EP3358273B1

EP3358273B1 - Heat pump utilization equipment

Info

Publication number: EP3358273B1
Application number: EP16906499.5A
Authority: EP
Inventors: Yasuhiro Suzuki; Kazutaka Suzuki; Hirokazu Minamisako; Taro Hattori
Original assignee: Mitsubishi Electric Corp
Current assignee: Mitsubishi Electric Corp
Priority date: 2016-12-21
Filing date: 2016-12-21
Publication date: 2019-08-14
Anticipated expiration: 2036-12-21
Also published as: EP3358273A4; JP6664516B2; CN110073152A; WO2018116404A1; US20190301750A1; JPWO2018116404A1; EP3358273A1; CN110073152B

Description

Technical Field

The present invention relates to a heat pump use apparatus including a refrigerant circuit and a heat medium circuit.

Background Art

In Patent Literature 1, there is described an outdoor unit for a heat pump cycle apparatus using flammable refrigerant. The outdoor unit includes a refrigerant circuit including a compressor, an air heat exchanger, an expansion device, and a water heat exchanger, which are connected to one another through pipes, and a pressure relief valve configured to prevent excessive rise of water pressure in a water circuit configured to supply water heated in the water heat exchanger. With this configuration, even when a partition wall configured to partition the refrigerant circuit and the water circuit is broken in the water heat exchanger so that the flammable refrigerant is mixed into the water circuit, the flammable refrigerant can be discharged to the outside through the pressure relief valve.
In document WO 2016/047278 A1 a load unit is described including a water circuit chamber configured to accommodate at least a part of a water circuit configured to allow water to flow therethrough, a fan, an air inlet formed at a height positioned different from that of the air inlet and configured to suck indoor air therethrough, an air outlet configured to blow indoors the air sucked through the air inlet, and an air passage formed between the air inlet and the air outlet so as to be isolated from the water circuit chamber. A load-side heat exchanger is provided in the air passage. Document WO 2016/047278 A1 discloses a heat pump use apparatus according to the preamble of claim 1.

Citation List

Patent Literature

Patent Literature 1: Japanese Unexamined Patent Application Publication No. 2013-167398

Summary of Invention

Technical Problem

In a heat pump use apparatus such as the heat pump cycle apparatus, in general, a pressure relief valve of the water circuit is provided in an indoor unit. There are various combinations of the outdoor unit and the indoor unit in the heat pump use apparatus. An outdoor unit and an indoor unit, which are manufactured by the same manufacturer, may be combined. Further, an outdoor unit and an indoor unit, which are manufactured by different manufacturers, may be combined. Therefore, the outdoor unit described in Patent Literature 1 may be combined with the indoor unit including the pressure relief valve.
However, in Patent Literature 1, when the refrigerant is leaked to the water circuit, the refrigerant mixed into water inside the water circuit may be discharged not only through the pressure relief valve provided in the outdoor unit, but also through the pressure relief valve provided in the indoor unit. Therefore, there is a problem in that the refrigerant may be leaked to a room through the water circuit.
The present invention has been made to solve the problem described above, and has an object to provide a heat pump use apparatus capable of preventing leakage of refrigerant to a room.

Solution to Problem

According to one embodiment of the present invention, a heat pump use apparatus according to claim 1 is provided. The apparatus includes: a refrigerant circuit configured to circulate refrigerant; a heat medium circuit configured to allow a heat medium to flow therethrough; and a heat exchanger configured to exchange heat between the refrigerant and the heat medium. The heat medium circuit includes a main passage extending through the heat exchanger. The main passage includes: a branching portion to which a plurality of branch passages branched from the main passage are connected, the branching portion being provided at a downstream end of the main passage; and a joining portion at which the plurality of branch passages are connected to each other to be joined to the main passage, the joining portion being provided at an upstream end of the main passage. The heat pump use apparatus further includes a pressure protection device and a refrigerant leakage detection device that are connected to the main passage. The pressure protection device is connected to the main passage at a connecting portion located between the heat exchanger and one of the branching portion and the joining portion. The main passage includes a first interruption device configured to be able to interrupt a flow from the heat exchanger to the connecting portion. The first interruption device is provided between the heat exchanger and the connecting portion. The main passage includes a second interruption device configured to be able to interrupt a flow from the heat exchanger to an other of the branching portion and the joining portion. The second interruption device is provided between the heat exchanger and the other of the branching portion and the joining portion.

Advantageous Effects of Invention

According to one embodiment of the present invention, even when the refrigerant is leaked to the heat medium circuit, a flow of the refrigerant mixed into the heat medium can be interrupted by the interruption device. Therefore, the leakage of the refrigerant from the pressure protection device to the room can be prevented.

Brief Description of Drawings

Fig. 1 is a circuit diagram for illustrating a schematic configuration of a heat pump use apparatus according to Embodiment 1 of the present invention.
Fig. 2 is a circuit diagram for illustrating a schematic configuration of a heat pump use apparatus of a modification example of Embodiment 1 of the present invention.
Fig. 3 is an explanatory view for illustrating examples of an arrangement position of a refrigerant leakage detection device 98 in the heat pump use apparatus according to Embodiment 1 of the present invention.
Fig. 4 is an explanatory view for illustrating an example, not belonging to the present invention, of the arrangement position of the refrigerant leakage detection device 98 in the heat pump use apparatus.
Fig. 5 is an explanatory view for illustrating the example of the arrangement position of the refrigerant leakage detection device 98 in the heat pump use apparatus according to Embodiment 1 of the present invention.
Fig. 6 is an explanatory view for illustrating the example of the arrangement position of the refrigerant leakage detection device 98 in the heat pump use apparatus according to Embodiment 1 of the present invention.
Fig. 7 is a circuit diagram for illustrating a schematic configuration of a heat pump use apparatus according to Embodiment 2 of the present invention.

