JP5488816B2 - Dual refrigeration equipment - Google Patents

Description

  The present invention includes first and second refrigerant circuits for generating hot water used for hot water supply or heating, and a single-stage cycle operation in which only one refrigerant circuit is operated according to the outside air temperature or the like. The present invention relates to a binary refrigeration apparatus that can be switched to a binary cycle operation that operates both refrigerant circuits.

  For example, when performing hot water heating by generating relatively high warm water using a heat pump, it is difficult to maintain refrigeration cycle operation when the outside air temperature is low, for example, at a low outside air temperature, such as a single refrigerant circuit. is there.

  That is, when the outside air temperature is below freezing point, the compression ratio of the compressor increases, and the discharge temperature is lightly over 100 ° C., possibly exceeding the allowable limit of 115 ° C. in some cases.

  In a hermetic compressor, the refrigerant discharged from the compression section is once blown into the hermetic container, so if the refrigerant temperature exceeds 115 ° C, the refrigeration oil deteriorates, and contamination and sludge are generated. Problems such as insulation deterioration of the compressor motor are caused.

  Therefore, the first and second refrigerant circuits are connected by an inter-refrigerant heat exchanger, and a single-stage cycle operation in which only one refrigerant circuit is operated according to the outside air temperature, and both refrigerant circuits are operated simultaneously. A binary refrigeration apparatus that switches between two-cycle operation as appropriate has been proposed (see, for example, Patent Document 1).

  In the binary refrigeration apparatus described in Patent Document 1, bypass pipes are connected to both ends of the evaporator of the secondary side refrigerant circuit via an open / close valve, and the condenser of the primary side refrigerant circuit on the heat source side has 1 The refrigerant circulation system path of the secondary refrigerant circuit and the bypass pipe path are passed through. During the dual cycle operation, the on-off valve of the bypass pipe is closed and each refrigerant circuit is operated as an independent cycle.

  On the other hand, at the time of single-stage cycle operation, the operation of the compressor of the primary refrigerant circuit is stopped, the on-off valve of the bypass pipe is opened, and the inter-refrigerant heat exchanger is disconnected from the secondary refrigerant circuit, The condenser of a primary side refrigerant circuit is used for the condenser of a secondary side refrigerant circuit.

  In this way, the two-cycle operation and the single-cycle operation can be switched. However, according to the conventional example, there are the following problems.

  First, in the secondary refrigerant circuit, when switching from single-stage cycle operation to dual cycle operation, a part of the refrigerant remains in the bypass pipe, so that it remains in the bypass pipe from the primary side. Heat is transferred to the refrigerant, which becomes a heat loss, and the efficiency of the primary side condensation is reduced accordingly.

  Second, since the path of the refrigerant circulation system of the primary refrigerant circuit and the path of the bypass pipe are passed in parallel in the condenser of the primary refrigerant circuit on the heat source side, the primary refrigerant The condenser of the circuit becomes large and is not preferable in terms of space.

JP 2000-274848 A

  Accordingly, an object of the present invention is to provide a high-side evaporator in a two-way refrigeration apparatus that has two refrigerant circuits of a high-side and a low-side, and can be switched between a single-stage cycle operation and a dual-cycle operation. In single-stage cycle operation using a low-side evaporator, the heat transfer that causes heat loss between the low-side refrigerant and the high-side refrigerant is prevented from occurring in the low-side evaporator. . In addition, the size of the evaporator can be reduced by sharing the path that passes through the evaporator of the refrigerant circuit on the heat source side.

In order to solve the above-mentioned problem, the invention described in claim 1 is a first refrigerant including a hot water generating unit that generates hot water, a first compressor, a first condensing unit, a first expansion valve, and a first evaporating unit. A first refrigerant circuit having a circulation system, and a second refrigerant circuit having a second refrigerant circulation system including a second compressor, a second condensing unit, a second expansion valve, and a second evaporation unit, the first condensing A water-refrigerant heat exchanger is provided between the hot water generator and the hot water generator, and an inter-refrigerant heat exchanger is provided between the first evaporator and the second condenser. And the hot water temperature as a control factor, in the two-stage refrigeration apparatus in which single-stage cycle operation and dual-cycle operation are selected, instead of the first evaporator in the first refrigerant circulation system during the single-stage cycle operation In addition, the second evaporator of the second refrigerant circulation system is used, and the second During cycle operation, as characterized by comprising a pipe switching means for substantially the same said single-stage cycle operation time and the binary cycle operation during the above first, the amount of refrigerant can be used in the second respective refrigerant circuits Yes.

