GB2567333A

GB2567333A - Heat pump device

Info

Publication number: GB2567333A
Application number: GB1819892.9A
Authority: GB
Inventors: Yanachi Satoru; Obayashi Tomoyoshi; Kadowaki Kimitaka; Saikusa Tetsuji; Otsubo Yusuke
Original assignee: Mitsubishi Electric Corp
Current assignee: Mitsubishi Electric Corp
Priority date: 2016-08-02
Filing date: 2016-08-02
Publication date: 2019-04-10
Anticipated expiration: 2036-08-02
Also published as: CN109511272A; GB2567333B; DE112016007113B4; JP6537733B2; JPWO2018025318A1; CN109511272B; WO2018025318A1; DE112016007113T5; GB201819892D0

Abstract

This heat pump device is provided with a first refrigerant circuit, second refrigerant circuit, heat storage circuit, and water circuit, the first refrigerant circuit has a configuration wherein a first heat exchanger, second heat exchanger, third heat exchanger, and fourth heat exchanger are connected, and the second refrigerant circuit has a configuration wherein a fifth heat exchanger and the second heat exchanger are connected. The water circuit has: a first water circuit, in which a pump, the first heat exchanger, and the fifth heat exchanger are connected; a second water circuit, which is branched from, between the pump and the first heat exchanger, the first water circuit, and connected to, between the first heat exchanger and the fifth heat exchanger, the first water circuit; and a third water circuit, which is branched from the first water circuit in the downstream of the fifth heat exchanger, and connected to the first water circuit in the upstream of the pump via the sixth heat exchanger.

Description

DESCRIPTION

Title of Invention

HEAT PUMP APPARATUS

Technical Field [0001]

The present invention relates to a heat pump apparatus including a cascade heat pump circuit.

Background Art [0002]

Patent Literature 1 describes a hot water supply apparatus. The hot water supply apparatus includes a hot water supply refrigerant circuit sequentially connecting a compressor, a first heat exchanger, an expansion mechanism, and a second heat exchanger and filled with carbon dioxide refrigerant. The first heat exchanger is a heat exchanger for producing hot water, and the second heat exchanger is a cascade heat exchanger that exchanges heat between the carbon dioxide refrigerant and refrigerant in a low stage-side refrigerant circuit of an apparatus such as an air-conditioning apparatus. With this configuration, the hot water supply apparatus performs a cascade heat pump cycle operation.

Citation List

Patent Literature [0003]

Patent Literature 1: Japanese Patent No. 3925383

Summary of Invention

Technical Problem [0004]

Fig. 13 and Fig. 14 are p-h diagrams illustrating an operation of CO2 refrigerant in an existing hot water supply apparatus. As illustrated in Fig. 13 and Fig. 14, there is no condensing temperature for CO2 refrigerant that operates at a pressure higher than the critical pressure thereof. Therefore, an enthalpy difference during a heat transfer process changes substantially in proportion to a temperature difference in the heat transfer process. Therefore, in the case of a low incoming water temperature (20 degrees Celsius, for example), as illustrated in Fig. 13, it is possible to increase the enthalpy difference in the heat transfer process, and thus to obtain a high COP. Meanwhile, if the incoming water temperature is increased (40 degrees Celsius, for example), as illustrated in Fig. 14, the enthalpy difference in the heat transfer process is reduced, therefore reducing the COP. The existing hot water supply apparatus, therefore, has an issue of difficulty in increasing the operation efficiency in both a hot water supply operation with a low incoming water temperature and a heat retaining operation with a high incoming water temperature.

[0005]

Further, the existing hot water supply apparatus has an issue of necessity to increase the unit size to enhance the maximum capacity.

[0006]

The present invention has been made to address at least one of the abovedescribed issues, and aims to provide a heat pump apparatus capable of increasing the operation efficiency, and enhancing the maximum capacity while suppressing an increase in the unit size.

Solution to Problem [0007]

A heat pump apparatus according to an embodiment of the present invention includes a first refrigerant circuit circulating a first refrigerant, a second refrigerant circuit circulating a second refrigerant, a heat storage circuit circulating a first fluid, and a water circuit flowing water. The first refrigerant circuit is formed by sequentially connecting, by piping, a first compressor, a first heat exchanger configured to exchange heat between the first refrigerant and the water, a second heat exchanger configured to exchange heat between the first refrigerant and the second refrigerant, a first expansion valve, a third heat exchanger configured to exchange heat between the first refrigerant and a second fluid, and a fourth heat exchanger configured to exchange heat between the first refrigerant and the first fluid. The second refrigerant circuit is formed by sequentially connecting, by piping, a second compressor, a fifth heat exchanger configured to exchange heat between the second refrigerant and water, a second expansion valve, and the second heat exchanger. The heat storage circuit includes a heat storage tank, a first circulation circuit circulating the first fluid between the heat storage tank and the fourth heat exchanger, a sixth heat exchanger configured to exchange heat between the first fluid and water, and a second circulation circuit circulating the first fluid between the heat storage tank and the sixth heat exchanger. The water circuit includes a first circuit connecting a pump configured to deliver water, the first heat exchanger, and the fifth heat exchanger, a second circuit branched from the first circuit at a part between the pump and the first heat exchanger, and connected to the first circuit at a part between the first heat exchanger and the fifth heat exchanger, and a third circuit branched from the first circuit at a part on a downstream side of the fifth heat exchanger, extending through the sixth heat exchanger, and connected to the first circuit at a part on an upstream side of the pump.

Advantageous Effects of Invention [0008]

According to the present invention, it is possible to increase the operation efficiency, and enhance the maximum capacity while suppressing the increase in the unit size.

Brief Description of Drawings [0009] [Fig. 1] Fig. 1 is a circuit diagram illustrating a schematic circuit configuration of a heat pump apparatus according to Embodiment 1 of the present invention.

[Fig. 2] Fig. 2 is a diagram illustrating a state of the heat pump apparatus according to Embodiment 1 of the present invention in hot water supply mode.

[Fig. 3] Fig. 3 is a diagram illustrating a state of the heat pump apparatus according to Embodiment 1 of the present invention in heat retention mode.

[Fig. 4] Fig. 4 is a diagram illustrating a state of the heat pump apparatus according to Embodiment 1 of the present invention in heat storage mode.

[Fig. 5] Fig. 5 is a diagram illustrating a state of the heat pump apparatus according to Embodiment 1 of the present invention in capacity enhancement mode.

[Fig. 6] Fig. 6 is a diagram illustrating a state of the heat pump apparatus according to Embodiment 1 of the present invention in hot water supply and heat storage mode.

[Fig. 7] Fig. 7 is a diagram illustrating a state of the heat pump apparatus according to Embodiment 1 of the present invention in heat retention and heat storage mode.

[Fig. 8] Fig. 8 is a diagram illustrating a state of the heat pump apparatus according to Embodiment 1 of the present invention in rapid start mode.

[Fig. 9] Fig. 9 is a diagram illustrating a schematic structure of a capsular heat storage material used in a heat pump apparatus according to Embodiment 4 of the present invention.

[Fig. 10] Fig. 10 is a circuit diagram illustrating a schematic circuit configuration of a heat pump apparatus according to Embodiment 6 of the present invention.

[Fig. 11] Fig. 11 is a circuit diagram illustrating a schematic circuit configuration of a heat pump apparatus according to Embodiment 7 of the present invention.

[Fig. 12] Fig. 12 is a schematic diagram illustrating a physical configuration of a heat pump apparatus according to Embodiment 10 of the present invention.

[Fig. 13] Fig. 13 is a p-h diagram illustrating an operation of CO2 refrigerant in an existing hot water supply apparatus.