Description of Embodiments

Embodiment

1

A heat pump use apparatus according to Embodiment 1 of the present invention is described. Fig. 1 is a circuit diagram for illustrating a schematic configuration of the heat pump use apparatus according to Embodiment 1. In Embodiment 1, a heat pump water heater 1000 is exemplified as the heat pump use apparatus. In the drawings including Fig. 1 referred to below, a dimensional relationship of components and a shape of each of the components may be different from those of actual components.
As illustrated in Fig. 1, the heat pump water heater 1000 includes a refrigerant circuit 110 configured to circulate refrigerant and a water circuit 210 configured to allow water to flow therethrough. Further, the heat pump water heater 1000 includes an outdoor unit 100 installed outside, for example, outdoor space, and an indoor unit 200 installed indoor space. The indoor unit 200 is installed, for example, in a kitchen, a bathroom, or a laundry room, or, further, in a storage space such as a closet inside a building.
The refrigerant circuit 110 includes a compressor 3, a refrigerant flow switching device 4, a load-side heat exchanger 2, a first pressure reducing device 6, an intermediate pressure receiver 5, a second pressure reducing device 7, and a heat source-side heat exchanger 1, which are annularly connected in order through refrigerant pipes. Through use of the refrigerant circuit 110, the heat pump water heater 1000 is capable of a normal operation, for example, heater water heating operation, for heating water flowing through the water circuit 210 and a defrosting operation for circulating the refrigerant reversely to the normal operation to defrost the heat source-side heat exchanger 1.
The compressor 3 is a fluid machine configured to compress sucked low-pressure refrigerant and to discharge the low-pressure refrigerant as high-pressure refrigerant. The compressor 3 of Embodiment 1 includes an inverter device, and is configured to change a driving frequency freely selectively, to thereby be able to change a capacity, that is, an amount of the refrigerant to be sent per unit time.
The refrigerant flow switching device 4 is configured to switch a flow direction of the refrigerant inside the refrigerant circuit 110 between the normal operation and the defrosting operation. As the refrigerant flow switching device 4, for example, a four-way valve is used.
The load-side heat exchanger 2 is a water-refrigerant heat exchanger configured to exchange heat between the refrigerant flowing through the refrigerant circuit 110 and the water flowing through the water circuit 210. As the load-side heat exchanger 2, for example, a plate heat exchanger is used. The load-side heat exchanger 2 includes a refrigerant flow passage for allowing refrigerant to flow therethrough as a part of the refrigerant circuit 110, a water flow passage for allowing water to flow therethrough as a part of the water circuit 210, and a thin plate-like partition wall configured to partition the refrigerant flow passage and the water flow passage. The load-side heat exchanger 2 functions as a condenser (radiator) configured to heat water during the normal operation, and functions as an evaporator (heat absorber) during the defrosting operation.
The first pressure reducing device 6 is configured to regulate a flow rate of refrigerant, for example, regulate a pressure of the refrigerant flowing into the load-side heat exchanger 2. The intermediate pressure receiver 5 is located between the first pressure reducing device 6 and the second pressure reducing device 7 in the refrigerant circuit 110, and is configured to accumulate an excess of the refrigerant. A suction pipe 11 connected to a suction side of the compressor 3 passes through the inside of the intermediate pressure receiver 5. In the intermediate pressure receiver 5, heat is exchanged between the refrigerant passing through the suction pipe 11 and the refrigerant inside the intermediate pressure receiver 5. Therefore, the intermediate pressure receiver 5 has a function as an internal heat exchanger for the refrigerant circuit 110. The second pressure reducing device 7 is configured to regulate the pressure of the refrigerant by regulating the flow rate of the refrigerant. The first pressure reducing device 6 and the second pressure reducing device 7 of Embodiment 1 are each an electronic expansion valve capable of changing an opening degree based on an instruction from a controller 101 described later.
The heat source-side heat exchanger 1 is an air-refrigerant heat exchanger configured to exchange heat between the refrigerant flowing through the refrigerant circuit 110 and outdoor air sent by an outdoor air-sending fan or other devices (not shown). The heat source-side heat exchanger 1 functions as an evaporator (heat absorber) during the normal operation, and functions as a condenser (radiator) during the defrosting operation.
Examples of refrigerants used as the refrigerants to be circulated through the refrigerant circuit 110 include a slightly flammable refrigerant such as R1234yf or R1234ze(E) and a strongly flammable refrigerant such as R290 or R1270. Those refrigerants may be each used as a single refrigerant, or may be used as a mixed refrigerant obtained by mixing two or more kinds of the refrigerants with each other. In the following description, the refrigerant having flammability equal to or higher than a slightly flammable level (for example, 2L or higher in category of ASHRAE34) may be referred to as "refrigerant having flammability" or "flammable refrigerant". Further, as the refrigerant to be circulated through the refrigerant circuit 110, a nonflammable refrigerant such as R407C or R410A having nonflammability (for example, 1 in the category of ASHRAE34) can be used. Those refrigerants have a density larger than that of air under an atmospheric pressure (for example, with a temperature being a room temperature (25 degrees Celsius)). Further, as the refrigerant to be circulated through the refrigerant circuit 110, a refrigerant having toxicity such as R717 (ammonia) may also be used.
The outdoor unit 100 accommodates the refrigerant circuit 110 including the compressor 3, the refrigerant flow switching device 4, the load-side heat exchanger 2, the first pressure reducing device 6, the intermediate pressure receiver 5, the second pressure reducing device 7, and the heat source-side heat exchanger 1.
Further, the outdoor unit 100 includes the controller 101 configured to mainly control an operation of the refrigerant circuit 110, for example, the compressor 3, the refrigerant flow switching device 4, the first pressure reducing device 6, the second pressure reducing device 7, and the outdoor air-sending fan (not shown). The controller 101 includes a microcomputer including a CPU, a ROM, a RAM, and an I/O port. The controller 101 can communicate with a controller 201 and an operation unit 202, which are described later, through a control line 102.
Next, an example of the operation of the refrigerant circuit 110 is described. In Fig. 1, the flow direction of the refrigerant in the refrigerant circuit 110 during the normal operation is indicated by solid arrows. The refrigerant circuit 110 is configured so that, during the normal operation, the refrigerant flow passage is switched by the refrigerant flow switching device 4 as indicated by the solid arrows to cause the high-temperature and high-pressure refrigerant to flow into the load-side heat exchanger 2.