The invention described in claim 2 is a first refrigerant having a first refrigerant circulation system including a hot water generator that generates hot water, and a first compressor, a first condenser, a first expansion valve, and a first evaporator. A circuit, and a second refrigerant circuit having a second refrigerant circulation system including a second compressor, a second condensing unit, a second expansion valve, and a second evaporating unit, the first condensing unit and the hot water generating unit, A water-refrigerant heat exchanger is provided between the first evaporator and the second condenser, and at least the outside air temperature and the hot water temperature are used as control factors. In the two-stage refrigeration apparatus in which the single-stage cycle operation and the dual-cycle operation are selected, the second refrigerant circulation is performed instead of the first evaporator of the first refrigerant circulation system during the single-stage cycle operation. When using the second evaporation part of the system and in the dual cycle operation, Single stage cycle operation time and the binary cycle operation during the above first, with a pipe switch means for substantially the same amount of refrigerant that can be used in the second respective refrigerant circuits, the piping switching means, the first expansion The pipe branches between the refrigerant outlet of the valve and the refrigerant inlet of the first evaporator through the first flow path switching valve and reaches the refrigerant inlet side of the second evaporator of the second refrigerant circulation system. The first bypass pipe branches from a pipe portion between the refrigerant outlet of the first evaporator and the suction side of the first compressor via a second flow path switching valve, and the second refrigerant circulation system A second bypass pipe reaching the refrigerant outlet side of the second evaporator, and an on-off valve provided between a connection point of the second bypass pipe and the suction side of the second compressor in the second refrigerant circulation system And control for controlling at least the compressors, the expansion valves, the flow path switching valves, and the on-off valves. It is characterized in that it comprises and.

  According to a third aspect of the present invention, in the second aspect of the present invention, in switching from the dual cycle operation to the single stage cycle operation, the control unit fully closes the second expansion valve and performs the second compression. The refrigerant is present in the piping system from the outlet side of the second expansion valve through the second evaporator to the suction side of the second compressor from the discharge side of the second compressor. After being collected in the piping system that reaches the second expansion valve through the second condensing unit, the on-off valve is closed, the second evaporating unit side of the first flow path switching valve is opened, and the first evaporating unit side is opened. Is closed, the first evaporation section side of the second flow path switching valve is closed, and the second evaporation section side is opened.

  According to a fourth aspect of the present invention, in the second aspect of the present invention, in switching from the single-stage cycle operation to the dual-cycle operation, the control unit fully closes the first expansion valve and performs the first compression. The refrigerant is present in the piping system from the refrigerant outlet side of the first expansion valve to the suction side of the first compressor from the refrigerant outlet side of the first expansion valve from the discharge side of the first compressor. After collecting in the piping system that reaches the first expansion valve through the first condensing unit, the first evaporation unit side of the first flow path switching valve is opened, the second evaporation unit side is closed, The on-off valve is opened after the first evaporation section side of the second flow path switching valve is opened and the second evaporation section side is closed.

  The invention described in claim 5 is characterized in that, in the above-mentioned claim 3 or 4, the rotation of the blower fan provided in the second evaporator is stopped when the refrigerant is recovered.

The invention described in claim 6 is a first refrigerant having a first refrigerant circulation system including a hot water generating unit that generates hot water, and a first compressor, a first condensing unit, a first expansion valve, and a first evaporating unit. A circuit, and a second refrigerant circuit having a second refrigerant circulation system including a second compressor, a second condensing unit, a second expansion valve, and a second evaporating unit, the first condensing unit and the hot water generating unit, A water-refrigerant heat exchanger is provided between the first evaporator and the second condenser, and at least the outside air temperature and the hot water temperature are used as control factors. In the binary refrigeration apparatus in which the single-stage cycle operation and the dual-cycle operation are selected, the first flow path from the pipe portion between the refrigerant outlet of the first expansion valve and the refrigerant inlet of the first evaporator Branching through a switching valve, the inside of the second evaporator is different from the path route of the second refrigerant circulation system A bypass pipe connected to a pipe portion between the refrigerant outlet of the first evaporator and the first compressor via a second flow path switching valve, and in the second refrigerant circulation system. An on-off valve provided between the refrigerant outlet side of the second evaporator and the suction side of the second compressor, at least the compressor, the expansion valve, the flow path switching valve, and the on-off valve. A controller for controlling the two-way cycle operation to the single-stage cycle operation, the control unit, after stopping the operation of the first compressor, The second evaporation section side is opened, the first evaporation section side is closed, the first evaporation section side of the second flow path switching valve is closed, the second evaporation section side is opened, and the second evaporation section side is opened. The second expansion valve is fully closed, the second compressor is operated, and the second evaporation is performed from the outlet side of the second expansion valve. The refrigerant existing in the piping system that reaches the suction side of the second compressor through the refrigerant is recovered from the discharge side of the second compressor into the piping system that reaches the second expansion valve via the second condensing unit. The on-off valve is closed.

