JP5824628B2 - Refrigeration cycle apparatus and hot water generating apparatus having the same - Google Patents

Description

  The present invention relates to a refrigeration cycle apparatus that supercools a refrigerant.

  Conventionally, in a refrigerant circuit formed by connecting a compressor, a condenser, an expansion valve, and an evaporator, the discharge temperature of the refrigerant discharged from the compressor, the condensation temperature in the condenser, and the evaporation temperature in the evaporator are detected. There is known a refrigeration air conditioner that estimates the degree of dryness of refrigerant gas sucked by a compressor and controls the opening degree of an expansion valve so that the degree of dryness of refrigerant gas sucked by the compressor becomes a predetermined target value (for example, , See Patent Document 1).

  The operation of this refrigeration air conditioner will be described with reference to the refrigerant circuit diagram shown in FIG. 5 and the control flowchart shown in FIG.

  In the cooling operation, the flow path of the four-way valve 3 is set so as to flow in the direction of the solid line in FIG. Then, the high-temperature and high-pressure gas refrigerant discharged from the compressor 2 passes through the four-way valve 3, and the refrigerant is condensed and liquefied by exchanging heat with the outdoor air around the outdoor unit 1 in the outdoor heat exchanger 4. The pressure is reduced by the expansion valve 5 to form a low-pressure two-phase refrigerant, and then flows into the indoor heat exchanger 7 through the liquid pipe 6.

  Then, in the indoor heat exchanger 7 serving as an evaporator, the refrigerant takes the heat of the indoor air while being evaporated and cooled. Thereafter, the refrigerant passes through the gas pipe 8 and the four-way valve 3 and is then sucked into the compressor 2.

  Further, the opening degree control of the electronic expansion valve 5 estimates the dryness Xs of the refrigerant sucked in the compressor 2 and follows the flowchart shown in FIG. 6 so that the estimated dryness Xs of the sucked refrigerant becomes the target value Xsm. Controlled.

  As a result, the energy efficiency COP becomes maximum when the suction dryness Xs = 0.95, and in the range of the suction dryness 0.9 to 1.0, the COP of the refrigeration air conditioner can be performed to the extent that it is reduced by 10% from the maximum COP. It can operate relatively efficiently.

Japanese Patent No. 3750457

  However, as opposed to refrigeration cycles with circuits that bypass the evaporator by adding a supercooling heat exchanger such as an economizer or refrigerant precooler, the dryness of refrigerant gas sucked by the compressor as in the conventional technology When the expansion valve opening degree control is performed so that the refrigerant gas dryness of the compressor suction reaches a predetermined target value, it is affected by both the main refrigerant circuit and the bypass circuit on the evaporator side. Therefore, proper control becomes impossible.

  Moreover, when using a bypass circuit to reduce the discharge temperature of the compressor, the operation of controlling the dryness on the compressor suction side to 0.9 to 1.0 cannot reduce the discharge temperature of the compressor. Serious problems can arise in the reliability of the compressor.

In view of such circumstances, an object of the present invention is to provide a refrigeration cycle apparatus that suppresses an increase in discharge temperature of a compressor in a refrigeration cycle that includes a circuit that bypasses an evaporator by adding a supercooling heat exchanger. And

In order to solve the above problems, a refrigeration cycle apparatus according to the present invention includes a compressor, a radiator, a supercooling heat exchanger, a main expansion means, a refrigerant circuit in which an evaporator is connected in an annular shape, and the supercooling heat exchanger. And the main expansion means, or branch from the refrigerant circuit between the radiator and the supercooling heat exchanger, and bypass the expansion means and the supercooling heat exchanger through the evaporator and the supercooling heat exchanger. A bypass circuit connected to the refrigerant circuit between the compressor, a refrigerant dryness detecting means for detecting the dryness of the refrigerant at the outlet of the supercooling heat exchanger of the bypass circuit, and a refrigerant flowing out of the evaporator Refrigerant superheat detection means for detecting the superheat degree, temperature detection means for detecting the temperature of the refrigerant discharged from the compressor, and the dryness of the refrigerant detected by the refrigerant dryness detection means is a predetermined first target. Said bypass expansion to be a value Controls stage, and a control unit for controlling the main expansion valve as the degree of superheating of the refrigerant becomes the second predetermined target value detected by the refrigerant superheating degree detecting means, wherein the control device , according to the temperature detected by said temperature detecting means, is configured to change the first target value, the control device, when setting the first target value, than the control of said main expansion means The control of the bypass expansion means is started before .

