JP2017161164A - Air-conditioning hot water supply system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an air-conditioning hot water supply system capable of preventing degradation of a heat transfer rate of a carbon dioxide refrigerant in a cascade heat exchanger and a refrigerant for air-conditioning, even at boiling-up termination in which a temperature of incoming water rises, and improving refrigeration cycle performance of a hot water supply system.SOLUTION: A liquid-phase refrigerant as a heat adsorption source is adhered and concentrated on an inner surface of an inner tube even when a flowing form of a high stage-side refrigerant is dominantly circular flow, in a so-called boiling-up termination operation in which a double tube-type heat exchanger composed of an outer tube 420 and an inner tube 410 is used as a cascade heat exchanger 340, and a water inflow temperature is increased by circulating a refrigerant for hot water supply to the inner tube 410, and an oil film as thermal resistance is adhered and concentrated on an inner surface of the outer tube 420, even when a superheated gas state is kept dominantly as a state of a low stage-side refrigerant in the boiling-up termination operation, thus a superheated gas refrigerant as a heat medium can be easily brought into contact with an outer surface of the inner tube 410 as a heat transfer face.SELECTED DRAWING: Figure 1

Description

  The present invention is an air conditioning hot water supply system capable of simultaneously supplying hot and cold heat necessary for cooling, heating, and hot water supply, is equipped with a refrigeration cycle that generates hot water for hot water supply, and is provided with air conditioning refrigerant and hot water supply refrigerant via a cascade heat exchanger. The present invention relates to an air conditioning hot water supply system that exchanges heat between the two.

  Conventionally, as a hot water supply device that generates hot water and stores it in a hot water storage tank and uses it for hot water supply, it has a refrigerant circuit through which refrigerant circulates and a water circuit through which water circulates, and the refrigerant circuit includes a compressor, a heat exchanger for generating hot water, There is a single-stage heat pump cycle in which an expansion valve and a heat source side heat exchanger are connected, and a carbon dioxide refrigerant is used as a refrigerant. Furthermore, in order to improve the operation efficiency of the hot water supply apparatus, a dual cycle hot water supply apparatus that is thermally connected to the air conditioning cycle has been proposed (see Patent Document 1).

The configuration of the dual cycle water heater described in Patent Document 1 is shown in FIG.
A hot water supply apparatus including a hot water supply compressor 310, a hot water supply heat exchanger 320, a hot water supply refrigerant flow rate adjustment valve 330, and a cascade heat exchanger 340, which are sequentially connected, and a hot water supply refrigerant circuit 300 filled with carbon dioxide refrigerant. The hot water supply heat exchanger 320 is configured to exchange heat between water in the hot water supply hot water circuit and the carbon dioxide refrigerant, and the cascade heat exchanger 340 includes the refrigerant in the air conditioning refrigerant circuit and the carbon dioxide refrigerant. It is configured to allow heat exchange.

As a result, even when the outdoor air temperature is low and the efficiency of the refrigeration cycle decreases due to the pressure ratio becoming too high in a single-stage heat pump cycle water heater, heat is extracted from the outdoor air in the air conditioning cycle. The hot water supply cycle can take out heat from the air-conditioning refrigerant that has been heated to generate hot water.
Therefore, both pressure ratios of the air conditioning cycle and the hot water supply cycle can be appropriately suppressed, the refrigeration cycle of the entire system can be made efficient, and hot water storage efficiency can be increased.
Also, in the refrigeration system, a dual refrigeration cycle has been proposed in the same manner as the hot water supply system, and as a configuration of the cascade heat exchanger 340, for example, as described in Patent Document 2, a double-pipe heat exchange is performed. There has been proposed a device in which a carbon dioxide refrigerant is allowed to flow through an outer tube.

The refrigeration system described in Patent Document 2 uses a carbon dioxide refrigerant as a low-stage side refrigerant and a refrigerant having a pressure lower than that of carbon dioxide as a high-stage side refrigerant, and a low-stage side refrigeration circuit and a high-stage side refrigeration circuit. And a two-stage refrigeration cycle that is thermally connected by a cascade heat exchanger.
In this case, as a cascade heat exchanger, the use of a double-tube heat exchanger having a cavity communicating with the outside in the middle between the inner tube and the outer tube damages the tube wall separating the inner tube and the outer tube. In this case, the low-stage carbon dioxide refrigerant is placed in the high-stage circuit by connecting the low-strength inner pipe and the cavity or the outer pipe and the cavity before the inner pipe and the outer pipe communicate with each other. It is possible to prevent the components of the high-stage refrigeration circuit from being damaged.
Moreover, as shown in FIG. 10, frost formation and dew condensation on the surface of the double-pipe heat exchanger can be suppressed by flowing the low-stage carbon dioxide refrigerant having a higher temperature than the high-stage side through the outer pipe.

JP 2004-132647 A (Patent No. 3925383) JP 2007-218459 A

  However, as in Patent Document 1, in a so-called air-conditioning hot-water supply system in which a low-stage cycle is used for air-conditioning and a high-stage cycle is used for hot-water supply, carbon dioxide refrigerant is used as the hot-water supply refrigerant, and cascade heat exchange is performed. When a double pipe heat exchanger is used as the vessel 340, if a carbon dioxide refrigerant is passed through the outer pipe of the double pipe heat exchanger as in Patent Document 2, the air conditioning refrigerant and the outer pipe that flow through the inner pipe flow. In the heat exchange with the carbon dioxide refrigerant, the heat transfer coefficient of the hot water supply refrigerant and the air conditioning refrigerant may decrease due to the flow pattern of the hot water supply refrigerant and the flow pattern of the air conditioning refrigerant.

First, the reduction in heat transfer coefficient due to the flow pattern of the hot water supply refrigerant will be described.
When carbon dioxide refrigerant is allowed to flow through the outer pipe of a double-pipe heat exchanger as in Patent Document 2, the flow pattern of the gas-liquid two-phase refrigerant that evaporates in the double-pipe heat exchanger is determined by the degree of dryness of the refrigerant. As shown in FIG. 6, the liquid phase refrigerant having a large heat capacity flows in a concentrated manner on the inner surface of the outer pipe away from the heat transfer surface, so that the carbon dioxide refrigerant in the heat exchange with the outer surface of the inner pipe. The heat transfer coefficient decreases.
The hot water supply refrigerant obtains heat from the air conditioning refrigerant in the cascade heat exchanger 340 and generates hot hot water of 60 to 90 ° C. in the hot water supply heat exchanger 320. In a hot water supply system in which hot water heated to a high temperature is stored in a hot water storage tank, the temperature of the water supplied from the hot water storage tank to the hot water supply heat exchanger 320, that is, the incoming water temperature changes depending on the amount of hot water in the hot water storage tank. . For example, the incoming water temperature is increased to 40 to 60 ° C. under the condition that the hot water in the hot water storage tank is near the full tank.

FIG. 5 shows a Mollier chart of the hot water supply cycle. 301 is a hot water supply cycle when the incoming water temperature is 5 ° C., and 302 is a hot water supply cycle when the incoming water temperature at the end of boiling is 60 ° C.
As shown in FIG. 5, the carbon dioxide refrigerant radiates heat to the water side in the hot water supply heat exchanger 320, and the temperature difference between the temperature of the carbon dioxide refrigerant at the outlet of the hot water supply heat exchanger 320 and the incoming water temperature is 5K.

  Therefore, when the incoming water temperature is 5 ° C., the temperature of the carbon dioxide refrigerant at the outlet of the hot water supply heat exchanger 320 is 10 ° C., and when the incoming water temperature is 60 ° C. at the end of boiling, the dioxide dioxide at the outlet of the hot water supply heat exchanger 320 is The temperature of the carbon refrigerant is 65 ° C. That is, the specific enthalpy of the carbon dioxide refrigerant at the outlet of the hot water supply heat exchanger 320 is higher when the incoming water temperature is 60 ° C. than when the incoming water temperature is 5 ° C.

  As a result, the dryness of the carbon dioxide refrigerant that flows out of the hot water supply heat exchanger 320 and isenentically expanded by the expansion valve 330 and then flows into the cascade heat exchanger 340 is 60 ° C. higher than that of the incoming water temperature of 5 ° C. When the water temperature is 60 ° C., a gas-rich gas-liquid two-phase state with a dryness of 0.8 is obtained.

The carbon dioxide refrigerant that has flowed into the cascade heat exchanger 340 at a dryness of 0.8 evaporates by exchanging heat with the air-conditioning refrigerant in the cascade heat exchanger 340 and flows out into a superheated gas state.
At this time, the flow mode of the carbon dioxide refrigerant in the cascade heat exchanger 340 is dominated by the annular flow, and the liquid phase refrigerant having a large heat capacity flows concentrated on the inner surface of the outer pipe away from the heat transfer surface. Therefore, the heat transfer coefficient of the carbon dioxide refrigerant in heat exchange with the outer surface of the inner tube is reduced.

