EP3882538B1

EP3882538B1 - Heat pump system having hot water preparation function and control method

Info

Publication number: EP3882538B1
Application number: EP19885035.6A
Authority: EP
Inventors: Yujun Liu; Lei Yang; Xiaowei Liu; Xianghua GUAN
Original assignee: Haier Smart Home Co Ltd; Qingdao Economic and Technological Development Zone Haier Water Heater Co Ltd; Qingdao Haier New Energy Electric Appliance Co Ltd
Current assignee: Haier Smart Home Co Ltd; Qingdao Economic and Technological Development Zone Haier Water Heater Co Ltd; Qingdao Haier New Energy Electric Appliance Co Ltd
Priority date: 2018-11-14
Filing date: 2019-06-12
Publication date: 2023-12-06
Anticipated expiration: 2039-06-12
Also published as: EP3882538A4; EP3882538A1; WO2020098263A1; CN111189138A; EP3882538C0

Description

The present invention belongs to the field of home appliances, in particular relates to a heat pump system with a water heating function comprising the features of the preamble portion of claim 1 and further relates to a control method for the heat pump system with a water heating function.
With the continuous improvement of people's living standards, installing air conditioning systems in living and indoor working environments to improve the comfort of living and working environments has become an important choice for people to meet the demand of improving the comfort. An air conditioner manufactured by virtue of a heat pump system has the advantages such as high efficiency, energy conservation and convenience in installation and maintenance so as to be an important direction to the development of an existing air conditioning technology. An existing heat pump system is generally composed of a compressor, an indoor heat exchanger, a throttling device and an outdoor heat exchanger which are connected by a pipeline to form a circulation flow passage. A refrigerant continuously flows in the circulation flow passage to exchange heat with an indoor airflow so as to correspondingly regulate the indoor temperature in a heat exchange manner. Meanwhile, in order to achieve a dual purpose of heating and refrigerating the indoor airflow, generally, the circulation flow passage is provided with a control valve group to correspondingly regulate a flow direction of the refrigerant in the circulation flow passage, thereby achieving the dual effect of heating and refrigerating the indoor airflow.
However, air conditioning equipment composed of the heat pump system still has the following problems:
when the outdoor heat exchanger of the heat pump system works as a condenser, before flowing through the outdoor heat exchanger so as to be condensed, the refrigerant which is not condensed may have a great deal of residual heat. At present, generally, the refrigerant directly flows through the outdoor heat exchanger so as to be condensed, but residual heat in the refrigerant which is not condensed is not collected, which results in heat loss of the overall heat pump system.
In addition, in a working process of the heat pump system, a dew-point temperature of the refrigerant is reduced due to the residual heat in the refrigerant which is not condensed, so that the refrigerant is not prone to generate condensed water and is low in condensation efficiency during condensation, furthermore, the operating efficiency of the overall heat pump system is affected, and the energy consumption is increased.
A heat pump system with a water heating function comprising the features of the preamble portion of claim 1 is known EP 2 891 849 A1 and also from CN 201 935 475 U .The technical problem to be solved by the present invention is to provide a alternative heat pump system with a water heating function to overcome defects in the prior art, namely integrating heating and refrigerating regulation of the indoor temperature of a user's home and preparation of hot water used by the user's home, and recycling residual heat in a refrigerant which is not condensed in the heat pump system for reducing the energy consumption and increasing the efficiency.
This technical problem is solved by a heat pump system with a water heating function comprising the features of claim 1 and further by a control method as indicated in claim 4.
Advantageous embodiments are indicated in further claims.
After the above-mentioned technical solutions are adopted, compared with the prior art, the present invention has the following beneficial effects.

