JP5637053B2 - Refrigeration cycle apparatus and hot water heating apparatus including the same - Google Patents

Description

  The present invention relates to a refrigeration cycle apparatus that bypasses a part of a refrigerant flowing out of a radiator and performs heat exchange between the mainstream refrigerant and the bypass refrigerant to supercool the mainstream refrigerant.

  Conventionally, this type of refrigeration cycle apparatus is provided with a supercooling heat exchanger on the downstream side of the radiator of the refrigerant circuit, and the refrigerant that has flowed out of the radiator by allowing the expanded refrigerant to flow into the supercooling heat exchanger. Is supercooled (see, for example, Patent Document 1).

  FIG. 4 shows a conventional refrigeration cycle apparatus described in Patent Document 1. As shown in FIG.

  As shown in FIG. 4, the refrigeration cycle apparatus 100 includes a refrigerant circuit 110 that circulates refrigerant and a bypass 120. The refrigerant circuit 110 is configured by connecting a compressor 111, a radiator 112, a supercooling heat exchanger 113, a main expansion valve 114, and an evaporator 115 in an annular shape by piping.

  The bypass 120 branches from the refrigerant circuit 110 between the supercooling heat exchanger 113 and the main expansion valve 114, and enters the refrigerant circuit 110 between the evaporator 115 and the compressor 111 via the supercooling heat exchanger 113. linked. The bypass passage 120 is provided with a bypass expansion valve 121 upstream of the supercooling heat exchanger 113.

  Further, the refrigeration cycle apparatus 100 includes a temperature sensor 141 that detects the temperature of the refrigerant discharged from the compressor 111 (compressor discharge pipe temperature) Td, and the temperature of the refrigerant that flows into the evaporator 115 (evaporator inlet temperature). A temperature sensor 142 for detecting Te, a temperature sensor 143 for detecting the temperature (bypass side inlet temperature) Tbi of the refrigerant flowing into the supercooling heat exchanger 113 in the bypass passage 120, and the supercooling heat exchanger 113 in the bypass passage 120 A temperature sensor 144 for detecting the temperature of the refrigerant flowing out of the refrigerant (bypass side outlet temperature) Tbo, and a target temperature Td (target) of the discharge pipe of the compressor is set from the evaporator inlet temperature Te detected by the temperature sensor 142 Yes.

  And the main expansion valve control part which controls the main expansion valve 114 so that the discharge pipe temperature Td detected by the temperature sensor 141 becomes the target temperature Td (target), and the bypass side in the supercooling heat exchanger 113 The bypass expansion valve control unit controls the bypass expansion valve 121 so that the difference (Tbo−Tbi) between the outlet temperature Tbo and the bypass side inlet temperature Tbi becomes a predetermined target value.

Japanese Patent Laid-Open No. 10-68553

  However, in the conventional configuration, the bypass expansion valve operates to control the temperature difference between the inlet side and the outlet side of the bypass passage, that is, the degree of superheat of the bypass passage outlet, so that the bypass outlet refrigerant state is controlled to be a wet state. Can not do it.

Therefore, it is necessary to limit the amount of bypass, and the supercooling heat exchanger cannot be utilized to the maximum extent, so that the effect of improving the operation efficiency by bypass cannot be maximized, and the outside air temperature is − In order to suppress discharge temperature rise due to bypass at extremely low temperatures, such as 20 ° C, or when the connecting pipe between the use side heat exchanger and heat source side heat exchanger becomes long, the pressure reduction amount of the main expansion valve is reduced. Therefore, there is a problem that it is necessary to obtain an operation state in which the evaporation temperature is raised, the efficiency is poor, and sufficient heating capacity cannot be secured.

  The present invention solves the above-mentioned conventional problems, and provides a refrigeration cycle apparatus capable of ensuring a sufficient heating capacity with high efficiency even at a low outside air temperature by always controlling to an appropriate refrigeration cycle state. The purpose is to do.

