EP4692681A1

EP4692681A1 - Heat pump system

Info

Publication number: EP4692681A1
Application number: EP23929887.0A
Authority: EP
Inventors: Yingli Yuan; Demao Yu; Shuang Wu; Xiewen HONG
Original assignee: Tyco Fire and Security GmbH; York Guangzhou Air Conditioning and Refrigeration Co Ltd
Current assignee: Tyco Fire and Security GmbH; York Guangzhou Air Conditioning and Refrigeration Co Ltd
Priority date: 2023-03-29
Filing date: 2023-10-19
Publication date: 2026-02-11
Also published as: WO2024198315A1; KR20260016467A; CN116336698A

Abstract

The present application provides a heat pump system, comprising a first one-way closed pipe assembly and a first discharge pipe assembly; the first discharge pipe assembly comprises a first discharge pipe; the first discharge pipe has a first discharge pipe outlet and a first discharge pipe inlet, the first discharge pipe inlet being connected to a first pipe, and the first discharge pipe outlet being connected to pipes and/or parts in the heat pump system except the first one-way closed pipe assembly. In the heat pump system, the first discharge pipe assembly allows a refrigerant in the first one-way closed pipe assembly to flow out of the first one-way closed pipe assembly, avoiding damage to the first one-way closed pipe assembly.

Description

Technical Field

The present application relates to a heat pump system.

Background Art

A heat pump system includes a compressor, three heat exchangers, and a valve device, and can meet the requirement for providing cooling capacity, heating capacity, and cooling capacity and heating capacity simultaneously to a user. However, when this heat pump system is shut down for maintenance, there may be a phenomenon of pipe rupture. Therefore, there is a need for a heat pump system that can avoid a pipe rupture when shut down for maintenance.

Summary of the Invention

To achieve the above object, the present application provides a heat pump system. The heat pump system includes a first one-way closed pipe assembly and a first discharge pipe assembly. The first discharge pipe assembly includes a first discharge pipe, the first discharge pipe has a first discharge pipe outlet and a first discharge pipe inlet, the first discharge pipe inlet is connected to a first pipe, and the first discharge pipe outlet is connected to pipes and/or parts in the heat pump system except the first one-way closed pipe assembly, thereby discharging a refrigerant in the first one-way closed pipe assembly out of the first one-way closed pipe assembly.
According to the above heat pump system, the first one-way closed pipe assembly is configured so that when the heat pump system is shut down, the refrigerant is capable of entering the first one-way closed pipe assembly and accumulating in the first one-way closed pipe assembly. The first one-way closed pipe assembly includes the first pipe, a stop valve, and at least one first pipe one-way valve. The first pipe has a first pipe outlet and at least one first pipe inlet. The stop valve is arranged at the first pipe outlet. The at least one first pipe one-way valve is correspondingly arranged at the at least one first pipe inlet and is configured to enable a fluid to enter the first pipe through the at least one first pipe one-way valve.
According to the above heat pump system, the first discharge pipe assembly further includes a first discharge one-way valve, and the first discharge one-way valve is arranged on the first discharge pipe and is configured to enable the fluid to flow to the first discharge pipe outlet through the first discharge pipe inlet. The first discharge pipe outlet is connected to at least one of a high-pressure side or a medium-pressure side of the heat pump system.
According to the above heat pump system, the first discharge pipe assembly further includes a first pressure relief valve, and the first pressure relief valve is arranged on the first discharge pipe and is configured to enable the fluid to flow to the first discharge pipe outlet through the first discharge pipe inlet. The first discharge pipe outlet is connected to a low-pressure side of the heat pump system.
According to the above heat pump system, the first pressure relief valve has a first pressure relief valve inlet and a first pressure relief valve outlet, and the first pressure relief valve is configured so that the first pressure relief valve inlet is in communication with the first pressure relief valve outlet when a pressure difference between the first pressure relief valve inlet and the first pressure relief valve outlet is equal to a first predetermined pressure difference or a pressure of the first pressure relief valve inlet is equal to a first predetermined pressure value.
According to the above heat pump system, the heat pump system further includes a second one-way closed pipe assembly and a second discharge pipe assembly. The second discharge pipe assembly comprises a second discharge pipe, the second discharge pipe has a second discharge pipe outlet and a second discharge pipe inlet, the second discharge pipe inlet is connected to a second pipe, and the second discharge pipe outlet is connected to pipes and/or parts in the heat pump system except the second one-way closed pipe assembly, thereby discharging a refrigerant in the second one-way closed pipe assembly out of the second one-way closed pipe assembly.
According to the above heat pump system, the second one-way closed pipe assembly is configured so that when the heat pump system is shut down, the refrigerant is capable of entering the second one-way closed pipe assembly and accumulating in the second one-way closed pipe assembly. The second one-way closed pipe assembly comprises a second pipe, a throttling device, and at least one second pipe one-way valve. The second pipe has a second pipe outlet and at least one second pipe inlet. The throttling device is arranged at the second pipe outlet. The at least one second pipe one-way valve is correspondingly arranged at the at least one second pipe inlet and is configured to enable the fluid to enter the second pipe through the at least one second pipe one-way valve.
According to the above heat pump system, the second discharge pipe assembly further includes a second discharge one-way valve, and the second discharge one-way valve is arranged on the second discharge pipe and is configured to enable the fluid to flow to the second discharge pipe outlet through the second discharge pipe inlet. The second discharge pipe outlet is connected to the high-pressure side of the heat pump system.
According to the above heat pump system, the second discharge pipe assembly further includes a second pressure relief valve, and the second pressure relief valve is arranged on the second discharge pipe and is configured to enable the fluid to flow to the second discharge pipe outlet through the second discharge pipe inlet. The second discharge pipe outlet is connected to the low-pressure side of the heat pump system.
According to the above heat pump system, the second pressure relief valve has a second pressure relief valve inlet and a second pressure relief valve outlet, and the second pressure relief valve is configured so that the second pressure relief valve inlet is in communication with the second pressure relief valve outlet when a pressure difference between the second pressure relief valve inlet and the second pressure relief valve outlet is equal to a second predetermined pressure difference or a pressure of the second pressure relief valve inlet is equal to a second predetermined pressure value. The second discharge pipe outlet is connected to the low-pressure side of the heat pump system.
In the heat pump system of present application, the first discharge pipe assembly allows the refrigerant in the first one-way closed pipe assembly to flow out of the first one-way closed pipe assembly, avoiding damage to the first one-way closed pipe assembly.
Other features, advantages and embodiments of the present application may be set forth or become apparent by consideration of the following detailed description, accompanying drawings and claims. In addition, it should be understood that the above summaries of the invention and the following specific embodiments are all exemplary and intended to provide further explanations rather than limit the scope of the present application to be claimed. However, the detailed description and specific examples indicate only preferred embodiments of the present application. Various changes and modifications within the spirit and scope of the present application will become apparent to those skilled in the art from this detailed description.