1. Due to the above-mentioned arrangement and control method, the purpose of integrating functions of heating and refrigerating regulation of the indoor temperature of the user's home and preparation of hot water used by the user's home on a single system is achieved, and the effect of integrally setting the functions of regulating and controlling the indoor temperature of the user' home, and/or heating and preparing the hot water used by the user's home is achieved.
2. In a refrigerating process of the indoor temperature, the compressed refrigerant firstly flows through the water tank to heat the water stored in the water tank, and then enters the outdoor heat exchanger so as to be condensed, so that the purpose of recycling the residual heat in the refrigerant which is not condensed in the heat pump system is achieved, and then, the effects of reducing the energy consumption and increasing the efficiency are achieved.

Specific implementation modes of the present invention will be further described in detail below in conjunction with accompanying drawings.
The accompanying drawing serving as a part of the present disclosure is provided for further understanding of the present disclosure. Exemplary embodiments of the present disclosure and their descriptions are intended to explain the present disclosure, rather than to constitute improper limitations on the present disclosure. Obviously, the accompanying drawing in the following description is merely some embodiments. Those of ordinary skill in the art can also obtain other accompanying drawings derived from this accompanying drawing without creative work. In the accompanying drawing:

Fig. 1: is a schematic diagram showing a structure of a heat pump system with a water heating function in accordance with the present invention.