The high-temperature and high-pressure gas refrigerant discharged from the compressor 3 passes through the refrigerant flow switching device 4, and flows into the refrigerant flow passage of the load-side heat exchanger 2. During the normal operation, the load-side heat exchanger 2 functions as a condenser. That is, in the load-side heat exchanger 2, heat is exchanged between the refrigerant flowing through the refrigerant flow passage and the water flowing through the water flow passage of the load-side heat exchanger 2, and the heat of condensation of the refrigerant is transferred to the water. With this operation, the refrigerant flowing through the refrigerant flow passage of the load-side heat exchanger 2 is condensed to become a high-pressure liquid refrigerant. Further, the water flowing through the water flow passage of the load-side heat exchanger 2 is heated by transfer heat from the refrigerant.
The high-pressure liquid refrigerant condensed by the load-side heat exchanger 2 flows into the first pressure reducing device 6, and has the pressure reduced slightly to become a two-phase refrigerant. The two-phase refrigerant flows into the intermediate pressure receiver 5, and is cooled by the heat exchange with a low-pressure gas refrigerant flowing through the suction pipe 11 to become a liquid refrigerant. The liquid refrigerant flows into the second pressure reducing device 7, and has the pressure reduced to become a low-pressure two-phase refrigerant. The low-pressure two-phase refrigerant flows into the heat source-side heat exchanger 1. During the normal operation, the heat source-side heat exchanger 1 functions as an evaporator. That is, in the heat source-side heat exchanger 1, heat is exchanged between the refrigerant circulated through the inside and the outdoor air sent by the outdoor air-sending fan, and the heat of evaporation of the refrigerant is received from the outdoor air. With this operation, the refrigerant that has flowed into the heat source-side heat exchanger 1 evaporates to become the low-pressure gas refrigerant. The low-pressure gas refrigerant passes through the refrigerant flow switching device 4, and flows into the suction pipe 11. The low-pressure gas refrigerant that has flowed into the suction pipe 11 is heated by the heat exchange with the refrigerant inside the intermediate pressure receiver 5, and is sucked by the compressor 3. The refrigerant sucked by the compressor 3 is compressed to become the high-temperature and high-pressure gas refrigerant. In the normal operation, the above-mentioned cycle is repeated.
Next, an example of the operation during the defrosting operation is described. In Fig. 1, the flow direction of the refrigerant in the refrigerant circuit 110 during the defrosting operation is indicated by the broken arrows. The refrigerant circuit 110 is configured so that, during the defrosting operation, the refrigerant flow passage is switched by the refrigerant flow switching device 4 as indicated by the broken arrows to cause the high-temperature and high-pressure refrigerant to flow into the heat source-side heat exchanger 1.
The high-temperature and high-pressure gas refrigerant discharged from the compressor 3 passes through the refrigerant flow switching device 4, and flows into the heat source-side heat exchanger 1. During the defrosting operation, the heat source-side heat exchanger 1 functions as a condenser. That is, in the heat source-side heat exchanger 1, the heat of condensation of the refrigerant circulated through the inside is transferred to frost adhering to a surface of the heat source-side heat exchanger 1. With this operation, the refrigerant circulated through the inside of the heat source-side heat exchanger 1 is condensed to become the high-pressure liquid refrigerant. Further, the frost adhering to the surface of the heat source-side heat exchanger 1 is melted by transfer heat from the refrigerant.
The high-pressure liquid refrigerant condensed by the heat source-side heat exchanger 1 passes through the second pressure reducing device 7, the intermediate pressure receiver 5, and the first pressure reducing device 6 to become the low-pressure two-phase refrigerant, and flows into the refrigerant flow passage of the load-side heat exchanger 2. The load-side heat exchanger 2 functions as an evaporator during the defrosting operation. That is, in the load-side heat exchanger 2, heat is exchanged between the refrigerant flowing through the refrigerant flow passage and the water flowing through the water flow passage, and heat of evaporation of the refrigerant is received from the water. With this operation, the refrigerant flowing through the refrigerant flow passage of the load-side heat exchanger 2 evaporates to become the low-pressure gas refrigerant. The gas refrigerant passes through the refrigerant flow switching device 4 and the suction pipe 11, and is sucked by the compressor 3. The refrigerant sucked by the compressor 3 is compressed to become the high-temperature and high-pressure gas refrigerant. In the defrosting operation, the above-mentioned cycle is continuously repeated.
Next, the water circuit 210 is described. The water circuit 210 of Embodiment 1 is a closed circuit configured to circulate water. In Fig. 1, the flow direction of the water is indicated by outline arrows. The water circuit 210 is constructed by a water circuit on the outdoor unit 100 side and a water circuit on the indoor unit 200 side, which are connected to each other. The water circuit 210 includes a main passage 220, a branch passage 221 constructing a hot water circuit, and a branch passage 222 constructing a part of a heater circuit. The main passage 220 constructs a part of the closed circuit. The branch passages 221 and 222 are each connected to the main passage 220 so as to be branched from the main passage 220. The branch passages 221 and 222 are provided in parallel to each other. The branch passage 221 constructs the closed circuit together with the main passage 220. The branch passage 222 constructs the closed circuit together with the main passage 220, a heater 300 connected to the branch passage 222, and other units. The heater 300 is provided indoor space separately from the indoor unit 200. As the heater 300, a radiator or a floor heater is used, for example.
In Embodiment 1, water is taken as an example of a heat medium circulated through the water circuit 210. However, as the heat medium, other liquid heat media such as brine may be used.
The main passage 220 includes a strainer 56, a flow switch 57, the load-side heat exchanger 2, a booster heater 54, and a pump 53, which are connected to one another through water pipes. A drain outlet 62 configured to drain water inside the water circuit 210 is formed in a halfway part of the water pipes that construct the water circuit 210. A downstream end of the main passage 220 is connected to an inflow port of a three-way valve 55 (example of a branching portion) having one inflow port and two outflow ports. At the three-way valve 55, the branch passages 221 and 222 are branched from the main passage 220. An upstream end of the main passage 220 is connected to a joining portion 230. At the joining portion 230, the branch passages 221 and 222 are joined to the main passage 220. The water circuit 210 extending from the joining portion 230 to the three-way valve 55 through the load-side heat exchanger 2 and other units corresponds to the main passage 220.
