difference in enthalpy in the evaporator 25 is increased by supercooling, and the refrigerant is bypassed by the bypass passage 3, so that the gas-phase refrigerant having a small endothermic effect flowing through the low-pressure side portion of the refrigerant circuit 2 is obtained. It is important to reduce the amount and thereby reduce the pressure loss at the low pressure side portion of the refrigerant circuit 2. If the pressure loss in the low pressure side portion of the refrigerant circuit 2 is reduced, the pressure of the refrigerant sucked into the compressor 21 is increased by that amount, and the specific volume is reduced, so that the refrigerant circulation amount is increased. Moreover, if the enthalpy difference in the evaporator 25 is increased, even if the mass flow rate of the refrigerant passing through the evaporator 25 is reduced by bypass, the heat absorption amount in the evaporator 25 can be secured. That is, by adjusting the degree of refrigerant supercooling and the amount of bypass, both the heating capacity improvement effect of the condenser 22 and the COP improvement effect of the refrigeration cycle apparatus 1 can be obtained.

  In the present embodiment, the supercooling heat exchanger 23 includes the main expansion valve 24 and the bypass expansion so that the dryness of the refrigerant flowing out from the supercooling heat exchanger 23 in the bypass passage 3 is 0.8 or more and less than 1.0. When the opening degree of the valve 31 is adjusted, the refrigerant decompressed in the bypass passage 3 in the supercooling heat exchanger 23 with respect to the heat exchange amount Qc between the refrigerant flowing into the condenser 22 and the water in the condenser 22 The heat exchange ratio Qsc / Qc, which is the ratio of the heat exchange amount Qsc with the refrigerant flowing out of the condenser 22, is designed to have a heat transfer area of 0.2 or more and 0.8 or less.

  According to this configuration, since the heat transfer area of the supercooling heat exchanger 23 is appropriately set, the dryness of the refrigerant flowing out of the supercooling heat exchanger 23 in the bypass passage 3 is set to 0.8 or more and 1.0. Even when the outside air temperature is low and the heating capacity required for the condenser 22 is increased, the refrigerant flowing through the refrigerant circuit 2 can be supercooled to an appropriate state.

  For example, when R407C is used as the refrigerant, the heat exchange ratio Qsc as shown in FIG. 2 (a) under the conditions of the outside air temperature AT = −25 ° C. and the refrigerant condensation temperature Tc = 70 ° C. in the condenser 22 If / Qc is in the range of 0.2 to 0.8, the dryness Xei of the refrigerant flowing into the evaporator 25 falls within the range of 0 to 0.55, and further, FIGS. If the dryness Xei of the refrigerant flowing into the evaporator 25 is 0 or more and 0.55 or less, the refrigerant flowing out of the supercooling heat exchanger 23 is in a supercooled state. Similarly, when R410A is used as the refrigerant, the conditions of the outside air temperature AT = −25 ° C. and the refrigerant condensation temperature Tc = 60 ° C. in the condenser 22 are shown in FIGS. 2B and 4A. From (b), if the heat exchange ratio Qsc / Qc is in the range of 0.2 to 0.8, the refrigerant flowing out of the supercooling heat exchanger 23 enters a supercooled state. Therefore, in this embodiment, the heat transfer area of the supercooling heat exchanger 23 is defined so that the heat exchange ratio Qsc / Qc is in the range of 0.2 to 0.8. 3 and 4, Pc indicates the pressure of the refrigerant passing through the condenser 22, and Ps indicates the pressure of the refrigerant passing through the evaporator 25.

  In a more preferred aspect, the supercooling heat exchanger 23 has a heat exchange ratio Qsc / when the dryness of the refrigerant flowing out of the supercooling heat exchanger 23 in the bypass passage 3 is maintained at 0.8 or more and less than 1.0. Qc has a heat transfer area of 0.2 or more and 0.7 or less. If it becomes like this, dryness Xei when using R410A as a refrigerant | coolant can be maintained at 0 or more and 0.45 or less, and the refrigerant | coolant which flows out from the supercooling heat exchanger 23 will be in a supercooled state (FIG. 2 (b) and FIGS. 4 (a) and 4 (b)).

  Next, control performed by the control device 4 will be described.

  As shown in FIG. 1, the bypass 3 has an inlet temperature sensor 61 that detects the temperature (inflow temperature) Tbi of the refrigerant flowing into the supercooling heat exchanger 23, and the refrigerant flowing out of the supercooling heat exchanger 23. An outlet temperature sensor 62 for detecting temperature (outflow temperature) Tbo is provided. The control device 4 controls the rotational speed of the compressor 21, switching of the four-way valve 28, and the opening degrees of the main expansion valve 24 and the bypass expansion valve 31 based on detection values detected by the various sensors 61 and 62. To do.