The invention described in claim 7 is a first refrigerant having a first refrigerant circulation system including a hot water generator that generates hot water, and a first compressor, a first condenser, a first expansion valve, and a first evaporator. A circuit, and a second refrigerant circuit having a second refrigerant circulation system including a second compressor, a second condensing unit, a second expansion valve, and a second evaporating unit, the first condensing unit and the hot water generating unit, A water-refrigerant heat exchanger is provided between the first evaporator and the second condenser, and at least the outside air temperature and the hot water temperature are used as control factors. In the binary refrigeration apparatus in which the single-stage cycle operation and the dual-cycle operation are selected, the first flow path from the pipe portion between the refrigerant outlet of the first expansion valve and the refrigerant inlet of the first evaporator Branching through a switching valve, the inside of the second evaporator is different from the path route of the second refrigerant circulation system A bypass pipe connected to a pipe portion between the refrigerant outlet of the first evaporator and the first compressor via a second flow path switching valve, and in the second refrigerant circulation system. An on-off valve provided between the refrigerant outlet side of the second evaporator and the suction side of the second compressor, at least the compressor, the expansion valve, the flow path switching valve, and the on-off valve. A controller that controls the first stage valve, and when switching from the single-stage cycle operation to the dual cycle operation, the control unit fully closes the first expansion valve and the first flow path switching valve. The first compressor is operated by opening the evaporator side, closing the second evaporator side, closing the first evaporator side of the second flow path switching valve, and opening the second evaporator side. Then, the refrigerant present in the bypass pipe is transferred from the discharge side of the first compressor to the first condenser through the first condensing part. After collecting in the pipe system leading to the expansion valve, the first evaporator side of the second channel switching valve opens, it is characterized in that to close the said second evaporation unit side.

  According to the present invention, at the time of single-stage cycle operation in which only the first refrigerant circuit (high source side) is operated, instead of the first evaporator of the first refrigerant circulation system, the second refrigerant circuit (low source side) Although the second evaporator is used, prior to the single-stage cycle operation, the refrigerant on the second evaporator side of the second refrigerant circuit is recovered (pumped down) into the pipe on the second condenser side by the second compressor. Thereby, since the refrigerant of each refrigerant circuit does not mix, the path of the second evaporation unit can be shared, and the second evaporation unit can be small.

  In addition, when switching from single-stage cycle operation to dual-cycle operation, the refrigerant in the first refrigerant circulation system that has flowed to the second evaporator side via the first and second bypass pipes is transferred by the first compressor. Since the refrigerant recovered in the pipe on the first condensing part side and remaining in the bypass pipe or the shared heat exchanger exchanges heat with the refrigerant in the second refrigerant circulation system, the heat loss is eliminated. Variation does not occur.

The refrigerant circuit figure of the binary refrigeration apparatus which concerns on 1st Embodiment of this invention. The refrigerant circuit figure of the dual freezing apparatus which concerns on 2nd Embodiment of this invention. The operation | movement flowchart at the time of the switch from the dual cycle operation in the said 1st Embodiment to a single stage cycle operation. The operation | movement flowchart at the time of the switch from the single stage cycle driving | operation in the said 1st Embodiment to a dual cycle driving | operation.

Next, an embodiment of the present invention will be described with reference to FIGS. 1 to 4 , but the present invention is not limited to this.

  First, referring to FIG. 1, the binary refrigeration apparatus according to the first embodiment includes a high-side first refrigerant circuit 10, a low-side second refrigerant circuit 20, and a hot water generator 30. . The 1st refrigerant circuit 10 and the warm water production | generation part 30 are connected via the water-refrigerant heat exchanger A, and the 1st refrigerant circuit 10 and the 2nd refrigerant circuit 20 are connected via the heat exchanger B between refrigerant | coolants. Yes.