Description for main elements in the drawing:
1-compressor, 2-first four-way valve, 3-second four-way valve, 4-second heat exchanger, 5-first heat exchanger, 6-throttling device, 7-outdoor heat exchanger, 8-outdoor fan, 9-outdoor fan motor, 10-first control valve, 11-second control valve, 12-third control valve, and 13-fourth control valve.
It should be noted that this accompanying drawing and text description are intended to describe the concept of the present invention for those skilled in the art with reference to specific embodiments.
In the description, it should be noted that orientation or positional relationships indicated by terms such as "upper", "lower", "front", "rear", "left", "right", "vertical", "inner" and "outer" are orientation or positional relationship based on the accompanying drawings, are merely intended to facilitate describing of the present invention and simplifying of the description, rather than to indicate or imply that the appointed device or element must have a specific orientation or be constructed and operated in the specific orientation so as not to be understood as restrictions on the present disclosure.
In the description, it should be noted that terms "installation", "connected" and "connection" should be understood in a broad sense unless otherwise specified and defined, for example, "connection" can be fixed connection or detachable connection or integrated connection, can be mechanical connection or electrical connection, and can be direct connection or indirect connection through an intermediate medium. For those of ordinary skill in the art, specific meanings of the above-mentioned terms in the present disclosure can be understood according to specific situations.
As shown in Fig. 1, an embodiment of the present invention introduces a heat pump system with a water heating function. The heat pump system comprises a compressor 1, an indoor heat exchanger, a throttling device 6 and an outdoor heat exchanger 7 which are connected by a pipeline to form a circulation flow passage, wherein the circulation flow passage is provided with a first control device to switch a flow direction of a refrigerant in the circulation flow passage; and the indoor heat exchanger comprises a first heat exchanger 5 for exchanging heat of an indoor airflow and a second heat exchanger 4 for exchanging heat of a water tank of a water heater, and the circulation flow passage is provided with a second control device, so that the first heat exchanger 5 or the second heat exchanger 4 is separately connected into the circulation flow passage or the first heat exchanger 5 and the second heat exchanger 4 are jointly connected into the circulation flow passage.
Due to the above-mentioned arrangement, the purpose of integrating functions of heating and refrigerating regulation of the indoor temperature of a user's home and preparation of hot water used by the user's home on a single system is achieved, and the effect of integrally setting the functions of regulating the indoor temperature of the user's home, and/or heating and preparing the hot water used by the user's home is achieved.
In the embodiment, the circulation flow passage is provided with a first four-way valve 2 and a second four-way valve 3, the first four-way valve 2 has four ports a, b, c and d, the second four-way valve 3 has four ports e, f, g and h, and each port is correspondingly connected with a corresponding component in the system by a corresponding pipeline so as to control the flow direction of the refrigerant in the circulation flow passage.
In the embodiment, the port a of the first four-way valve 2 is connected with an outlet of the compressor 1 by a pipeline, the port b of the first four-way valve 2 is connected with the port e of the second four-way valve 3, the port c of the first four-way valve 2 is connected with an inlet of the compressor 1 by a pipeline, and the port d of the first four-way valve 2 is connected with a first port of the first heat exchanger 5; and the port e of the second four-way valve 3 is connected with the port b of the first four-way valve 2, the port f of the second four-way valve 3 is connected with an inlet of the second heat exchanger 4, the port g of the second four-way valve 3 is connected, by a fourth connecting pipeline, to a pipeline connected between the port c of the first four-way valve and the inlet of the compressor 1, the port h of the second four-way valve 3 is connected with an outlet of the second heat exchanger 3 by a second connecting pipeline, and the port h of the second four-way valve 3 is connected with a first port of the outdoor heat exchanger 7 by a pipeline.
In the embodiment, a second port of the first heat exchanger 5 is connected with a first port of the throttling device 6 by a first connecting pipeline, and a second port of the throttling device 6 is connected with a second port of the outdoor heat exchanger 7 by a pipeline; and a third connecting pipeline communicates with the second connecting pipeline by the first connecting pipeline.
In the embodiment, the first connecting pipeline, the second connecting pipeline, the third connecting pipeline and the fourth connecting pipeline are respectively provided with a first control valve 10, a second control valve 11, a third control valve 12 and a fourth control valve 13 for controlling the corresponding pipelines to be connected or disconnected.
In the embodiment, the second control valve 11 is arranged between an intersection of the first connecting pipeline and the second connecting pipeline and the second four-way valve 3, and the third control valve 12 is arranged between an intersection of the first connecting pipeline and the third connecting pipeline and the first heat exchanger 5.
In the embodiment, the first heat exchanger 5 and the second heat exchanger 4 are both arranged inside the user's home, and the outdoor heat exchanger 7, the throttling device 6 and the compressor 1 are all arranged outside the user's home; and pipelines, going through the inside and outside of the user's home, in the circulation flow passage are connected by a connector to realize the connection and assembly between an indoor component and an outdoor component of the overall system.
In the embodiment, an outdoor fan 8 is installed at the outdoor heat exchanger 7, and the outdoor fan 8 is driven by an outdoor fan motor 9 to rotate to form an outdoor heat exchange airflow after an outdoor airflow flows through the outdoor heat exchanger, so that the outdoor heat exchange airflow exchanges heat with the refrigerant flowing through the outdoor heat exchanger. Similarly, the inside of the user's home is further provided with an indoor fan for forming an indoor heat exchange airflow after an indoor airflow flows through the first heat exchanger 5, so that the indoor heat exchange airflow exchanges heat with the refrigerant flowing through the first heat exchanger 5.
In the embodiment, the second heat exchanger 4 is a heat exchange pipeline wound on the outer wall of the water tank, and the heat exchange pipeline is arranged in a manner of winding around the water tank from top to bottom; and the upper end of the heat exchange pipeline is the inlet of the second heat exchanger 4, and the lower end of the heat exchange pipeline is the outlet of the second heat exchanger 4. The water tank is further provided with a water inlet allowing water to flow in and a water outlet allowing heated hot water to flow out.