[Fig. 14] Fig. 14 is a p-h diagram illustrating the operation of the CO2 refrigerant in the existing hot water supply apparatus.

Description of Embodiments [0010]

Embodiment 1

A heat pump apparatus according to Embodiment 1 of the present invention will be described. Fig. 1 is a circuit diagram illustrating a schematic circuit configuration of the heat pump apparatus according to Embodiment 1. As illustrated in Fig. 1, the heat pump apparatus includes a cascade heat pump circuit 103 including a low-stage-side first refrigerant circuit 101 that circulates a first refrigerant and a high-stage-side second refrigerant circuit 102 that circulates a second refrigerant. The heat pump apparatus further includes a heat storage circuit 110 that circulates a first fluid and a water circuit

120 that flows water.

[0011] (First Refrigerant Circuit 101)

The first refrigerant circuit 101 is formed by sequentially and circularly connecting, via refrigerant pipes, a first compressor 1, a first heat exchanger 2, a second heat exchanger 3, a first expansion valve 4, a third heat exchanger 5, and a fourth heat exchanger 6. For example, refrigerant operating in the supercritical region thereof when at least the first refrigerant circuit 101 is operated alone (refrigerant containing CO2 at least as a component thereof, for example) is used as the first refrigerant circulating in the first refrigerant circuit 101. That is, when at least the first refrigerant circuit 101 is operated alone, a high-pressure-side pressure of the first refrigerant circuit 101 is equal to or higher than the critical pressure of the first refrigerant.

[0012]

The first compressor 1 is a fluid machine that sucks and compresses the first refrigerant having a low pressure, and discharges the first refrigerant as high-pressure refrigerant.

[0013]

Each of the first heat exchanger 2 and the second heat exchanger 3 is a highpressure-side heat exchanger of the first refrigerant circuit 101, and functions as a radiator that transfers heat from the first refrigerant. The first heat exchanger 2 is a water-refrigerant heat exchanger that exchanges heat between the water and the first refrigerant. The first heat exchanger 2 transfers heat from the first refrigerant to the water, heating the water and cooling the first refrigerant. The second heat exchanger 3 is a cascade heat exchanger that exchanges heat between the low-stage-side first refrigerant and the high-stage-side second refrigerant. The second heat exchanger 3 transfers heat from the first refrigerant to the second refrigerant, heating the second refrigerant and further cooling the first refrigerant.

[0014]

The first expansion valve 4 isenthalpically reduces the pressure of the first refrigerant having a high pressure, and discharges the first refrigerant as low-pressure refrigerant. An expansion valve such as an electronic expansion valve, the opening degree of which is adjustable by the control of a controller, is used as the first expansion valve 4.

[0015]

Each of the third heat exchanger 5 and the fourth heat exchanger 6 is a lowpressure-side heat exchanger of the first refrigerant circuit 101, and functions as an evaporator that causes the first refrigerant to receive heat and evaporate. The third heat exchanger 5 is a heat exchanger that exchanges heat between the first refrigerant and a second fluid. In the present example, outdoor air supplied by a not-shown airsending fan is used as the second fluid. The third heat exchanger 5 is therefore an airrefrigerant heat exchanger that exchanges heat between the outdoor air and the first refrigerant. The third heat exchanger 5 transfers heat from the second fluid to the first refrigerant, heating the first refrigerant. The fourth heat exchanger 6 is a heat exchanger that exchanges heat between the first refrigerant and the first fluid. The fourth heat exchanger 6 transfers heat from the first fluid to the first refrigerant, heating the first refrigerant and cooling the first fluid.

[0016] (Second Refrigerant Circuit 102)

The second refrigerant circuit 102 is formed by sequentially and connecting in circuit, via refrigerant pipes, a second compressor 7, a fifth heat exchanger 8, a second expansion valve 9, and the above-described second heat exchanger 3. For example, refrigerant operating in or below the supercritical region thereof is used as the second refrigerant circulating in the second refrigerant circuit 102. That is, a high-pressureside pressure of the second refrigerant circuit 102 is equal to or lower than the critical pressure of the second refrigerant.

[0017]

The second compressor 7 is a fluid machine that sucks and compresses the second refrigerant having a low pressure, and discharges the second refrigerant as high-temperature refrigerant.

[0018]

The fifth heat exchanger 8 is a high-pressure-side heat exchanger of the second refrigerant circuit 102, and functions as a radiator (condenser) that transfers heat from the second refrigerant to condense the second refrigerant. The fifth heat exchanger 8 is a water-refrigerant heat exchanger that exchanges heat between the water and the second refrigerant. The fifth heat exchanger 8 transfers heat from the second refrigerant to the water, heating the water and cooling the second refrigerant.

[0019]

The second expansion valve 9 isenthalpically reduces the pressure of the second refrigerant having a high pressure, and discharges the second refrigerant as lowpressure refrigerant. An expansion valve such as an electronic expansion valve, the opening degree of which is adjustable by the control of a controller, is used as the second expansion valve 9.

[0020]

The second heat exchanger 3 is a low-pressure-side heat exchanger of the second refrigerant circuit 102, and functions as an evaporator that causes the second refrigerant to receive heat and evaporate. As described above, the second heat exchanger 3 is a cascade heat exchanger that exchanges heat between the first refrigerant and the second refrigerant.

[0021] (Heat Storage Circuit 110)

The heat storage circuit 110 includes a heat storage tank 10, and a first circulation circuit 111 and a second circulation circuit 112 which circulate the first fluid. The heat storage tank 10 of the present example contains a gel-like heat storage material sealed therein. A material having a heat capacity greater than that of water is used as the heat storage material. In the heat storage tank 10, the first fluid and the heat storage material exchange heat with each other. A liquid heat medium such as water or brine is used as the first fluid of the present example.

[0022]

The first circulation circuit 111 circulates the first fluid between the heat storage tank 10 and the fourth heat exchanger 6. The first circulation circuit 111 is equipped with a pump 11 that delivers the first fluid. As described above, the fourth heat exchanger 6 is a heat exchanger that exchanges heat between the first refrigerant and the first fluid. The fourth heat exchanger 6 transfers heat from the first fluid to the first refrigerant, heating the first refrigerant and cooling the first fluid.

[0023]

The second circulation circuit 112 circulates the first fluid between the heat storage tank 10 and the sixth heat exchanger 17. In the present example, the second circulation circuit 112 shares the pump 11 with the first circulation circuit 111, and branches from the first circulation circuit 111. A flow switching device 16 is provided to a branching part of the second circulation circuit 112 branching from the first circulation circuit 111. The flow switching device 16 is formed as a three-way valve or a plurality of two-way valves, for example. The flow switching device 16 switches to allow the first fluid delivered by the pump 11 to circulate the first fluid in the first circulation circuit 111 or to circulate in the second circulation circuit 112. That is, the flow switching device 16 switches to allow the first fluid to flow into the fourth heat exchanger 6 or into the sixth heat exchanger 17.

[0024]

The sixth heat exchanger 17 is a heat exchanger that exchanges heat between the first fluid and the water. The sixth heat exchanger 17 transfers heat from the water to the first fluid, heating the first fluid.

[0025] (Water Circuit 120)

The water circuit 120 includes a first circuit 121, a second circuit 122, and a third circuit 123 which flow the water. As well as water, a liquid heat medium such as brine is usable as the fluid flowing through the water circuit 120.

[0026]

The first circuit 121 is formed by sequentially connecting, via water pipes, a pump 12 that delivers the water, the above-described first heat exchanger 2, and the abovedescribed fifth heat exchanger 8. An inlet 120a (a water inlet) into which water or lowtemperature hot water flows from the outside of the heat pump apparatus is provided at an upstream end of the first circuit 121 has. An outlet 120b (a hot water outlet) from which hot water is discharged to the outside of the heat pump apparatus is provided at a downstream end of the first circuit 121 has.