The load-side heat exchanger 2 of the main passage 220 is provided in the outdoor unit 100. Of the units of the main passage 220, units other than the load-side heat exchanger 2 are provided in the indoor unit 200. That is, the main passage 220 of the water circuit 210 is provided across the outdoor unit 100 and the indoor unit 200. A part of the main passage 220 is provided in the outdoor unit 100, and an other part of the main passage 220 is provided in the indoor unit 200. The outdoor unit 100 and the indoor unit 200 are connected to each other through two connecting pipes 211 and 212 constructing parts of the main passage 220.
The pump 53 is a device configured to apply pressure to the water inside the water circuit 210 to circulate the water through the inside of the water circuit 210. The booster heater 54 is a device configured to further heat the water inside the water circuit 210 when, for example, the outdoor unit 100 has insufficient heating capacity. The three-way valve 55 is a device configured to switch a flow of the water inside the water circuit 210. For example, the three-way valve 55 switches a destination to which the water inside the main passage 220 is to be circulated between the branch passage 221 side and the branch passage 222 side. The strainer 56 is a device configured to remove scale inside the water circuit 210. The flow switch 57 is a device configured to detect whether or not the flow rate of the water circulated through the inside of the water circuit 210 is equal to or larger than a fixed amount. A flow rate sensor may also be used instead of the flow switch 57.
A pressure relief valve 70 (example of a pressure protection device) is connected to the booster heater 54. That is, the booster heater 54 serves as a connecting portion for the pressure relief valve 70 (example of the pressure protection device). In the following, the connecting portion for the pressure relief valve 70 may be simply expressed as the "connecting portion". The pressure relief valve 70 is a protection device configured to prevent excessive rise of the pressure in the water circuit 210, which is caused by temperature change of water. The pressure relief valve 70 is configured to release water to the outside of the water circuit 210 based on pressure in the water circuit 210. For example, when the pressure in the water circuit 210 is increased to exceed a pressure control range of an expansion tank 52 described later, the pressure relief valve 70 is opened, and the water inside the water circuit 210 is released to the outside through the pressure relief valve 70. The pressure relief valve 70 is provided in the indoor unit 200. The pressure relief valve 70 is provided in the indoor unit 200 so as to protect the pressure in the water circuit 210 in the indoor unit 200.
One end of a pipe 72, which is a water flow passage branched from the main passage 220, is connected to a casing of the booster heater 54. The pressure relief valve 70 is mounted to an other end of the pipe 72. That is, the pressure relief valve 70 is connected to the booster heater 54 through the pipe 72. The booster heater 54 serves as the connecting portion for connecting the pressure relief valve 70 to the main passage 220. In the main passage 220, a water temperature becomes the highest in the booster heater 54. Therefore, the booster heater 54 is optimum as the connecting portion for connecting the pressure relief valve 70. Further, when the pressure relief valve 70 is connected to the branch passages 221 and 222, the pressure relief valve 70 needs to be provided for each of the branch passages 221 and 222. In Embodiment 1, the pressure relief valve 70 is connected to the main passage 220. Therefore, it is only necessary to provide one pressure relief valve 70.
A branching portion 72a is provided on a halfway part of the pipe 72. One end of a pipe 75 is connected to the branching portion 72a. The expansion tank 52 is connected to an other end of the pipe 75. That is, the expansion tank 52 is connected to the booster heater 54 through the pipes 75 and 72. The expansion tank 52 is a device configured to control the pressure change inside the water circuit 210, which is caused by temperature change of water, within a predetermined range.
An interruption device 77 is provided downstream of the load-side heat exchanger 2 as a first interruption device. The interruption device 77 is provided in the main passage 220 at a portion between the load-side heat exchanger 2 and the booster heater 54, that is, the connecting portion for connecting the pressure relief valve 70. As the interruption device 77, there may be used an on-off valve such as a solenoid valve, a flow control valve, or an electronic expansion valve. The interruption device 77 is in a closed state during the normal operation. When the interruption device 77 is in the closed state, the interruption device 77 interrupts a flow from the load-side heat exchanger 2 toward the booster heater 54. The interruption device 77 is controlled by the controller 201 described later. When the connecting portion for connecting the pressure relief valve 70 is provided between the load-side heat exchanger 2 and the joining portion 230, the interruption device 77 is provided as a second interruption device in the main passage 220 at a portion between the load-side heat exchanger 2 and the three-way valve 55 (branching portion).
An interruption device 78 is provided upstream of the load-side heat exchanger 2 as the second interruption device. The interruption device 78 is provided in the main passage 220 at a portion between the load-side heat exchanger 2 and the joining portion 230. As the interruption device 78, there may be used a check valve configured to allow a flow of water from the joining portion 230 to the load-side heat exchanger 2, and to interrupt a flow from the load-side heat exchanger 2 to the joining portion 230. Further, as the interruption device 78, there may also be used an on-off valve such as a solenoid valve, a flow control valve, or an electronic expansion valve. When the on-off valve is used as the interruption device 78, the interruption device 78 is controlled by the controller 201 described later, or is operated in association with the interruption device 77. When the connecting portion for connecting the pressure relief valve 70 is provided between the load-side heat exchanger 2 and the joining portion 230, the interruption device 78 is provided as the first interruption device in the main passage 220 at a portion between the load-side heat exchanger 2 and the connecting portion.
A refrigerant leakage detection device 98 is provided downstream of the interruption device 77. The refrigerant leakage detection device 98 is connected to the main passage 220 at a portion between the interruption device 77 and the booster heater 54 (connecting portion). The refrigerant leakage detection device 98 is a device configured to detect leakage of refrigerant from the refrigerant circuit 110 to the water circuit 210. When the refrigerant is leaked from the refrigerant circuit 110 to the water circuit 210, the pressure in the water circuit 210 rises. Therefore, the refrigerant leakage detection device 98 is capable of detecting the leakage of the refrigerant into the water circuit 210 based on the pressure in the water circuit 210, that is, a value of the pressure or temporal change of the pressure. As the refrigerant leakage detection device 98, for example, a pressure sensor or a pressure switch (high-pressure switch) configured to detect the pressure in the water circuit 210 is used. For example, the pressure switch may be an electric pressure switch or a mechanical pressure switch using a diaphragm. The refrigerant leakage detection device 98 is configured to output a detection signal to the controller 201.