An embodiment further provides a control method for the above-mentioned heat pump system with the water heating function. When water stored in the water tank of the water heater is heated and the indoor airflow is refrigerated by an air conditioning system, the refrigerant flowing out of the compressor firstly exchanges heat with the water stored in a water tank of a heat pump to heat the water stored in the water tank, and then exchanges heat with an outdoor airflow so as to be condensed.
In an indoor refrigerating process, the compressed refrigerant firstly flows through the water tank to heat the water stored in the water tank, and then enters the outdoor heat exchanger so as to be condensed, so that the purpose of recycling the residual heat in the refrigerant which is not condensed in the heat pump system is achieved, and then, the effects of reducing the energy consumption and increasing the efficiency are achieved.
In the embodiment, the heat pump system with the water heating function has four modes including a water heating mode, a refrigerating heat recovery mode, a refrigerating mode and a heating mode respectively corresponding to that the first heat exchanger is separately connected into the circulation flow passage, the first heat exchanger and the second heat exchanger are jointly connected into the circulation flow passage, the second heat exchanger is separately connected into the circulation flow passage, and the second heat exchanger is separately connected into the circulation flow passage.
In the embodiment, the flow direction of the refrigerant in the circulation flow passage in the heating mode is set to be opposite to the flow direction of the refrigerant in the circulation flow passage in the refrigerating mode.
In the embodiment, in the refrigerating heat recovery mode, the first heat exchanger is connected between the outlet of the compressor and the throttling device, the second heat exchanger is connected between the inlet of the compressor and the outdoor heat exchanger, and therefore, before exchanging heat with the outdoor airflow so as to be condensed, the refrigerant exchanges heat with the water stored in the water tank to heat, by virtue of residual heat in the refrigerant before condensation, the water stored in the water tank.
In the embodiment, when the heat pump system with the water heating function is in the water heating mode, the refrigerant circularly flows along the outlet of the compressor, the port a of the first four-way valve, the port b of the first four-way valve, the port e of the second four-way valve, the port f of the second four-way valve, the second heat exchanger, the throttling device, the outdoor heat exchanger, the port h of the second four-way valve, the port g of the second four-way valve and the inlet of the compressor.
When the heat pump system with the water heating function is in the refrigerating heat recovery mode, the refrigerant circularly flows along the outlet of the compressor, the port a of the first four-way valve, the port b of the first four-way valve, the port e of the second four-way valve, the port f of the second four-way valve, the second heat exchanger, the outdoor heat exchanger, the throttling device, the first heat exchanger, the port d of the first four-way valve, the port c of the first four-way valve and the inlet of the compressor.
When the heat pump system with the water heating function is in the heating mode, the refrigerant circularly flows along the outlet of the compressor, the port a of the first four-way valve, the port d of the first four-way valve, the first heat exchanger, the throttling device, the outdoor heat exchanger, the port h of the second four-way valve, the port g of the second four-way valve and the inlet of the compressor.
When the heat pump system with the water heating function is in the refrigerating mode, the refrigerant circularly flows along the outlet of the compressor, the port a of the first four-way valve, the port b of the first four-way valve, the port e of the second four-way valve, the port h of the second four-way valve, the outdoor heat exchanger, the throttling device, the first heat exchanger, the port d of the first four-way valve, the port c of the first four-way valve and the inlet of the compressor.
In the embodiment, when the heat pump system with the water heating function is in the water heating mode, the first control valve on the circulation flow passage is opened, the second control valve on the circulation flow passage is closed, the third control valve on the circulation flow passage is closed, the fourth control valve on the circulation flow passage is opened, the port a of the first four-way valve communicates with the port b of the first four-way valve, the port e of the second four-way valve communicates with the port f of the second four-way valve, and the port g of the second four-way valve communicates with the port h of the second four-way valve.
When the heat pump system with the water heating function is in the refrigerating heat recovery mode, the first control valve on the circulation flow passage is closed, the second control valve on the circulation flow passage is opened, the third control valve on the circulation flow passage is opened, the fourth control valve on the circulation flow passage is closed, the port a of the first four-way valve communicates with the port b of the first four-way valve, the port c of the first four-way valve communicates with the port d of the first four-way valve, and the port e of the second four-way valve communicates with the port f of the second four-way valve.
When the heat pump system with the water heating function is in the heating mode, the first control valve on the circulation flow passage is closed, the second control valve on the circulation flow passage is closed, the third control valve on the circulation flow passage is opened, the fourth control valve on the circulation flow passage is opened, the port a of the first four-way valve communicates with the port d of the first four-way valve, and the port g of the second four-way valve communicates with the port h of the second four-way valve.
When the heat pump system with the water heating function is in the refrigerating mode, the first control valve on the circulation flow passage is closed, the second control valve on the circulation flow passage is closed, the third control valve on the circulation flow passage is opened, the fourth control valve on the circulation flow passage is closed, the port a of the first four-way valve communicates with the port b of the first four-way valve, the port c of the first four-way valve communicates with the port d of the first four-way valve, and the port e of the second four-way valve communicates with the port h of the second four-way valve.
A specific control way for the heat pump system with the water heating function is described as follows:

step S 1, a user selecting a working mode;
step S2, the heating mode being executed, the first control valve on the circulation flow passage being closed, the second control valve on the circulation flow passage being closed, the third control valve on the circulation flow passage being opened, the fourth control valve on the circulation flow passage being opened, the port a of the first four-way valve being communicated with the port d of the first four-way valve, and the port g of the second four-way valve being communicated with the port h of the second four-way valve; and the refrigerant circularly flowing along the outlet of the compressor, the port a of the first four-way valve, the port d of the first four-way valve, the first heat exchanger, the throttling device, the outdoor heat exchanger, the port h of the second four-way valve, the port g of the second four-way valve and the inlet of the compressor;
step S3, the refrigerating mode being executed, it is determined whether a user needs to prepare hot water, if so, step S5 is performed, and if not, step S4 is performed;
step S4, the refrigerating mode under the condition that hot water is not prepared being executed, the first control valve on the circulation flow passage being closed, the second control valve on the circulation flow passage being closed, the third control valve on the circulation flow passage being opened, the fourth control valve on the circulation flow passage being closed, the port a of the first four-way valve being communicated with the port b of the first four-way valve, and the port c of the first four-way valve being communicated with the port d of the first four-way valve, and the port e of the second four-way valve being communicated with the port h of the second four-way valve; and the refrigerant circularly flowing along the outlet of the compressor, the port a of the first four-way valve, the port b of the first four-way valve, the port e of the second four-way valve, the port h of the second four-way valve, the outdoor heat exchanger, the throttling device, the first heat exchanger, the port d of the first four-way valve, the port c of the first four-way valve and the inlet of the compressor;
step S5, the refrigerating heat recovery mode being executed, the first control valve on the circulation flow passage being closed, the second control valve on the circulation flow passage being opened, the third control valve on the circulation flow passage being opened, the fourth control valve on the circulation flow passage being closed, the port a of the first four-way valve being communicated with the port b of the first four-way valve, and the port c of the first four-way valve being communicated with the port d of the first four-way valve, and the port e of the second four-way valve being communicated with the port f of the second four-way valve; and the first heat exchanger being connected between the outlet of the compressor and the throttling device, the second heat exchanger being connected between the inlet of the compressor and the outdoor heat exchanger, and therefore, before exchanging heat with the outdoor airflow so as to be condensed, the refrigerant exchanges heat with the water stored in the water tank to heat, by virtue of residual heat in the refrigerant before condensation, the water stored in the water tank; and
step S6, the water heating mode under the working condition that indoor refrigerating is not performed being executed, the first control valve on the circulation flow passage being opened, the second control valve on the circulation flow passage being closed, the third control valve on the circulation flow passage being closed, the fourth control valve on the circulation flow passage being opened, the port a of the first four-way valve being communicated with the port b of the first four-way valve, the port e of the second four-way valve being communicated with the port f of the second four-way valve, and the port g of the second four-way valve being communicated with the port h of the second four-way valve; and the refrigerant circularly flowing along the outlet of the compressor, the port a of the first four-way valve, the port b of the first four-way valve, the port e of the second four-way valve, the port f of the second four-way valve, the second heat exchanger, the throttling device, the outdoor heat exchanger, the port h of the second four-way valve, the port g of the second four-way valve and the inlet of the compressor.