  In order to solve the conventional problems, a refrigeration cycle apparatus of the present invention includes a refrigerant circuit in which a compressor, a radiator, a supercooling heat exchanger, a main expansion unit, and an evaporator are connected in an annular shape, and the radiator. Branched from the refrigerant circuit between the main expansion means, and connected to the compressor circuit of the compressor or the refrigerant circuit between the evaporator and the compressor via the supercooling heat exchanger A bypass passage, bypass expansion means provided upstream of the subcooling heat exchanger in the bypass passage, a first temperature sensor for detecting the temperature of the refrigerant flowing out of the supercooling heat exchanger, and the compressor First saturation temperature detecting means for detecting the saturation temperature of the refrigerant sucked into the second, second temperature sensor for detecting the temperature of the refrigerant flowing out of the radiator, and second for detecting the saturation temperature of the refrigerant of the radiator. Saturation temperature detection means and control device When the detected temperature of the first temperature sensor is higher than the detected temperature of the first saturation temperature detecting means, the detected temperature of the first temperature sensor approaches the detected temperature of the first saturated temperature detecting means. When the bypass expansion means is operated and the detected temperature of the first temperature sensor is substantially the same as the detected temperature of the first saturation temperature detecting means, the detected temperature of the second temperature sensor is detected as the second saturation temperature detection. The bypass expansion means is operated so as to be lower than a detected temperature of the means by a predetermined temperature.

  As a result, the bypass outlet refrigerant is controlled so as to be always saturated, and when the bypass outlet refrigerant is saturated, the degree of supercooling of the radiator outlet is appropriately controlled. It is possible to prevent over-closing and to set the bypass amount to an appropriate amount.

  According to the present invention, it is possible to provide a refrigeration cycle apparatus capable of ensuring a sufficient heating capacity with high efficiency even at a low outside air temperature by always controlling to an appropriate refrigeration cycle state.

Schematic configuration diagram of a refrigeration cycle apparatus according to Embodiment 1 of the present invention. Mollier diagram of the refrigeration cycle apparatus shown in FIG. Another Mollier diagram of the refrigeration cycle apparatus shown in FIG. Flowchart of operation control of the refrigeration cycle apparatus in Embodiment 1 of the present invention. Schematic configuration diagram of a conventional refrigeration cycle apparatus

A first invention is a refrigerant circuit in which a compressor, a radiator, a supercooling heat exchanger, a main expansion unit and an evaporator are connected in an annular shape, and branches from the refrigerant circuit between the radiator and the main expansion unit And, via the supercooling heat exchanger, a bypass passage connected to the compressor chamber of the compressor or the refrigerant circuit between the evaporator and the compressor, and the supercooling of the bypass passage Bypass expansion means provided on the upstream side of the heat exchanger, a first temperature sensor for detecting the temperature of the refrigerant flowing out of the supercooling heat exchanger, and a first temperature sensor for detecting the saturation temperature of the refrigerant sucked into the compressor 1 saturation temperature detection means, a second temperature sensor for detecting the temperature of the refrigerant flowing out of the radiator, a second saturation temperature detection means for detecting the saturation temperature of the refrigerant of the radiator, and a control device, The detected temperature of the first temperature sensor is the first saturation. When the detected temperature of the first temperature sensor is higher than the detected temperature of the degree detecting means, the bypass expansion means is operated so that the detected temperature of the first temperature sensor approaches the detected temperature of the first saturated temperature detecting means, and the detection of the first temperature sensor is performed. When the temperature and the detected temperature of the first saturation temperature detecting means are substantially the same, the bypass temperature is set so that the detected temperature of the second temperature sensor is lower than the detected temperature of the second saturated temperature detecting means. A refrigeration cycle apparatus characterized by operating expansion means.

  As a result, the bypass outlet refrigerant is controlled to be always saturated, and when the bypass outlet refrigerant is saturated, the degree of supercooling of the radiator outlet is appropriately controlled. , Over-closing is suppressed, and the bypass amount can be set to an appropriate amount.

  Therefore, it is possible to maximize the effect of increasing the enthalpy difference in the evaporator by heat exchange between the mainstream refrigerant and the bypass refrigerant in the supercooling heat exchanger and the pressure loss reducing effect in the low-pressure side refrigerant path due to the refrigerant bypass. Thus, even when the outside air temperature is extremely low such as −20 ° C., higher operating efficiency and sufficient heating capacity can be obtained while suppressing an abnormal increase in the discharge temperature.