In Embodiment 1, both of the interruption devices 77 and 78 and the refrigerant leakage detection device 98 are provided in the indoor unit 200. With this configuration, each of the interruption devices 77 and 78 and the refrigerant leakage detection device 98 can be connected to the controller 201 through a control line in the indoor unit 200. Thus, costs can be reduced. All of the interruption devices 77 and 78 and the refrigerant leakage detection device 98 may be provided in the outdoor unit 100. With this configuration, each of the interruption devices 77 and 78 and the refrigerant leakage detection device 98 can be connected to the controller 101 through a control line in the outdoor unit 100. Thus, costs can be reduced.
The branch passage 221 constructing the hot water circuit is provided in the indoor unit 200. An upstream end of the branch passage 221 is connected to one outflow port of the three-way valve 55. A downstream end of the branch passage 221 is connected to the joining portion 230. A coil 61 is provided in the branch passage 221. The coil 61 is built in a hot-water storage tank 51 configured to store water therein. The coil 61 is a heating unit configured to heat the water accumulated in the hot-water storage tank 51 through heat exchange with water (hot water) circulated through the branch passage 221 of the water circuit 210. Further, the hot-water storage tank 51 includes an immersion heater 60 built therein. The immersion heater 60 is a heating unit configured to further heat the water accumulated in the hot-water storage tank 51.
A sanitary circuit-side pipe 81a (for example, a hot water pipe), which is to be connected to, for example, a shower, is connected to an upper portion inside the hot-water storage tank 51. A sanitary circuit-side pipe 81b (for example, a makeup water pipe) is connected to a lower portion inside the hot-water storage tank 51. A drain outlet 63 configured to drain water in the hot-water storage tank 51 is formed in a lower portion of the hot-water storage tank 51. In order to prevent decrease in temperature of the water inside the hot-water storage tank 51 due to heat transfer to the outside, the hot-water storage tank 51 is covered with a heat insulating material (not shown). Examples of the heat insulating material to be used include felt, Thinsulate (trademark), and a vacuum insulation panel (VIP).
The branch passage 222 constructing the part of the heater circuit is provided in the indoor unit 200. The branch passage 222 includes a supply pipe 222a and a return pipe 222b. An upstream end of the supply pipe 222a is connected to the other outflow port of the three-way valve 55. A downstream end of the supply pipe 222a and an upstream end of the return pipe 222b are connected to heater circuit- side pipes 82a and 82b, respectively. A downstream end of the return pipe 222b is connected to the joining portion 230. With this configuration, the supply pipe 222a and the return pipe 222b are connected to the heater 300 through the heater circuit- side pipes 82a and 82b, respectively. The heater circuit- side pipes 82a and 82b and the heater 300 are provided indoor space but outside the indoor unit 200. The branch passage 222 constructs the heater circuit together with the heater circuit- side pipes 82a and 82b and the heater 300.
A pressure relief valve 301 is connected to the heater circuit-side pipe 82a. The pressure relief valve 301 is a protection device configured to prevent excessive rise of the pressure in the water circuit 210, and, for example, has the structure similar to that of the pressure relief valve 70. For example, when the pressure in the heater circuit-side pipe 82a is increased to exceed set pressure, the pressure relief valve 301 is opened, and water in the heater circuit-side pipe 82a is released to the outside through the pressure relief valve 301. The pressure relief valve 301 is provided indoor space but outside the indoor unit 200.
The heater 300, the heater circuit- side pipes 82a and 82b, and the pressure relief valve 301 in Embodiment 1 are not parts of the heat pump water heater 1000, but units installed by an on-site installation worker depending on circumstances of each building. For example, in an existing facility using a boiler as a heat source device for the heater 300, the heat source device may be replaced by the heat pump water heater 1000. In such a case, unless it is inconvenient, the heater 300, the heater circuit- side pipes 82a and 82b, and the pressure relief valve 301 are used as they are. Therefore, it is desired that the heat pump water heater 1000 be able to be connected to various facilities irrespective of presence or absence of the pressure relief valve 301.
The indoor unit 200 includes the controller 201 configured to mainly control an operation of the water circuit 210, for example, the pump 53, the booster heater 54, the three-way valve 55, and the interruption device 77. The controller 201 includes a microcomputer including a CPU, a ROM, a RAM, and an I/O port. The controller 201 can communicate with the controller 101 and the operation unit 202. The controller 201, for example, sets the interruption device 77 to the closed state when the controller 201 detects the leakage of the refrigerant into the water circuit 210 based on the detection signal from the refrigerant leakage detection device 98. When the refrigerant leakage detection device 98 is configured to output a contact signal at the time of the leakage of the refrigerant, the refrigerant leakage detection device 98 may be directly connected to the interruption device 77 without connection through the controller 201.
The operation unit 202 allows a user to conduct the operation or various settings of the heat pump water heater 1000. The operation unit 202 of Embodiment 1 includes a display unit 203. The display unit 203 can display various kinds of information including a state of the heat pump water heater 1000. The operation unit 202 is provided, for example, on a surface of the casing of the indoor unit 200.
Next, description is made of an operation in a case where the partition wall configured to partition the refrigerant flow passage and the water flow passage in the load-side heat exchanger 2 is broken. The load-side heat exchanger 2 functions as an evaporator during the defrosting operation. Therefore, the partition wall of the load-side heat exchanger 2 may be broken due to freezing of water or other causes particularly during the defrosting operation. In general, the pressure of the refrigerant flowing through the refrigerant flow passage of the load-side heat exchanger 2 is higher than the pressure of the water flowing through the water flow passage of the load-side heat exchanger 2 both during the normal operation and during the defrosting operation. Therefore, when the partition wall of the load-side heat exchanger 2 is broken, the refrigerant in the refrigerant flow passage flows out to the water flow passage both during the normal operation and during the defrosting operation, and the refrigerant is mixed into the water inside the water flow passage. At this time, the refrigerant mixed into the water is gasified due to pressure decrease. Further, the refrigerant having the pressure higher than that of the water is mixed into the water, with the result that the pressure in the water circuit 210 is increased.