  Next, a description will be given of a decrease in heat exchange efficiency due to the flow mode of the air conditioning refrigerant. As shown in FIG. 5, under the boiling end condition where the incoming water temperature becomes higher, the specific enthalpy difference between the inlet and outlet of the carbon dioxide refrigerant in the cascade heat exchanger 340 becomes smaller, so the amount of exchange heat decreases. Therefore, the air-conditioning refrigerant that flows into the cascade heat exchanger 340 in a superheated gas state is not sufficiently condensed.

FIG. 7 shows a Mollier chart of the air conditioning cycle. 101 is an air conditioning cycle when the incoming water temperature is 5 ° C., and 102 is an air conditioning cycle when the incoming water temperature at the end of boiling is 60 ° C.
As shown in FIG. 7, since the air-conditioning refrigerant is not sufficiently condensed in the boiling end condition, the air-conditioning refrigerant that has flowed into the cascade heat exchanger 340 in a superheated gas state is a gas-liquid with a high degree of dryness. It flows out in a two-phase state. Therefore, most of the air-conditioning refrigerant flowing in the cascade heat exchanger 340 is in a superheated gas state.

When the mixed fluid of the refrigerating machine oil and the refrigerant flows through the pipe in the superheated gas state, the refrigerating machine oil adheres to the inner surface of the pipe and forms an oil film as shown in FIG. The oil film becomes a thermal resistance and hinders the heat transfer of the refrigerant.
Therefore, when the air-conditioning refrigerant is allowed to flow through the inner pipe of the double-pipe heat exchanger as in Patent Document 2, an oil film that becomes a thermal resistance is closely concentrated on the inner pipe inner surface under the condition that the boiling water temperature becomes high. The heat transfer coefficient of the air-conditioning refrigerant in heat exchange with the inner surface of the outer pipe is reduced.

As described above, the refrigeration cycle of the hot water supply system in the boiling end condition due to the decrease in the heat transfer coefficient of the hot water supply refrigerant and the air conditioning refrigerant in the cascade heat exchanger 340 due to the flow patterns of the hot water supply refrigerant and the air conditioning refrigerant. There was a problem that the performance deteriorated.
The present invention solves the above-mentioned problem, and prevents the heat transfer rate of the carbon dioxide refrigerant and the air-conditioning refrigerant in the cascade heat exchanger from decreasing even at the end of boiling when the incoming water temperature becomes high, and It aims at providing the air-conditioning hot-water supply system which can improve refrigeration cycle performance.

  In order to solve the above problems, an air-conditioning hot water supply system of the present invention includes a hot water supply compressor that compresses a hot water supply refrigerant, a hot water supply heat exchanger that exchanges heat between the hot water supply refrigerant and the hot water supply heat medium, and a hot water supply A first refrigeration cycle in which a flow rate control valve for hot water supply for controlling the flow rate of the refrigerant, a cascade heat exchanger for exchanging heat between the hot water supply refrigerant and the air conditioning refrigerant, and the cascade heat exchanger, The 1st circuit which connected the heat generation unit refrigerant | coolant flow rate adjustment valve which controls the flow volume of the said air-conditioning refrigerant | coolant supplied to a cascade heat exchanger in series, and the indoor heat exchanger with which the said air-conditioning refrigerant | coolant and room air exchange heat And at least one second circuit in which an indoor unit refrigerant flow rate adjustment valve for controlling the flow rate of the air conditioning refrigerant supplied to the indoor heat exchanger is connected in series, and the first circuit and the second circuit are connected in parallel. The thermal load circuit connected to In an air conditioning hot water supply system comprising an air conditioning compressor for compressing an air conditioning refrigerant and a second refrigeration cycle connected to an outdoor heat exchanger, the cascade heat exchanger includes a double pipe composed of an outer pipe and an inner pipe. A hot water supply refrigerant is circulated through the inner pipe using a pipe heat exchanger.

In the air-conditioning hot water supply system of the present invention, when the incoming water temperature becomes high after boiling, the specific enthalpy difference between the inlet and outlet of the carbon dioxide refrigerant in the hot water heat exchanger decreases, so carbon dioxide flowing into the cascade heat exchanger The refrigerant enters a gas-rich gas-liquid two-phase state with a dryness of 0.8.
In this case, the flow form of the carbon dioxide refrigerant flowing in the double-pipe heat exchanger is dominated by the annular flow, but by flowing the carbon dioxide refrigerant through the inner pipe, the liquid phase refrigerant having a large heat capacity can be obtained. Since it flows in close contact with the inner surface of the inner tube, which is the heat transfer surface, the heat transfer coefficient of the carbon dioxide refrigerant in heat exchange with the inner surface of the inner tube is increased.

In addition, when the water temperature rises after boiling and the specific enthalpy difference between the inlet and outlet of the carbon dioxide refrigerant in the cascade heat exchanger decreases, the amount of exchange heat in the double-tube heat exchanger decreases, and the cascade heat The air-conditioning refrigerant flowing into the exchanger in the superheated gas state is not sufficiently condensed, and flows out of the cascade heat exchanger in a gas-liquid two-phase state with a high degree of dryness.
In this case, most of the air-conditioning refrigerant flowing in the double-pipe heat exchanger is in a superheated gas state, but the low-stage air-conditioning refrigerant is circulated in the outer pipe of the double-pipe heat exchanger. , Because the oil film that becomes the heat resistance concentrates closely on the inner surface of the outer tube, and the superheated gas refrigerant that is the heat medium flows in contact with the outer surface of the inner tube that is the heat transfer surface, The heat transfer coefficient of the air conditioning refrigerant is increased.

  In the air conditioning and hot water supply system of the present invention, the high-stage carbon dioxide refrigerant is circulated through the inner pipe of the double-pipe heat exchanger, so that the hot water supply refrigerant in the cascade heat exchanger at the end of boiling when the incoming water temperature rises. In addition, the heat transfer coefficient of the air conditioning refrigerant can be increased, and the refrigeration cycle performance of the hot water supply system can be improved.

Refrigeration cycle block diagram of the air conditioning and hot water supply system in Embodiment 1 of the present invention The top view which shows the internal structure of the heat generation unit of this embodiment The front view which shows the internal structure of the heat generation unit of this embodiment Sectional drawing of the connection part of the cascade heat exchanger and refrigerant | coolant piping of this invention Mollier chart of hot water supply cycle Diagram showing how annular flow flows in a cascade heat exchanger Moliere diagram of air conditioning cycle Diagram showing how superheated gas and refrigeration oil flow in cascade heat exchangers Refrigeration cycle configuration diagram of air-conditioning hot water supply system in Patent Document 1 The figure which showed the cross-sectional view and low-stage side carbon dioxide refrigerant flow path of the cascade heat exchanger in patent document 2

  A first aspect of the invention is a hot water supply compressor that compresses a hot water supply refrigerant, a hot water supply heat exchanger that exchanges heat between the hot water supply refrigerant and a hot water supply heat medium, and a hot water supply refrigerant flow rate that controls the flow rate of the hot water supply refrigerant. A first refrigeration cycle in which a regulating valve, a cascade heat exchanger for exchanging heat between the hot water supply refrigerant and the air conditioning refrigerant are connected in an annular shape, the cascade heat exchanger, and the air conditioning supply to the cascade heat exchanger A first circuit in which a heat generation unit refrigerant flow rate regulating valve for controlling the flow rate of the refrigerant is connected in series, an indoor heat exchanger in which the air-conditioning refrigerant and room air exchange heat, and the supply to the indoor heat exchanger An air conditioner comprising: at least one second circuit connected in series with an indoor unit refrigerant flow control valve for controlling the flow rate of the refrigerant for air conditioning; and a heat load circuit connected in parallel with the first circuit and the second circuit. An air conditioning compressor that compresses the refrigerant for the room, and a chamber And a second refrigeration cycle connected to a heat exchanger, wherein the cascade heat exchanger uses a double-tube heat exchanger composed of an outer pipe and an inner pipe, An air-conditioning hot-water supply system that is circulated in an inner pipe.

  As a result, by circulating the hot water supply refrigerant through the inner pipe of the double-pipe heat exchanger, the temperature of the incoming water becomes high at the end of boiling. When the flow becomes dominant, the liquid phase refrigerant having a large heat capacity flows in a concentrated manner on the inner surface of the inner pipe, which is the heat transfer surface, so that the heat transfer coefficient of the hot water supply refrigerant in the heat exchange with the inner surface of the inner pipe is high. Get higher.

In addition, the water temperature rises at the end of boiling, the amount of heat exchanged in the double-pipe heat exchanger decreases, and the air-conditioning refrigerant flowing in the double-pipe heat exchanger is cascaded with high dryness. When most of the air-conditioning refrigerant in the cascade heat exchanger is in a superheated gas state by flowing out of the heat exchanger, the oil film that becomes the heat resistance is closely concentrated on the inner surface of the outer pipe, and the superheated gas refrigerant that is the heat medium Since it flows in contact with the outer surface of the inner pipe which is the heat transfer surface, the heat transfer coefficient of the air-conditioning refrigerant in heat exchange with the outer surface of the inner pipe is increased.
Therefore, even when the incoming water temperature becomes high after boiling, the heat transfer rates of the hot water supply refrigerant and the air conditioning refrigerant in the cascade heat exchanger can be increased, and the refrigeration cycle performance of the hot water supply system can be improved.