  The hot water generation unit 30 includes a water circulation circuit 31 including a pump 32, and a part of the water circulation circuit 31 is piped in the water-refrigerant heat exchanger A as a heat receiving unit 31a. The water circulation circuit 31 includes a hot water use terminal 33.

  In this embodiment, the hot water use terminal 33 uses the hot water fan convector 34 having the blower fan 35, but may be a floor heating panel heater or a radiator. Moreover, the hot water use terminal 33 may be a hot water supply facility having a hot water storage tank.

  The first refrigerant circuit 10 includes, as a basic configuration, a first refrigerant circulation system 10 a including a first compressor 11, a first condensing unit 12, a first expansion valve 13, a first evaporation unit 15, and a first accumulator 17. The 1st condensation part 12 is arranged in water-refrigerant heat exchanger A, and the 1st evaporation part 15 is arranged in heat exchanger B between refrigerants. An electronic expansion valve is preferably used as the first expansion valve 13.

  Similarly, the second refrigerant circuit 20 includes a second compressor 21, a second condensing unit 22, a second expansion valve 23, a second evaporating unit 24, and a second accumulator 27 as a basic configuration. The system 20a is provided, and the second condensing unit 22 is disposed in the inter-refrigerant heat exchanger B. The second evaporator 24 is an air-refrigerant heat exchanger having a blower fan 25 and is disposed outdoors. An electronic expansion valve is preferably used for the second expansion valve 23 as well.

  In order to switch between the dual cycle operation and the single-stage cycle operation, the first and second bypass pipes 18, 19 extend from the first refrigerant circulation system 10 a of the first refrigerant circuit 10 to the second refrigerant circulation system 20 a of the second refrigerant circuit 20. Is piped.

  Therefore, a first flow path switching valve 14 is provided in a pipe portion between the refrigerant outlet of the first expansion valve 13 and the refrigerant inlet 15a of the first evaporator 15 in the first refrigerant circulation system 10a, and the first A second flow path switching valve 16 is provided in a piping portion between the refrigerant outlet 15 b of the evaporation unit 15 and the first accumulator 17. A three-way valve is used for both the first flow path switching valve 14 and the second flow path switching valve 16.

  The first flow path switching valve 14 has one inflow port 14 a and two outflow ports 14 b and 14 c that are selectively opened and closed, and the inflow port 14 a is connected to the refrigerant outlet side of the first expansion valve 13. One outlet 14b is connected to the refrigerant inlet 15a side of the first evaporator 15.

  One end of the first bypass pipe 18 is connected to the other outlet 14c, and the other end of the first bypass pipe 18 is the refrigerant of the second expansion valve 23 and the second evaporator 24 in the second refrigerant circulation system 20a. It is connected to a pipe portion between the inlet 24a.

  The second flow path switching valve 16 has one outlet 16a and two inlets 16b and 16c that are selectively opened and closed, and the outlet 16a is connected to the first accumulator 17 side, The inlet 16b is connected to the refrigerant outlet 15b side of the first evaporator 15.

  One end of the second bypass pipe 19 is connected to the other inlet 16c, and the other end of the second bypass pipe 19 is connected to the refrigerant outlet 24b of the second evaporator 24 and the second accumulator in the second refrigerant circulation system 20a. 27 is connected to the piping portion between the two.

  If the connection point of the other end of the second bypass pipe 19 with respect to the second refrigerant circulation system 20a is 19a, an opening / closing valve 26 is provided on the second refrigerant circuit 20 side at a pipe portion extending from the connection point 19a to the second accumulator 27. Provided.

  A path 24c serving as a refrigerant flow path is passed through the second evaporator 24. In this first embodiment, the path 24c is shared both during dual cycle operation and during single stage cycle operation. The

  Next, the operation of the first embodiment will be described. The first and second compressors 11 and 21, the first and second expansion valves 13 and 23, the first and second flow path switching valves 14 and 16, and the on-off valve 26 are controlled by the control unit 40. The control unit 40 is input with the indicated hot water temperature t1, the outside air temperature t2, the suction pressure Ps of each compressor, the discharge pressure Pd, and the like as control factors.

[Switching from dual cycle operation to single-stage cycle operation in the first embodiment]
Referring to the operation flowchart of FIG. 3, when the indicated hot water temperature t1 is lower than a preset reference temperature tA and the outside air temperature t2 is higher than a preset reference temperature tC (for example, −2 ° C.). First, the first compressor 11 of the first refrigerant circuit 10 is temporarily stopped.