  As a result, when the overheat protection control of the discharge temperature is necessary, the main expansion means is controlled by reducing the opening of the main expansion means by a predetermined opening so that the refrigerant superheat degree at the outlet of the evaporator becomes a predetermined value or more. The opening degree of the bypass expansion means is increased so that it is not excessively opened and the refrigerant dryness at the outlet of the bypass circuit is equal to or less than a predetermined value.

  As a result, the liquid refrigerant component at the outlet side of the bypass circuit can be increased while preventing the refrigerant flow rate on the evaporator side from becoming excessive.

  ADVANTAGE OF THE INVENTION According to this invention, the refrigerating cycle apparatus which suppresses the discharge temperature rise of a compressor can be provided in the refrigerating cycle with the circuit which adds a supercooling heat exchanger and bypasses an evaporator.

1 is a schematic configuration diagram of a refrigeration cycle apparatus according to Embodiment 1 of the present invention. Flow chart of discharge temperature control of the refrigeration cycle apparatus Flow chart of bypass expansion valve control of the refrigeration cycle apparatus Flowchart of main expansion valve control of the refrigeration cycle apparatus Refrigerant circuit diagram of a conventional refrigeration air conditioner Control flow chart of the refrigeration air conditioner

The first invention includes a compressor, a radiator, a supercooling heat exchanger, main expansion means, a refrigerant circuit in which an evaporator is connected in an annular shape, and between the supercooling heat exchanger and the main expansion means, or Branching from the refrigerant circuit between the radiator and the supercooling heat exchanger, and bypassing expansion means, via the supercooling heat exchanger, to the refrigerant circuit between the evaporator and the compressor A connected bypass circuit; a refrigerant dryness detection means for detecting the dryness of the refrigerant at the outlet of the supercooling heat exchanger of the bypass circuit; and a refrigerant superheat detection means for detecting the superheat degree of the refrigerant flowing out of the evaporator And a temperature detecting means for detecting the temperature of the refrigerant discharged from the compressor, and the bypass expansion means so that the dryness of the refrigerant detected by the refrigerant dryness detecting means becomes a predetermined first target value. Controlled by the refrigerant superheat detection means. And a control device for the degree of superheat of refrigerant to be detected to control the main expansion valve so that the second target value set in advance, the control device, according to the temperature detected by said temperature detecting means Te, is configured to change the first target value, the control device, when setting the first target value, to initiate control of the bypass expansion means before control of said main expansion means The refrigeration cycle apparatus characterized by the above.

As a result, when the discharge temperature overheating prevention control is required, the opening degree of the main expansion means is set to a predetermined opening degree so that the refrigerant superheat degree at the outlet of the evaporator becomes a predetermined value or more. Since the opening of the bypass expansion means is increased so that the outlet refrigerant dryness of the bypass circuit is equal to or less than a predetermined value, the refrigerant flow rate on the bypass circuit side can be increased.

  As a result, when it is necessary to prevent discharge temperature from rising excessively, it is possible not only to suppress an increase in discharge temperature, but also to prevent a liquid compression phenomenon in a compressor due to excessive liquid refrigerant, thereby improving reliability. Since the refrigerant flow rate on the evaporator side does not become excessive, the liquid refrigerant component to the compressor suction side can be controlled stably.