  According to a second invention, in the first invention, a third temperature sensor for detecting a temperature of the refrigerant flowing out of the evaporator is provided, the detected temperature of the third temperature sensor and the detected temperature of the first saturation temperature detecting means. The value of the predetermined temperature is smaller as the temperature difference between is larger.

  Thus, it is possible to determine the shortage state of the refrigerant amount from the superheat degree of the evaporator outlet refrigerant, and when the refrigerant amount is in a shortage state, the supercooling degree of the radiator outlet refrigerant is controlled to be small. It is possible to prevent a decrease in the low pressure due to the excess.

  Therefore, in addition to the effect of the first aspect of the invention, even when the connecting pipe between the use side heat exchanger and the heat source side heat exchanger becomes long, the gas amount shortage state is detected and the suction due to the expansion means being closed too much is detected. Since an efficient heating operation can be maintained while preventing a pressure drop, the degree of freedom of equipment installation is improved.

  3rd invention is a hot water heating apparatus provided with the refrigerating cycle device of the 1st or 2nd invention, and not only when a radiator is a refrigerant-to-air heat exchanger, but also in the case of a refrigerant-to-water heat exchanger In addition, the same effects as those of the first or second invention can be obtained.

  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 shows a schematic configuration diagram of a refrigeration cycle apparatus and a hot water heater in the first embodiment of the present invention. In FIG. 1, the refrigeration cycle apparatus 1 </ b> A includes a refrigerant circuit 2 that circulates refrigerant, a bypass 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 includes a compressor 21, a radiator 22, a supercooling heat exchanger 23, a main expansion valve (main expansion means) 24, and an evaporator 25 that are annularly connected 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 1A constitutes heating means of a hot water heating apparatus that uses hot water generated by the heating means for heating, and the radiator 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 radiator 22, water is supplied to the radiator 22 through the supply pipe 71, and water (hot water) heated by the radiator 22 is the recovery pipe 72. It has come to be collected through. The hot water collected by the collection pipe 72 is sent to a heater such as a radiator directly or via a hot water storage tank, and thereby heating is performed.

  In the present embodiment, the bypass passage 3 branches from the refrigerant circuit 2 between the supercooling heat exchanger 23 and the main expansion valve 24, and the evaporator 25 and the compressor 21 are connected via the supercooling heat exchanger 23. The refrigerant 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 (bypass expansion means) 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 radiator 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 radiator 22 and radiates heat to the water passing through the radiator 22. The high-pressure refrigerant flowing out of the radiator 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 distributed to the main expansion valve 24 side and the bypass expansion valve 31 side.

  The high-pressure refrigerant distributed to the main expansion valve 24 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 distributed to the bypass expansion valve 31 side is decompressed by the bypass expansion valve 31 and expanded, 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 radiator 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.

  In the configuration of the refrigeration cycle apparatus 1A according to the present embodiment, 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 radiator 22. It is for preventing.

  In order to realize this, the amount of gas-phase refrigerant having a small endothermic effect that flows through the low pressure side portion of the refrigerant circuit 2 by increasing the enthalpy difference in the evaporator 25 by supercooling and bypassing the refrigerant by the bypass passage 3. It is important to 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, if the degree of supercooling of the refrigerant and the amount of bypass are maximized, the maximum heating capacity improvement effect of the radiator 22 and the coefficient of performance improvement effect of the refrigeration cycle apparatus 1A can be obtained.

  In the present embodiment, as will be described in detail later, the control device 4 operates the bypass expansion valve 31 so that the outlet refrigerant of the bypass passage 3 is saturated when the outlet refrigerant is in an overheated state. When the outlet refrigerant of the passage 3 is in a saturated state, the bypass expansion valve 31 is controlled to operate so that the degree of supercooling at the outlet of the radiator 22 becomes a predetermined degree of supercooling set in advance. . Moreover, it sets so that the predetermined supercooling degree of the radiator 22 outlet may become small, so that the superheating degree of the evaporator 25 is large.

  Thereby, the refrigerant | coolant state of the bypass 3 exit is always controlled to a saturated state like the point a, b point, and c point in FIG. However, even if the refrigerant state at the outlet of the bypass passage 3 is saturated as indicated by points a and c in FIG. 2, the amount of bypass may be excessive or excessive. In such a case, since the degree of supercooling at the outlet of the radiator 22 becomes excessive and excessive as shown by points a 'and c' in FIG. Can be determined to be inappropriate, and by controlling the degree of supercooling to a predetermined value (point b ′ in FIG. 2), the amount of bypass is appropriately adjusted as shown by point b in FIG. Will be controlled.