[0027]

The second circuit 122 branches from the first circuit 121 at a part between the pump 12 and the first heat exchanger 2, and is connected to the first circuit 121 at a part between the first heat exchanger 2 and the fifth heat exchanger 8. That is, the second circuit 122 is a circuit connecting the pump 12 and the fifth heat exchanger 8 of the first circuit 121 without extending through the first heat exchanger 2. A flow switching device 14 is provided at a branching part of the second circuit 122 branching from the first circuit 121. The flow switching device 14 is formed as a three-way valve or a plurality of two-way valves, for example. The flow switching device 14 switches to allow the water delivered by the pump 12 to pass either through the first heat exchanger 2 or through the second circuit 122.

[0028]

The third circuit 123 branches from the first circuit 121 at a part on a downstream side of the fifth heat exchanger 8, extends through the sixth heat exchanger 17, and is connected to the first circuit 121 at a part on an upstream side of the pump 12. [0029]

A flow switching device 15 is provided at a branching part of the third circuit 123 branching from the first circuit 121. The flow switching device 15 is formed as a threeway valve or a plurality of two-way valves, for example. The flow switching device 15 switches to allow the water having passed through the fifth heat exchanger 8 to flow to the outside via the outlet 120b or return to the upstream side of the pump 12 via the sixth heat exchanger 17. Further, the flow switching device 15 is capable of not merely switching of a passage but also adjusting the flow rate ratio between the flow rate of the water flowing to the outside via the outlet 120b and the flow rate of the water returning to the upstream side of the pump 12 via the sixth heat exchanger 17. The flow switching device 15 may be formed as a combination of a switch valve that switches a passage and a flow control valve that adjusts the flow rate, for example.

[0030]

A flow switching device 13 is provided at a connecting part connecting the third circuit 123 and the first circuit 121. The flow switching device 13 is formed as a threeway valve or a plurality of two-way valves, for example. The flow switching device 13 switches between allowing the incoming water flowing from the outside via the inlet 120a to be sucked by the pump 12 and the water returning to the upstream side of the pump 12 via the sixth heat exchanger 17 to be sucked by the pump 12. Further, the flow switching device 13 is capable of not only simply switching a passage but also adjusting the flow rate ratio between the flow rate of the incoming water flowing from the outside via the inlet 120a and the flow rate of the water returning to the upstream side of the pump 12 via the sixth heat exchanger 17. The flow switching device 13 may be formed as a combination of a switch valve that switches a passage and a flow control valve that adjusts the flow rate, for example.

[0031] (Controller 200)

The heat pump apparatus further includes a controller 200 that controls the entire heat pump apparatus including the first refrigerant circuit 101, the second refrigerant circuit 102, the heat storage circuit 110, and the water circuit 120. The controller 200 includes a microcomputer including components such as a CPU, a ROM, a RAM, an I/O port, and a timer. Based on information such as the setting of operation mode or detections signals from not-shown sensors, the controller 200 controls the operations of a variety of actuators, such as the first compressor 1, the second compressor 7, the first expansion valve 4, the second expansion valve 9, the pump 11, the flow switching device 16, the pump 12, the flow switching devices 13, 14, and 15, and the not-shown air-sending fan.

[0032]

As operation modes of the heat pump apparatus, the controller 200 is capable of executing hot water supply mode (an example of a first operation mode), heat retention mode (an example of a second operation mode), heat storage mode (an example of a third operation mode), capacity enhancement mode (an example of a fourth operation mode), hot water supply and heat storage mode (an example of a fifth operation mode), heat retention and heat storage mode (an example of a sixth operation mode), and rapid start mode (an example of a seventh operation mode). Switching between the operation modes is performed based on an operation performed by a user, an external command, or the detection signals from the sensors, for example. The operation modes will be described below. The operations of a variety of actuators described below are exemplary ones for executing the operation modes.

[0033] (Hot Water Supply Mode)

Fig. 2 is a diagram illustrating a state of the heat pump apparatus according to Embodiment 1 in the hot water supply mode. In the hot water supply mode, the first compressor 1 is controlled such that an outgoing hot water temperature becomes a target value thereof. The first expansion valve 4 is controlled such that a degree of superheat, a discharge temperature, or a discharge pressure of the first refrigerant circuit 101 becomes a target value thereof. The third heat exchanger 5 exchanges heat between the outdoor air sent by the air-sending fan and the first refrigerant. The second compressor 7 and the pump 11 are stopped. The pump 12 is operating. The flow switching devices 13, 14, and 15 are set such that the incoming water flowing from the outside via the inlet 120a sequentially passes through the first heat exchanger 2 and the fifth heat exchanger 8 in series, and flows to the outside via the outlet 120b. Since the second compressor 7 is stopped, the fifth heat exchanger 8 does not exchange heat between the second refrigerant and the water.

[0034]

In the hot water supply mode, the incoming water flowing from the outside is heated by heat exchange in the first heat exchanger 2, and flows to the outside as high temperature hot water. In the hot water supply mode, therefore, it is possible to supply hot water with the heat collected from the outdoor air. Since the first refrigerant circuit 101 is operating at a pressure equal to or higher than the critical pressure, it is possible to perform an operation with a high COP.

[0035] (Heat Retention Mode)

Fig. 3 is a diagram illustrating a state of the heat pump apparatus according to Embodiment 1 in the heat retention mode. The heat retention mode is an operation mode executed when the temperature difference between an incoming water temperature and the outgoing hot water temperature is reduced owing to an increase in the incoming water temperature. For example, the heat retention mode is executed when the incoming water temperature is equal to or higher than a predetermined temperature or the temperature difference between the incoming water temperature and a target outgoing hot water temperature is equal to or less than a predetermined value during the execution of the hot water supply mode.

[0036]

In the heat retention mode, the first compressor 1 is controlled such that the discharge pressure of the first refrigerant circuit 101 becomes the target value thereof. The first expansion valve 4 is controlled such that the degree of superheat or the discharge temperature of the first refrigerant circuit 101 becomes the target value thereof. The third heat exchanger 5 exchanges heat between the outdoor air sent by the air-sending fan and the first refrigerant. The second compressor 7 is controlled such that the outgoing hot water temperature becomes a target value thereof. The control target of the first compressor 1 and the control target of the second compressor 7 may be switched. That is, the first compressor 1 may be controlled such that the outgoing hot water temperature becomes the target value thereof, and the second compressor 7 may be controlled such that the discharge pressure of the first refrigerant circuit 101 becomes the target value thereof. The second expansion valve 9 is controlled such that a degree of superheat, a discharge temperature, or a discharge pressure of the second refrigerant circuit 102 becomes a target value thereof. The pump 11 is stopped. The pump 12 is operating. The flow switching devices 13, 14, and 15 are set such that the incoming water flowing from the outside via the inlet 120a passes through the fifth heat exchanger 8 via the second circuit 122 and flows to the outside via the outlet 120b.

[0037]

In the heat retention mode, the first refrigerant circuit 101 and the second refrigerant circuit 102 form a cascade cycle. It is therefore possible to operate both the first refrigerant circuit 101 and the second refrigerant circuit 102 at a pressure equal to or lower than the critical pressure, and thus to condense the refrigerant in both the first refrigerant circuit 101 and the second refrigerant circuit 102. Therefore, even if the temperature difference between the incoming water temperature and the outgoing hot water temperature is reduced owing to an increase in the incoming water temperature, it is possible to secure an increased enthalpy difference, and thus to perform an operation with a high COP.