  A second aspect of the present invention is the air conditioning and hot water supply system according to the first aspect, wherein the inner pipe and the outer pipe of the cascade heat exchanger are respectively connected to a hot water supply refrigerant pipe and an air conditioning refrigerant pipe. The outer pipe and the air conditioning refrigerant pipe are connected in a direction substantially perpendicular to the flow direction of the air conditioning refrigerant flowing in the vicinity of the branch portion in the cascade heat exchanger, and the inner pipe and the hot water supply refrigerant pipe are The air conditioning and hot water supply system is connected in a substantially horizontal direction with respect to a flow direction of the hot water supply refrigerant flowing in the vicinity of the branch portion in the cascade heat exchanger.

  As a result, the air conditioning load increases, the condensation temperature of the air conditioning refrigerant flowing through the first circuit decreases, the evaporation temperature of the hot water supply refrigerant that exchanges heat with the air conditioning refrigerant in the cascade heat exchanger decreases, and the first refrigeration cycle. Even when the viscosity of the refrigerating machine oil enclosed in the pipe becomes high, it prevents the stagnation at the branch part where the inner pipe of the cascade heat exchanger and the refrigerant pipe for hot water supply are connected, and for hot water supply in the cascade heat exchanger. Since the excessive pressure loss of the refrigerant does not occur, the efficiency of the first refrigeration cycle does not decrease.

  Therefore, in the present invention, in addition to the first invention, even when the air conditioning load becomes large and the condensation temperature of the air conditioning refrigerant flowing through the first circuit decreases, the cascade that causes the efficiency of the first refrigeration cycle decreases. Since the pressure loss of the hot water supply refrigerant can be suppressed at the branch portion where the inner pipe of the heat exchanger and the hot water supply refrigerant pipe are connected, the efficiency of the first refrigeration cycle can be increased.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In addition, this invention is not limited by this embodiment.

(Embodiment 1)
FIG. 1 is a cycle configuration diagram of an air conditioning and hot water supply system according to an embodiment of the present invention.
The air conditioning and hot water supply system of FIG. 1 includes an outdoor unit 100, an indoor unit 200, and a heat generation unit 300. In the present embodiment, two indoor units and one heat generating unit are connected to one outdoor unit. The refrigeration cycle configuration is not limited to that shown in FIG. For example, two or more outdoor units, one or three indoor units, and two or more heat generation units can be connected in parallel.

  The outdoor unit 100, the indoor unit 200, and the heat generation unit 300 are connected by a pipe through which air-conditioning refrigerant flows. The outdoor unit 100 and the indoor unit 200 are a gas pipe 150 through which high-temperature and high-pressure gasified air-conditioning refrigerant flows, a suction pipe 160 through which low-pressure air-conditioning refrigerant flows, and a liquid pipe 170 through which high-pressure liquefied air-conditioning refrigerant flows. And connected with. When there are two indoor units 200 as shown in FIG. 1, the indoor units 200 are connected in parallel to three pipes. On the other hand, the outdoor unit 100 and the heat generation unit 300 are connected in parallel to the piping as in the indoor unit 200, but only the gas pipe 150 and the liquid pipe 170 communicate with each other.

  The outdoor unit 100 includes an air conditioning compressor 110 that compresses the air conditioning refrigerant. An accumulator 111 that supplies a gas refrigerant to the air conditioning compressor 110 is connected to the suction side of the air conditioning compressor 110. An oil separator 112 that separates the refrigerating machine oil contained in the discharged air-conditioning refrigerant is connected to the discharge side of the air-conditioning compressor 110. The refrigerating machine oil separated by the oil separator 112 is returned to the air conditioning compressor 110 through the oil return pipe 113a. The communication of the oil return pipe 113a is controlled by opening and closing the oil return pipe on / off valve 113b.

Further, the outdoor unit 100 includes an outdoor heat exchanger 115, and an outdoor fan 116 that supplies air around the outdoor unit 100 to the outdoor heat exchanger 115 is provided in the vicinity of the outdoor heat exchanger 115. ing. The outdoor air heat exchanger 115 is configured to exchange heat between the air sent by the outdoor blower fan 116 and the air-conditioning refrigerant. Generally, fin-tube type or microtube type heat exchange is performed. A vessel is used.
The outdoor unit 100 includes an outdoor refrigerant flow rate adjustment valve 120 that adjusts the flow rate of the air-conditioning refrigerant supplied to the outdoor heat exchanger 115, an outdoor gas pipe opening / closing valve 121 that controls the flow rate of the air-conditioning refrigerant in the gas pipe 150, An outdoor suction pipe opening / closing valve 122 for controlling the flow rate of the air conditioning refrigerant in the pipe 26 is provided.

The indoor unit 200 adjusts the flow rate of the indoor heat exchanger 215, the indoor blower fan 216 that supplies air around the indoor unit 200 to the indoor heat exchanger 215, and the air conditioning refrigerant that is supplied to the indoor heat exchanger 215. And an indoor refrigerant flow rate adjustment valve 220. The indoor heat exchanger 215 is configured to exchange heat between the air sent by the indoor fan 216 and the air-conditioning refrigerant. Generally, a fin-tube or microtube heat exchanger is used. Is done.
In addition, the indoor unit 200 includes an indoor gas pipe opening / closing valve 221 that controls the flow of air-conditioning refrigerant with the gas pipe 150 and an indoor suction pipe opening / closing valve that controls the flow of the air-conditioning refrigerant with the suction pipe 160. 222.

The heat generating unit 300 adjusts the flow rate of the hot water supply refrigerant, the hot water supply compressor 310 that compresses the hot water supply refrigerant, the hot water supply heat exchanger 320 that exchanges heat with the heat medium mainly composed of the hot water supply refrigerant and water, and the hot water supply refrigerant. The hot water supply refrigerant flow rate adjustment valve 330 is provided.
The heat generation unit 300 also adjusts the flow rate of the cascade heat exchanger 340 that exchanges heat between the air-conditioning refrigerant supplied from the gas pipe 150 and the hot water supply refrigerant, and the air-conditioning refrigerant supplied to the cascade heat exchanger 340. A heat generation unit refrigerant flow rate adjustment valve 350 and a heat medium pump 360 that supplies a heat medium to the hot water supply heat exchanger 320 are provided.

Here, the hot water supply compressor 310, the hot water supply heat exchanger 320, the hot water supply refrigerant flow rate adjustment valve 330, and the cascade heat exchanger 340 are connected in an annular shape to constitute the first refrigeration cycle 500.
Further, the first circuit 501 in which the cascade heat exchanger 340 and the heat generation unit refrigerant flow rate adjustment valve 350 are connected in series, the indoor heat exchanger 215, and the indoor refrigerant flow rate adjustment valve 220 supplied to the indoor heat exchanger 215. At least one second circuit 502 connected in series, and a heat load circuit in which the first circuit 501 and the second circuit 502 are connected in parallel to the air conditioning compressor 110 and the outdoor heat exchanger 115 Thus, the second refrigeration cycle 510 is configured.

Note that a chlorofluorocarbon refrigerant or a carbon dioxide refrigerant is used as the hot water supply refrigerant, and water or antifreeze is used as the heat medium. Hereinafter, a case where carbon dioxide refrigerant is used as the hot water supply refrigerant and water is used as the heat medium will be described.
Moreover, R410A, R32, R407C etc. which are refrigerants generally used for home air conditioners and building air conditioners are used as air conditioning refrigerants.

  Regarding the physical properties of carbon dioxide, Reference Fluid Thermodynamic and Transport Properties Ver. Published by the National Institute of Standards and Technology (hereinafter abbreviated as NIST). The value derived from 9.0 (hereinafter abbreviated as Refprop Ver. 9.0) is used.

Next, the internal structure of the heat generation unit 300 in this embodiment will be described.
FIG. 2 is a plan view showing the internal structure of the heat generation unit 300 in the present embodiment, and FIG. 3 is a front view showing the internal structure of the heat generation unit 300.
The heat generation unit 300 includes a hot water supply compressor 310, a hot water supply heat exchanger 320, a hot water supply refrigerant flow rate adjustment valve 330, and a cascade heat exchanger 340, and a heat generation unit refrigerant flow rate adjustment valve 350. And the heat medium pump 360 are stored in the casing 401.

  In the present embodiment, for example, a double pipe heat exchanger is used as the hot water supply heat exchanger 320. The double tube heat exchanger is a heat exchanger formed by inserting one or more tubes (inner tubes) into a tube (outer tube) having a substantially circular cross section. When there are a plurality of inner tubes, the inner tubes are inserted into the outer tube by spiraling. When carbon dioxide refrigerant is used as the hot water supply refrigerant, carbon dioxide refrigerant is passed through the inner pipe of the hot water supply heat exchanger 320 and water is allowed to flow between the outer pipe and the inner pipe.