  Next, the second expansion valve 23 of the second refrigerant circuit 20 is fully closed, preferably the rotation of the blower fan 25 of the second evaporator 24 is stopped, and the second compressor 21 is operated at a low speed, Refrigerant existing in the pipe from the refrigerant outlet side of the second expansion valve 23 to the second accumulator 27 is recovered (pump down) in the pipe from the discharge side of the second compressor 21 to the second expansion valve 23. To do.

  After that, when the second compressor 21 is operated for a predetermined time or when the suction pressure Ps and the discharge pressure Pd of the second compressor 21 become predetermined pressures, the on-off valve 26 is fully closed, The compressor 21 is stopped and the refrigerant recovery is finished.

  After the pump-down is completed, the outlet 14c side of the first flow path switching valve 14 is opened, the outlet 14b side is closed, the inlet 16c side of the second flow path switching valve 16 is opened, and the inlet 16b side is opened. It is closed and the refrigerant in the first refrigerant circulation system 10a flows into the second evaporator 24 on the second refrigerant circuit 20 side via the first and second bypass pipes 18 and 19, whereby the inter-refrigerant heat exchanger B A single-stage cycle that does not use is completed.

  Even when the path of the second evaporator 24 is shared by performing the refrigerant recovery pump-down in the low refrigerant side second refrigerant circuit 20 when switching to the single-stage cycle operation, the refrigerant in the second refrigerant circuit 20 is shared. The initial enclosed amount can be maintained as much as possible.

  Further, when pumping down is performed, by stopping the rotation of the blower fan 25 of the second evaporator 24, the suction pressure is reduced and the refrigerant is easily recovered.

[Switching from single-stage cycle operation to dual-cycle operation in the first embodiment]
Referring to the operation flowchart of FIG. 4, when the indicated hot water temperature t1 is equal to or higher than a preset reference temperature tA, or the outside air temperature t2 is lower than a preset reference temperature tC (for example, −2 ° C.). First, the first expansion valve 13 of the first refrigerant circuit 10 is fully closed, the outlet 14c side of the first flow path switching valve 14 is opened, and the outlet 14b side is closed. The inlet 16b side of the first flow path switching valve 16 is closed and the inlet 16c side is open.

  Next, preferably after the rotation of the blower fan 25 of the second evaporator 24 is stopped, the first compressor 11 is operated at a low speed, and the first bypass pipe 18, the path 24 c of the second evaporator 24, and the second The refrigerant of the first refrigerant circulation system 10 a existing in the bypass pipe 19 is collected (pumped down) into the pipe from the discharge side of the first compressor 11 to the first expansion valve 13.

  Thereafter, when the first compressor 11 is operated for a predetermined time, or when the suction pressure Ps and the discharge pressure Pd of the first compressor 11 reach the predetermined pressure, the outlet of the first flow path switching valve 14 14c side is closed, outlet 14b side is opened, inlet 16c side of second flow rate switching valve 16 is closed, inlet 16b side is opened, first compressor 11 is stopped, and refrigerant recovery (pump DOWN).

  After the pump-down, the first refrigerant circuit 10 side opens or fully opens the first expansion valve 13 in an arbitrary step so that the refrigerant flows into the first refrigerant circulation system 10a. On the second refrigerant circuit 20 side, The on-off valve 26 is opened so that the refrigerant flows into the second refrigerant circulation system 20a.

  In this way, the refrigerant of the first refrigerant circuit 10 is not mixed with the refrigerant of the second refrigerant circuit 20, and the initial amount of refrigerant enclosed in the first refrigerant circuit 10 is maintained as much as possible to achieve the binary. You can switch to a cycle.

  In the said 1st Embodiment, it is preferable that each refrigerant | coolant of the 1st refrigerant circuit 10 and the 2nd refrigerant circuit 20 is the same refrigerant | coolant (both are R410A for example).

  When different refrigerants are used in the first refrigerant circuit 10 and the second refrigerant circuit 20 (for example, the high element side is R134a and the low element side is R410A), the second embodiment shown in FIG. 2 may be adopted. .

  That is, in the second embodiment, the first bypass pipe 18 and the second bypass pipe 19 are provided in the second evaporator 24 shared by the single-stage cycle operation separately from the path 24c for the second refrigerant circulation system 20a. A path 24d for the first refrigerant circulation system 10a connected between the two is provided to provide a complete separation type. Other configurations may be the same as those in the first embodiment.