  Also, if the connection pipe length becomes longer due to the installation state of the equipment, the refrigerant amount will be insufficient as a refrigeration cycle. Therefore, the same degree of supercooling as the appropriate refrigerant amount as shown by point a 'in FIG. When used and controlled, the amount of pressure reduction by the bypass expansion valve becomes excessive, and the suction pressure decreases. In such a case, since the refrigerant state at the outlet of the evaporator 25 becomes an overheated state as indicated by point a in FIG. 3, the control device 4 performs predetermined supercooling as indicated by point b ′ in FIG. Therefore, the pressure reduction amount of the bypass expansion valve is reduced and the bypass amount is appropriately controlled.

  Hereinafter, the operation control operation will be described.

  The refrigerant circuit 2 detects a first pressure sensor 51 that detects the pressure (suction pressure) Ps of the refrigerant sucked into the compressor 21, and a pressure (radiator outlet pressure) Pc of the refrigerant that flows out of the radiator 22. The second pressure sensor 52, the second temperature sensor 62 that detects the temperature of the refrigerant that flows out of the radiator 22 (heat radiator outlet temperature) Tco, and the temperature of the refrigerant that flows out of the evaporator 25 (evaporator outlet temperature) Teo A third temperature sensor 63 for detecting and a fourth temperature sensor 64 for detecting the temperature (discharge temperature) Td of the refrigerant discharged from the compressor 21 are provided. On the other hand, the bypass passage 3 is provided with a first temperature sensor 61 that detects the temperature (bypass passage outlet temperature) Tbo of the refrigerant flowing out of the supercooling heat exchanger 23.

  Based on the detection values detected by the various sensors 51, 52, 61, 62, 63, 64, the control device 4 switches the rotation speed of the compressor 21, the four-way valve 28, the main expansion valve 24 and the bypass. The opening degree of the expansion valve 31 is operated.

  In the present embodiment, the control device 4 operates the main expansion valve 24 so that the discharge temperature Td becomes a predetermined target temperature Tdt determined in advance during normal operation.

In addition, the control device 4 operates the bypass expansion valve 31 so that the bypass passage outlet temperature Tbo becomes the suction saturation temperature Ts calculated based on the suction pressure Ps during the normal operation, and the bypass passage outlet temperature Tbo. Is substantially equal to the suction saturation temperature Ts, the radiator outlet subcooling degree Sc obtained by the difference between the radiator saturation temperature Tc calculated based on the radiator outlet pressure Pc and the radiator outlet temperature Tco is The bypass expansion valve 31 is operated so that the radiator outlet target supercooling degree Sct is determined based on the evaporator outlet superheat degree Sh determined by the difference between the saturation temperature Ts and the evaporator outlet temperature Teo.

  Next, the control of the control device 4 during normal operation will be described in detail with reference to the flowchart shown in FIG.

  First, the control device 4 detects the discharge temperature Td with the fourth temperature sensor 64 (step S1), and operates the main expansion valve 24 so that the discharge temperature Td becomes equal to the preset target discharge temperature Tdm. (Step S2).

  Next, the control device 4 detects the suction pressure Ps with the pressure sensor 51, and detects the bypass passage outlet temperature Tbo with the first temperature sensor 61 (step S3). Then, the suction saturation temperature Ts at the pressure of the refrigerant sucked into the compressor 21 is calculated from the suction pressure Ps detected by the pressure sensor 51 (step S4). The calculation of the suction saturation temperature Ts is performed using a refrigerant physical property formula.

  Thereafter, the control device 4 compares the bypass passage outlet temperature Tbo with the suction saturation temperature Ts and determines whether Tbo and Ts are equal (step S5). If the bypass passage outlet temperature Tbo is not equal to the suction saturation temperature Ts (NO in step S5), it is determined that the bypass passage outlet refrigerant is in an overheated state, and the bypass passage outlet temperature Tbo becomes equal to the suction saturation temperature Ts. Thus, the opening degree of the bypass expansion valve 31 is adjusted (step S6), and the process returns to step S1.