In addition, when using a double pipe type heat exchanger as the heat exchanger 320 for hot water supply, a copper pipe with high heat conductivity is often used as the material of the double pipe type heat exchanger.
The hot water supply heat exchanger 320 may be a plate heat exchanger, a shell and tube heat exchanger, or the like.

  The heat exchange capacity of the double pipe heat exchanger is proportional to the length of the double pipe. Therefore, the double-pipe heat exchanger is formed by winding a double pipe in order to secure the maximum heat exchange capability within a limited installation volume. When installing a double-pipe heat exchanger, make sure that the double pipe is as horizontal as possible in order to prevent air from accumulating in the part where the heat medium passes through the double pipe and causing a significant decline in heat exchange performance. To do.

  The cascade heat exchanger 340 is a double pipe heat exchanger. The double tube heat exchanger is a heat exchanger formed by inserting one or more tubes (inner tubes) into a tube (outer tube) having a substantially circular cross section. When there are a plurality of inner tubes, the inner tubes are inserted into the outer tube by spiraling. When a carbon dioxide refrigerant is used as the hot water supply refrigerant, the carbon dioxide refrigerant is passed through the inner pipe of the cascade heat exchanger 340 and the air conditioning refrigerant is passed between the outer pipe and the inner pipe.

FIG. 4 is a cross-sectional view of a connection portion between the cascade heat exchanger 340 and the refrigerant pipe. As shown in FIG. 4, the inner pipe 410 of the cascade heat exchanger 340 is connected to the hot water supply refrigerant pipe, and the outer pipe 420 is connected to the air conditioning refrigerant pipe.
The inner pipe 410 and the outer pipe 420 are branch sections connected to the hot water supply refrigerant pipe and the air conditioning refrigerant pipe, respectively. The outer pipe 420 and the air conditioning refrigerant pipe flow in the vicinity of the branch section in the cascade heat exchanger 340. They are connected so as to be substantially perpendicular to the flow direction of the air conditioning refrigerant. Further, the inner pipe 410 and the hot water supply refrigerant pipe are connected so as to be substantially horizontal with respect to the flow direction of the hot water supply refrigerant flowing in the vicinity of the branch portion in the cascade heat exchanger 340.

As shown in FIGS. 2 and 3, the hot water supply compressor 310 is fixed to the bottom plate member 370 by a fixing member 312 with a vibration isolating member 311 such as rubber interposed therebetween.
Further, the hot water supply heat exchanger 320 is also fixed on the bottom plate member 370, and the cascade heat exchanger 340 is installed above the hot water supply heat exchanger 320.
Moreover, the lower end surface of the heat medium pump 360 is installed at a position lower than the lower end surface of the cascade heat exchanger 340.

  Each of the hot water supply heat exchanger 320 and the cascade heat exchanger 340 shown in FIGS. 2 and 3 includes a heat insulating material such as foamed polystyrene or thick felt, and further includes a component surrounding the heat insulating material. In particular, since the heat exchanger 320 for hot water supply is assumed to be deformed by heat due to the weight of the cascade heat exchanger 340 installed at the top, it is surrounded by a high-strength iron plate to protect the surface of the heat insulator.

  The cascade heat exchanger 340 is not necessarily in contact with the components surrounding the hot water supply heat exchanger 320. In this case, the cascade heat exchanger 340 and the heat insulating material around the cascade heat exchanger 340 are surrounded by components having sufficient strength to support their weight, and at least the side member 400 and the bottom plate member 370 of the heat generating unit 300 are used. It is fixed by a component connected to one side.

  Further, as shown in FIGS. 2 and 3, the bottom plate member 370 has a drain port 390 in a region projected by the hot water heat exchanger 320 and the heat medium pump 360 onto the bottom plate member 370 when viewed from above. Is provided. The upper surface of the bottom plate member 370 is provided with an appropriate slope toward the drain port 390 so that water can be quickly discharged from the drain port 390 to the outside of the heat generation unit 300.

  The flow of the heat medium in the heat medium pipes 380a, 380b, and 380c is generated by driving the heat medium pump 360. The heat medium that has flowed into the heat generating unit 300 flows into the heat medium pump 360 via the heat medium pipe 380a and is sent to the heat medium pipe 380b. Furthermore, the heat medium enters the heat exchanger for hot water supply 320, is heated by the hot water supply refrigerant and reaches a high temperature of 70 to 90 ° C., and then is sent out of the heat generation unit 300 via the heat medium pipe 380c. Is done.

Next, the flow mode of the fluid flowing through the cascade heat exchanger 340 will be described.
First, the temperature of the heat medium flowing into the hot water supply heat exchanger 320 varies between 5 ° C. and 60 ° C. under the influence of the outside air temperature and the heat medium temperature in the hot water storage tank.
In hot water supply heat exchanger 320, the temperature at which the heat medium that has become hot due to heat absorption from the hot water supply refrigerant flows out of hot water supply heat exchanger 320 varies between 65 and 90 ° C. Moreover, in the hot water supply heat exchanger 320, the flow direction of water and the carbon dioxide refrigerant is used in a counterflow so that the logarithm average temperature difference is increased.

Here, when the incoming water temperature is 5 ° C. and the outgoing hot water temperature is 90 ° C., the temperature difference between the carbon dioxide refrigerant and the incoming water temperature is generally 5K on the outlet side of the carbon dioxide refrigerant of the hot water supply heat exchanger 320. Therefore, the temperature of the carbon dioxide refrigerant at the outlet of the hot water supply heat exchanger 320 is 10 ° C.
On the other hand, the refrigerant temperature on the inlet side of the carbon dioxide refrigerant in the hot water supply heat exchanger 320 is 110 ° C., which is equal to the discharge refrigerant temperature of the hot water supply compressor 310. In the hot water supply heat exchanger 320, the pinch temperature between water and carbon dioxide refrigerant is generally 5K. Since the incoming water temperature is 5 ° C., the hot water temperature is 90 ° C., the refrigerant temperature on the carbon dioxide inlet side is 110 ° C., and the refrigerant temperature on the outlet side is 10 ° C., the hot water supply temperature is 5K. The high pressure in cycle 10 is 12.4 MPa.

Next, the carbon dioxide refrigerant that has exited the hot water supply heat exchanger 320 in a state where the pressure is 12.4 MPa and the temperature is 10 ° C. is isenthalpy-expanded by the hot water supply refrigerant flow rate adjustment valve 330 and flows into the cascade heat exchanger 340. In the cascade heat exchanger 340, the carbon dioxide refrigerant absorbs heat and evaporates from the air conditioning refrigerant, and flows out of the cascade heat exchanger 340 in a superheated gas state.
The condensation temperature of the air conditioning refrigerant flowing into the cascade heat exchanger is 45 to 55 ° C., and the temperature difference between the air conditioning refrigerant and the carbon dioxide refrigerant is generally 10 K. In this case, the carbon dioxide is It becomes 35-45 degreeC and will be in a supercritical state.

  If the carbon dioxide refrigerant flowing into the hot water supply compressor 310 is in a supercritical state, the viscosity of the refrigerating machine oil in the compressor is significantly reduced, the effect as a lubricating oil is reduced, and a problem such as seizure of the sliding portion may occur. is there.

For this reason, the evaporation temperature of the carbon dioxide refrigerant is set to 20 ° C., which is 11K lower than the critical temperature of 31.1 ° C., so that the efficiency of the refrigeration cycle is high and the reliability of the hot water supply compressor 310 is increased. good.
Accordingly, the carbon dioxide refrigerant that has exited the hot water supply heat exchanger 320 in a state where the pressure is 12.4 MPa and the temperature of 10 ° C. is isenthalpy-expanded by the hot water supply refrigerant flow rate adjustment valve 330 to a pressure corresponding to an evaporation temperature of 20 ° C. It flows into the cascade heat exchanger 340 at 7 MPa, and the state of the carbon dioxide refrigerant at this time is a supercooled state.
In the evaporation process, a gas-liquid two-phase refrigerant having a dryness of 0.8 or more generally flows in an annular flow, but flows into the cascade heat exchanger 340 in a supercooled state and flows out as a superheated gas. In this case, the proportion of the annular flow is 20% or less.

On the other hand, when the incoming water temperature is 60 ° C. and the outgoing hot water temperature is 90 ° C., the temperature difference between the carbon dioxide refrigerant and the incoming water temperature is 5K on the outlet side of the carbon dioxide refrigerant in the hot water supply heat exchanger 320 as described above. Since it is general, the temperature of the carbon dioxide refrigerant at the outlet of the hot water supply heat exchanger 320 is 65 ° C.
On the other hand, the refrigerant temperature on the inlet side of the carbon dioxide refrigerant in the hot water supply heat exchanger 320 is 110 ° C., which is equal to the discharge refrigerant temperature of the hot water supply compressor 310. In the hot water supply heat exchanger 320, the pinch temperature between water and carbon dioxide refrigerant is generally 5K, the incoming water temperature is 60 ° C., the outgoing hot water temperature is 90 ° C., and the refrigerant temperature on the carbon dioxide inlet side is 110 ° C. Since the refrigerant temperature on the outlet side is 65 ° C., the high pressure in the hot water supply cycle 10 where the pinch temperature between water and the carbon dioxide refrigerant is 5K is 14.2 MPa.