  In particular, in the refrigeration cycle apparatus according to the first aspect of the present invention, the higher the temperature detected by the temperature detection means, the smaller the target value of the refrigerant dryness detected by the refrigerant dryness detection means. It is characterized by setting.

  As a result, the set opening degree of the bypass expansion means is increased so that the liquid component ratio is set to be large in the total refrigerant weight flow rate sucked into the compressor, so that the refrigerant flow rate of the bypass circuit increases, The refrigerant cannot be sufficiently heated in the supercooling heat exchanger, the liquid component at the bypass circuit outlet increases, and the refrigerant liquid component sucked into the compressor increases.

  As a result, the refrigerant liquid component at the outlet of the bypass circuit can be increased as the discharge temperature is higher, so that the discharge temperature reduction effect of the compressor is increased.

  In particular, the third invention is a hot water generator provided with the refrigeration cycle device of the first or second invention, wherein the radiator is a refrigerant-to-air heat exchanger by generating hot water with a radiator and using it for heating. This can be applied not only to the case of the above but also to the case of a refrigerant-to-water heat exchanger.

  As a result, convection-type cooling operation and radiation-type floor heating operation can be performed on the use side, and the degree of freedom on the use side can be improved.

  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 refrigeration cycle apparatus according to a first embodiment of the present invention. The refrigeration cycle apparatus includes a refrigerant circuit 2 that circulates refrigerant, a bypass circuit 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 such as R290 can be used.

  In the present embodiment, the main refrigerant circuit (refrigerant circuit) 2 includes a compressor 21, a condenser (heat radiator) 22, a supercooling heat exchanger 23, a main expansion valve (main expansion means) 24, and an evaporator 25. Are connected in a ring shape. Among them, the condenser 22, which is a condenser, is a refrigerant-to-water heat exchanger, and includes a refrigerant flow path through which the refrigerant flows and a heat medium flow path through which a heat medium such as water flows. It is a finned tube heat exchanger. The main refrigerant circuit 2 is provided with a four-way valve 28 for switching the flow direction of the refrigerant.

  The bypass circuit 3 branches from the main refrigerant circuit 2 between the supercooling heat exchanger 23 and the evaporator 25, and compresses with the four-way valve 28 via the secondary side heat exchange portion 23 b of the supercooling heat exchanger 23. The main refrigerant circuit 2 is joined with the machine 21. Further, the bypass circuit 3 is provided with a bypass expansion valve (bypass expansion means) 31 which is a flow rate adjusting means of the present invention upstream of the supercooling heat exchanger 23.

  The main refrigerant circuit 2 includes a discharge pressure sensor 51 for detecting the discharge side refrigerant pressure Pd of the compressor 21, an inlet of the supercooling heat exchanger 23, and a supercooling heat exchanger inlet temperature sensor for detecting the refrigerant temperature on the outlet side. 62, a supercooling heat exchanger outlet temperature sensor 63, an inlet of the evaporator 25, an evaporator inlet temperature sensor 64 for detecting the refrigerant temperature on the outlet side, and an evaporator outlet temperature sensor 65 are provided.

  The control device 4 controls the opening degree of the main expansion valve 24 and the bypass expansion valve 31 based on the detection values detected by the various sensors 51, 61, 62, 63, 64 and 65, as well as the compressor. 21 operation frequency is controlled.

  A supply pipe 41 and a recovery pipe 42 are connected to the heat medium flow path of the condenser 22. Water is supplied to the condenser 22 through the supply pipe 41, and heat is exchanged with the refrigerant in the condenser 22 to be heated. Water (warm water) is collected through the collection pipe 42.

  The operation of the refrigeration cycle apparatus configured as described above will be described.

  In the heating operation, the refrigerant discharged from the compressor 21 is sent to the condenser 22 via the four-way valve 28, and hot water is generated by heat exchange between the high-temperature refrigerant and water (heat medium) in the condenser 22, Used for heating. In FIG. 1, the flow direction of the refrigerant and water (heat medium) during the heating operation is indicated by arrows.