The refrigerant mixed into the water inside the water circuit 210 in the load-side heat exchanger 2 not only flows in a direction along a flow of water at a normal time, that is, a direction from the load-side heat exchanger 2 toward the booster heater 5, but, due to a pressure difference, also flows in a direction opposite to the direction along the flow of water at the normal time, that is, a direction from the load-side heat exchanger 2 toward the joining portion 230. When the pressure relief valve 70 is provided in the main passage 220 of the water circuit 210 as in Embodiment 1, the refrigerant mixed into the water may be released from the pressure relief valve 70 to a room together with the water. Further, when the pressure relief valve 301 is provided in the heater circuit-side pipe 82a or the heater circuit-side pipe 82b as in Embodiment 1, the refrigerant mixed into the water may be released from the pressure relief valve 301 to the room together with the water. That is, both of the pressure relief valves 70 and 301 function as valves configured to release the refrigerant mixed into the water inside the water circuit 210 to the outside of the water circuit 210. When the refrigerant has flammability, there is a fear in that a flammable concentration region may be generated in the room due to the refrigerant released to the room.
However, in Embodiment 1, the interruption device 77 is provided between the load-side heat exchanger 2 and the booster heater 54. Thus, a flow of the refrigerant from the load-side heat exchanger 2 to the booster heater 54 can be interrupted. Therefore, leakage of the refrigerant from the pressure relief valve 70 to the room can be prevented. Further, in Embodiment 1, the interruption device 78 is provided between the load-side heat exchanger 2 and the joining portion 230. Thus, a flow of the refrigerant from the load-side heat exchanger 2 to the joining portion 230 can be interrupted. Therefore, leakage of the refrigerant from the pressure relief valve 301 to the room can be prevented.
Fig. 2 is a circuit diagram for illustrating a schematic configuration of a heat pump use apparatus of a modification example of Embodiment 1. As illustrated in Fig. 2, this modification example is different from the configuration illustrated in Fig. 1 in that the load-side heat exchanger 2 is accommodated in the indoor unit 200. The refrigerant circuit 110 is provided across the outdoor unit 100 and the indoor unit 200. A part of the refrigerant circuit 110 is provided in the outdoor unit 100, and an other part of the refrigerant circuit 110 is provided in the indoor unit 200. The outdoor unit 100 and the indoor unit 200 are connected to each other through two connecting pipes 111 and 112 constructing parts of the refrigerant circuit 110. Also according to this modification example, effects similar to those of the configuration illustrated in Fig. 1 can be obtained. Further, in this modification example, all of the interruption devices 77 and 78 and the refrigerant leakage detection device 98 are provided in the indoor unit 200. With this configuration, each of the interruption devices 77 and 78 and the refrigerant leakage detection device 98 can be connected to the controller 201 through the control line in the indoor unit 200. Thus, costs can be reduced.
Next, an arrangement position of the refrigerant leakage detection device 98 is described. Fig. 3 to Fig. 6 are explanatory views for illustrating examples of the arrangement position of the refrigerant leakage detection device 98 in the heat pump use apparatus according to Embodiment 1. In Fig. 3, as the examples of the arrangement position of the refrigerant leakage detection device 98, four arrangement positions A to D are illustrated. When the refrigerant leakage detection device 98 is arranged at the arrangement position A or B, the refrigerant leakage detection device 98 is connected to the pipe 72. That is, similarly to the pressure relief valve 70, the refrigerant leakage detection device 98 is connected to the main passage 220 at the booster heater 54 (connecting portion). In such a case, before the refrigerant, which is leaked to the water circuit 210 at the load-side heat exchanger 2, is released from the pressure relief valve 70, the leakage of the refrigerant can reliably be detected by the refrigerant leakage detection device 98. The similar effect is obtained also when the refrigerant leakage detection device 98 is connected to the main passage 220 at the load-side heat exchanger 2, a portion between the load-side heat exchanger 2 and the booster heater 54, or the booster heater 54.
Further, the refrigerant is gasified at a time point when the refrigerant is leaked to the water circuit 210. Therefore, due to a difference in specific volume between gas and a liquid, mass velocity when the refrigerant is leaked from the pressure relief valve 70 is reduced to about one thousandth of that when the liquid refrigerant is leaked. Therefore, an amount of the refrigerant, which may be released from the pressure relief valve 70 during a time period from detection of the leakage of the refrigerant to interruption of a flow at the interruption device 77, does not reach an amount which leads to generation of the flammable concentration region in the room.
Meanwhile, when the refrigerant leakage detection device 98 is arranged at the arrangement position C or D, the refrigerant leakage detection device 98 is connected to the main passage 220 at a portion between the booster heater 54 (connecting portion) and the three-way valve 55. In this case, before the leakage of the refrigerant is detected by the refrigerant leakage detection device 98, the refrigerant may be released from the pressure relief valve 70. However, due to the difference in specific volume between gas and a liquid as described above, the amount of the refrigerant that may be released from the pressure relief valve 70 does not reach the amount which leads to the generation of the flammable concentration region in the room.
Further, as illustrated in Fig. 4 (example not belonging to the present invention), when the refrigerant leakage detection device 98 is provided between the load-side heat exchanger 2 and the interruption device 77, through the setting of the interruption device 77 to the closed state immediately after the leakage of the refrigerant is detected, the amount of the refrigerant released from the pressure relief valve 70 can be reduced to almost exactly zero. Similarly, as illustrated in Fig. 5, when the refrigerant leakage detection device 98 is provided between the load-side heat exchanger 2 and the interruption device 78, an amount of the refrigerant released from the pressure relief valve 301 can be reduced to almost exactly zero. That is, in order to reduce the amount of the refrigerant released to the room to almost exactly zero, it is desired that the refrigerant leakage detection device 98 be connected to the main passage 220 at a portion between the interruption device 77 and the interruption device 78.