  Next, the carbon dioxide refrigerant that has exited the hot water supply heat exchanger 320 in a state where the pressure is 14.2 MPa and the temperature is 65 ° C. is isoenthalpy-expanded by the hot water supply refrigerant flow rate adjustment valve 330 and flows into the cascade heat exchanger 340. In the cascade heat exchanger 340, the carbon dioxide refrigerant absorbs heat and evaporates from the air conditioning refrigerant, and flows out of the cascade heat exchanger 340 in a superheated gas state. Since the evaporation temperature of the carbon dioxide refrigerant is preferably 20 ° C. as described above, the carbon dioxide refrigerant that has exited the hot water supply heat exchanger 320 in a state where the pressure is 14.2 MPa and the temperature is 65 ° C. is the refrigerant flow rate adjustment valve for hot water supply. The carbon dioxide refrigerant at this time flows into the cascade heat exchanger 340 at a pressure of 5.7 MPa which is expanded by an enthalpy expansion at 330 and corresponds to an evaporation temperature of 20 ° C., and the carbon dioxide refrigerant at this time has a dryness of 0.8.

  Further, in the cascade heat exchanger 340, the carbon dioxide refrigerant absorbs heat and evaporates from the air conditioning refrigerant and flows out of the cascade heat exchanger 340 as superheated gas. The superheated gas flowing out from the cascade heat exchanger 340 is sucked into the hot water supply compressor 310 and is discharged as high-temperature and high-pressure superheated gas through an isentropic compression process. As described above, since the high-temperature and high-pressure superheated gas discharged from the hot water supply compressor 310 has a pressure of 14.3 MPa and a temperature of 110 ° C., the refrigerant sucked into the hot water supply compressor 310 has a pressure of 5.7 MPa and a temperature of 40 ° C. It is.

That is, in the cascade heat exchanger 340, the carbon dioxide refrigerant flows in a gas-liquid two-phase state with a pressure of 5.7 MPa, a temperature of 20 ° C., and a dryness of 0.8, and evaporates by absorbing heat from the air conditioning refrigerant. It flows out in a superheated gas state at 5.7 MPa and a temperature of 40 ° C.
Therefore, the flow mode of the carbon dioxide refrigerant in the cascade heat exchanger 340 when the incoming water temperature is 60 ° C. and the outgoing hot water temperature is 90 ° C. is mostly an annular flow.

  Here, the flow of the gas-liquid two-phase refrigerant in the annular flow is such that the liquid-phase refrigerant having a large heat capacity is concentrated on the tube wall. In this embodiment, since the flow path of the carbon dioxide refrigerant flowing through the cascade heat exchanger 340 is disposed in the inner pipe 410, the carbon dioxide refrigerant flowing in the gas-liquid two-phase state with a dryness of 0.8 is annular. A liquid phase refrigerant having a large heat capacity is formed in close contact with the inner surface of the inner tube 410 serving as a heat transfer surface. Therefore, it is possible to efficiently absorb heat from the air-conditioning refrigerant flowing through the outer tube 420 of the cascade heat exchanger 340.

Further, when the incoming water temperature is 60 ° C. and the outgoing hot water temperature is 90 ° C., the state of the suction refrigerant of the hot water supply compressor 310 is 5.7 MPa and the temperature is 35 ° C. as described above, so the density is 146 kg / m 3.
Moreover, since the state of the inlet refrigerant of the hot water supply heat exchanger 320 is a pressure of 14.2 MPa and a temperature of 110 ° C., the specific enthalpy is 488 kJ / kg. Moreover, since the state of the outlet refrigerant of the hot water supply heat exchanger 320 is a pressure of 14.2 MPa and a temperature of 65 ° C., the specific enthalpy is 373 kJ / kg.
Therefore, the heating capacity per volume of the suction refrigerant of the hot water supply compressor 310 is such that the difference in the specific enthalpy of the refrigerant at the inlet and outlet of the hot water heat exchanger 320 is 115 kJ / kg, and the density of the suction refrigerant of the hot water compressor 310 is It is obtained by multiplying by 146 kg / m3 and is 16790 kJ / m3.

When the inlet water temperature is 5 ° C. and the hot water temperature is 90 ° C., the heating capacity per volume of the suction refrigerant of the hot water supply compressor 310 is 36170 kJ / m 3 in the same manner.
Therefore, at the end of boiling when the incoming water temperature rises to 60 ° C., the heating capacity when operating at the same frequency of the hot water supply compressor 310 is 46% compared to when the incoming water temperature is 5 ° C.

In addition, the state of the refrigerant at the inlet of the cascade heat exchanger 340 is a pressure of 5.7 MPa and a temperature of 65 ° C., and the refrigerant flowing out of the hot water supply heat exchanger 320 is expanded by equal enthalpy in the hot water supply refrigerant flow rate adjustment valve 330 to cascade. Since it flows into the heat exchanger 340, the specific enthalpy is 373 kJ / kg. Moreover, since the state of the outlet refrigerant of the cascade heat exchanger 340 is a pressure of 5.7 MPa and a temperature of 35 ° C., the specific enthalpy is 448 kJ / kg.
Therefore, the heat exchange amount of the refrigerant evaporated in the cascade heat exchanger 340 per volume of the refrigerant sucked in the hot water supply compressor 310 is equal to the difference in specific enthalpy of the refrigerant at the inlet and outlet of the cascade heat exchanger 340 to 75 kJ / kg. It is 10950 kJ / m3, which is obtained by multiplying the density of the suction refrigerant of the compressor 310 for the engine 146 kg / m3.

The heat exchange amount of the refrigerant evaporated in the cascade heat exchanger 340 per volume of the refrigerant sucked in the hot water supply compressor 310 when the incoming water temperature is 5 ° C. and the outgoing hot water temperature 90 ° C. is 32500 kJ / m 3.
Therefore, at the end of boiling when the incoming water temperature rises to 60 ° C., the heat exchange amount of the refrigerant evaporated in the cascade heat exchanger 340 when operating at the same frequency of the hot water supply compressor 310 is 5 ° C. Compared to the time of 34%.

When the inlet water temperature is 5 ° C. and the tapping temperature is 90 ° C., the air-conditioning refrigerant flowing through the outer pipe of the cascade heat exchanger 340 is condensed in the cascade heat exchanger 340 by flowing into the superheated gas state and dissipating heat to the carbon dioxide refrigerant. However, it flows out in a supercooled state.
However, when the incoming water temperature is 60 ° C. and the outgoing hot water temperature is 90 ° C., the amount of heat of the refrigerant evaporated in the carbon dioxide refrigerant cascade heat exchanger 340 is reduced to 34% as compared with the incoming water temperature of 5 ° C. and the outgoing hot water temperature of 90 ° C. Then, it flows out of the cascade heat exchanger 340 in a gas-liquid two-phase state with a dryness of 0.8. Therefore, at the incoming water temperature of 60 ° C., the superheated gas state occupies most (60 to 70%) of the air conditioning refrigerant flowing through the cascade heat exchanger 340.

By the way, in the mixed fluid of refrigeration oil and refrigerant, when flowing in the pipe in a superheated gas state, the refrigeration oil adheres to the inner surface of the pipe and forms an oil film. The oil film becomes a thermal resistance and hinders the heat transfer of the refrigerant.
In this embodiment, since the flow path of the air-conditioning refrigerant flowing through the cascade heat exchanger 340 is arranged in the outer pipe 420, the heat resistance is generated in the mixed fluid of the air-conditioning refrigerant and the refrigerating machine oil flowing in with the superheated gas. The oil film concentrates closely on the inner surface of the outer tube 420, and the superheated gas refrigerant as the heat medium comes into contact with the outer surface of the inner tube 410 as the heat transfer surface. Therefore, it is possible to efficiently dissipate heat to the carbon dioxide refrigerant flowing through the inner pipe 410 of the cascade heat exchanger 340.

Next, the flow of the refrigerating machine oil at the branch portion connecting the inner pipe 410 of the cascade heat exchanger 340 and the hot water supply refrigerant pipe will be described.
The evaporation temperature of the hot water supply refrigerant that exchanges heat with the air conditioning refrigerant in the cascade heat exchanger 340 is affected by the condensation temperature of the air conditioning refrigerant. For example, the condensation of the air conditioning refrigerant flowing through the first circuit 501 due to an increased air conditioning load. When the temperature decreases, the evaporation temperature of the hot water supply refrigerant that exchanges heat with the air conditioning refrigerant in the cascade heat exchanger 340 decreases.