[0038] (Heat Storage Mode)

Fig. 4 is a diagram illustrating a state of the heat pump apparatus according to Embodiment 1 in the heat storage mode. The heat storage mode is executed when there is no amount of heat required by a load and thus the operation in the hot water supply mode or the heat retention mode is not performed, when a remaining heat storage amount of the heat storage tank 10 is insufficient, or when a shortage of the remaining heat storage amount of the heat storage tank 10 is expected, for example. [0039]

In the heat storage mode, the first compressor 1 is controlled such that the discharge pressure of the first refrigerant circuit 101 becomes the target value thereof. The first expansion valve 4 is controlled such that the degree of superheat or the discharge temperature of the first refrigerant circuit 101 becomes the target value thereof. The third heat exchanger 5 exchanges heat between the outdoor air sent by the air-sending fan and the first refrigerant. The second compressor 7 is controlled such that the outgoing hot water temperature becomes the target value thereof. The control target of the first compressor 1 and the control target of the second compressor 7 may be switched. The second expansion valve 9 is controlled such that the degree of superheat, the discharge temperature, or the discharge pressure of the second refrigerant circuit 102 becomes the target value thereof. The pump 11 is operating. The flow switching device 16 is set to circulate the first fluid in the second circulation circuit 112. The pump 12 is operating. The flow switching devices 13, 14, and 15 are set to form a closed circuit in which the water circulates through the pump 12, the second circuit 122, the fifth heat exchanger 8, the third circuit 123, and the sixth heat exchanger 17. Thereby, the sixth heat exchanger 17 heats the first fluid with the heat received from the water. The heat storage tank 10 stores the heat transferred from the first fluid into the heat storage material.

[0040]

In the heat storage mode, the first refrigerant circuit 101 and the second refrigerant circuit 102 form a cascade cycle. It is therefore possible to operate both the first refrigerant circuit 101 and the second refrigerant circuit 102 at a pressure equal to or lower than the critical pressure, and thus to condense the refrigerant in both the first refrigerant circuit 101 and the second refrigerant circuit 102. It is therefore possible to secure an increased enthalpy difference even in a heat storage operation involving an increase in the incoming water temperature, and thus to perform an operation with a high COP.

[0041] (Capacity Enhancement Mode)

Fig. 5 is a diagram illustrating a state of the heat pump apparatus according to Embodiment 1 in the capacity enhancement mode. The capacity enhancement mode is executed when the frequency of the first compressor 1 reaches the upper limit thereof, when the outgoing hot water temperature does not reach the target outgoing hot water temperature even after the high-pressure-side pressure of the first refrigerant circuit 101 reaches a predetermined value, or when an outgoing hot water amount does not reach a target outgoing hot water amount, for example.

[0042]

In the capacity enhancement mode, the first compressor 1 is controlled such that the discharge pressure of the first refrigerant circuit 101 becomes the target value thereof. The first expansion valve 4 is controlled such that the degree of superheat or the discharge temperature of the first refrigerant circuit 101 becomes the target value thereof. The third heat exchanger 5 does not exchange heat between the outdoor air and the first refrigerant. That is, the air-sending fan is stopped. The second compressor 7 is controlled such that the outgoing hot water temperature reaches the target value thereof. The control target of the first compressor 1 and the control target of the second compressor 7 may be switched. The second expansion valve 9 is controlled such that the degree of superheat, the discharge temperature, or the discharge pressure of the second refrigerant circuit 102 becomes the target value thereof. The pump 11 is operating. The flow switching device 16 is set to circulate the first fluid in the first circulation circuit 111. In the fourth heat exchanger 6, therefore, the first refrigerant evaporates with the heat received from the first fluid. The pump 12 is operating. The flow switching devices 13, 14, and 15 are set such that the incoming water flowing from the outside via the inlet 120a sequentially passes through the first heat exchanger 2 and the fifth heat exchanger 8 in series and flows to the outside via the outlet 120b.

[0043]

In the capacity enhancement mode, the water is heated at two stages by the first heat exchanger 2 and the fifth heat exchanger 8. It is thereby possible to enhance the hot water supply capacity, and thus to increase the outgoing hot water temperature or the outgoing hot water amount. Further, in the capacity enhancement mode, it is possible to increase the suction pressure of the first compressor 1 by supplying the first refrigerant circuit 101 with the heat from the heat storage material, and thus to realize high performance irrespective of outdoor air temperature. Further, with the low-stageside first refrigerant circuit 101 cooled by the high-stage-side second refrigerant circuit 102, it is possible to suppress an increase in the discharge pressure of the first refrigerant circuit 101 even if the suction pressure of the first refrigerant circuit 101 is increased. It is therefore possible to set the reduced design pressure of the first refrigerant circuit 101, and thus to set the reduced thicknesses of components such as pipes and containers. Further, in the capacity enhancement mode, the heat stored with a high COP is used as a heat source, therefore making it possible to perform an operation with a high COP. As described above, in the capacity enhancement mode, it is possible to obtain high performance, and thus to reduce the number of units in the heat pump apparatus and the installation area of the heat pump apparatus.

[0044] (Hot Water Supply and Heat Storage Mode)

Fig. 6 is a diagram illustrating a state of the heat pump apparatus according to Embodiment 1 in the hot water supply and heat storage mode. The hot water supply and heat storage mode is executed when the remaining heat storage amount of the heat storage tank 10 is insufficient during the execution of the hot water supply mode, or when a shortage of the remaining heat storage amount of the heat storage tank 10 is expected during the execution of the hot water supply mode, for example.

[0045]

In the hot water supply and heat storage mode, the first compressor 1 is controlled such that the outgoing hot water temperature becomes the target value thereof. The first expansion valve 4 is controlled such that the degree of superheat or the discharge temperature of the first refrigerant circuit 101 becomes the target value thereof. The third heat exchanger 5 exchanges heat between the outdoor air sent by the air-sending fan and the first refrigerant. The second compressor 7 is stopped. The pump 11 is operating. The flow switching device 16 is set to circulate the first fluid in the second circulation circuit 112. The pump 12 is operating. The flow switching devices 13, 14, and 15 are set such that the incoming water flowing from the outside via the inlet 120a sequentially passes through the first heat exchanger 2 and the fifth heat exchanger 8 in series and flows to the outside via the outlet 120b, and that a part of the water having passed through the fifth heat exchanger 8 flows into the third circuit 123. The flow rate of the water flowing to the outside via the outlet 120b is adjusted based on the amount of heat requested by the load. Since the second compressor 7 is stopped, the fifth heat exchanger 8 does not exchange heat between the second refrigerant and the water.

[0046]

In the hot water supply and heat storage mode, it is possible to store an excess amount of heat while supplying the load with hot water having a necessary amount of heat. It is therefore unnecessary to separately perform the operation in the heat storage mode, making it possible to reduce the waste of energy. Further, since the first refrigerant circuit 101 is operating at a pressure equal to or higher than the critical pressure, it is possible to perform an operation with a high COP.

[0047] (Heat Retention and Heat Storage Mode)

Fig. 7 is a diagram illustrating a state of the heat pump apparatus according to Embodiment 1 in the heat retention and heat storage mode. The heat retention and heat storage mode is executed when the remaining heat storage amount of the heat storage tank 10 is insufficient during the execution of the heat retention mode, or when a shortage of the remaining heat storage amount of the heat storage tank 10 is expected during the execution of the heat retention mode, for example. Further, the heat retention and heat storage mode is executed when the incoming water temperature is equal to or higher than a predetermined temperature or the temperature difference between the incoming water temperature and the target outgoing hot water temperature is equal to or less than a predetermined value during the execution of the hot water supply and heat storage mode, for example.