Further, as illustrated in Fig. 6, when the interruption device 78 is not the check valve but the on-off valve, the refrigerant leakage detection device 98 may be connected to the main passage 220 at a portion between the interruption device 78 and the joining portion 230.
In all of the configurations illustrated in Fig. 1 to Fig. 6, the refrigerant leakage detection device 98 is not connected to the branch passage, for example, the heater circuit- side pipe 82a or 82b or the heater 300, which is installed by an on-site installation worker, but is connected to the main passage 220. Therefore, mounting of the refrigerant leakage detection device 98 and connection between the refrigerant leakage detection device 98 and the controller 201 can be carried out by a manufacturer of the indoor unit 200. Therefore, it is possible to avoid such a human error as to forget to mount the refrigerant leakage detection device 98 and connect the refrigerant leakage detection device 98.
As described above, the heat pump water heater 1000 (example of the heat pump use apparatus) according to Embodiment 1 includes the refrigerant circuit 110 configured to circulate the refrigerant, the water circuit 210 (example of the heat medium circuit) configured to allow water (example of the heat medium) to flow therethrough, and the load-side heat exchanger 2 (example of the heat exchanger) configured to exchange heat between the refrigerant and the water. The water circuit 210 includes the main passage 220 extending through the load-side heat exchanger 2. The main passage 220 includes the three-way valve 55 (example of the branching portion) to which the plurality of branch passages 221 and 222 branched from the main passage 220 are connected, and the joining portion 230 at which the plurality of branch passages 221 and 222 are connected to each other to be joined to the main passage 220. The three-way valve 55 is provided at the downstream end of the main passage 220. The joining portion 230 is provided at the upstream end of the main passage 220. The pressure relief valve 70 (example of the pressure protection device) and the refrigerant leakage detection device 98 are connected to the main passage 220. The pressure relief valve 70 is configured to release water to the outside of the water circuit 210 based on the pressure in the water circuit 210. The refrigerant leakage detection device 98 is configured to detect the leakage of the refrigerant from the refrigerant circuit 110 to the water circuit 210. The pressure relief valve 70 is connected to the main passage 220 at the booster heater 54 (example of the connecting portion) located between the load-side heat exchanger 2 and one of the three-way valve 55 and the joining portion 230. The interruption device 77 (example of the first interruption device) configured to be able to interrupt a flow from the load-side heat exchanger 2 to the booster heater 54 is provided in the main passage 220 at a portion between the load-side heat exchanger 2 and the booster heater 54. The interruption device 78 (example of the second interruption device) configured to be able to interrupt a flow from the load-side heat exchanger 2 to an other of the three-way valve 55 and the joining portion 230 is provided in the main passage 220 at a portion between the load-side heat exchanger 2 and the other of the three-way valve 55 and the joining portion 230.
According to this configuration, even when the refrigerant is leaked to the water circuit 210 in the load-side heat exchanger 2, a flow of the refrigerant mixed into the water can be interrupted by the interruption devices 77 and 78. Therefore, the leakage of the refrigerant from the pressure relief valve 70 to the room can be prevented. Further, there can also be prevented the leakage of the refrigerant to the room from the pressure relief valve 301 which may be provided to a circuit provided ahead of the branching portion, for example, the heater circuit- side pipes 82a and 82b.
In the heat pump water heater 1000 according to Embodiment 1, each of the interruption devices 77 and 78 is the on-off valve which is closed when the leakage of the refrigerant into the water circuit 210 is detected. According to this configuration, when the refrigerant is leaked to the water circuit 210, the flow of the refrigerant mixed into the water can further reliably be interrupted.
In the heat pump water heater 1000 according to Embodiment 1, the refrigerant leakage detection device 98 is connected to the main passage 220 at the joining portion 230, a portion between the joining portion 230 and the booster heater 54, or the booster heater 54. According to this configuration, the leakage of the refrigerant can reliably be detected before the refrigerant leaked to the water circuit 210 is released to the room.
In the heat pump water heater 1000 according to Embodiment 1, of the interruption devices 77 and 78, the interruption device 78, which is provided between the load-side heat exchanger 2 and the joining portion 230, is the check valve. Further, the refrigerant leakage detection device 98 is connected to the main passage 220 at a portion between the check valve and the booster heater 54 or at the booster heater 54. According to this configuration, the leakage of the refrigerant can reliably be detected before the refrigerant leaked to the water circuit 210 is released to the room.
In the heat pump water heater 1000 according to Embodiment 1, the refrigerant leakage detection device 98 is connected to the main passage 220 at a portion between the interruption device 77 and the interruption device 78. According to this configuration, the amount of the refrigerant released from the pressure relief valve can be reduced to almost exactly zero.
In the heat pump water heater 1000 according to Embodiment 1, the refrigerant leakage detection device 98 is configured to detect the leakage of the refrigerant into the water circuit 210 based on the pressure in the water circuit 210. According to this configuration, the leakage of the refrigerant can reliably be detected.
The heat pump water heater 1000 according to Embodiment 1 further includes the outdoor unit 100 accommodating the refrigerant circuit 110, a part of the water circuit 210, and the load-side heat exchanger 2, and the indoor unit 200 accommodating an other part of the water circuit 210. One of the outdoor unit 100 and the indoor unit 200 accommodates the interruption devices 77 and 78 and the refrigerant leakage detection device 98. According to this configuration, the controller 101 or the controller 201 can be connected to each of the interruption devices 77 and 78 and the refrigerant leakage detection device 98 in the outdoor unit 100 or the indoor unit 200. Thus, costs can be reduced.
The heat pump water heater 1000 according to Embodiment 1 further includes the outdoor unit 100 accommodating a part of the refrigerant circuit 110, and the indoor unit 200 accommodating an other part of the refrigerant circuit 110, the water circuit 210, and the load-side heat exchanger 2. The indoor unit 200 accommodates the interruption devices 77 and 78 and the refrigerant leakage detection device 98. According to this configuration, the controller 201 can be connected to each of the interruption devices 77 and 78 and the refrigerant leakage detection device 98 in the indoor unit 200. Thus, costs can be reduced.
In the heat pump water heater 1000 according to Embodiment 1, the refrigerant may be flammable refrigerant or toxic refrigerant.