When the evaporation temperature of the hot water supply refrigerant decreases, the viscosity of the refrigerating machine oil enclosed in the first refrigeration cycle flowing through the cascade heat exchanger 340 increases. When the viscosity of the refrigerating machine oil increases, it stays at the bent portion of the pipe, obstructs the flow of the hot water supply refrigerant, and causes pressure loss.
In the present embodiment, the outer pipe 420 of the cascade heat exchanger 340 and the air conditioning refrigerant pipe are substantially perpendicular to the flow direction of the air conditioning refrigerant flowing in the vicinity of the branch portion in the cascade heat exchanger 340. And the inner pipe 410 of the cascade heat exchanger 340 and the hot water supply refrigerant pipe are substantially horizontal to the flow direction of the hot water supply refrigerant flowing in the vicinity of the branch portion in the cascade heat exchanger 340. Therefore, refrigerating machine oil is prevented from staying at the branch portion where the inner pipe 410 of the cascade heat exchanger 340 and the hot water supply refrigerant pipe are connected, and the pressure loss of the hot water supply refrigerant in the cascade heat exchanger 340 Can be suppressed.

Next, operations of the outdoor unit 100, the indoor unit 200, and the heat generation unit 300 will be described with reference to the refrigeration cycle diagram of FIG.
During cooling only operation, in the outdoor unit 100, the outdoor gas pipe opening / closing valve 121 is opened and the outdoor suction pipe opening / closing valve 122 is closed, and in the indoor unit 200, the indoor gas pipe opening / closing valve 221 is closed and the indoor suction pipe opening / closing is opened. The valve 222 is set to open, and in the heat generation unit 300, the heat generation unit refrigerant flow rate adjustment valve 350 is set to fully closed.

  The high-temperature and high-pressure air-conditioning refrigerant compressed by the air-conditioning compressor 110 enters the outdoor air heat exchanger 115 via the outdoor gas pipe on-off valve 121 and is cooled by the air around the outdoor unit 100 to be in a liquid state. The liquid-state air-conditioning refrigerant flows into the liquid pipe 170 via the fully opened outdoor refrigerant flow rate adjustment valve 120 and reaches the indoor unit 200.

  The air-conditioning refrigerant that has reached the indoor unit 200 is depressurized by the indoor refrigerant flow rate adjustment valve 220 to be in a low-temperature low-pressure gas-liquid two-phase state, and then flows into the indoor heat exchanger 215 to take heat away from the indoor air. To cool. In this process, the air-conditioning refrigerant evaporates, enters the suction pipe 160 via the indoor suction pipe opening / closing valve 222, and returns to the outdoor unit 100. The air conditioning refrigerant that has returned to the outdoor unit 100 returns to the air conditioning compressor 110 via the accumulator 111.

  During the single heating operation, in the outdoor unit 100, the outdoor gas pipe on / off valve 121 is closed and the outdoor suction pipe on / off valve 122 is set to open. In the indoor unit 200, the indoor gas pipe on / off valve 221 is opened and the indoor suction pipe on / off is opened. The valve 222 is set to be closed, and in the heat generation unit 300, the heat generation unit refrigerant flow rate adjustment valve 350 is set to be fully closed.

  The high-temperature and high-pressure air-conditioning refrigerant compressed by the air-conditioning compressor 110 flows into the gas pipe 150 and reaches the indoor unit 200. The air-conditioning refrigerant that has reached the indoor unit 200 flows into the indoor heat exchanger 215 via the indoor gas pipe opening / closing valve 221 and radiates heat to the indoor air to perform heating. In this process, the air-conditioning refrigerant is condensed and liquefied, flows into the liquid pipe 170 via the fully opened indoor refrigerant flow rate adjustment valve 220, and returns to the outdoor unit 100.

  The air-conditioning refrigerant that has returned to the outdoor unit 100 is decompressed by the outdoor refrigerant flow control valve 120 to be in a low-temperature and low-pressure gas-liquid two-phase state, and then enters the outdoor air heat exchanger 115, and the air around the outdoor unit 100 Evaporates when heated. The evaporated and vaporized refrigerant for air conditioning returns to the air conditioning compressor 110 via the outdoor suction pipe on-off valve 122 and the accumulator 111.

  During the hot water supply independent operation, in the outdoor unit 100, the outdoor gas pipe on / off valve 121 is closed and the outdoor suction pipe on / off valve 122 is set to open. In the indoor unit 200, the indoor gas pipe on / off valve 221 and the indoor suction pipe on / off valve 222 are set. Are both closed, and in the heat generation unit 300, the heat generation unit refrigerant flow rate adjustment valve 350 is opened.

  The high-temperature and high-pressure air-conditioning refrigerant compressed by the air-conditioning compressor 110 flows into the gas pipe 150 and reaches the heat generation unit 300. On the other hand, in the heat generating unit 300, the hot water supply compressor 310 is operated, and the hot water supply refrigerant is the hot water supply compressor 310, the hot water supply heat exchanger 320, the hot water supply refrigerant flow rate adjustment valve 330, and the cascade heat exchanger 340. It circulates in the order.

The air-conditioning refrigerant that has reached the heat generating unit 300 heats the hot water supply refrigerant in the cascade heat exchanger 340 and cools and liquefies itself, and then passes through the heat generating unit refrigerant flow rate adjustment valve 350 to the liquid pipe. It flows into 170 and returns to the outdoor unit 100.
The air-conditioning refrigerant that has returned to the outdoor unit 100 is decompressed by the outdoor refrigerant flow control valve 120 to be in a low-temperature and low-pressure gas-liquid two-phase state, and then enters the outdoor air heat exchanger 115, and the air around the outdoor unit 100 Evaporates when heated. The evaporated and vaporized refrigerant for air conditioning returns to the air conditioning compressor 110 via the outdoor suction pipe on-off valve 122 and the accumulator 111.

  On the other hand, the hot water supply refrigerant heated by the air conditioning refrigerant in the cascade heat exchanger 340 is vaporized and enters the hot water supply compressor 310. The hot water supply refrigerant compressed to a high temperature and high pressure by the hot water supply compressor 310 enters the hot water supply heat exchanger 320 and heats the heat medium to 70 to 90 ° C. In this process, the hot water supply refrigerant is cooled and liquefied, decompressed by the hot water supply refrigerant flow rate adjustment valve 330, and then returned to the cascade heat exchanger 340 again.

If the cooling load and the heating load are substantially equal during the simultaneous cooling and heating operation, both the outdoor gas pipe opening / closing valve 121 and the outdoor intake pipe opening / closing valve 122 are set to be closed in the outdoor unit 100.
In the indoor unit 200 that performs cooling, the indoor gas pipe open / close valve 221 is closed and the indoor intake pipe open / close valve 222 is set to open. In the indoor unit 200 that performs heating, the indoor gas pipe open / close valve 221 is opened and the indoor intake pipe open / close is opened. Valve 222 is set to closed. Further, in the heat generation unit 300, the heat generation unit refrigerant flow rate adjustment valve 350 is set to be fully closed.

  The high-temperature and high-pressure air-conditioning refrigerant compressed by the air-conditioning compressor 110 flows into the gas pipe 150 and reaches the indoor unit 200 that performs heating. The air-conditioning refrigerant that has reached the indoor unit 200 that performs heating flows into the indoor heat exchanger 215 via the indoor gas pipe opening / closing valve 221, dissipates heat to the indoor air, and performs heating. In this process, the air-conditioning refrigerant is condensed and liquefied, and flows into the liquid pipe 170 through the fully opened indoor refrigerant flow rate adjustment valve 220.

  The liquid-state air-conditioning refrigerant that has flowed into the liquid pipe 170 reaches the indoor unit 200 that performs cooling. The air-conditioning refrigerant that has reached the indoor unit 200 for cooling is decompressed by the indoor refrigerant flow rate adjustment valve 220 to be in a low-temperature and low-pressure gas-liquid two-phase state, and then flows into the indoor heat exchanger 215 from the indoor air. Take away heat and cool. In this process, the air-conditioning refrigerant evaporates, enters the suction pipe 160 via the indoor suction pipe opening / closing valve 222, and returns to the outdoor unit 100. The air conditioning refrigerant that has returned to the outdoor unit 100 returns to the air conditioning compressor 110 via the accumulator 111.

When the cooling load is larger than the heating load, since there is not enough liquid refrigerant to be supplied from the indoor unit 200 that performs heating to the indoor unit 200 that performs cooling, a part of the outdoor unit 100 performs outdoor air heat exchange. It is generated by the device 115.
That is, the outdoor gas pipe on / off valve 121 is opened while the outdoor suction pipe on / off valve 122 is closed, and a part of the refrigerant discharged from the air conditioning compressor 110 is supplied to the outdoor air heat exchanger 115 to be liquefied. Then, the refrigerant is supplied to the indoor unit 200 that performs cooling via the outdoor refrigerant flow rate adjustment valve 120 and the liquid pipe 170.

On the contrary, when the heating load is larger than the cooling load, the liquid refrigerant supplied from the indoor unit 200 that performs heating cannot be completely evaporated in the indoor unit 200 that performs cooling. Evaporation is performed by the outdoor air heat exchanger 115 of the outdoor unit 100.
That is, the outdoor suction pipe on / off valve 122 is opened while the outdoor gas pipe on / off valve 121 is closed, and the liquid refrigerant flowing out from the indoor unit 200 for heating is returned to the outdoor unit 100 via the liquid pipe 170. The liquid refrigerant that has returned to the outdoor unit 100 is depressurized by the outdoor refrigerant flow control valve 120 and then evaporated by the outdoor air heat exchanger 115. The vaporized air-conditioning refrigerant returns to the accumulator 111 and the air-conditioning compressor 110 via the outdoor suction pipe opening / closing valve 122.