  Specifically, the hot water recovered by the recovery pipe 42 is sent to a heat exchange unit (not shown) such as a radiator, for example, directly or via a hot water storage tank (not shown), thereby heating. Is called.

  That is, in the heating operation, the high-pressure gas refrigerant discharged from the compressor 21 flows into the condenser 22, is supplied to the condenser 22 through the supply pipe 41, heats the water by exchanging heat with water, and the refrigerant itself dissipates heat. Then, it is liquefied and condensed to become a saturated liquid state or a supercooled liquid state. The high-pressure liquid refrigerant that has flowed out of the condenser 22 is branched on the outlet side of the supercooling heat exchanger 23 into the secondary heat exchange section 23b and the evaporator 25 side of the supercooling heat exchanger.

  The high-pressure refrigerant branched to the main expansion valve 24 is decompressed and expanded by the main expansion valve 24 and then flows into the evaporator 25. The low-pressure two-phase refrigerant that has flowed into the evaporator 25, which is a fin-tube heat exchanger, evaporates here and absorbs heat from the air side, and the refrigerant itself is heated to be in a saturated gas or superheated gas state.

  On the other hand, the low-pressure refrigerant flowing into the secondary heat exchange section 23b on the supercooling heat exchanger 23 side and decompressed by the bypass expansion valve 31 flows through the primary heat exchange section 23a on the supercooling heat exchanger 23 side. The refrigerant in the saturated liquid state or the supercooled liquid state is cooled, and the low-pressure refrigerant itself is heated to a saturated gas or superheated gas state. The low-pressure refrigerant that has flowed out from the secondary heat exchange section 23 b 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.

  Next, detection and calculation methods of the outlet-side refrigerant superheat degree SHe of the evaporator 25 and the outlet-side refrigerant dryness Xbp of the secondary-side heat exchanger 23b of the supercooling heat exchanger in the control device 4 will be described.

First, the discharge pressure Pd by the discharge pressure sensor 51, the subcooling heat exchanger inlet and outlet temperature sensors 62 and 63, the supercooling heat exchanger inlet temperature Tsci and the outlet temperature Tsco are detected, and the supercooling heat exchanger Refrigerant enthalpies hsci and hsco at the inlet and outlet of the primary heat exchange section 23a are calculated.

  As a result, the evaporation temperature Te of the evaporator 25 is estimated by the evaporator inlet temperature sensor 64, and the temperature difference (Teo-Te) from the outlet temperature Teo of the evaporator 25 detected by the evaporator outlet temperature sensor 65 is calculated. Then, the outlet side superheat degree SHe of the evaporator 25 is detected, and the saturated liquid refrigerant enthalpy hL and the saturated vapor refrigerant enthalpy hv at the evaporation temperature Te are calculated.

  Further, in the control device 4, the operation frequency Fq that outputs an operation instruction to the compressor 21, the compressor-specific compression chamber volume that is input in advance, and the total refrigerant mass flow rate that is discharged from the compressor due to volumetric efficiency. Calculate Go. After branching into two circuits on the outlet side of the supercooling heat exchanger 23, if the evaporator-side refrigerant mass flow rate flowing through the evaporator 25 side is Ge, and the bypass-side refrigerant mass flow rate flowing through the bypass circuit 3 side is Gb, The mass conservation relational expression shown in Equation 1 holds among the total refrigerant mass flow rate Go, the evaporator-side refrigerant mass flow rate Ge, and the bypass-side refrigerant mass flow rate Gb.

  And if the refrigerant enthalpy at the outlet of the secondary side heat exchange part 23b of the supercooling heat exchanger is hbpo, the primary side heat exchange part 23a (high pressure refrigerant side) in the supercooling heat exchanger 23 and the secondary side heat exchange. The relational expression of the heat balance shown in Formula 2 is established between the portion 23b (low pressure refrigerant side).