The above descriptions are merely preferred embodiments of the present invention. Although the preferred embodiments of the present invention have been disclosed as above, they are not intended to limit the present invention. Those skilled in the art can make some alterations or modifications to the embodiments by virtue of the above-mentioned technical contents without departing from the scope of the claims.

Claims

A heat pump system with a water heating function, comprising a compressor (1), an indoor heat exchanger, a throttling device (6) and an outdoor heat exchanger (7) which are connected by a pipeline to form a circulation flow passage, wherein the circulation flow passage is provided with a first control device to switch a flow direction of a refrigerant in the circulation flow passage; the indoor heat exchanger comprises a first heat exchanger (5) for exchanging heat of an indoor airflow and a second heat exchanger (4) for exchanging heat of a water tank of a water heater, and the circulation flow passage is provided with a second control device, so that the first heat exchanger (5) or the second heat exchanger (4) is separately connected into the circulation flow passage, or the first heat exchanger (5) and the second heat exchanger (4) are jointly connected into the circulation flow passage; the first switching device comprises a first four-way valve (2) and the second switching device comprises a second four-way valve (3), the first four-way valve (2) has four ports a, b, c and d, the second four-way valve (3) has four ports e, f, g and h, and each port is correspondingly connected with a corresponding component in the heat pump system by a corresponding pipeline so as to control the flow direction of the refrigerant in the circulation flow passage,
characterized in that,
the port a of the first four-way valve (2) is connected with an outlet of the compressor (1) by a pipeline, the port b of the first four-way valve (2) is connected with the port e of the second four-way valve (3), the port c of the first four-way valve (2) is connected with an inlet of the compressor (1) by a pipeline, and the port d of the first four-way valve (2) is connected with a first port of the first heat exchanger (5); the port e of the second four-way valve (3) is connected with the port b of the first four-way valve (2), the port f of the second four-way valve (3) is connected with an inlet of the second heat exchanger (4), the port g of the second four-way valve (3) is connected, by a fourth connecting pipeline, to a pipeline connected between the port c of the first four-way valve (2) and the inlet of the compressor (1), the port h of the second four-way valve (3) is connected with an outlet of the second heat exchanger (4) by a second connecting pipeline, and the port h of the second four-way valve (3) is connected with a first port of the outdoor heat exchanger (7) by a pipeline.
The heat pump system with a water heating function according to claim 1, characterized in that a second port of the first heat exchanger (5) is connected with a first port of the throttling device (6) by a first connecting pipeline, and a second port of the throttling device (6) is connected with a second port of the outdoor heat exchanger (7) by a pipeline; and a third connecting pipeline communicates with the second connecting pipeline by the first connecting pipeline.
The heat pump system with a water heating function according to claim 2, characterized in that the first connecting pipeline, the second connecting pipeline, the third connecting pipeline and the fourth connecting pipeline are respectively provided with a first control valve (10), a second control valve (11), a third control valve (12) and a fourth control valve (13) for controlling the corresponding pipelines to be connected or disconnected;
preferably, the second control valve (11) is arranged between an intersection of the first connecting pipeline and the second connecting pipeline and the second four-way valve (3), and the third control valve (12) is arranged between an intersection of the first connecting pipeline and the third connecting pipeline and the first heat exchanger (5).
A control method for the heat pump system with a water heating function according to claim 3, characterized in that when water stored in the water tank of the water heater is heated and the indoor airflow is refrigerated by an air conditioning system, the refrigerant flowing out of the compressor (1) firstly exchanges heat with the water stored in a water tank of a heat pump to heat the water stored in the water tank, and then exchanges heat with an outdoor airflow so as to be condensed.
The control method according to claim 4, characterized in that the heat pump system has four modes comprising a water heating mode, a refrigerating heat recovery mode, a refrigerating mode and a heating mode respectively corresponding to that the first heat exchanger (5) is separately connected into the circulation flow passage, the first heat exchanger (5) and the second heat exchanger (4) are jointly connected into the circulation flow passage, the second heat exchanger (4) is separately connected into the circulation flow passage, and the second heat exchanger (4) is separately connected into the circulation flow passage;
preferably, the flow direction of the refrigerant in the circulation flow passage in the heating mode is set to be opposite to the flow direction of the refrigerant in the circulation flow passage in the refrigerating mode.
The control method according to claim 5, characterized in that in the refrigerating heat recovery mode, the first heat exchanger (5) is connected between the outlet of the compressor (1) and the throttling device (6), the second heat exchanger (4) is connected between the inlet of the compressor (1) and the outdoor heat exchanger (7), and before exchanging heat with the outdoor airflow so as to be condensed, the refrigerant exchanges heat with the water stored in the water tank to heat, by virtue of residual heat in the refrigerant before condensation, the water stored in the water tank.
The control method according to claim 6, characterized in that:
in the water heating mode, the refrigerant circularly flows along the outlet of the compressor (1), the port a of the first four-way valve (2), the port b of the first four-way valve (2), the port e of the second four-way valve (3), the port f of the second four-way valve (3), the second heat exchanger (4), the throttling device (6), the outdoor heat exchanger (7), the port h of the second four-way valve (3), the port g of the second four-way valve (3) and the inlet of the compressor (1);