If the cooling load and the hot water supply load are substantially equal during the simultaneous operation of cooling and hot water supply, in the outdoor unit 100, both the outdoor gas pipe open / close valve 121 and the outdoor intake pipe open / close valve 122 are set to be closed.
In the indoor unit 200 that performs cooling, the indoor gas pipe opening / closing valve 221 is closed, the indoor intake pipe opening / closing valve 222 is set to open, and the heat generation unit refrigerant flow rate adjustment valve 350 is opened in the heat generation unit 300.

  The high-temperature and high-pressure air-conditioning refrigerant compressed by the air-conditioning compressor 110 flows into the gas pipe 150 and reaches the heat generation unit 300. On the other hand, in the heat generating unit 300, the hot water supply compressor 310 is operated, and the hot water supply refrigerant is the hot water supply compressor 310, the hot water supply heat exchanger 320, the hot water supply refrigerant flow rate adjustment valve 330, and the cascade heat exchanger 340. It circulates in the order.

  The air-conditioning refrigerant that has reached the heat generating unit 300 heats the hot water supply refrigerant in the cascade heat exchanger 340 and cools and liquefies itself, and then passes through the heat generating unit refrigerant flow rate adjustment valve 350 to the liquid pipe. Flows into 170.

The liquid-state air-conditioning refrigerant that has flowed into the liquid pipe 170 reaches the indoor unit 200 that performs cooling. The air-conditioning refrigerant that has reached the indoor unit 200 for cooling is decompressed by the indoor refrigerant flow rate adjustment valve 220 to be in a low-temperature and low-pressure gas-liquid two-phase state, and then flows into the indoor heat exchanger 215 from the indoor air. Take away heat and cool.
In this process, the air-conditioning refrigerant evaporates, enters the suction pipe 160 via the indoor suction pipe opening / closing valve 222, and returns to the outdoor unit 100. The air conditioning refrigerant that has returned to the outdoor unit 100 returns to the air conditioning compressor 110 via the accumulator 111.

On the other hand, the hot water supply refrigerant heated by the air conditioning refrigerant in the cascade heat exchanger 340 is vaporized and enters the hot water supply compressor 310. The hot water supply refrigerant compressed to a high temperature and high pressure by the hot water supply compressor 310 enters the hot water supply heat exchanger 320 and heats the heat medium to 70 to 90 ° C.
In this process, the hot water supply refrigerant is cooled and liquefied, and is depressurized by the hot water supply refrigerant flow rate adjustment valve 330, and then returns to the cascade heat exchanger 340 again.

When the cooling load is larger than the hot water supply load, since there is not enough liquid refrigerant to be supplied from the heat generation unit 300 to the indoor unit 200 that performs cooling, a part of the refrigerant is generated by the outdoor air heat exchanger 115 of the outdoor unit 100. To do.
That is, with the outdoor suction pipe on / off valve 122 closed, the outdoor gas pipe on / off valve 121 is opened, and a part of the refrigerant discharged from the air conditioning compressor 110 is supplied to the outdoor air heat exchanger 115 to be liquefied. Then, the refrigerant is supplied to the indoor unit 200 that performs cooling via the outdoor refrigerant flow rate adjustment valve 120 and the liquid pipe 170.

On the other hand, when the hot water supply load is larger than the cooling load, the liquid refrigerant supplied from the heat generation unit 300 cannot be completely evaporated in the indoor unit 200 that performs cooling. The outdoor air heat exchanger 115 evaporates.
That is, the outdoor suction pipe on / off valve 122 is opened while the outdoor gas pipe on / off valve 121 is closed, and a part of the liquid refrigerant flowing out from the indoor unit 200 that performs heating is returned to the outdoor unit 100 via the liquid pipe 170. .

  The liquid refrigerant that has returned to the outdoor unit 100 is depressurized by the outdoor refrigerant flow control valve 120 and then evaporated by the outdoor air heat exchanger 115. The vaporized air-conditioning refrigerant returns to the accumulator 111 and the air-conditioning compressor 110 via the outdoor suction pipe opening / closing valve 122.

  During simultaneous operation of heating and hot water supply, in the outdoor unit 100, the outdoor gas pipe on / off valve 121 is closed and the outdoor suction pipe on / off valve 122 is set to open. In the indoor unit 200, the indoor gas pipe on / off valve 221 is opened, The suction pipe opening / closing valve 222 is set to be closed, and the heat generation unit refrigerant flow rate adjustment valve 350 is opened in the heat generation unit 300.

  The high-temperature and high-pressure air-conditioning refrigerant compressed by the air-conditioning compressor 110 flows into the gas pipe 150 and reaches the indoor unit 200 and the heat generation unit 300. The air-conditioning refrigerant that has reached the indoor unit 200 flows into the indoor heat exchanger 215 via the indoor gas pipe opening / closing valve 221 and radiates heat to the indoor air to perform heating. In this process, the air-conditioning refrigerant is condensed and liquefied, and flows into the liquid pipe 170 through the fully opened indoor refrigerant flow rate adjustment valve 220.

The air-conditioning refrigerant that has reached the heat generating unit 300 heats the hot water supply refrigerant in the cascade heat exchanger 340 and cools and liquefies itself, and then passes through the heat generating unit refrigerant flow rate adjustment valve 350 to the liquid pipe. Flows into 170.
This liquid refrigerant merges with the liquid refrigerant that has flowed out of the indoor unit 200 that performs heating, and returns to the outdoor unit 100. The liquid refrigerant returned to the outdoor unit is depressurized by the outdoor refrigerant flow control valve 120 and then evaporated by the outdoor air heat exchanger 115. The vaporized air-conditioning refrigerant returns to the accumulator 111 and the air-conditioning compressor 110 via the outdoor suction pipe opening / closing valve 122.

On the other hand, the hot water supply refrigerant heated by the air conditioning refrigerant in the cascade heat exchanger 340 is vaporized and enters the hot water supply compressor 310. The hot water supply refrigerant compressed to a high temperature and high pressure by the hot water supply compressor 310 enters the hot water supply heat exchanger 320 and heats the heat medium to 70 to 90 ° C.
In this process, the hot water supply refrigerant is cooled and liquefied, decompressed by the hot water supply refrigerant flow rate adjustment valve 330, and then returned to the cascade heat exchanger 340 again.

During simultaneous operation of cooling, heating and hot water supply, if the sum of the cooling load and the heating load and hot water supply load is substantially equal, in the outdoor unit 100, both the outdoor gas pipe open / close valve 121 and the outdoor intake pipe open / close valve 122 are closed. Set to.
In the indoor unit 200 that performs cooling, the indoor gas pipe open / close valve 221 is closed and the indoor intake pipe open / close valve 222 is set to open. In the indoor unit 200 that performs heating, the indoor gas pipe open / close valve 221 is opened and the indoor intake pipe open / close is opened. Valve 222 is set to closed. In the heat generation unit 300, the heat generation unit refrigerant flow rate adjustment valve 350 is opened.

The high-temperature and high-pressure air-conditioning refrigerant compressed by the air-conditioning compressor 110 flows into the gas pipe 150 and reaches the indoor unit 200 and the heat generation unit 300 that perform heating. On the other hand, in the heat generating unit 300, the hot water supply compressor 310 is operated, and the hot water supply refrigerant is the hot water supply compressor 310, the hot water supply heat exchanger 320, the hot water supply refrigerant flow rate adjustment valve 330, and the cascade heat exchanger 340. It circulates in the order.
The air-conditioning refrigerant that has reached the indoor unit 200 that performs heating flows into the indoor heat exchanger 215 via the indoor gas pipe opening / closing valve 221, dissipates heat to the indoor air, and performs heating. In this process, the air-conditioning refrigerant is condensed and liquefied, and flows into the liquid pipe 170 through the fully opened indoor refrigerant flow rate adjustment valve 220.

The air-conditioning refrigerant that has reached the heat generating unit 300 heats the hot water supply refrigerant in the cascade heat exchanger 340 and cools and liquefies itself, and then passes through the heat generating unit refrigerant flow rate adjustment valve 350 to the liquid pipe. Flows into 170.
The indoor unit 200 that performs heating and the liquefied air-conditioning refrigerant that has flowed into the liquid pipe 170 from the heat generation unit 300 merge to reach the indoor unit 200 that performs cooling.
The air-conditioning refrigerant that has reached the indoor unit 200 for cooling is decompressed by the indoor refrigerant flow rate adjustment valve 220 to be in a low-temperature and low-pressure gas-liquid two-phase state, and then flows into the indoor heat exchanger 215 from the indoor air. Take away heat and cool. In this process, the air-conditioning refrigerant evaporates, enters the suction pipe 160 via the indoor suction pipe opening / closing valve 222, and returns to the outdoor unit 100.
The air conditioning refrigerant that has returned to the outdoor unit 100 returns to the air conditioning compressor 110 via the accumulator 111.