Embodiment 2

A heat pump use apparatus according to Embodiment 2 of the present invention is described. Fig. 7 is a circuit diagram for illustrating a schematic configuration of the heat pump use apparatus according to Embodiment 2. In Fig. 7, a configuration of the indoor unit 200 is mainly illustrated. Components having the same functions and actions as those of Embodiment 1 are denoted by the same reference symbols, and description thereof is omitted. As illustrated in Fig. 7, in Embodiment 2, a boiler circuit 240 configured to heat water accumulated inside the hot-water storage tank 51 is provided outside the hot-water storage tank 51. The boiler circuit 240 includes a water flow passage for connecting a lower portion and an upper portion of the hot-water storage tank 51. The boiler circuit 240 includes a boiler pump 241 and a boiler heat exchanger 242 configured to exchange heat between water flowing through the boiler circuit 240 and water flowing through the branch passage 221. When the boiler pump 241 is operated, water in the lower portion of the hot-water storage tank 51 flows into the boiler circuit 240. The water flowing into the boiler circuit 240 is heated through heat exchange in the boiler heat exchanger 242, and is returned to the upper portion of the hot-water storage tank 51. Also according to Embodiment 2, effects similar to those of Embodiment 1 can be obtained.
The present invention is not limited to the above-mentioned embodiments, and various modifications may be made thereto.
For example, in the above-mentioned embodiments, the plate heat exchanger is given as an example of the load-side heat exchanger 2. However, the load-side heat exchanger 2 may be a heat exchanger other than the plate heat exchanger, such as a double-pipe heat exchanger as long as the heat exchanger is configured to exchange heat between refrigerant and a heat medium.
Further, in the above-mentioned embodiments, the heat pump water heater 1000 is given as an example of the heat pump use apparatus. However, the present invention is also applicable to other heat pump use apparatus, such as a chiller.
Further, in the above-mentioned embodiments, the indoor unit 200 including the hot-water storage tank 51 is given as an example. However, the hot-water storage tank may be provided separately from the indoor unit 200.
The embodiments described above and the modification may be carried out in combinations.

Reference Signs List

1 heat source-side heat exchanger 2 load-side heat exchanger 3 compressor 4 refrigerant flow switching device 5 intermediate pressure receiver
6 first pressure reducing device 7 second pressure reducing device 11 suction pipe 51 hot-water storage tank 52 expansion tank 53 pump 54 booster heater 55 three-way valve 56 strainer 57 flow switch 60 immersion heater 61 coil 62,63 drain outlet 70 pressure relief valve 72 pipe 72a branching portion 75 pipe 77, 78 interruption device 81a, 81b sanitary circuit- side pipe 82a, 82b heater circuit-side pipe 98 refrigerant leakage detection device 100 outdoor unit 101 controller 102 control line
110 refrigerant circuit 111, 112 connecting pipe 200 indoor unit
201 controller 202 operation unit 203 display unit 210 water circuit 211, 212 connecting pipe 220 main passage 221, 222 branch passage 222a supply pipe 222b return pipe 230 joining portion 240 boiler circuit 241 boiler pump 242 boiler heat exchanger 300 heater 301 pressure relief valve 1000 heat pump water heater

Claims

A heat pump use apparatus, comprising:
a refrigerant circuit (110) configured to circulate refrigerant;

a heat medium circuit (210) configured to allow a heat medium to flow therethrough; and

a heat exchanger (2) configured to exchange heat between the refrigerant and the heat medium,

the heat medium circuit including a main passage (220) extending through the heat exchanger,

the main passage including
a branching portion (55) to which a plurality of branch passages (221, 222) branched from the main passage are connected, the branching portion being provided at a downstream end of the main passage, and

a joining portion (230) at which the plurality of branch passages are connected to each other to be joined to the main passage, the joining portion being provided at an upstream end of the main passage,

the heat pump use apparatus further comprising a pressure protection device (70) and a refrigerant leakage detection device (98),

the pressure protection device being connected to the main passage at a connecting portion (54) located between the heat exchanger and one (55) of the branching portion and the joining portion, characterised by

the main passage including a first interruption device (77) configured to interrupt a flow from the heat exchanger to the connecting portion, the first interruption device being provided between the heat exchanger and the connecting portion,

the main passage including a second interruption device (78) configured to interrupt a flow from the heat exchanger to an other (230) of the branching portion and the joining portion, the second interruption device being provided between the heat exchanger and the other of the branching portion and the joining portion, and

the refrigerant leakage detection device (98) being connected to the main passage at a portion between the first interruption device (77) and the connecting portion (54), at the connecting portion (54), at a portion between the connecting portion (54) and the branching portion (55), at a portion between the second interruption device (78) and the heat exchanger (2), or at a portion between the joining portion (230) and the second interruption device (78) with respect to a flow direction of the heat medium.
The heat pump use apparatus of claim 1, wherein each of the first interruption device and the second interruption device comprises an on-off valve which is closed when leakage of the refrigerant into the heat medium circuit is detected.
The heat pump use apparatus of claim 1,
wherein one interruption device (78) of the first interruption device and the second interruption device, which is provided between the heat exchanger and the joining portion, comprises a check valve, and
wherein the refrigerant leakage detection device is connected to the main passage at a portion between the check valve and the connecting portion or at the connecting portion.
The heat pump use apparatus of any one of claims 1 to 3, wherein the refrigerant leakage detection device is configured to detect the leakage of the refrigerant into the heat medium circuit based on pressure in the heat medium circuit.
The heat pump use apparatus of any one of claims 1 to 4, further comprising:
an outdoor unit (100) accommodating the refrigerant circuit, a part of the heat medium circuit, and the heat exchanger; and

an indoor unit accommodating an other part of the heat medium circuit,

wherein one of the outdoor unit and the indoor unit accommodates the first interruption device, the second interruption device, and the refrigerant leakage detection device.
The heat pump use apparatus of any one of claims 1 to 4, further comprising:
an outdoor unit (100) accommodating a part of the refrigerant circuit; and

an indoor unit (200) accommodating an other part of the refrigerant circuit, the heat medium circuit, and the heat exchanger,

wherein the indoor unit accommodates the first interruption device, the second interruption device, and the refrigerant leakage detection device.
The heat pump use apparatus of any one of claims 1 to 6, wherein the refrigerant comprises flammable refrigerant or toxic refrigerant.