Brief Description of the Drawings

The features and advantages of the present application may be better understood by reading the following detailed description with reference to the accompanying drawings, in which like reference numerals refer to like parts throughout.

FIGS. 1A-1B are system diagrams of a first embodiment of a heat pump system of the present application;
FIG. 2 is a system diagram of a second embodiment of the heat pump system of the present application;
FIG. 3 is a system diagram of a third embodiment of the heat pump system of the present application;
FIG. 4 is a system diagram of a fourth embodiment of the heat pump system of the present application;
FIG. 5 is a system diagram of a fifth embodiment of the heat pump system of the present application;
FIG. 6 is a system diagram of a sixth embodiment of the heat pump system of the present application; and
FIG. 7 is a system diagram of a seventh embodiment of the heat pump system of the present application.

Detailed Description of Embodiments

Various specific implementations of the present invention will be described below with reference to the accompanying drawings, which constitute a part of the Specification. It should be understood that ordinal numbers, such as "first" and "second" used in the present application are only for distinction and identification, and do not have any other meaning. Unless otherwise specified, they do not indicate a specific order, nor do they have a specific relevance. For example, the term "first heat exchanger" by itself does not imply the presence of a "second heat exchanger", nor does the term "second heat exchanger" by itself imply the presence of a "first heat exchanger".
FIG. 1A-FIG. 1B are system diagrams of a first embodiment of a heat pump system of the present application to show various parts in the heat pump system and their connection relationships. As shown in FIG. 1A-FIG. 1B, the heat pump system includes a compressor 108, a first heat exchanger 101, a second heat exchanger 102, a third heat exchanger 103, a four-way valve 140, a gas-liquid separator 106, a first one-way closed pipe assembly, a second one-way closed pipe assembly, and other pipes and a plurality of valves to be described below.
The four-way valve 140 includes a four-way valve first port 1401, a four-way valve second port 1402, a four-way valve third port 1403, a four-way valve fourth port 1404, a first communication channel, and a second communication channel. The four-way valve 140 has a first state and a second state. When the four-way valve 140 is in the first state (as shown in FIG. 1A), the first communication channel is in communication with the four-way valve first port 1401 and the four-way valve second port 1402, and the second communication channel is in communication with the four-way valve third port 1403 and the four-way valve fourth port 1404. When the four-way valve 140 is in the second state (as shown in FIG. 1B), the first communication channel is in communication with the four-way valve first port 1401 and the four-way valve fourth port 1404, and the second communication channel is in communication with the four-way valve second port 1402 and the four-way valve third port 1403.
The first one-way closed pipe assembly comprises a first pipe 152, a stop valve 164, and two first pipe one-way valves (i.e., a first pipe first one-way valve 1621 and a first pipe second one-way valve 1622). The first pipe 152 has a first pipe outlet 154 and two first pipe inlets (i.e., a first pipe first inlet 1561 and a first pipe second inlet 1562). The stop valve 164 is arranged at the first pipe outlet 154. The first pipe first one-way valve 1621 and the first pipe second one-way valve 1622 are respectively arranged at the first pipe first inlet 1561 and the first pipe second inlet 1562, and are respectively configured to enable a fluid to enter the first pipe 152 through the first pipe first one-way valve 1621 and the first pipe second one-way valve 1622 respectively. More specifically, the first pipe 152 includes a first main pipe and two first branch pipes. Inlets of the two first branch pipes are a first pipe first inlet 1561 and a first pipe second inlet 1562 respectively. Outlets of the two first branch pipes are connected to an inlet of the first main pipe. An outlet of the first main pipe is the first pipe outlet 154.
The second one-way closed pipe assembly comprises a second pipe 182, a throttling device 131, and two second pipe one-way valves (i.e., a second pipe first one-way valve 1921 and a second pipe second one-way valve 1922). The second pipe 182 has a second pipe outlet 186 and two second pipe inlets (i.e., a second pipe first inlet 1841 and a second pipe second inlet 1842). The throttling device 131 is arranged at the second pipe outlet 186. The second pipe first one-way valve 1921 and the second pipe second one-way valve 1922 are respectively arranged at the second pipe first inlet 1841 and the second pipe second inlet 1842, and are respectively configured to enable the fluid to enter the second pipe 182 through the second pipe first one-way valve 1921 and the second pipe second one-way valve 1922 respectively. More specifically, the second pipe 182 includes a second main pipe and two second branch pipes. Inlets of the two second branch pipes are a second pipe first inlet 1841 and a second pipe second inlet 1842 respectively. Outlets of the two second branch pipes are connected to an inlet of the second main pipe. An outlet of the second main pipe is the second pipe outlet 186.
The four-way valve first port 1401 is connected to a compressor outlet 1082 through a pipe 163. The pipe 163 is provided with a compressor stop valve 165. The four-way valve second port 1402 is connected to a first heat exchanger first port 1011 of the first heat exchanger 101. The four-way valve third port 1403 is connected to an inlet of the first pipe first one-way valve 1621. The four-way valve fourth port 1404 is connected to a third heat exchanger first port 1031 of the third heat exchanger 103. A compressor inlet 1081 is connected to a gas-liquid separator outlet 1062 of the gas-liquid separator 106. A gas-liquid separator inlet 1061 of the gas-liquid separator 106 is connected to an outlet of the stop valve 164. A first heat exchanger second port 1012 of the first heat exchanger 101 is connected to an inlet of the second pipe first one-way valve 1921. A second heat exchanger first port 1021 of the second heat exchanger 102 is connected to the inlet of the second pipe first one-way valve 1921 through a first connecting pipe 1001. In a pipe direction from the second heat exchanger first port 1021 to the second pipe first one-way valve 1921, the first connecting pipe 1001 is sequentially provided with a first electrically controlled valve 1102, a second electrically controlled valve 1104, and a first one-way valve 1003. The first one-way valve 1003 is arranged to enable the fluid to flow from an outlet of the throttling device 131 toward the second pipe first one-way valve 1921. The second heat exchanger second port 1022 of the second heat exchanger 102 is connected to the inlet of the first pipe second one-way valve 1622. A third heat exchanger second port 1032 is connected to the inlet of the second pipe second one-way valve 1922. The outlet of the throttling device 131 is connected to the first connecting pipe 1001 through a second connecting pipe 1004. More specifically, the outlet of the throttling device 131 is connected between the first electrically controlled valve 1102 and the second electrically controlled valve 1104 through the second connecting pipe 1004. In addition, a first end of the third connecting pipe 1005 is connected to the second connecting pipe 1004, and a second end of the third connecting pipe 1005 is connected to the inlet of the second pipe second one-way valve 1922. In a pipe direction from the first end to the second end of the third connecting pipe 1005, the third connecting pipe 1005 is provided with a third electrically controlled valve 1106 and a second one-way valve 1007 sequentially. The second one-way valve 1007 is configured to enable the fluid to flow from the first end toward the second end of the third connecting pipe 1005.