  In the present embodiment, the control device 4 controls the main expansion valve 24 and the main expansion valve 24 so that the dryness of the refrigerant flowing out of the supercooling heat exchanger 23 in the bypass passage 3 is 0.8 or more and less than 1.0 during normal operation. The bypass expansion valve 31 is controlled. At this time, since the heat transfer area of the supercooling heat exchanger 23 is appropriately set, the heat exchange ratio Qsc / Qc is 0.2 or more and 0.8 or less.

  The heat transfer area of the supercooling heat exchanger 23 is not limited, and for example, a pressure sensor or a temperature sensor is provided in the condenser 22 to obtain the condensation temperature of the condenser 22, and a temperature sensor is provided at the outlet of the condenser 22. The degree of dryness of the refrigerant flowing out of the supercooling heat exchanger 23 is maintained at 0.8 to 1 while maintaining the supercooling degree on the outlet side of the condenser 22, which is the difference temperature, at about 1 to 5K. If the main expansion valve 24 and the bypass expansion valve 31 are controlled so as to be less than 0, the heat exchange ratio Qsc / Qc can be controlled to be 0.2 or more and 0.8 or less.

  In addition, the subcooling is controlled by controlling the main expansion valve 24 and the bypass expansion valve 31 so that the dryness of the refrigerant flowing out from the supercooling heat exchanger 23 in the bypass passage 3 is 0.8 or more and less than 1.0. Since the supercooling effect of the heat exchanger 23 can be ensured to the maximum, the refrigerant enthalpy difference between the inlet and outlet of the evaporator 25 can be expanded. At the same time, since the wettability of the refrigerant at the inlet of the evaporator 25 can be increased, an increase in meaningless pressure loss in the evaporator 25 can be suppressed, that is, the suction pressure of the compressor 21 can be increased, the refrigerant flow rate can be increased, and the condensation (heating) ability Can be increased.

  Specifically, the control device 4 controls the main expansion valve 24 and the bypass expansion valve 31 so that the inflow temperature Tbi and the outflow temperature Tbo are substantially equal.

  In place of the inlet temperature sensor 61, a pressure sensor is installed at the outlet of the supercooling heat exchanger 23 in the bypass passage 3 or between the evaporator 25 and the compressor 21, and the pressure detected by this pressure sensor is set. Based on this, the main expansion valve 24 and the bypass expansion valve 31 may be controlled so that the dryness of the refrigerant flowing out from the supercooling heat exchanger 23 in the bypass passage 3 is 0.8 or more and less than 1.0.

  Specifically, the saturation temperature may be obtained from the pressure detected by the pressure sensor and controlled so that the outflow temperature Tbo becomes the saturation temperature.

  In general, the lower the outside air temperature AT, the lower the evaporation pressure in the evaporator 25. Therefore, when the degree of supercooling in the supercooling heat exchanger 23 is the same, the dryness of the refrigerant flowing into the evaporator 25 increases. Since there are many refrigerant gas components that do not contribute to evaporation, the heat absorption capability of the evaporator is reduced. In such a case, it is preferable to control the main expansion valve 24 and the bypass expansion 31 so that the heat exchange ratio Qsc / Qc increases as the outside air temperature AT decreases as shown in FIG.

  In this way, the degree of supercooling at the outlet of the supercooling heat exchanger 23 can be increased, and by reducing the enthalpy of the refrigerant flowing into the evaporator 25, evaporation can be performed compared to the case where the heat exchange ratio Qsc / Qc is small. The amount of change in the enthalpy of the refrigerant in the vessel 25 can be increased, that is, the endothermic capacity can be increased. As a result, when the outside air temperature AT is lowered, it is possible to compensate for the decrease in the heat absorption amount of the refrigerant in the evaporator 25 due to the increase in the enthalpy of the refrigerant flowing into the evaporator 25. The outside air temperature AT may be detected by an outside air temperature sensor, for example.

  Further, when the refrigerant condensing temperature Tc is higher, when the enthalpy of the refrigerant at the inlet of the evaporator 25 is the same, the degree of supercooling at the outlet of the supercooling heat exchanger 23 needs to be increased. It is necessary to increase the heat exchange amount of the condenser 23 with respect to the heat exchange amount in the condenser 22. In such a case, as shown in FIG. 5, it is preferable to control the main expansion valve 24 and the bypass expansion 31 such that the heat exchange ratio Qsc / Qc increases as the refrigerant condensation temperature Tc in the condenser 22 increases. .