  Next, the operation of the second embodiment will be described. Note that FIG. 3 is used as the operation flowchart when switching from the two-cycle operation to the single-cycle operation, and FIG. 4 is used as the operation flowchart when switching from the single-cycle operation to the two-cycle operation.

[Switching from dual cycle operation to single-stage cycle operation in the second embodiment]
When the indicated hot water temperature t1 is lower than a preset reference temperature tA and the outside air temperature t2 is higher than a preset reference temperature tC (for example, −2 ° C.), first, the first refrigerant circuit 10 The first compressor 11 is temporarily stopped.

  Next, the second expansion valve 23 of the second refrigerant circuit 20 is fully closed, preferably the rotation of the blower fan 25 of the second evaporator 24 is stopped, and the second compressor 21 is operated at a low speed, Refrigerant existing in the pipe from the refrigerant outlet side of the second expansion valve 23 to the second accumulator 27 is recovered (pump down) in the pipe from the discharge side of the second compressor 21 to the second expansion valve 23. To do.

  After that, when the second compressor 21 is operated for a predetermined time or when the suction pressure Ps and the discharge pressure Pd of the second compressor 21 become predetermined pressures, the on-off valve 26 is fully closed, The compressor 21 is stopped and the refrigerant recovery is finished.

  After the pump-down is completed, the outlet 14c side of the first flow path switching valve 14 is opened, the outlet 14b side is closed, the inlet 16c side of the second flow path switching valve 16 is opened, and the inlet 16b side is opened. It is closed and the refrigerant in the first refrigerant circulation system 10a flows into the path 24d of the second evaporator 24 through the first and second bypass pipes 18 and 19, so that the inter-refrigerant heat exchanger B is not used. The stage cycle is completed.

  At the time of switching to single-stage cycle operation, the low refrigerant side second refrigerant circuit 20 pumps down the refrigerant recovery, and the low element side path 24c is emptied, so that the low element inside the second evaporator 24 is low. Heat transfer that causes heat loss between the side refrigerant and the high-side refrigerant can be prevented.

  Further, when pumping down, as in the first embodiment, the suction pressure is lowered by stopping the rotation of the blower fan 25 of the second evaporator 24, and the refrigerant is easily recovered.

[Switching from single-stage cycle operation to dual-cycle operation in the second embodiment]
When the indicated hot water temperature t1 is equal to or higher than a preset reference temperature tA or the outside air temperature t2 is lower than a preset reference temperature tC (for example, −2 ° C.), first, the first refrigerant circuit 10 The first expansion valve 13 is fully closed, the outlet 14c side of the first flow path switching valve 14 is opened, and the outlet 14b side is closed. The inlet 16b side of the first flow path switching valve 16 is closed and the inlet 16c side is open.

  Next, the rotation of the blower fan 25 of the second evaporator 24 is preferably stopped. As described above, this is performed for the purpose of lowering the suction pressure in order to facilitate the recovery of the refrigerant to the high original high pressure side when the first compressor 11 is started.

  Then, the first compressor 11 is operated at a low speed, and the refrigerant in the first refrigerant circulation system 10 a existing in the first bypass pipe 18, the path 24 d and the second bypass pipe 19 is supplied to the first compressor 11. Recovery (pump down) is performed in the piping from the discharge side to the first expansion valve 13.

  Thereafter, when the first compressor 11 is operated for a predetermined time, or when the suction pressure Ps and the discharge pressure Pd of the first compressor 11 reach the predetermined pressure, the outlet of the first flow path switching valve 14 14c side is opened, outlet 14b side is closed, inlet 16c side of second flow rate switching valve 16 is closed, inlet 16b side is opened, first compressor 11 is stopped, and refrigerant recovery (pump DOWN).

  After the pump-down is completed, the first expansion valve 13 of the first refrigerant circuit 10 is opened or fully opened in an arbitrary step so that the refrigerant flows into the first refrigerant circulation system 10a, and the on-off valve of the second refrigerant circuit 20 26 is opened so that the refrigerant flows into the second refrigerant circulation system 20a.