As shown in FIGS. 1A and 1B, the heat pump system further includes a first discharge pipe assembly. The first discharge pipe assembly includes a first discharge pipe 172 and a first discharge one-way valve 178. A first discharge pipe inlet 174 of the first discharge pipe 172 is connected to the first main pipe of the first pipe 152. A first discharge pipe outlet 176 of the first discharge pipe 172 is connected to the second main pipe of the second pipe 182. The first discharge one-way valve 178 is arranged on the first discharge pipe 172 and is configured to enable the fluid to flow to the first discharge pipe outlet 176 through the first discharge pipe inlet 174.
The state of the four-way valve 140 and the communication and dis-communication of the other valves above may all be controlled by a control system (not shown). By adjusting the state of the four-way valve 140 and the communication and dis-communication of the other valves above, the above parts (e.g., the compressor 108, the first heat exchanger 101, the second heat exchanger 102, the third heat exchanger 103, the four-way valve 140, and the gas-liquid separator 106) are controllably in communication and dis-communication. The heat pump system can achieve at least the following three operating conditions, respectively for providing cooling capacity, heat capacity or simultaneously providing cooling capacity and heat capacity.
A flow condition of the refrigerant in pipes when the heat pump system provides cooling capacity is described below in conjunction with FIG. 1A, in which the four-way valve 140 is in the first state, the second electronically controlled valve 1104 and the third electronically controlled valve 1106 are in a switch-off state, and the first electronically controlled valve 1102, the stop valve 164, and the compressor stop valve 165 are in a switch-on state. As shown in FIG. 1A, a high-temperature and high-pressure gaseous refrigerant flowing out of the compressor outlet 1082 flows to the first heat exchanger 101 after sequentially passing through the compressor stop valve 165, the four-way valve first port 1401, and the four-way valve second port 1402. In the first heat exchanger 101, the high-temperature and high-pressure gaseous refrigerant exchanges heat with air, thereby changing into a high-pressure liquid refrigerant. The high-pressure liquid refrigerant flows out of the first heat exchanger 101 and then sequentially flows through the second pipe first one-way valve 1921 to the throttling device 131. The high-pressure liquid refrigerant becomes a low-temperature and low-pressure refrigerant after flowing through the throttling device 131. The low-temperature and low-pressure refrigerant enters the second heat exchanger 102 from the second heat exchanger first port 1021 after passing through the first electronically controlled valve 1102. In the second heat exchanger 102, the low-temperature and low-pressure refrigerant exchanges heat with a higher-temperature fluid on a user side, thereby lowering a temperature of the fluid on the user side to provide a lower-temperature fluid (i.e., to provide cooling capacity) for the user side. The low-temperature and low-pressure refrigerant becomes a low-pressure gaseous refrigerant after exchanging heat with the fluid on the user side in the second heat exchanger 102. The low-pressure gaseous refrigerant flows out of the second heat exchanger second port 1022, then passes through the first pipe second one-way valve 1622, the stop valve 164, and the gas-liquid separator 106, and then enters the compressor 108 from the compressor inlet 1081 again to become a high-temperature and high-pressure gaseous refrigerant, so as to complete the cycle of the refrigerant.
In the above cycle of the refrigerant, the pipe where the refrigerant flows from the compressor outlet 1082, passes through the first heat exchanger 101 and flows to the throttling device 131 is a high-pressure side of the heat pump system. The pipe where the refrigerant flows from throttling device 131, passes through the second heat exchanger 102 and flows to the compressor inlet 1081 is a low-pressure side of the heat pump system. In the above cycle of the refrigerant, the first heat exchanger 101 is a condenser, and the second heat exchanger 102 is an evaporator. In other words, the pipe where the refrigerant flows from the compressor outlet 1082, passes through the condenser and flows to the throttling device 131 is the high-pressure side of the heat pump system. The pipe where the refrigerant flows from throttling device 131, passes through the evaporator and flows to the compressor inlet 1081 is the low-pressure side of the heat pump system.
A flow condition of the refrigerant in pipes when the heat pump system provides heat capacity is described below in conjunction with FIG. 1B, in which the four-way valve 140 is in the second state, the third electronically controlled valve 1106 and the first electronically controlled valve 1102 are in a switch-off state, and the second electronically controlled valve 1104, the stop valve 164, and the compressor stop valve 165 are in a switch-on state. As shown in FIG. 1B, a high-temperature and high-pressure gaseous refrigerant flowing out of the compressor outlet 1082 flows to the third heat exchanger first port 1031 after sequentially passing through the compressor stop valve 165, the four-way valve first port 1401, and the four-way valve fourth port 1404. In the third heat exchanger 103, the high-temperature and high-pressure gaseous refrigerant exchanges heat with a lower-temperature fluid on the user side, thereby increasing a temperature of the fluid on the user side (i.e., providing heat capacity). The high-temperature and high-pressure gaseous refrigerant becomes a high-pressure liquid refrigerant after exchanging heat with the fluid on the user side in the third heat exchanger 103. The high-pressure liquid refrigerant flows out of the third heat exchanger 103 and then flows to the throttling device 131 through the second pipe second one-way valve 1922. The high-pressure liquid refrigerant becomes a low-temperature and low-pressure refrigerant after flowing through the throttling device 131, and enters the first heat exchanger 101 after passing through the second electronically controlled valve 1104 and the first one-way valve 1003 sequentially. In the first heat exchanger 101, the low-temperature and low-pressure refrigerant exchanges heat with air, thereby changing into a low-pressure gaseous refrigerant. The low-pressure gaseous refrigerant flows out of the first heat exchanger first port 1011, then sequentially passes through the four-way valve second port 1402, the four-way valve third port 1403, the first pipe first one-way valve 1621, the stop valve 164, and the gas-liquid separator 106, and then enters the compressor 108 from the compressor inlet 1081 again to become a high-temperature and high-pressure gaseous refrigerant, so as to complete the cycle of the refrigerant.