  Further, the ratio Gb / Ge of the bypass-side refrigerant mass flow rate Gb with respect to the evaporator-side refrigerant mass flow rate Ge is the flow coefficients K1 and K2 of the main expansion valve 24 and the bypass expansion valve 31 and the set opening degrees Pls1. , Pls2 can be estimated by the function f, and the relational expression shown in Equation 3 is established.

  From the above three formulas, the refrigerant enthalpy hbpo at the outlet of the secondary side heat exchange part 23b of the supercooling heat exchanger is calculated and the refrigerant enthalpy hbpo is used to obtain the secondary side heat exchange part 23b of the supercooling heat exchanger. The outlet side refrigerant dryness Xbp can be detected from the relational expression shown in Equation 4.

  Next, the discharge temperature control of the compressor related to the present invention will be described in detail with reference to the flowchart shown in FIG.

First, the discharge temperature Td of the compressor is detected in step S1, and the magnitude relationship between the discharge temperature Td and the first predetermined temperature Td1 is compared in step S2. If Td ≧ Td1, step S1 is performed.
3. After setting the target refrigerant dryness Xbpo on the outlet side of the secondary heat exchanger 23b of the subcooling heat exchanger to X1, the process proceeds to bypass expansion valve control in step S4.

  On the other hand, if Td <Td1, the magnitude relationship between the first predetermined temperature Td1 and the second predetermined temperature Td2 is compared in step S5. If Td2 ≦ Td <Td1, the secondary side heat of the supercooling heat exchanger is compared. After setting the target refrigerant dryness Xbpo on the outlet side of the exchange unit 23b to X2 (where X1 <X2), the process proceeds to the bypass expansion valve control in step S4, and if Td <Td2, the process returns to step S1.

  Then, after step S4 is completed, the process proceeds to main expansion valve control in step S7.

  Next, the refrigerant flow control by the bypass expansion valve 31 related to the present invention will be described in detail with reference to the flowchart shown in FIG.

  The control device 4 controls the flow rate of the refrigerant flowing through the bypass circuit 3 by controlling the opening degree of the bypass expansion valve 31.

  First, in step S11, the discharge pressure Pd, the inlet side refrigerant temperature Tsci and the outlet side refrigerant temperature Tsco of the primary side heat exchange part 23a of the supercooling heat exchanger are detected.

  In step S12, the inlet side refrigerant enthalpy hsci and the outlet side refrigerant enthalpy hsco of the primary heat exchanger 23a of the supercooling heat exchanger are calculated using the pressure and temperature.

  In step S13, the inlet temperature Te (≈evaporation temperature) of the evaporator 25 is detected, and in step S14, the saturated liquid refrigerant enthalpy hL and the saturated vapor refrigerant enthalpy hv at the evaporation temperature Te are calculated.

  In a normal refrigeration cycle, the refrigerant at the inlet of the evaporator 25 is in a two-phase state. Therefore, in a pseudo-azeotropic refrigerant mixture such as R410A or a single refrigerant such as R290, the refrigerant temperature Te can be regarded as a substantially saturated temperature. The saturation pressure Pe with respect to the evaporator inlet is calculated from the physical properties of the refrigerant.

  For non-azeotropic refrigerants such as R407C, it is possible to detect the refrigerant pressure Pe at the evaporator inlet by separately providing a pressure detection means.

  Further, in step S15, the compressor frequency Fq is detected, and the total refrigerant mass flow rate Go is calculated. In step S16, the opening degrees PLS1, PLS2 of the main expansion valve 24 and the bypass expansion valve 31 are detected, and the flow rate is determined. The ratio Gb / Ge is calculated from the relational expression shown in Equation 3.

  Then, in step 17, by substituting the refrigerant enthalpy hbpo at the outlet of the secondary side heat exchange part 23b of the supercooling heat exchanger, which is obtained by solving the above three equations, into the supercooling heat exchange, The refrigerant dryness Xbp on the outlet side of the secondary side heat exchanging portion 23b is calculated.