[0048]

In the heat retention and heat storage mode, the first compressor 1 is controlled such that the discharge pressure of the first refrigerant circuit 101 becomes the target value thereof. The first expansion valve 4 is controlled such that the degree of superheat or the discharge temperature of the first refrigerant circuit 101 becomes the target value thereof. The third heat exchanger 5 exchanges heat between the outdoor air sent by the air-sending fan and the first refrigerant. The second compressor 7 is controlled such that the outgoing hot water temperature becomes the target value thereof. The control target of the first compressor 1 and the control target of the second compressor 7 may be switched. That is, the first compressor 1 may be controlled such that the outgoing hot water temperature becomes the target value thereof, and the second compressor 7 may be controlled such that the discharge pressure of the first refrigerant circuit 101 becomes the target value thereof. The second expansion valve 9 is controlled such that the degree of superheat, the discharge temperature, or the discharge pressure of the second refrigerant circuit 102 becomes the target value thereof. The pump 11 is operating. The flow switching device 16 is controlled to circulate the first fluid in the second circulation circuit 112. The pump 12 is operating. The flow switching devices 13, 14, and 15 are set such that the incoming water flowing from the outside via the inlet 120a passes through the fifth heat exchanger 8 via the second circuit 122 and flows to the outside via the outlet 120b, and that a part of the water having passed through the fifth heat exchanger 8 flows into the third circuit 123. The flow rate of the water flowing to the outside via the outlet 120b is adjusted based on the amount of heat requested by the load.

[0049]

In the heat retention and heat storage mode, it is possible to store an excess amount of heat while supplying the load with hot water having a necessary amount of heat. It is therefore unnecessary to separately perform the operation in the heat storage mode, making it possible to reduce the waste of energy. Further, it is possible to operate both refrigerant circuit 101 and the second refrigerant circuit 102 at a pressure equal to or lower than the critical pressure, and thus to perform an operation with a high COP even if the temperature difference between the incoming water temperature and the outgoing hot water temperature is reduced owing to an increase in the incoming water temperature.

[0050] (Rapid Start Mode)

Fig. 8 is a diagram illustrating a state of the heat pump apparatus according to Embodiment 1 in the rapid start mode. The rapid start mode is executed when starting at least one of the first compressor 1 and the second compressor 7, for example. After the execution of the rapid start mode, the operation mode may be switched to one of the hot water supply mode, the heat retention mode, the heat storage mode, the capacity enhancement mode, the hot water supply and heat storage mode, and the heat retention and heat storage mode.

[0051]

In the rapid start mode, the pump 11 of the heat storage circuit 110 operates, and the flow switching device 16 is set to circulate the first fluid in the first circulation circuit

111. Further, in the rapid start mode, the first refrigerant circuit 101, the second refrigerant circuit 102, and the water circuit 120 are controlled similarly as in one of the hot water supply mode, the heat retention mode, the heat storage mode, the capacity enhancement mode, the hot water supply and heat storage mode, and the heat retention and heat storage mode. In the example illustrated in Fig. 8, the first refrigerant circuit 101, the second refrigerant circuit 102, and the water circuit 120 are controlled similarly as in the hot water supply mode.

[0052]

In the rapid start mode, the heat storage material is used as the heat source, therefore making it possible to reduce a start-up time. Further, with the execution of the rapid start mode, a necessary outgoing hot water temperature is immediately obtained. Therefore, there is no need to equip the heat pump apparatus with a large hot water storage tank, making it possible to reduce the installation area and costs of the heat pump apparatus. Further, in the event of liquid backflow, a circuit configuration similar to that in the rapid start mode immediately eliminates the liquid backflow. Accordingly, it is possible to improve the reliability of the heat pump apparatus.

[0053]

As described above, the heat pump apparatus according to Embodiment 1 includes the first refrigerant circuit 101 that circulates the first refrigerant, the second refrigerant circuit 102 that circulates the second refrigerant, the heat storage circuit 110 that circulates the first fluid, the water circuit 120 that flows the water, and the controller 200 that controls the first refrigerant circuit 101, the second refrigerant circuit 102, the heat storage circuit 110, and the water circuit 120. The first refrigerant circuit 101 is formed by sequentially connecting, by piping, the first compressor 1, the first heat exchanger 2 that exchanges heat between the first refrigerant and the water, the second heat exchanger 3 that exchanges heat between the first refrigerant and the second refrigerant, the first expansion valve 4, the third heat exchanger 5 that exchanges heat between the first refrigerant and the second fluid, and the fourth heat exchanger 6 that exchanges heat between the first refrigerant and the first fluid. The second refrigerant circuit 102 is formed by sequentially connecting, by piping, the second compressor 7, the fifth heat exchanger 8 that exchanges heat between the second refrigerant and the water, the second expansion valve 9, and the second heat exchanger 3. The heat storage circuit 110 includes the heat storage tank 10, the first circulation circuit 111 that circulates the first fluid between the heat storage tank 10 and the fourth heat exchanger 6, and the second circulation circuit 112 that circulates the first fluid between the heat storage tank 10 and a sixth heat exchanger 17 that exchanges heat between the first fluid and the water. The water circuit 120 includes the first circuit 121, the second circuit 122 and the third circuit 123. The first circuit is formed by sequentially connecting, by piping, the pump 12 that delivers the water, the first heat exchanger 2, and the fifth heat exchanger 8. The second circuit 122 is branched from the first circuit 121 at a part between the pump 12 and the first heat exchanger 2 and is connected to the first circuit 121 at a part between the first heat exchanger 2 and the fifth heat exchanger 8. The third circuit 123 branches from the first circuit 121 at a part on a downstream of the fifth heat exchanger 8, extending through the sixth heat exchanger 17, and is connected to the first circuit 121 at a part on an upstream side of the pump

12.

[0054]

According to this configuration, it is possible in the heat retention mode to operate both the first refrigerant circuit 101 and the second refrigerant circuit 102 at a pressure equal to or lower than the critical pressure. According to Embodiment 1, therefore, it is possible to obtain a high COP not only in the hot water supply mode but also in the heat retention mode. Further, according to this configuration, it is possible in the capacity enhancement mode to heat the water at two stages with the first heat exchanger 2 and the fifth heat exchanger 8. According to Embodiment 1, therefore, it is possible to enhance the maximum capacity while suppressing an increase in the unit size of the heat pump apparatus. In other words, it is possible to reduce the number of units and the installation area while maintaining the maximum capacity of the heat pump apparatus. Further, according to this configuration, it is possible to store an excess amount of heat in the hot water supply and heat storage mode and the heat retention and heat storage mode. According to Embodiment 1, therefore, it is possible to reduce the waste of energy. Further, according to this configuration, the heat exchange between the heat storage material and the water in the heat storage tank 10 is performed via the first fluid. Therefore, there is no heat exchange between the heat storage material and the water in a heat exchanger, making it possible to prevent the heat storage material from leaking to the load.

[0055]

Further, in the heat pump apparatus according to Embodiment 1, the controller 200 is capable of executing the first operation mode (the hot water supply mode, for example). In the first operation mode, the water circuit 120 is controlled to operate the first compressor 1 and stop the second compressor 7, and allow the water delivered by the pump 12 to flow out through the first heat exchanger 2 and the fifth heat exchanger 8.