In the above cycle of the refrigerant, the pipe where the refrigerant flows from the compressor outlet 1082, passes through the third heat exchanger 103 and flows to the throttling device 131 is a high-pressure side of the heat pump system. The pipe where the refrigerant flows from throttling device 131, passes through the first heat exchanger 101 and flows to the compressor inlet 1081 is a low-pressure side of the heat pump system. In the above cycle of the refrigerant, the third heat exchanger 103 is a condenser, and the first heat exchanger 101 is an evaporator. In other words, the pipe where the refrigerant flows from the compressor outlet 1082, passes through the condenser and flows to the throttling device 131 is the high-pressure side of the heat pump system. The pipe where the refrigerant flows from throttling device 131, passes through the evaporator and flows to the compressor inlet 1081 is the low-pressure side of the heat pump system.
In addition, the heat pump system can provide cooling capacity and heat capacity simultaneously. Continuing to refer to FIG. 1B, the four-way valve 140 is in the second state, the third electrically controlled valve 1106 is in a switch-off state, the second electrically controlled valve 1104 is in a switch-off state, and the first electronically controlled valve 1102, the stop valve 164, and the compressor stop valve 165 are in a switch-on state. As shown in FIG. 1B, a high-temperature and high-pressure gaseous refrigerant flowing out of the compressor outlet 1082 flows to the third heat exchanger first port 1031 after sequentially passing through the compressor stop valve 165, the four-way valve first port 1401, and the four-way valve fourth port 1404. In the third heat exchanger 103, the high-temperature and high-pressure gaseous refrigerant exchanges heat with a lower-temperature fluid on the user side, thereby increasing a temperature of the fluid on the user side (i.e., providing heat capacity). The high-temperature and high-pressure gaseous refrigerant becomes a high-pressure liquid refrigerant after exchanging heat with the fluid on the user side in the third heat exchanger 103. The high-pressure liquid refrigerant flows out of the third heat exchanger 103 and then flows to the throttling device 131 through the second pipe second one-way valve 1922. The high-pressure liquid refrigerant becomes a low-temperature and low-pressure refrigerant after flowing through the throttling device 131. The low-temperature and low-pressure refrigerant enters the second heat exchanger 102 after passing through the first electronically controlled valve 1102. In the second heat exchanger 102, the low-temperature and low-pressure refrigerant exchanges heat with a higher-temperature fluid on a user side, thereby lowering a temperature of the fluid on the user side to provide a lower-temperature fluid (i.e., to provide cooling capacity) for the user side. The low-temperature and low-pressure refrigerant becomes a low-pressure gaseous refrigerant after exchanging heat with the fluid on the user side in the second heat exchanger 102. The low-pressure gaseous refrigerant flows out of the second heat exchanger second port 1022, then sequentially passes through the first pipe second one-way valve 1622, the stop valve 164, and the gas-liquid separator 106, and then enters the compressor 108 from the compressor inlet 1081 again to become a high-temperature and high-pressure gaseous refrigerant, so as to complete the cycle of the refrigerant.
In the above cycle of the refrigerant, the pipe where the refrigerant flows from the compressor outlet 1082, passes through the third heat exchanger 103 and flows to the throttling device 131 is a high-pressure side of the heat pump system. The pipe where the refrigerant flows from throttling device 131, passes through the first heat exchanger 101 and the second heat exchanger 102 and flows to the compressor inlet 1081 is a low-pressure side of the heat pump system. In the above cycle of the refrigerant, the third heat exchanger 103 is a condenser, and the second heat exchanger 102 is an evaporator. In other words, the pipe where the refrigerant flows from the compressor outlet 1082, passes through the condenser and flows to the throttling device 131 is the high-pressure side of the heat pump system. The pipe where the refrigerant flows from throttling device 131, passes through the evaporator and flows to the compressor inlet 1081 is the low-pressure side of the heat pump system.
It should be noted that in the working conditions of the above three heat pump systems, the pressure of the first main pipe of the first pipe 152 is lower than the pressure at the second main pipe of the second pipe 182, so the refrigerant does not flow from the first pipe 152 to the second pipe 182 through the first discharge pipe assembly.
In a heat pump system of the prior art, after operation of the heat pump system is over (i.e., the heat pump system is shut down), a refrigerant leakage occurs sometimes at a first pipe 152 in a first one-way closed pipe assembly. The inventors of the present application find that this is caused by the expansion of a liquid refrigerant in a one-way closed pipe due to the migration of the refrigerant in the heat pump system. Specifically, after the heat pump system is shut down, a stop valve 164 and a compressor stop valve 165 in the heat pump system need to be switched off. However, due to the existence of the first one-way closed pipe assembly (for example, a first one-way valve is arranged at a first pipe inlet, and the stop valve 164 is arranged at the first pipe outlet 154), the refrigerant continuously migrates toward the first one-way closed pipe assembly and accumulates in the first pipe 152. When an ambient temperature rises, the liquid refrigerant in the one-way closed pipe assembly expands and breaks the pipe, resulting in a leak of the refrigerant.
The first discharge pipe assembly of the present application can avoid damage to the first one-way closed pipe assembly. Specifically, when the heat pump system is shut down, the throttling device 131 is in a switch-on state, and one of the second electronically controlled valve 1104, the first electronically controlled valve 1102, and the third electronically controlled valve 1106 is made in a switch-on state, and the other two are in a switch-off state. When the refrigerant continuously enters the first one-way closed pipe assembly and gradually accumulates in the first pipe 152, the pressure of the refrigerant in the first pipe 152 increases and is greater than the pressure of the refrigerant in the second main pipe of the second pipe 182. The refrigerant located in the first pipe 152 can flow into the second main pipe through the first discharge pipe assembly, and then flows into the first heat exchanger 101, the second heat exchanger 102 or the third heat exchanger 103 sequentially through the throttling device 131 and the valve in the switch-on state in the second electrically controlled valve 1104, the first electrically controlled valve 1102 and the third electrically controlled valve 1106. More specifically, when the second electronically controlled valve 1104 is in the switch-on state, the refrigerant flowing to the second main pipe can flow into the first heat exchanger 101 sequentially through the throttling device 131, the second electronically controlled valve 1104, and the first one-way valve 1003. When the first electronically controlled valve 1102 is in the switch-on state, the refrigerant flowing to the second main pipe can flow into the second heat exchanger 102 sequentially through the throttling device 131 and the first electronically controlled valve 1102. When the third electronically controlled valve 1106 is in the switch-on state, the refrigerant flowing to the second main pipe can flow into the third heat exchanger 103 sequentially through the throttling device 131, the third electronically controlled valve 1106, and the second one-way valve 1007. Since the heat exchangers (i.e,, the first heat exchanger 101, the second heat exchanger 102, and the third heat exchanger 103) each have a large refrigerant accommodating capacity, the refrigerant can flow into and be accommodated in the heat exchangers. Thus, the refrigerant in the first one-way closed pipe assembly can flow out of the first one-way closed pipe assembly, avoiding damage to the first one-way closed pipe assembly.