  Next, in step S18, the refrigerant dryness Xbp is compared with the target refrigerant dryness Xbpo set in step S3 or S6. If Xbp ≧ Xbpo, the bypass expansion valve 31 is set in step S19. After performing the operation of opening the opening PLS2 by the first predetermined opening dP2, the process proceeds to step S7 in FIG.

On the other hand, if Xbp <Xbpo, in step S20, the magnitude relationship between the refrigerant dryness Xbp and Xbpo-dX smaller than the target refrigerant dryness Xbpo by a predetermined dryness dX is compared, and if Xbp <Xbpo-dX, After the operation of closing the opening PLS2 of the bypass expansion valve 31 by the first predetermined opening dP2 in step S21, the process proceeds to step S7 in FIG.

  Next, refrigerant flow rate control by the main expansion valve 24 related to the present invention will be described in detail with reference to the flowchart shown in FIG.

  After performing the opening degree control of the bypass expansion valve 31 in step S4, the control device 4 controls the flow rate of the refrigerant flowing through the main refrigerant circuit 2 by the opening degree control of the main expansion valve 24 in step S7.

  First, the refrigerant temperature Te at the evaporator inlet and the refrigerant temperature Teo at the outlet are detected in step S31, the refrigerant superheat degree SHe at the evaporator outlet is calculated from Teo-Te in step S32, and the target refrigerant overheat is obtained in step S33. Set the degree SHo.

  Then, the refrigerant superheat degree SHe at the evaporator outlet detected in step S34 is compared with the target value SHo of the refrigerant superheat degree by adding a predetermined value dT (SHo + dT), and the relationship of SHe> SHo + dT is compared. If satisfied, the process proceeds to step S35, and after opening the opening PLS1 of the main expansion valve 24 by the first predetermined pulse dP1, the process returns to step S1 in FIG.

  On the other hand, if SHe ≦ SHo + dT, a comparison of the magnitude relationship between the refrigerant superheat degree SH at the evaporator outlet and the predetermined value dT subtracted from the target value Sho of the refrigerant superheat degree (SHo-dT) is performed in step S36. When the relationship of SH <SHo-dT is satisfied, the process proceeds to step S37 to perform an operation of closing the opening PLS1 of the main expansion valve 24 by the first predetermined pulse dP1.

  On the other hand, if the relationship of SH <SHo-dT is not satisfied in step S36, it is determined that control is not necessary, and the process returns to step S1 in FIG.

  As described above, the discharge temperature control of the compressor by the main expansion valve 24 and the bypass expansion valve 31 of the control device 4 repeats the operations of step S1 to step S37.

  As described above, the main refrigerant circuit 2 including the supercooling heat exchanger 23 and the upstream side or the downstream side of the primary heat exchange part 23a of the supercooling heat exchanger 23 are branched in the present embodiment. The bypass circuit 3 that joins the refrigerant circuit between the evaporator 25 and the compressor 21 via the bypass expansion valve 31 and the secondary heat exchange portion 23b of the supercooling heat exchanger 23, and the supercooling heat exchanger 23 in the bypass circuit 3 Temperature sensors 62 and 63 for detecting the temperature of the refrigerant at the inlet and outlet of the primary side heat exchange section 23a, the discharge temperature sensor 61 on the discharge side of the compressor, the temperature sensor 64 on the inlet and outlet sides of the evaporator, 65, and when the discharge temperature Td is equal to or higher than the predetermined value Td1, the main expansion valve 24 is set so that the refrigerant superheat degree SHe on the outlet side of the evaporator 25 is equal to or higher than a predetermined target value (SHo-dT). Control and dry the refrigerant at the outlet of bypass circuit 3 Xbp controls the bypass expansion valve 31 to be equal to or less than the predetermined target value Xbpo.