  On the other hand, when the bypass passage outlet temperature Tbo is substantially equal to the suction saturation temperature Ts (YES in step S5), it is determined that the bypass passage outlet refrigerant is in a saturated state, and the process proceeds to a control step for optimizing the bypass flow rate. .

  First, the second pressure sensor 52 detects the radiator outlet pressure Pc, the second temperature sensor 62 detects the radiator outlet temperature Tco, the third temperature sensor detects the evaporator outlet temperature Teo (step S7), and The radiator saturation temperature Tc at the refrigerant pressure flowing out of the radiator 22 is calculated from the radiator outlet pressure Pc detected by the pressure sensor 52 (step S8). The calculation of the radiator saturation temperature Tc is also performed using the refrigerant physical property formula.

  Thereafter, the control device 4 calculates the refrigerant supercooling degree Sc at the outlet of the radiator 22 by Sc = Tc−Tco, and further calculates the refrigerant superheat degree Sh at the outlet of the evaporator 25 by Sh = Teo−Ts. Then, the target subcooling degree Sct at the outlet of the radiator 22 is calculated by an expression such as Sct = a × Sh + b (step S10). Here, a and b are coefficients, and a is a positive real number.

  And the control apparatus 4 adjusts the opening degree of the bypass expansion valve 31 so that the radiator outlet subcooling degree Sc becomes equal to the radiator outlet target supercooling degree Sct (step S11), and returns to step S1.

  As described above, in the present embodiment, in the refrigerant circuit 2, the first pressure sensor 51 that detects the pressure of the refrigerant sucked into the compressor 21 and the second pressure that detects the pressure of the refrigerant flowing out of the radiator 22. A pressure sensor 52, a second temperature sensor 62 that detects the temperature of the refrigerant flowing out of the radiator 22, a third temperature sensor that detects the temperature of the refrigerant flowing out of the evaporator 25, and the refrigerant discharged from the compressor 21 The temperature sensor 64 includes a fourth temperature sensor 64 that detects the temperature of the refrigerant, a first temperature sensor 61 that detects the temperature of the refrigerant flowing out of the supercooling heat exchanger 23 in the bypass passage 3, and the control device 4.

  Then, the control device 4 operates the main expansion valve 24 so that the discharge temperature Td detected by the fourth temperature sensor 64 becomes a predetermined target temperature Tdt set in advance, and further the first temperature sensor 61. When the bypass passage outlet temperature Tbo detected in step S is not equal to the suction saturation temperature Ts calculated based on the suction pressure Ps detected by the pressure sensor 51, the bypass expansion valve is set equal to the saturation state Ts. 31 is operated.

  Further, when the bypass passage outlet temperature Tbo is substantially equal to the suction saturation temperature Ts, the radiator saturation temperature Tc calculated based on the radiator outlet temperature Tco and the radiator outlet pressure Pc detected by the pressure sensor 52. Is determined based on the evaporator outlet superheat degree Sh determined by the difference between the suction saturation temperature Ts and the evaporator outlet temperature Teo, and the radiator outlet target supercool degree Sct The bypass expansion valve 31 is operated so that

  As a result, the outlet refrigerant of the bypass passage 3 is controlled to be always saturated, and when the outlet refrigerant of the bypass passage 3 is saturated, the degree of supercooling at the outlet of the radiator 22 is appropriately controlled. Too much opening and closing of the expansion valve 31 are suppressed, and the bypass amount can be set to an appropriate amount.

  Therefore, the effect of increasing the enthalpy difference in the evaporator 25 due to heat exchange between the mainstream refrigerant and the bypass refrigerant in the supercooling heat exchanger 23 and the effect of reducing the pressure loss in the low-pressure side refrigerant path due to refrigerant bypass are maximized. Even when the outside air temperature is extremely low such as −20 ° C., it is possible to obtain higher operating efficiency and sufficient heating capacity while suppressing an abnormal increase in the discharge temperature.

  Furthermore, even when the refrigerant connection pipes of the radiator 22 and the evaporator 25 are long, it is efficient while detecting an insufficient gas amount state and preventing a reduction in suction pressure due to the bypass expansion valve 31 being too closed. Since the heating operation can be maintained, the degree of freedom of equipment installation is also improved.