FIG. 2 is a system diagram of a second embodiment of the heat pump system of the present application. The same aspects of the second embodiment of the heat pump system shown in FIG. 2 as the first embodiment of the heat pump system shown in FIGS. 1A-FIG. 1B will not be repeated. A difference between the second embodiment of the heat pump system shown in FIG. 2 and the first embodiment of the heat pump system shown in FIGS. 1A-1B is mainly in that in the second embodiment of the heat pump system shown in FIG. 2, the first discharge pipe outlet 176 of the first discharge pipe assembly is connected to the compressor outlet 1082. More specifically, the first discharge pipe outlet 176 is arranged on the pipe 163 between the compressor outlet 1082 and the four-way valve first port 1401. When the heat pump system is shut down, the four-way valve first port 1401 is in communication with the first heat exchanger 101 through the first communication channel or in communication with the third heat exchanger 103 through the second communication channel, so that the refrigerant accumulating in the first one-way closed pipe assembly can flow out of the first one-way closed pipe assembly and flow into the first heat exchanger 101 or the third heat exchanger 103, thereby avoiding damage to the first one-way closed pipe assembly.
It should be noted that although the first discharge pipe outlet 176 in the first embodiment of the heat pump system of the present application is connected to the second main pipe of the second pipe 182, and the first discharge pipe outlet 176 in the second embodiment of the heat pump system of the present application is connected to the compressor outlet 1082, in other embodiments, the first discharge pipe outlet 176 can be connected to the high-pressure side of the heat pump system.
FIG. 3 is a system diagram of a third embodiment of the heat pump system of the present application. The same aspects of the third embodiment of the heat pump system shown in FIG. 3 as the first embodiment of the heat pump system shown in FIGS. 1A-FIG. 1B will not be repeated. Differences between the third embodiment of the heat pump system shown in FIG. 3 and the first embodiment of the heat pump system shown in FIG. 1A-FIG. 1B are mainly in that: first, in the third embodiment of the heat pump system shown in FIG. 3, the first discharge pipe outlet 176 of the first discharge pipe assembly is connected to the gas-liquid separator inlet 1061 of the gas-liquid separator 106; and second, in the third embodiment of the heat pump system shown in FIG. 3, the first discharge pipe assembly comprises a first pressure relief valve 302. The first pressure relief valve 302 is arranged on the first discharge pipe 172 and is configured to enable the fluid to flow to the first discharge pipe outlet 176 through the first discharge pipe inlet 174 when a pressure difference between two sides of the first pressure relief valve 302 is equal to a first predetermined pressure difference or when a pressure of the first pressure relief valve inlet 3021 reaches a first predetermined pressure value. More specifically, the first pressure relief valve 302 has a first pressure relief valve inlet 3021 and a first pressure relief valve outlet 3022. The first pressure relief valve 302 is configured to be in communication with the first pressure relief valve inlet 3021 and the first pressure relief valve outlet 3022 and enable the fluid to flow from the first pressure relief valve inlet 3021 to the first pressure relief valve outlet 3022 in one direction when the pressure of the first pressure relief valve inlet 3021 is greater than the pressure of the first pressure relief valve outlet 3022, and the pressure difference between the first pressure relief valve inlet 3021 and the first pressure relief valve outlet 3022 is equal to the first predetermined pressure difference or the pressure of the first pressure relief valve inlet 3021 is equal to the first predetermined pressure value (for example, the first predetermined pressure value is 45 atmospheres). When the heat pump system is shut down, the refrigerant continuously migrates into the first one-way closed pipe assembly and gradually accumulates in the first pipe 152. When the pressure difference between the first pressure relief valve inlet 3021 and the first pressure relief valve outlet 3022 is equal to the first predetermined pressure difference or the pressure of the first pressure relief valve inlet is equal to the first predetermined pressure value, the first pressure relief valve inlet 3021 is in communication with the first pressure relief valve outlet 3022, so that the refrigerant accumulating in the first one-way closed pipe assembly can flow into the gas-liquid separator 106. Since the gas-liquid separator 106 has a large refrigerant accommodating capacity inside, the refrigerant can flow into and be accommodated in the gas-liquid separator 106. Thus, the refrigerant in the first one-way closed pipe assembly can flow out, avoiding damage to the first one-way closed pipe assembly.
It should be noted that although the first discharge pipe outlet 176 in the third embodiment of the heat pump system of the present application is connected to the gas-liquid separator inlet 1061, in other embodiments, the first discharge pipe outlet 176 can be connected to the low-pressure side of the heat pump system.
FIG. 4 is a system diagram of a fourth embodiment of the heat pump system of the present application. The same aspects of the fourth embodiment of the heat pump system shown in FIG. 4 as the second embodiment of the heat pump system shown in FIG. 2 will not be repeated. A difference between the fourth embodiment of the heat pump system shown in FIG. 4 and the second embodiment of the heat pump system shown in FIG. 2 is mainly in that the fourth embodiment of the heat pump system shown in FIG. 4 also includes a second discharge pipe assembly. The second discharge pipe assembly comprises a second discharge pipe 402 and a second discharge one-way valve 412. The second discharge pipe inlet 404 of the second discharge pipe 402 is connected to the second main pipe of the second pipe 182. The second discharge pipe outlet 406 of second discharge pipe 402 is connected to the pipe 163 between the compressor outlet 1082 and the four-way valve first port 1401. The second discharge one-way valve 412 is arranged on the second discharge pipe 402 and is configured to enable the fluid to flow to the second discharge pipe outlet 406 through the second discharge pipe inlet 404.
In the heat pump system of the prior art, after operation of the heat pump system is over (i.e., the heat pump system is shut down), a refrigerant leakage occurs sometimes at the second pipe 182 in the second one-way closed pipe assembly. The inventors of the present application find that this is caused by the expansion of a liquid refrigerant in a one-way closed pipe due to the migration of the refrigerant in the heat pump system. Specifically, after the heat pump system is shut down, the throttling device 131 in the heat pump system is switched off. However, due to the existence of the second one-way closed pipe assembly (for example, the second pipe one-way valve is arranged at the second pipe inlet, and the throttling device 131 is arranged at the second pipe outlet 186), when the refrigerant continuously migrates toward the second one-way closed pipe assembly and accumulates in the second pipe 182, and when the ambient temperature rises, the liquid refrigerant in the one-way closed pipe assembly expands and breaks the pipe, thereby causing the refrigerant leakage.