  Thereby, when the overheat protection control of the discharge temperature is necessary, the main expansion valve 24 is throttled by a predetermined opening degree so that the refrigerant superheat degree at the outlet of the evaporator 25 becomes a predetermined value or more. The opening degree of the bypass expansion valve 31 is increased so that the valve is prevented from opening excessively and the refrigerant dryness Xbp at the outlet of the bypass circuit 3 is equal to or less than a predetermined value.

  As a result, the liquid refrigerant component on the outlet side of the bypass circuit 3 can be increased while preventing the refrigerant flow rate on the evaporator 25 side from becoming excessive.

  As a result, when discharge temperature rise protection control is required in a refrigeration cycle with a bypass circuit 3 to which a supercooling heat exchanger is added, it is possible to suppress the discharge temperature rise of the compressor 21, and due to excessive liquid refrigerant excess The liquid compression phenomenon in the compressor can be prevented, and the reliability can be improved.

  Furthermore, since the refrigerant flow rate on the evaporator 25 side does not become excessive, refrigeration cycle control with stable control of the liquid refrigerant component to the suction side of the compressor 21 can be performed.

  The bypass circuit 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 not provided between the condenser 22 and the supercooling heat exchanger 23. You may branch from.

  Furthermore, the main expansion valve 24 and the bypass expansion valve 31 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.

  Further, by adopting a fin tube heat exchanger as the condenser 22 and a refrigerant-to-water heat exchanger as the evaporator 25, it is possible to generate cold water in the refrigerant-to-water heat exchanger that is the evaporator 25. It becomes possible.

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

1 Refrigeration cycle equipment 2 Main refrigerant circuit (refrigerant circuit)
3 Bypass circuit 4 Control device 21 Compressor 22 Condenser (heat radiator)
23 Supercooling heat exchanger 24 Main expansion valve (main expansion means)
25 Evaporator 31 Bypass expansion valve (Bypass expansion means)
51 Discharge pressure sensor (refrigerant dryness detection means)
61 Discharge temperature sensor (temperature detection means)
62 Supercooling heat exchanger inlet temperature sensor (refrigerant dryness detection means)
63 Supercooling heat exchanger outlet temperature sensor (refrigerant dryness detection means)
64 Evaporator inlet temperature sensor (refrigerant superheat detection means)
65 Evaporator outlet temperature sensor (refrigerant superheat detection means)

Claims (3)

A compressor, a radiator, a supercooling heat exchanger, a main expansion means, a refrigerant circuit in which an evaporator is annularly connected, and between the supercooling heat exchanger and the main expansion means, or the radiator and the A bypass circuit branched from the refrigerant circuit between the supercooling heat exchanger and connected to the refrigerant circuit between the evaporator and the compressor via bypass expansion means and the supercooling heat exchanger;
Refrigerant dryness detection means for detecting the dryness of the refrigerant at the outlet of the supercooling heat exchanger of the bypass circuit;
Refrigerant superheat degree detecting means for detecting the superheat degree of the refrigerant flowing out of the evaporator;
Temperature detecting means for detecting the temperature of the refrigerant discharged from the compressor;
The bypass expansion means is controlled so that the dryness of the refrigerant detected by the refrigerant dryness detection means becomes a predetermined first target value, and the superheat degree of the refrigerant detected by the refrigerant superheat degree detection means is determined in advance. and a control unit for controlling the main expansion valve so that the second target value which is the control device according to the temperature detected by said temperature detecting means, for changing the first target value Configured as
The said control apparatus starts the control of the said bypass expansion means before control of the said main expansion means, when the said 1st target value is set, The refrigeration cycle apparatus characterized by the above-mentioned . The said control apparatus sets the target value of the dryness of the refrigerant | coolant detected by the said refrigerant | coolant dryness detection means small, so that the temperature detected by the said temperature detection means is high. Refrigeration cycle equipment. A hot water generator comprising the refrigeration cycle apparatus according to claim 1 or 2.