[0056]

Further, in the heat pump apparatus according to Embodiment 1, the controller 200 is capable of executing the second operation mode (the heat retention mode, for example). In the second operation mode, the water circuit 120 is controlled to operate the first compressor 1 and the second compressor 7, and allow the water delivered by the pump 12 to flow out through the second circuit 122 and the fifth heat exchanger 8. [0057]

Further, in the heat pump apparatus according to Embodiment 1, the controller 200 causes the heat pump apparatus to operate in the second operation mode when the water temperature of the incoming water is equal to or higher than a predetermined temperature, or when the difference between the water temperature of the incoming water and the target outgoing hot water temperature is equal to or less than a predetermined value.

[0058]

Further, in the heat pump apparatus according to Embodiment 1, the controller

200 is capable of executing the third operation mode (the heat storage mode, for example). In the third operation mode, the heat storage circuit 110 is controlled to operate the first compressor 1 and the second compressor 7, and circulate the first fluid in the second circulation circuit 112, and the water circuit 120 is controlled to allow the water delivered by the pump 12 to circulate in the second circuit 122, the fifth heat exchanger 8, and the third circuit 123.

[0059]

Further, in the heat pump apparatus according to Embodiment 1, the controller

200 causes the heat pump apparatus to operate in the third operation mode when the remaining heat storage amount of the heat storage tank 10 is insufficient, or when a shortage of the remaining heat storage amount of the heat storage tank 10 is expected. [0060]

Further, in the heat pump apparatus according to Embodiment 1, the controller

200 is capable of executing the fourth operation mode (the capacity enhancement mode, for example). In the fourth operation mode, the first compressor 1 and the second compressor 7 are operated, and the heat storage circuit 110 is controlled to circulate the first fluid in the first circulation circuit 111, and the water circuit 120 is controlled to allow the water delivered by the pump 12 to flow out through the first heat exchanger 2 and the fifth heat exchanger 8.

[0061]

Further, in the heat pump apparatus according to Embodiment 1, the controller

200 causes the heat pump apparatus to operate in the fourth operation mode when the frequency of the first compressor 1 reaches the upper limit thereof, or when the outgoing hot water temperature does not reach the target outgoing hot water temperature even after the high-pressure-side pressure of the first refrigerant circuit 101 reaches a predetermined value, or when the outgoing hot water amount does not reach the target outgoing hot water amount.

[0062]

Further, in the heat pump apparatus according to Embodiment 1, the controller 200 is capable of executing the fifth operation mode (the hot water supply and heat storage mode, for example). In the fifth operation mode, the first compressor 1 is operated and the second compressor 7 is stopped, and the heat storage circuit 110 is controlled to circulate the first fluid in the second circulation circuit 112, and the water circuit 120 is controlled to allow the water delivered by the pump 12 to flow out through the first heat exchanger 2 and the fifth heat exchanger 8, and allow a part of the water passed through the fifth heat exchanger 8 to flow into the third circuit 123.

[0063]

Further, in the heat pump apparatus according to Embodiment 1, the controller 200 causes the heat pump apparatus to operate in the fifth operation mode when the remaining heat storage amount of the heat storage tank 10 is insufficient, or when a shortage of the remaining heat storage amount of the heat storage tank 10 is expected. [0064]

Further, in the heat pump apparatus according to Embodiment 1, the controller 200 is capable of executing the sixth operation mode (the heat retention and heat storage mode, for example). In the sixth operation mode, the first compressor 1 and the second compressor 7 are operated, and the heat storage circuit 110 is controlled to circulate the first fluid in the second circulation circuit 112, and the water circuit 120 is controlled to allow the water delivered by the pump 12 to flow out through the second circuit 122 and the fifth heat exchanger 8, and allow a part of the water passing through the fifth heat exchanger 8 to flow into the third circuit 123.

[0065]

Further, in the heat pump apparatus according to Embodiment 1, the controller 200 causes the heat pump apparatus to operate in the sixth operation mode when the incoming water temperature is equal to or higher than a predetermined temperature, or when the difference between the incoming water temperature and the target outgoing hot water temperature is equal to or less than a predetermined value.

[0066]

Further, in the heat pump apparatus according to Embodiment 1, the controller

200 causes the heat pump apparatus to operate in the sixth operation mode when the remaining heat storage amount of the heat storage tank 10 is insufficient, or when a shortage of the remaining heat storage amount of the heat storage tank 10 is expected. [0067]

Further, in the heat pump apparatus according to Embodiment 1, the controller

200 is capable of executing the seventh operation mode (the rapid start mode, for example) when starting at least one of the first compressor 1 and the second compressor 7. In the seventh operation mode, the heat storage circuit 110 is controlled to circulate the first fluid in the first circulation circuit 111.

[0068]

Further, in the heat pump apparatus according to Embodiment 1, the first fluid is the heat medium that exchanges heat with the heat storage material in the heat storage tank 10.

[0069]

Further, in the heat pump apparatus according to Embodiment 1, the first refrigerant operates at a pressure equal to or higher than the critical pressure thereof in an operating state in which at least the first compressor 1 operates and the second compressor 7 is stopped.

[0070]

Further, in the heat pump apparatus according to Embodiment 1, the first refrigerant contains CO2 at least as a component thereof.

[0071]

Further, in the heat pump apparatus according to Embodiment 1, the second refrigerant operates at a pressure equal to or lower than the critical pressure thereof. [0072]

Further, in the heat pump apparatus according to Embodiment 1, an operating pressure of the second refrigerant is lower than an operating pressure of the first refrigerant.

[0073]

Embodiment 2

A heat pump apparatus according to Embodiment 2 of the present invention will be described. In Embodiment 2, a latent heat storage material having a melting point higher than 0 degrees Celsius is used as the heat storage material sealed in the heat storage tank 10. For example, if the heat storage material is used as the heat source in the capacity enhancement mode, the solidification temperature is kept constant until the entire heat storage material is solidified. Accordingly, it is possible to maintain constant performance without a reduction in the evaporating temperature in the first refrigerant circuit 101.

[0074]

Embodiment 3

A heat pump apparatus according to Embodiment 3 of the present invention will be described. In Embodiment 3, a fluid heat storage material is used as the heat storage material. The fluid heat storage material per se is used as the first fluid circulating in the heat storage circuit 110. It is thereby possible to flow the heat storage material with the pump 11.

[0075]

Embodiment 4

A heat pump apparatus according to Embodiment 4 of the present invention will be described. In Embodiment 4, a capsular heat storage material is used as the heat storage material. Fig. 9 is a diagram illustrating a schematic structure of the capsular heat storage material used in the heat pump apparatus according to Embodiment 4. As illustrated in Fig. 9, the capsular heat storage material includes a capsule 131 (a microcapsule, for example) containing a heat storage material 130 (a latent heat storage material, for example). In Embodiment 4, liquid containing a plurality of capsules 131 each containing the heat storage material 130 and dispersed in the liquid is used as the first fluid circulating in the heat storage circuit 110.

[0076]

The capsular heat storage material is not treated as a hazardous material. According to Embodiment 4, therefore, it is possible to improve the safety of the heat pump apparatus. Further, the heat storage material is covered by a capsule, and thus does not stack on a cooling surface even when solidified. Therefore, thermal resistance is unlikely to increase, making it possible to maintain high heat transfer performance.