The second discharge pipe assembly of the present application can avoid damage to the second one-way closed pipe assembly. Specifically, when the heat pump system is shut down and the throttling device 131 is switched off, the pressure of the refrigerant accumulating in the second pipe 182 is increased and is greater than the pressure of the refrigerant in the pipe 163. The refrigerant located in the second pipe 182 can flow into the pipe 163 through the second discharge pipe assembly and then enters the first heat exchanger 101 or the third heat exchanger 103 through the four-way valve 140. The first heat exchanger 101 and the third heat exchanger 103 each have a large refrigerant accommodating capacity inside, so the refrigerant can flow into and be accommodated in the heat exchangers. Thus, the refrigerant in the second one-way closed pipe assembly can flow out, thereby avoiding damage to the second one-way closed pipe assembly.
It should be noted that although the second discharge pipe outlet 406 in the fourth embodiment of the heat pump system of the present application is connected to the pipe 163 between the compressor outlet 1082 and the four-way valve first port 1401, in other embodiments, the second discharge pipe outlet 406 can be connected to the high-pressure side of the heat pump system.
FIG. 5 is a system diagram of a fifth embodiment of the heat pump system of the present application. The same aspects of the fifth embodiment of the heat pump system shown in FIG. 5 as the fourth embodiment of the heat pump system shown in FIG. 4 will not be repeated. Differences between the fifth embodiment of the heat pump system shown in FIG. 5 and the fourth embodiment of the heat pump system shown in FIG. 4 are mainly in that: first, in the fifth embodiment of the heat pump system shown in FIG. 5, the second discharge pipe outlet 406 of the second discharge pipe assembly is connected to the gas-liquid separator inlet 1061 of the gas-liquid separator 106; and second, in the fifth embodiment of the heat pump system shown in FIG. 5, the second discharge pipe assembly comprises a second pressure relief valve 502. The second pressure relief valve 502 is arranged on the second discharge pipe 402 and is configured to enable the fluid to flow to the second discharge pipe outlet 406 through the second discharge pipe inlet 404 when a pressure difference between two sides of the second pressure relief valve 502 is equal to a second predetermined pressure difference or when a pressure of the second pressure relief valve inlet 5021 is equal to a second predetermined pressure value. More specifically, the second pressure relief valve 502 has a second pressure relief valve inlet 5021 and a second pressure relief valve outlet 5022. The second pressure relief valve 502 is configured to be in communication with the second pressure relief valve inlet 5021 and the second pressure relief valve outlet 5022 and enable the fluid to flow from the second pressure relief valve inlet 5021 to the second pressure relief valve outlet 5022 in one direction when the pressure of the second pressure relief valve inlet 5021 is greater than the pressure of the second pressure relief valve outlet 5022, and the pressure difference between the second pressure relief valve inlet 5021 and the second pressure relief valve outlet 5022 is equal to the second predetermined pressure difference or the pressure of the second pressure relief valve inlet 5021 is equal to the second predetermined pressure value (for example, the second predetermined pressure value is 45 atmospheres). When the heat pump system is shut down, the refrigerant migrates into the second one-way closed pipe assembly and gradually accumulates in the second pipe 182. When the pressure difference between the second pressure relief valve inlet 5021 and the second pressure relief valve outlet 5022 is equal to the second predetermined pressure difference or the pressure of the second pressure relief valve inlet 5021 is equal to the second predetermined pressure value, the second pressure relief valve inlet 5021 is in communication with the second pressure relief valve outlet 5022, so that the refrigerant accumulating in the second one-way closed pipe assembly can flow into the gas-liquid separator 106. Since the gas-liquid separator 106 has a large refrigerant accommodating capacity inside, the refrigerant can flow into and be accommodated in the gas-liquid separator 106. Thus, the refrigerant in the second one-way closed pipe assembly can flow out, thereby avoiding damage to the second one-way closed pipe assembly.
It should be noted that although the second discharge pipe outlet 406 in the fifth embodiment of the heat pump system of the present application is connected to the gas-liquid separator inlet 1061, in other embodiments, the second discharge pipe outlet 406 can be connected to the low-pressure side of the heat pump system.
It should be noted that although the second discharge pipe outlets 406 in the fourth embodiment and the fifth embodiment of the heat pump system of the present application are respectively connected to the high-pressure side and the low-pressure side of the heat pump system, in other embodiments, the second discharge pipe outlet 406 is connected to pipes and/or parts in the heat pump system except the second one-way closed pipe assembly, so as to discharge the refrigerant in the second one-way closed pipe assembly out of the second one-way closed pipe assembly. For example, in another embodiment, the second discharge pipe outlet 406 may be connected to the first one-way closed pipe assembly such that the refrigerant in the first one-way closed pipe assembly and the refrigerant in the second one-way closed pipe assembly are discharged out of the first one-way closed pipe assembly and the second one-way closed pipe assembly via the first discharge assembly.
The pipes and/or parts in the heat pump system of the present application except the second one-way closed pipe assembly are configured to discharge the refrigerant in the second one-way closed pipe assembly into an accommodating part (e.g., a heat exchanger, and a gas-liquid separator) with a large refrigerant accommodating capacity when the heat pump system is shut down.
In addition, the outlet of the second discharge pipe assembly in the present application (i.e., the second discharge pipe outlet 406) is connected to the pipes and/or parts in the heat pump system except the second one-way closed pipe assembly, so that the refrigerant in the heat pump system is stored in the heat pump system without the need to leak the refrigerant from the heat pump system, avoiding wasting the refrigerant.
FIG. 6 is a system diagram of a sixth embodiment of the heat pump system of the present application. The same aspects of the sixth embodiment of the heat pump system shown in FIG. 6 as the first embodiment of the heat pump system shown in FIGS. 1A-FIG. 1B will not be repeated. A difference between the sixth embodiment of the heat pump system shown in FIG. 6 and the first embodiment of the heat pump system shown in FIG. 1A-FIG. 1B is mainly in that the sixth embodiment of the heat pump system shown in FIG. 6 includes an additional heat exchanger 601, an additional throttling device 603, and an additional valve 605. The additional heat exchanger 601 has an additional heat exchanger first port 6011, an additional heat exchanger second port 6012, an additional heat exchanger third port 6013, and an additional heat exchanger fourth port 6014. The additional heat exchanger first port 6011 is connected to the second pipe outlet 186 of the second pipe 182. The additional heat exchanger second port 6012 is connected to the inlet of the throttling device 131. The additional heat exchanger third port 6013 is connected to a compression cavity (not shown) in the compressor 108 through a first additional pipe 611. The additional valve 605 is arranged on the first additional pipe 611. The additional heat exchanger fourth port 6014 is connected to the inlet of the throttling device 131 through the second additional pipe 613. The additional throttling device 603 is arranged on the second additional pipe 613. It should be noted that in the additional heat exchanger 601, the additional heat exchanger first port 6011 is in fluid communication with the additional heat exchanger second port 6012, and a first flow path is formed in the additional heat exchanger 601. The additional heat exchanger third port 6013 is in fluid communication with the additional heat exchanger fourth port 6014, and a second flow path is formed in the additional heat exchanger 601. The fluid in the first flow path can exchange heat with the fluid in the second flow path. The first discharge pipe outlet 176 of the first discharge pipe assembly is connected to the first additional pipe 611 and is arranged between the additional valve 605 and the additional heat exchanger third port 6013. The first additional pipe 611 from the additional heat exchanger third port 6013 to the compression cavity of the compressor 108 is the medium-pressure side of the heat pump system.