  In FIG. 1, the first pressure sensor 51 is provided between the position where the bypass path 3 in the refrigerant circuit 2 is connected and the main accumulator 27, but the first pressure sensor 51 is connected to the evaporator 25 and the compressor 21. As long as it is between, it may be provided at any position in the refrigerant circuit 2. Alternatively, the pressure sensor 51 may be provided on the downstream side of the subcooling heat exchanger 23 in the bypass passage 3.

  Further, in the present embodiment, the suction saturation temperature is calculated by the first pressure sensor 51, but the suction saturation temperature detects the temperature of the portion where the low-pressure two-phase refrigerant flows in the refrigerant circuit 2 and the bypass passage 3. It may be substituted.

  Moreover, although the 2nd pressure sensor 52 is provided in the exit position of the heat radiator 22 in the refrigerant circuit 2, if the 2nd pressure sensor 52 is between the compressor 21 and the main expansion valve 24, the refrigerant circuit 2 It may be provided in any position, and it is even better if the pressure loss between the radiator outlet position and the second pressure sensor position is calculated from the refrigerant flow rate and corrected.

  Moreover, although the saturation temperature of the radiator 22 is calculated by the second pressure sensor 52, the saturation temperature may be detected by detecting the temperature of the portion of the radiator 22 where the high-pressure two-phase refrigerant flows.

  Further, the bypass passage 3 is not necessarily branched from the refrigerant circuit 2 between the supercooling heat exchanger 23 and the main expansion valve 24, and the refrigerant circuit 2 is interposed between the radiator 22 and the supercooling heat exchanger 23. You may branch from.

Moreover, the connection part of the bypass path 3 does not necessarily need to be the suction piping of the compressor 21, and in the case of a compressor having an injection mechanism, it may be connected to, for example, an injection port.

  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.

  INDUSTRIAL APPLICABILITY The present invention is particularly useful for a hot water heater that generates hot water using a refrigeration cycle apparatus and uses the hot water for heating.

DESCRIPTION OF SYMBOLS 1A Refrigeration cycle apparatus 2 Refrigerant circuit 3 Bypass path 4 Control apparatus 21 Compressor 22 Radiator 23 Supercooling heat exchanger 24 Main expansion valve (main expansion means)
25 Evaporator 31 Bypass expansion valve (Bypass expansion means)
51 1st pressure sensor (1st saturation temperature detection means)
52 Second pressure sensor (second saturation temperature detecting means)
61 1st temperature sensor 62 2nd temperature sensor 63 3rd temperature sensor

Claims (3)

A refrigerant circuit in which a compressor, a radiator, a supercooling heat exchanger, a main expansion unit and an evaporator are annularly connected, and a branch from the refrigerant circuit between the radiator and the main expansion unit; A bypass path connected to the compressor chamber of the compressor or the refrigerant circuit between the evaporator and the compressor via an exchanger, and an upstream side of the subcooling heat exchanger of the bypass path A bypass expansion means provided in the first, a first temperature sensor for detecting a temperature of the refrigerant flowing out of the supercooling heat exchanger, and a first saturation temperature detection means for detecting a saturation temperature of the refrigerant sucked into the compressor. A second temperature sensor for detecting a temperature of the refrigerant flowing out of the radiator, a second saturation temperature detecting means for detecting a saturation temperature of the refrigerant of the radiator, and a control device; The detected temperature of the first saturation temperature detecting means When the temperature is higher than the outlet temperature, the bypass expansion means is operated so that the detected temperature of the first temperature sensor approaches the detected temperature of the first saturation temperature detecting means, and the detected temperature of the first temperature sensor and the first temperature of the first temperature sensor are detected. When the detected temperature of the first saturation temperature detecting means is substantially the same, the bypass expansion means is operated so that the detected temperature of the second temperature sensor is lower than the detected temperature of the second saturated temperature detecting means. A refrigeration cycle apparatus characterized in that A third temperature sensor for detecting the temperature of the refrigerant flowing out of the evaporator; the larger the temperature difference between the detected temperature of the third temperature sensor and the detected temperature of the first saturation temperature detecting means, the higher the predetermined temperature. The refrigeration cycle apparatus according to claim 1, wherein the value is small. A hot water heater provided with the refrigeration cycle apparatus according to claim 1 or 2.

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