  In this way, according to the second embodiment, the refrigerant in the first refrigerant circuit 10 and the refrigerant in the second refrigerant circuit 20 are completely supplied in both cases of single-stage cycle operation and dual-cycle operation. Thus, the refrigerant is not mixed at all, and the initial charging amount of the refrigerant in the first refrigerant circuit 10 can be maintained as much as possible to easily switch from the single-stage cycle to the dual cycle. Further, heat transfer that causes a heat loss between the low-side refrigerant and the high-side refrigerant in the second evaporator 24 during the single-stage cycle operation can be prevented.

10 First refrigerant circuit (high-end side)
DESCRIPTION OF SYMBOLS 11 1st compressor 12 1st condensation part 13 1st expansion valve 14 1st flow path switching valve 15 1st evaporation part 16 2nd flow path switching valve 17 1st accumulator 20 2nd refrigerant circuit (low original side)
DESCRIPTION OF SYMBOLS 21 2nd compressor 22 2nd condensation part 23 2nd expansion valve 24 2nd evaporation part 25 Blower fan 26 On-off valve 27 2nd accumulator 30 Hot water production | generation part 33 Hot water fan convector 40 Control part A Water-refrigerant heat exchanger B Refrigerant Heat exchanger

Claims (7)

A first refrigerant circuit having a first refrigerant circulation system including a hot water generating unit for generating hot water, a first compressor, a first condensing unit, a first expansion valve and a first evaporating unit; a second compressor; A second refrigerant circuit having a second refrigerant circulation system including a condensing unit, a second expansion valve, and a second evaporating unit, and a water-refrigerant heat exchanger between the first condensing unit and the hot water generating unit. And an inter-refrigerant heat exchanger is provided between the first evaporator and the second condensing unit, and at least the outside air temperature and the hot water temperature are used as control factors, and a single-stage cycle operation and a dual cycle In the dual refrigeration system for which operation is selected,
During the single-stage cycle operation, the second evaporator section of the second refrigerant circulation system is used instead of the first evaporation section of the first refrigerant circulation system, and during the dual cycle operation, the single-stage cycle is used. A binary refrigeration apparatus comprising pipe switching means for making the amount of refrigerant usable in each of the first and second refrigerant circuits substantially the same during operation and during the dual cycle operation. A first refrigerant circuit having a first refrigerant circulation system including a hot water generating unit for generating hot water, a first compressor, a first condensing unit, a first expansion valve and a first evaporating unit; a second compressor; A second refrigerant circuit having a second refrigerant circulation system including a condensing unit, a second expansion valve, and a second evaporating unit, and a water-refrigerant heat exchanger between the first condensing unit and the hot water generating unit. And an inter-refrigerant heat exchanger is provided between the first evaporator and the second condensing unit, and at least the outside air temperature and the hot water temperature are used as control factors, and a single-stage cycle operation and a dual cycle In the dual refrigeration system for which operation is selected,
During the single-stage cycle operation, the second evaporator section of the second refrigerant circulation system is used instead of the first evaporation section of the first refrigerant circulation system, and during the dual cycle operation, the single-stage cycle is used. Pipe switching means for making the amount of refrigerant that can be used in the first and second refrigerant circuits substantially the same during operation and during the dual cycle operation,
The pipe switching means branches from a pipe portion between a refrigerant outlet of the first expansion valve and a refrigerant inlet of the first evaporation section via a first flow path switching valve, and the pipe of the second refrigerant circulation system Branches from the first bypass pipe reaching the refrigerant inlet side of the second evaporation section and the pipe section between the refrigerant outlet of the first evaporation section and the suction side of the first compressor via the second flow path switching valve. And a second bypass pipe reaching the refrigerant outlet side of the second evaporator in the second refrigerant circulation system, a connection point of the second bypass pipe in the second refrigerant circulation system, and an intake of the second compressor An on-off valve provided between the side and
A binary refrigeration apparatus comprising at least each compressor, each expansion valve, each flow path switching valve, and a control unit that controls the on-off valve.   In switching from the dual cycle operation to the single-stage cycle operation, the control unit operates the second compressor with the second expansion valve fully closed, and performs the above operation from the outlet side of the second expansion valve. The refrigerant existing in the piping system that reaches the suction side of the second compressor through the second evaporation section passes through the second condensation section from the discharge side of the second compressor to the second expansion valve in the piping system. The first on-off valve is closed, the second evaporation side of the first flow path switching valve is opened, the first evaporation side is closed, and the first evaporation of the second flow path switching valve is closed. The two-sided refrigeration apparatus according to claim 2, wherein the section side is closed and the second evaporation section side is opened.   