The first discharge pipe assembly of the present application can avoid damage to the first one-way closed pipe assembly. Specifically, when the heat pump system is shut down, the additional valve 605 is in a switch-off state, the additional throttling device 603 and the throttling device 131 are in a switch-on state, one of the second electronically controlled valve 1104, the first electronically controlled valve 1102, and the third electronically controlled valve 1106 is in a switch-on state, and the other two are in a switch-off state. When the refrigerant continuously enters the first one-way closed pipe assembly and gradually accumulates in the first pipe 152, the pressure of the refrigerant in the first pipe 152 increases and is greater than a pressure of the refrigerant in the first additional pipe 611. The refrigerant located in the first pipe 152 can flow into the first heat exchanger 101, the second heat exchanger 102 or the third heat exchanger 103 through the first discharge pipe assembly and through the first additional pipe 611, the additional throttling device 603, the throttling device 131, and the valve in the switch-on state in the second electrically controlled valve 1104, the first electrically controlled valve 1102 and the third electrically controlled valve 1106. Thus, the refrigerant in the first one-way closed pipe assembly can flow out, avoiding damage to the first one-way closed pipe assembly.
It should be noted that although the first discharge pipe outlets 176 in the first to sixth embodiments of the heat pump system of the present application are respectively connected to specific locations of the high-pressure side, the medium-pressure side or the low-pressure side of the heat pump system, in other embodiments, the first discharge pipe outlet 176 is connected to pipes and/or parts in the heat pump system except the first one-way closed pipe assembly, so as to discharge the refrigerant in the first one-way closed pipe assembly out of the first one-way closed pipe assembly. The pipes and/or parts in the heat pump system of the present application except the first one-way closed pipe assembly are configured to discharge the refrigerant in the first one-way closed pipe assembly into an accommodating part (e.g., a heat exchanger, and a gas-liquid separator) with a large refrigerant accommodating capacity when the heat pump system is shut down. In addition, the outlet of the first discharge pipe assembly in the present application (i.e., the first discharge pipe outlet 176) is connected to the pipes and/or parts in the heat pump system except the first one-way closed pipe assembly, so that the refrigerant in the heat pump system can be stored in the heat pump system without the need to leak the refrigerant from the heat pump system, avoiding wasting the refrigerant.
FIG. 7 is a system diagram of a seventh embodiment of the heat pump system of the present application. The same aspects of the seventh embodiment of the heat pump system shown in FIG. 7 as the first embodiment of the heat pump system shown in FIGS. 1A-FIG. 1B will not be repeated. Differences between the seventh embodiment of the heat pump system shown in FIG. 7 and the first embodiment of the heat pump system shown in FIG. 1A-FIG. 1B are mainly in that: first, no stop valve 164 is arranged at the first pipe outlet 154; and second, the heat pump system also includes a first additional stop valve 702 and a second additional stop valve 704. Specifically, the first additional stop valve 702 and the second additional stop valve 704 are arranged at the two first pipe inlets. More specifically, the first additional stop valve 702 is arranged on the pipe between the first pipe first one-way valve 1621 and the four-way valve third port 1403. The second additional stop valve 704 is arranged on the pipe between the first pipe second one-way valve 1622 and the second heat exchanger second port 1022.
When the heat pump system is shut down and the first additional stop valve 702 and the second additional stop valve 704 are switched off, the throttling device 131 is switched on so that no pipe is formed in the heat pump system where the refrigerant can continuously enter in one direction and accumulate. Thus, the pipe in the heat pump system can avoid damage caused by liquid seals (i.e., the accumulation of liquid refrigerant in the pipe causes the pipe to be burst).
It should be noted that although the first one-way closed pipe assembly in the present application comprises two first pipe inlets, any first one-way closed pipe assembly that comprises at least one first pipe inlet is also within the scope of protection of the present application. Although the second one-way closed pipe assembly in the present application comprises two second pipe inlets, any second one-way closed pipe assembly that comprises at least one second pipe inlet is also within the scope of protection of the present application.
It should be noted that although the first one-way closed pipe assembly in the present application comprises the stop valve and the one-way valve arranged at its outlet and inlet, and the second one-way closed pipe assembly comprises the throttling device and the one-way valve arranged at its outlet and inlet, thereby forming the one-way closed pipe assemblies, in other embodiments, the first one-way closed pipe assembly and the second one-way closed pipe assembly are configured so that when the heat pump system is shut down, the refrigerant can enter the first one-way closed pipe assembly and the second one-way closed pipe assembly and accumulate in the first one-way closed pipe assembly and the second one-way closed pipe assembly.
Although the present disclosure has been described in conjunction with the examples of embodiments outlined above, various alternatives, modifications, variations, improvements and/or substantial equivalents, whether known or foreseeable now or soon, may become apparent to those of ordinary skill in the art. In addition, the technical effects and/or technical problems described in this specification are exemplary rather than restrictive. Therefore, the disclosures in this specification may be used to solve other technical problems and have other technical effects and/or can solve other technical problems. Accordingly, the examples of embodiments of the present disclosure set forth above are intended to be illustrative rather than restrictive. Various changes may be made without departing from the spirit or scope of the present disclosure. Accordingly, the present disclosure is intended to embrace all known or earlier developed alternatives, modifications, variations, improvements and/or substantial equivalents.