[0077]

Embodiment 5

A heat pump apparatus according to Embodiment 5 of the present invention will be described. The first circuit 121 of Embodiment 5 is connected to a hot water storage tank (not illustrated) at a part on a downstream side of the branching part (the flow switching device 15) at which the third circuit 123 branches from the first circuit 121. The hot water storage tank may be disposed as a part of the heat pump apparatus, or may be disposed separately from the heat pump apparatus. The hot water storage tank has a size allowing the hot water storage tank to supply a predetermined amount of heat to the load during a time from the start of the heat pump apparatus until the outgoing hot water temperature reaches a predetermined outgoing hot water temperature. The heat storage capacity of the hot water storage tank is less than the heat storage capacity of the heat storage tank 10. In Embodiment 5, hot water is discharged from the hot water storage tank during the time from the start of the heat pump apparatus until the outgoing hot water temperature reaches the predetermined outgoing hot water temperature or the discharge pressure reaches a predetermined discharge pressure. According to Embodiment 5, it is possible to obtain the predetermined outgoing hot water temperature faster than in the rapid start mode. [0078]

Embodiment 6

A heat pump apparatus according to Embodiment 6 of the present invention will be described. Fig. 10 is a circuit diagram illustrating a schematic circuit configuration of the heat pump apparatus according to Embodiment 6. As illustrated in Fig. 10, the first refrigerant circuit 101 includes a bypass 20 as a defrosting circuit that defrosts the third heat exchanger 5. The bypass 20 branches from the first refrigerant circuit 101 at a part between the first compressor 1 and the first heat exchanger 2, and is connected to the first refrigerant circuit 101 at a part between the first expansion valve 4 and the third heat exchanger 5. The bypass 20 is equipped with a bypass valve 21 that is opened in the defrosting operation.

[0079]

In the defrosting operation, the first compressor 1 and the pump 11 are operated, and the second compressor 7 and the pump 12 are stopped. The first expansion valve 4 is set to the minimum opening degree. The bypass valve 21 is opened. The flow switching device 16 is set to circulate the first fluid in the first circulation circuit 111. The flow switching device 13 is set to be closed on the side of the inlet 120a. Thereby, hot gas flows through the third heat exchanger 5, and frost formed on the third heat exchanger 5 melts. The refrigerant condensed in the third heat exchanger 5 evaporates in the fourth heat exchanger 6 by using the heat storage material as the heat source. Therefore, it is possible to suppress liquid backflow into the first compressor 1, and thus to improve the reliability of the heat pump apparatus. Further, with the heat storage material used as the heat source, it is possible to reduce a defrosting time. Further, the defrosting is performed with the amount of heat stored with a high COP, therefore making it possible to achieve high operation efficiency. [0080]

Embodiment 7

A heat pump apparatus according to Embodiment 7 of the present invention will be described. Fig. 11 is a circuit diagram illustrating a schematic circuit configuration of the heat pump apparatus according to Embodiment 7. As illustrated in Fig. 11, a third expansion valve 22 is disposed between the third heat exchanger 5 and the fourth heat exchanger 6 in the first refrigerant circuit 101. Embodiment 7 is similar to Embodiment 6 in the other configurations.

[0081]

In the defrosting operation, in addition to an operation similar to that of Embodiment 6, the third expansion valve 22 is set to a predetermined opening degree or controlled such that a degree of suction superheat, a discharge temperature, or a degree of discharge superheat of the first compressor 1 becomes a target value thereof. Thereby, the discharge pressure of the first compressor 1 is increased, and the temperature of the refrigerant flowing into the third heat exchanger 5 is increased. Accordingly, it is possible to efficiently defrost the third heat exchanger 5.

[0082] Embodiment 8

A heat pump apparatus according to Embodiment 8 of the present invention will be described. In Embodiment 8, the controller 200 estimates the remaining heat storage amount in the heat storage tank 10 based on the amount of heat of the hot water discharged from the heat pump apparatus or the amount of heat stored in the heat storage tank 10. For example, the controller 200 estimates the remaining heat storage amount in the heat storage tank 10 based on the flow rate of the first fluid in the heat storage circuit 110 and an inlet temperature and an outlet temperature of the heat storage tank 10. Alternatively, the controller 200 may calculate the remaining heat storage amount in the heat storage tank 10 based on the temperature distribution in the heat storage tank 10. Based on the estimated or calculated remaining heat storage amount, the controller 200 causes the heat pump apparatus to operate in the heat storage operation (the operation in the heat storage mode, the hot water supply and heat storage mode, or the heat retention and heat storage mode, for example) to prevent a shortage of the heat storage amount. It is thereby possible to prevent a shortage of the heat storage amount, and thus to constantly respond to the capacity enhancement mode or the rapid start mode.

[0083] Embodiment 9

A heat pump apparatus according to Embodiment 9 of the present invention will be described. In Embodiment 9, the controller 200 learns a necessary heat storage amount from the daily operating state of the heat pump apparatus, and causes the heat pump apparatus to operate in the heat storage operation to prevent a shortage of the heat storage amount. It is thereby possible to prevent a shortage of the heat storage amount, and thus to constantly respond to the capacity enhancement mode or the rapid start mode.

[0084]

Embodiment 10

A heat pump apparatus according to Embodiment 10 of the present invention will be described. Fig. 12 is a schematic diagram illustrating a physical configuration of the heat pump apparatus according to Embodiment 10. As illustrated in Fig. 12, the heat pump apparatus includes a first casing 105 that stores at least the first refrigerant circuit 101 and a second casing 106 that stores at least the second refrigerant circuit 102. The first casing 105 and the second casing 106 are stacked on each other, with the first casing 105 stacked on an upper part of the second casing 106.

[0085]

The first refrigerant circuit 101 includes the third heat exchanger 5 being an airrefrigerant heat exchanger and an air-sending fan 107 that sends air to the third heat exchanger 5. The third heat exchanger 5 is disposed on a side part of the first casing 105, and the air-sending fan 107 is disposed in a top part of the first casing 105. As represented by arrows in Fig. 12, the air sent by the air-sending fan 107 flows from the side part of the first casing 105 toward the top part of the first casing 105. According to Embodiment 10, it is possible to prevent an airflow in the first casing 105 from being hindered by the second casing 106, and to reduce the installation area of the heat pump apparatus.

[0086]

Embodiments 1 to 10 described above may be implemented in combination with each other.

Reference Signs List [0087] first compressor 2 first heat exchanger 3 second heat exchanger 4 first expansion valve 5 third heat exchanger 6 fourth heat exchanger 7 second compressor 8 fifth heat exchanger 9 second expansion valve 10 heat storage tank 11,12 pump 13,14,15,16 flow switching device 17 sixth heat exchanger bypass 21 bypass valve 22 third expansion valve 101 first refrigerant circuit 102 second refrigerant circuit 103 cascade heat pump circuit 105 first casing 106 second casing 107 air-sending fan 110 heat storage circuit 111 first circulation circuit 112 second circulation circuit 120 water circuit 120a inlet

120b outlet 121 first circuit 122 second circuit 123 third circuit 130 heat storage material 131 capsule 200 controller

Claims

CLAIMS [Claim 1]

A heat pump apparatus comprising:

a first refrigerant circuit circulating a first refrigerant;

a second refrigerant circuit circulating a second refrigerant;

a heat storage circuit circulating a first fluid; and a water circuit flowing water, the first refrigerant circuit being formed by sequentially connecting, by piping, a first compressor, a first heat exchanger configured to exchange heat between the first refrigerant and the water, a second heat exchanger configured to exchange heat between the first refrigerant and the second refrigerant, a first expansion valve, a third heat exchanger configured to exchange heat between the first refrigerant and a second fluid, and a fourth heat exchanger configured to exchange heat between the first refrigerant and the first fluid, the second refrigerant circuit being formed by sequentially connecting, by piping, a second compressor, a fifth heat exchanger configured to exchange heat between the second refrigerant and water, a second expansion valve, and the second heat exchanger, the heat storage circuit including a heat storage tank, a first circulation circuit circulating the first fluid between the heat storage tank and the fourth heat exchanger, and a second circulation circuit circulating the first fluid between the heat storage tank and a sixth heat exchanger configured to exchange heat between the first fluid and water, the water circuit including a first circuit connecting, a pump configured to deliver water, the first heat exchanger, and the fifth heat exchanger, a second circuit branched from the first circuit at a part between the pump and the first heat exchanger, and connected to the first circuit at a part between the first heat exchanger and the fifth heat exchanger, and a third circuit branched from the first circuit at a part on a downstream side of the fifth heat exchanger, extending through the sixth heat exchanger, and connected to the first circuit at a part on an upstream side of the pump.
[Claim 2]