On the other hand, the hot water supply refrigerant heated by the air conditioning refrigerant in the cascade heat exchanger 340 is vaporized and enters the hot water supply compressor 310. The hot water supply refrigerant compressed to a high temperature and high pressure by the hot water supply compressor 310 enters the hot water supply heat exchanger 320 and heats the heat medium to 70 to 90 ° C.
In this process, the hot water supply refrigerant is cooled and liquefied, decompressed by the hot water supply refrigerant flow rate adjustment valve 330, and then returned to the cascade heat exchanger 340 again.

Note that when the cooling load is larger than the sum of the heating load and the hot water supply load, there is not enough liquid refrigerant to be supplied from the indoor unit 200 that performs heating and the indoor unit 200 that performs cooling from the heat generation unit 300. Is generated by the outdoor air heat exchanger 115 of the outdoor unit 100.
That is, the outdoor gas pipe on / off valve 121 is opened while the outdoor suction pipe on / off valve 122 is closed, and a part of the refrigerant discharged from the air conditioning compressor 110 is supplied to the outdoor air heat exchanger 115 to be liquefied. Then, the refrigerant is supplied to the indoor unit 200 that performs cooling via the outdoor refrigerant flow rate adjustment valve 120 and the liquid pipe 170.

On the other hand, when the sum of the heating load and the hot water supply load is larger than the cooling load, the liquid refrigerant supplied from the indoor unit 200 that performs heating and the heat generation unit 300 cannot be completely evaporated in the indoor unit 200 that performs cooling. A part of the liquid refrigerant is evaporated by the outdoor air heat exchanger 115 of the outdoor unit 100.
That is, the outdoor suction pipe on / off valve 122 is opened while the outdoor gas pipe on / off valve 121 is closed, and a part of the liquid refrigerant flowing out from the indoor unit 200 for heating and the heat generating unit 300 is passed through the liquid pipe 170. Return to the outdoor unit 100.

  The liquid refrigerant that has returned to the outdoor unit 100 is depressurized by the outdoor refrigerant flow control valve 120 and then evaporated by the outdoor air heat exchanger 115. The vaporized air-conditioning refrigerant returns to the accumulator 111 and the air-conditioning compressor 110 via the outdoor suction pipe opening / closing valve 122.

Next, the operation of the heat medium in the heat generation unit 300 will be described with reference to FIGS.
The hot water supply compressor 310 and the heat medium pump 360 operate during a single hot water supply operation, a simultaneous operation of cooling and hot water supply, a simultaneous operation of heating and hot water supply, and a simultaneous operation of cooling, heating and hot water supply.
While the heat medium pump 360 is in operation, the heat medium flows into the heat generation unit 300 from outside the heat generation unit 300 such as a water supply, and enters the heat medium pump 360 through the heat medium pipe 380a.

The heat medium flowing into the heat medium pump 360 flows into the heat medium pipe 380b from the discharge port and enters the heat exchanger 320 for hot water supply. The heat medium exchanges heat with the hot water supply refrigerant discharged from the hot water supply compressor 310 in the hot water supply heat exchanger 320 which is a double-pipe heat exchanger, and is heated to 70 to 90 ° C. It is sent out of the heat generation unit 300 via the heat medium pipe 380c.
In the air conditioning and hot water supply system, when hot water is stored in the hot water storage tank, water having a relatively low temperature below the hot water storage tank is supplied to the heat generating unit 300. However, when hot water in the hot water storage tank has accumulated, the heat generating unit The temperature of the water supplied to 300 rises gradually, so-called boiling end operation.

  As is clear from the above description, in the present embodiment, a double-pipe heat exchanger composed of an outer tube 420 and an inner tube 410 is used as the cascade heat exchanger 340, and hot water supply refrigerant is circulated to the inner tube 410. Therefore, in the so-called end-of-boiling operation where the incoming water temperature rises, even when the flow form of the high-stage refrigerant is dominated by the annular flow, the liquid-phase refrigerant as the heat absorption source is closely concentrated on the inner pipe inner surface. In addition, even when the superheated gas state is dominant as the state of the low-stage refrigerant in the operation at the end of boiling, the oil film that becomes the thermal resistance is closely concentrated on the inner surface of the outer tube 420, and the superheated gas that is the heat medium It becomes easy for the refrigerant to come into contact with the outer surface of the inner tube 410 that is the heat transfer surface.

Therefore, even when the incoming water temperature supplied to the heat generation unit 300 becomes high in the operation after boiling, heat is efficiently exchanged between the high-stage side refrigerant and the low-stage side refrigerant in the cascade heat exchanger 340. The operating efficiency of the system can be improved.
In addition, even when the air conditioning load increases and the condensation temperature of the air conditioning refrigerant flowing through the first circuit 501 decreases, the inner pipe 410 of the cascade heat exchanger 340 that causes the efficiency of the first refrigeration cycle 500 to decrease Since it is possible to prevent the refrigeration oil from staying in the branch portion connected to the hot water supply refrigerant pipe and suppress the pressure loss of the hot water supply refrigerant, the efficiency of the first refrigeration cycle 500 can be increased.

  Further, in the present embodiment, the outer pipe 420 and the air conditioning refrigerant pipe are connected at a branch portion where the inner pipe 410 and the outer pipe 420 of the cascade heat exchanger 340 are connected to the hot water supply refrigerant pipe and the air conditioning refrigerant pipe, respectively. The inner pipe 410 and the hot water supply refrigerant pipe are connected in the vicinity of the branch portion in the cascade heat exchanger 340. Since the air conditioning load increases and the condensation temperature of the air conditioning refrigerant flowing through the first circuit 501 decreases, the first refrigeration is performed. The pressure loss of the hot water supply refrigerant can be suppressed at the branch portion where the inner pipe 410 of the cascade heat exchanger 340 and the hot water supply refrigerant pipe that cause the efficiency reduction of the cycle 500 are connected. It is possible to increase the efficiency of the freezing cycle 500.

  The present invention is an air-conditioning hot water supply system capable of simultaneously supplying hot and cold heat necessary for cooling, heating, and hot water supply. Even when the incoming water temperature becomes high after boiling, the heat of the high-stage refrigerant and the low-stage refrigerant in the cascade heat exchanger 340 It can be suitably used as one that provides a hot water supply system with high operating efficiency without lowering the transmission rate.

DESCRIPTION OF SYMBOLS 100 Outdoor unit 110 Air-conditioning compressor 115 Outdoor heat exchanger 150 Gas pipe 160 Intake pipe 170 Liquid pipe 200 Indoor unit 215 Indoor heat exchanger 220 Indoor unit refrigerant flow rate adjustment valve 300 Heat generating unit 310 Hot water supply compressor 320 Hot water supply heat Exchanger 330 Hot water supply refrigerant flow rate adjustment valve 340 Cascade heat exchanger 350 Heat generation unit refrigerant flow rate adjustment valve 360 Heat medium pump 380 Heat medium pipe 390 Drain port 400 Side plate member 410 Inner pipe 420 Outer pipe 500 First refrigeration cycle 501 First Circuit 502 Second circuit 510 Second refrigeration cycle

Claims (2)

A hot water supply compressor that compresses the hot water supply refrigerant, a hot water supply heat exchanger that exchanges heat between the hot water supply refrigerant and the hot water heating medium, a hot water supply refrigerant flow rate adjustment valve that controls the flow rate of the hot water supply refrigerant, and a hot water supply A first refrigeration cycle in which a cascade heat exchanger for exchanging heat between the refrigerant and the air-conditioning refrigerant is annularly connected;
A first circuit in which the cascade heat exchanger and a heat generation unit refrigerant flow rate regulating valve for controlling a flow rate of the air conditioning refrigerant supplied to the cascade heat exchanger are connected in series; the air conditioning refrigerant and room air; At least one second circuit in which an indoor heat exchanger for exchanging heat and an indoor unit refrigerant flow rate adjusting valve for controlling the flow rate of the air-conditioning refrigerant supplied to the indoor heat exchanger are connected in series, and And a second refrigeration cycle connected to an air conditioning compressor that compresses the air conditioning refrigerant and an outdoor heat exchanger.
In the air conditioning and hot water supply system equipped with
An air-conditioning hot water supply system using a double-pipe heat exchanger composed of an outer pipe and an inner pipe as the cascade heat exchanger, and circulating a hot water supply refrigerant through the inner pipe.   In the branch section where the inner pipe and the outer pipe of the cascade heat exchanger are connected to a hot water supply refrigerant pipe and an air conditioning refrigerant pipe, respectively, the outer pipe and the air conditioning refrigerant pipe are connected to the inside of the cascade heat exchanger. The hot water supply refrigerant that is connected in a direction substantially perpendicular to the flow direction of the air conditioning refrigerant that flows in the vicinity of the branch portion and that flows through the inner pipe and the hot water supply refrigerant pipe in the vicinity of the branch portion in the cascade heat exchanger The air-conditioning hot-water supply system according to claim 1, wherein the air-conditioning hot-water supply system is connected in a substantially horizontal direction with respect to the flow direction.

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