Claims

A heat pump system, wherein the heat pump system comprises:
a first one-way closed pipe assembly; and

a first discharge pipe assembly, wherein the first discharge pipe assembly comprises a first discharge pipe (172), the first discharge pipe (172) has a first discharge pipe outlet (176) and a first discharge pipe inlet (174), the first discharge pipe inlet (174) is connected to the first one-way closed pipe assembly, and the first discharge pipe outlet (176) is connected to pipes and/or parts in the heat pump system except the first one-way closed pipe assembly, thereby discharging a refrigerant in the first one-way closed pipe assembly out of the first one-way closed pipe assembly.
The heat pump system according to claim 1, wherein:
the first one-way closed pipe assembly is configured so that when the heat pump system is shut down, the refrigerant is capable of entering the first one-way closed pipe assembly and accumulating in the first one-way closed pipe assembly; and

the first one-way closed pipe assembly comprises:
a first pipe (152), wherein the first pipe (152) has a first pipe outlet (154) and at least one first pipe inlet;

a stop valve (164), wherein the stop valve (164) is arranged at the first pipe outlet (154); and

at least one first pipe one-way valve, wherein the at least one first pipe one-way valve is correspondingly arranged at the at least one first pipe inlet and is configured to enable a fluid to enter the first pipe (152) through the at least one first pipe one-way valve.
The heat pump system according to claim 2, wherein:
the first discharge pipe assembly further comprises a first discharge one-way valve (178), and the first discharge one-way valve (178) is arranged on the first discharge pipe (172) and is configured to enable the fluid to flow to the first discharge pipe outlet (176) through the first discharge pipe inlet (174); and

the first discharge pipe outlet (176) is connected to at least one of a high-pressure side or a medium-pressure side of the heat pump system.
The heat pump system according to claim 2, wherein:
the first discharge pipe assembly further comprises a first pressure relief valve (302), and the first pressure relief valve (302) is arranged on the first discharge pipe (172) and is configured to enable the fluid to flow to the first discharge pipe outlet (176) through the first discharge pipe inlet (174); and

the first discharge pipe outlet (176) is connected to a low-pressure side of the heat pump system.
The heat pump system according to claim 4, wherein:
the first pressure relief valve (302) has a first pressure relief valve inlet (3021) and a first pressure relief valve outlet (3022), and the first pressure relief valve (302) is configured so that the first pressure relief valve inlet (3021) is in communication with the first pressure relief valve outlet (3022) when a pressure difference between the first pressure relief valve inlet (3021) and the first pressure relief valve outlet (3022) is equal to a first predetermined pressure difference or a pressure of the first pressure relief valve inlet (3021) is equal to a first predetermined pressure value.
The heat pump system according to claim 2, wherein the heat pump system further comprises:
a second one-way closed pipe assembly; and

a second discharge pipe assembly, wherein the second discharge pipe assembly comprises a second discharge pipe (402), the second discharge pipe (402) has a second discharge pipe outlet (406) and a second discharge pipe inlet (404), the second discharge pipe inlet (404) is connected to the second one-way closed pipe assembly, and the second discharge pipe outlet (406) is connected to pipes and/or parts in the heat pump system except the second one-way closed pipe assembly, thereby discharging a refrigerant in the second one-way closed pipe assembly out of the second one-way closed pipe assembly.
The heat pump system according to claim 6, wherein:
the second one-way closed pipe assembly is configured so that when the heat pump system is shut down, the refrigerant is capable of entering the second one-way closed pipe assembly and accumulating in the second one-way closed pipe assembly; and

the second one-way closed pipe assembly comprises:
a second pipe (182), wherein the second pipe (182) has a second pipe outlet (186) and at least one second pipe inlet;

a throttling device (131), wherein the throttling device (131) is arranged at the second pipe outlet (186); and

at least one second pipe one-way valve, wherein the at least one second pipe one-way valve is correspondingly arranged at the at least one second pipe inlet and is configured to enable the fluid to enter the second pipe (182) through the at least one second pipe one-way valve.
The heat pump system according to claim 6, wherein:
the second discharge pipe assembly further comprises a second discharge one-way valve (412), and the second discharge one-way valve (412) is arranged on the second discharge pipe (402) and is configured to enable the fluid to flow to the second discharge pipe outlet (406) through the second discharge pipe inlet (404); and

the second discharge pipe outlet (406) is connected to the high-pressure side of the heat pump system.
The heat pump system according to claim 7, wherein:
the second discharge pipe assembly further comprises a second pressure relief valve (502), and the second pressure relief valve (502) is arranged on the second discharge pipe (402) and is configured to enable the fluid to flow to the second discharge pipe outlet (406) through the second discharge pipe inlet (404); and

the second discharge pipe outlet (406) is connected to the low-pressure side of the heat pump system.
The heat pump system according to claim 9, wherein:
the second pressure relief valve (502) has a second pressure relief valve inlet and a second pressure relief valve outlet, and the second pressure relief valve (502) is configured so that the second pressure relief valve inlet is in communication with the second pressure relief valve outlet when a pressure difference between the second pressure relief valve inlet and the second pressure relief valve outlet is equal to a second predetermined pressure difference or a pressure of the second pressure relief valve inlet is equal to a second predetermined pressure value; and

the second discharge pipe outlet (406) is connected to the low-pressure side of the heat pump system.