  In this way, the heat exchange amount of the supercooling heat exchanger 23 becomes larger than the heat exchange amount in the condenser 22, and the enthalpy of the refrigerant at the inlet of the evaporator 25 can be reduced, and the heat exchange ratio Qsc Compared with the case where / Qc is small, the refrigerant enthalpy change amount in the evaporator 25 can be increased, that is, the heat absorption capacity can be increased. As a result, it is possible to compensate for a decrease in the heat absorption amount of the refrigerant in the evaporator 25 due to an increase in the enthalpy of the refrigerant flowing into the evaporator 25 due to an increase in the condensation temperature Tc.

  The condensation temperature Tc may be the outflow temperature Tbo.

  The bypass passage 3 does not necessarily have to branch from the refrigerant circuit 2 between the supercooling heat exchanger 23 and the main expansion valve 24, and the refrigerant circuit 2 between the condenser 22 and the supercooling heat exchanger 23. You may branch from.

  Furthermore, the main expansion means and bypass expansion means of the present invention are not necessarily expansion valves, and may be an expander that recovers power from the expanding refrigerant. In this case, for example, the rotational speed of the expander may be controlled by changing the load with a generator connected to the expander.

  Further, the fluid to be heated that is heated by the condenser 22 is not necessarily water, and may be air. That is, the present invention can also be applied to an air conditioner.

  The present invention is particularly useful for a hot water heating apparatus in which water is heated by a refrigeration cycle apparatus and the water is used for heating.

DESCRIPTION OF SYMBOLS 1 Refrigeration cycle apparatus 2 Refrigerant circuit 21 Compressor 22 Condenser 23 Supercooling heat exchanger 24 Main expansion valve (main expansion means)
25 Evaporator 3 Bypass path 31 Bypass expansion valve (bypass expansion means)
4 control device 61 inlet temperature sensor 62 outlet temperature sensor

Claims (8)

A refrigerant circuit in which a compressor, a condenser, a supercooling heat exchanger, a main expansion means and an evaporator are connected in an annular shape;
Branch from the refrigerant circuit between the supercooling heat exchanger and the main expansion means or between the condenser and the supercooling heat exchanger, and via the supercooling heat exchanger, the evaporator and the compression A bypass that leads to the refrigerant circuit between the machines,
Bypass expansion means provided on the upstream side of the subcooling heat exchanger of the bypass path;
With
When the opening degree of the bypass expansion means is adjusted so that the dryness of the refrigerant flowing out from the supercooling heat exchanger in the bypass passage is 0.8 or more and less than 1.0 in the bypass passage The refrigerant depressurized by the bypass expansion means in the supercooling heat exchanger and the refrigerant flowing out of the condenser with respect to the heat exchange amount between the refrigerant flowing into the condenser and the fluid to be heated in the condenser The heat exchange ratio, which is the ratio of the amount of heat exchange between, is configured to be 0.2 or more and 0.8 or less,
Refrigeration cycle equipment. A control device for controlling the bypass expansion means such that the dryness of the refrigerant flowing out of the supercooling heat exchanger in the bypass passage is 0.8 or more and less than 1.0;
The refrigeration cycle apparatus according to claim 1. An inlet temperature sensor for detecting the temperature of the refrigerant flowing into the supercooling heat exchanger in the bypass path;
An outlet temperature sensor for detecting the temperature of the refrigerant flowing out of the supercooling heat exchanger in the bypass path,
The control device controls the bypass expansion means so that a temperature detected by the outlet temperature sensor is substantially equal to a temperature detected by the inlet temperature sensor;
The refrigeration cycle apparatus according to claim 2. An outlet temperature sensor for detecting the temperature of the refrigerant flowing out of the supercooling heat exchanger in the bypass path;
A pressure sensor for detecting the pressure of the refrigerant sucked into the compressor,
The control device controls the bypass control means so that a temperature detected by the outlet temperature sensor becomes a saturation temperature obtained from a pressure detected by the pressure sensor;
The refrigeration cycle apparatus according to claim 2.   The said control apparatus is a refrigerating-cycle apparatus as described in any one of Claims 2-4 which controls the said bypass expansion means so that the said heat exchange ratio becomes large, so that external temperature becomes low.   The said control apparatus controls the said bypass expansion means so that the said heat exchange ratio becomes large, so that the condensation temperature of the refrigerant | coolant in the said condenser becomes high, The refrigeration cycle apparatus as described in any one of Claims 2-4. .   The refrigeration cycle apparatus according to any one of claims 1 to 6, wherein the condenser is a heat exchanger that heats the heated fluid by performing heat exchange between the refrigerant and the heated fluid. A hot water heater that uses hot water generated by a heating means for heating,
A hot water heating apparatus comprising the refrigeration cycle apparatus according to claim 7 as the heating means.

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