In switching from the single-stage cycle operation to the dual cycle operation, the control unit operates the first compressor with the first expansion valve fully closed, from the refrigerant outlet side of the first expansion valve. Piping system in which the refrigerant existing in the piping system that reaches the suction side of the first compressor through the second evaporation section passes from the discharge side of the first compressor to the first expansion valve through the first condensation section. The first evaporation section side of the first flow path switching valve is opened, the second evaporation section side is closed, and the first evaporation section side of the second flow path switching valve is opened. The two-way refrigeration apparatus according to claim 2, wherein the on-off valve is opened after closing the second evaporation section.   5. The dual refrigeration apparatus according to claim 3, wherein during the refrigerant recovery, the rotation of the blower fan included in the second evaporator is stopped. A first refrigerant circuit having a first refrigerant circulation system including a hot water generating unit for generating hot water, a first compressor, a first condensing unit, a first expansion valve and a first evaporating unit; a second compressor; A second refrigerant circuit having a second refrigerant circulation system including a condensing unit, a second expansion valve, and a second evaporating unit, and a water-refrigerant heat exchanger between the first condensing unit and the hot water generating unit. And an inter-refrigerant heat exchanger is provided between the first evaporator and the second condensing unit, and at least the outside air temperature and the hot water temperature are used as control factors, and a single-stage cycle operation and a dual cycle In the dual refrigeration system for which operation is selected,
A pipe portion between the refrigerant outlet of the first expansion valve and the refrigerant inlet of the first evaporator is branched via a first flow path switching valve, and the second evaporator circulation path passes through the second evaporator. A bypass pipe that passes through a path different from the path and is connected to a pipe portion between the refrigerant outlet of the first evaporator and the first compressor via a second flow path switching valve; and the second pipe An on-off valve provided between the refrigerant outlet side of the second evaporator and the suction side of the second compressor in the refrigerant circulation system, at least the compressors, the expansion valves, and the flow path switches. A control unit for controlling the valve and the on-off valve ,
In switching from the dual cycle operation to the single stage cycle operation, the control unit opens the second evaporation unit side of the first flow path switching valve after stopping the operation of the first compressor, The first evaporation section side is closed, the first evaporation section side of the second flow path switching valve is closed, the second evaporation section side is opened, and the second expansion valve is fully closed. Operating the two compressors, the refrigerant present in the piping system from the outlet side of the second expansion valve through the second evaporator to the suction side of the second compressor is discharged to the discharge side of the second compressor The two- way refrigeration apparatus is characterized in that the on-off valve is closed after being collected in a piping system that reaches the second expansion valve through the second condensing part . A first refrigerant circuit having a first refrigerant circulation system including a hot water generating unit for generating hot water, a first compressor, a first condensing unit, a first expansion valve and a first evaporating unit; a second compressor; A second refrigerant circuit having a second refrigerant circulation system including a condensing unit, a second expansion valve, and a second evaporating unit, and a water-refrigerant heat exchanger between the first condensing unit and the hot water generating unit. And an inter-refrigerant heat exchanger is provided between the first evaporator and the second condensing unit, and at least the outside air temperature and the hot water temperature are used as control factors, and a single-stage cycle operation and a dual cycle In the dual refrigeration system for which operation is selected,
A pipe portion between the refrigerant outlet of the first expansion valve and the refrigerant inlet of the first evaporator is branched via a first flow path switching valve, and the second evaporator circulation path passes through the second evaporator. A bypass pipe that passes through a path different from the path and is connected to a pipe portion between the refrigerant outlet of the first evaporator and the first compressor via a second flow path switching valve; and the second pipe An on-off valve provided between the refrigerant outlet side of the second evaporator and the suction side of the second compressor in the refrigerant circulation system, at least the compressors, the expansion valves, and the flow path switches. A control unit for controlling the valve and the on-off valve,
In switching from the single-stage cycle operation to the dual cycle operation, the control unit fully closes the first expansion valve, opens the first evaporation unit side of the first flow path switching valve, and The evaporator side is closed, the first evaporator side of the second flow path switching valve is closed, the second evaporator part side is opened, and the first compressor is operated to exist in the bypass pipe. The refrigerant to be recovered is collected from the discharge side of the first compressor into the piping system that reaches the first expansion valve through the first condensing unit, and then opens the first evaporation unit side of the second flow path switching valve. , characterized in that said second evaporation unit side in a closed two-way refrigeration system.

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