in the refrigerating heat recovery mode, the refrigerant circularly flows along the outlet of the compressor (1), the port a of the first four-way valve (2), the port b of the first four-way valve (2), the port e of the second four-way valve (3), the port f of the second four-way valve (3), the second heat exchanger (4), the outdoor heat exchanger (7), the throttling device (6), the first heat exchanger (5), the port d of the first four-way valve (2), the port c of the first four-way valve (2) and the inlet of the compressor (1);

in the heating mode, the refrigerant circularly flows along the outlet of the compressor (1), the port a of the first four-way valve (2), the port d of the first four-way valve (2), the first heat exchanger (5), the throttling device (6), the outdoor heat exchanger (7), the port h of the second four-way valve (3), the port g of the second four-way valve (3) and the inlet of the compressor (1);

in the refrigerating mode, the refrigerant circularly flows along the outlet of the compressor (1), the port a of the first four-way valve (2), the port b of the first four-way valve (2), the port e of the second four-way valve (3), the port h of the second four-way valve (3), the outdoor heat exchanger (7), the throttling device (6), the first heat exchanger (5), the port d of the first four-way valve (2), the port c of the first four-way valve (2) and the inlet of the compressor (1).
The control method according to claim 7, characterized in that:
in the water heating mode, the first control valve (10) on the circulation flow passage is opened, the second control valve (11) on the circulation flow passage is closed, the third control valve (12) on the circulation flow passage is closed, the fourth control valve (13) on the circulation flow passage is opened, the port a of the first four-way valve (2) communicates with the port b of the first four-way valve (2), the port e of the second four-way valve (3) communicates with the port f of the second four-way valve (3), and the port g of the second four-way valve (3) communicates with the port h of the second four-way valve (3);

in the refrigerating heat recovery mode, the first control valve (10) on the circulation flow passage is closed, the second control valve (11) on the circulation flow passage is opened, the third control valve (12) on the circulation flow passage is opened, the fourth control valve (13) on the circulation flow passage is closed, the port a of the first four-way valve (2) communicates with the port b of the first four-way valve (2), the port c of the first four-way valve (2) communicates with the port d of the first four-way valve (2), and the port e of the second four-way valve (3) communicates with the port f of the second four-way valve (3);

in the heating mode, the first control valve (10) on the circulation flow passage is closed, the second control valve (11) on the circulation flow passage is closed, the third control valve (12) on the circulation flow passage is opened, the fourth control valve (13) on the circulation flow passage is opened, the port a of the first four-way valve (2) communicates with the port d of the first four-way valve (2), and the port g of the second four-way valve (3) communicates with the port h of the second four-way valve (3);

in the refrigerating mode, the first control valve (10) on the circulation flow passage is closed, the second control valve (11) on the circulation flow passage is closed, the third control valve (12) on the circulation flow passage is opened, the fourth control valve (13) on the circulation flow passage is closed, the port a of the first four-way valve (2) communicates with the port b of the first four-way valve (2), the port c of the first four-way valve (2) communicates with the port d of the first four-way valve (2), and the port e of the second four-way valve (3) communicates with the port h of the second four-way valve (3).