The heat pump apparatus of claim 1, further comprising a controller configured to control the first refrigerant circuit, the second refrigerant circuit, the heat storage circuit, and the water circuit.
[Claim 3]

The heat pump apparatus of claim 2, wherein the controller is capable of executing a first operation mode in which the first compressor is operated and the second compressor is stopped, and the water circuit is controlled to allow the water delivered by the pump to flow out through the first heat exchanger and the fifth heat exchanger.
[Claim 4]

The heat pump apparatus of claim 2 or 3, wherein the controller is capable of executing a second operation mode in which the first compressor is operated and the second compressor is operated, and the water circuit is controlled to allow the water delivered by the pump to flow out through the second circuit and the fifth heat exchanger.
[Claim 5]

The heat pump apparatus of claim 4, wherein when a water temperature of incoming water is equal to or higher than a predetermined temperature, or when a difference between the water temperature of the incoming water and a target outgoing hot water temperature is equal to or less than a predetermined value, the controller causes the heat pump apparatus to operate in the second operation mode.
[Claim 6]

The heat pump apparatus of one of claims 2 to 5, wherein the controller is capable of executing a third operation mode in which the first compressor and the second compressor are operated, and the heat storage circuit is controlled to circulate the first fluid in the second circulation circuit, and the water circuit is controlled to allow the water delivered by the pump to circulate in the second circuit, the fifth heat exchanger, and the third circuit.
[Claim 7]

The heat pump apparatus of claim 6, wherein when a remaining heat storage amount of the heat storage tank is insufficient, or when a shortage of the remaining heat storage amount of the heat storage tank is expected, the controller causes the heat pump apparatus to operate in the third operation mode.
[Claim 8]

The heat pump apparatus of one of claims 2 to 7, wherein the controller is capable of executing a fourth operation mode in which the first compressor and the second compressor are operated, and the heat storage circuit is controlled to circulate the first fluid in the first circulation circuit, and the water circuit is controlled to allow the water delivered by the pump to flow out through the first heat exchanger and the fifth heat exchanger.
[Claim 9]

The heat pump apparatus of claim 8, wherein, when a frequency of the first compressor reaches an upper limit thereof, or when an outgoing hot water temperature does not reach a target outgoing hot water temperature even after a high-pressure-side pressure of the first refrigerant circuit reaches a predetermined value, or when an outgoing hot water amount does not reach a target outgoing hot water amount, the controller causes the heat pump apparatus to operate in the fourth operation mode.
[Claim 10]

The heat pump apparatus of one of claims 2 to 9, wherein the controller is capable of executing a fifth operation mode in which the first compressor is operated and the second compressor is stopped, and the heat storage circuit is controlled to circulate the first fluid in the second circulation circuit, and the water circuit is controlled to allow the water delivered by the pump to flow out through the first heat exchanger and the fifth heat exchanger, and allow a part of the water passed through the fifth heat exchanger to flow into the third circuit.
[Claim 11]

The heat pump apparatus of claim 10, wherein when a remaining heat storage amount of the heat storage tank is insufficient, or when a shortage of the remaining heat storage amount of the heat storage tank is expected, the controller causes the heat pump apparatus to operate in the fifth operation mode.
[Claim 12]

The heat pump apparatus of one of claims 2 to 11, wherein the controller is capable of executing a sixth operation mode in which the first compressor and the second compressor are operated, and the heat storage circuit is controlled to circulate the first fluid in the second circulation circuit, and the water circuit is controlled to allow the water delivered by the pump to flow out through the second circuit and the fifth heat exchanger, and allow a part of the water passed through the fifth heat exchanger to flow into the third circuit.
[Claim 13]

The heat pump apparatus of claim 12, wherein when an incoming water temperature is equal to or higher than a predetermined temperature, or when a difference between the incoming water temperature and a target outgoing hot water temperature is equal to or less than a predetermined value, the controller causes the heat pump apparatus to operate in the sixth operation mode.
[Claim 14]

The heat pump apparatus of claim 12, wherein when a remaining heat storage amount of the heat storage tank is insufficient, or when a shortage of the remaining heat storage amount of the heat storage tank is expected, the controller causes the heat pump apparatus to operate in the sixth operation mode.
[Claim 15]

The heat pump apparatus of one of claims 2 to 14, wherein when starting at least one of the first compressor and the second compressor, the controller is capable of executing a seventh operation mode in which the heat storage circuit is controlled to circulate the first fluid in the first circulation circuit.
[Claim 16]

The heat pump apparatus of one of claims 2 to 15, wherein the controller calculates a remaining heat storage amount of the heat storage tank based on an amount of heat of outgoing hot water or an amount of heat stored in the heat storage tank.
[Claim 17]

The heat pump apparatus of one of claims 2 to 15, wherein the controller calculates a remaining heat storage amount of the heat storage tank based on a temperature distribution in the heat storage tank.
[Claim 18]

The heat pump apparatus of one of claims 1 to 17, further comprising a bypass branched from the first refrigerant circuit at a part between the first compressor and the first heat exchanger, connected to the first refrigerant circuit at a part between the first expansion valve and the third heat exchanger, and including a bypass valve.
[Claim 19]

The heat pump apparatus of claim 18, wherein the first refrigerant circuit includes a third expansion valve provided between the third heat exchanger and the fourth heat exchanger.
[Claim 20]

The heat pump apparatus of one of claims 1 to 19, wherein the first fluid is a fluid heat storage material.
[Claim 21]

The heat pump apparatus of one of claims 1 to 20, wherein the first fluid is liquid containing a plurality of capsules, each of which contains a heat storage material and which are dispersed in the liquid.
[Claim 22]

The heat pump apparatus of one of claims 1 to 19, wherein the first fluid is a heat medium that exchanges heat with a heat storage material in the heat storage tank. [Claim 23]

The heat pump apparatus of one of claims 20 to 22, wherein the heat storage material is a latent heat storage material.

[Claim 24]

The heat pump apparatus of one of claims 1 to 23, wherein the first refrigerant operates at a pressure equal to or higher than a critical pressure thereof in an operating state in which at least the first compressor operates and the second compressor is stopped.

[Claim 25]

The heat pump apparatus of one of claims 1 to 24, wherein the first refrigerant contains CO2 at least as a component thereof.

[Claim 26]

The heat pump apparatus of one of claims 1 to 25, wherein the second refrigerant operates at a pressure equal to or lower than a critical pressure thereof.

[Claim 27]

The heat pump apparatus of one of claims 1 to 26, wherein an operating pressure of the second refrigerant is lower than an operating pressure of the first refrigerant. [Claim 28]

The heat pump apparatus of one of claims 1 to 27, wherein the first circuit is connected to a hot water storage tank at a part on a downstream side of a branching part at which the third circuit branches from the first circuit.

[Claim 29]

The heat pump apparatus of claim 28, wherein a heat storage capacity of the hot water storage tank is less than a heat storage capacity of the heat storage tank. [Claim 30]

The heat pump apparatus of one of claims 1 to 29, further comprising:

a first casing storing at least the first refrigerant circuit; and a second casing storing at least the second refrigerant circuit, the first casing being stacked on an upper part of the second casing.