US20230296295A1

US20230296295A1 - Heat pump system and the control method thereof

Info

Publication number: US20230296295A1
Application number: US18/184,089
Authority: US
Inventors: Yilin Zhang; Peng Su
Original assignee: Carrier Corp
Current assignee: Carrier Corp
Priority date: 2022-03-18
Filing date: 2023-03-15
Publication date: 2023-09-21
Also published as: EP4249829A1; CN116792970A

Abstract

A heat pump system and a control method thereof. The heat pump system includes a compressor; a reversing valve configured to selectively connect the compressor inlet and the compressor outlet to a first flow path and a second flow path; a heat source-side heat exchanger on the first flow path; a user-side heat exchanger on the second flow path; a first branch and a second branch between the first flow path and the second flow path, the first branch is provided with a first valve and a second valve, and the second branch is provided with a first throttling device and a second throttling device; and an economizer connected between a first position between the first valve and the second valve on the first branch and a second position between the first throttling device and the second throttling device on the second branch.

Description

FOREIGN PRIORITY

This application claims priority to Chinese Patent Application No. 202210268739.5, filed Mar. 18, 2022, and all the benefits accruing therefrom under 35 U.S.C. § 119, the contents of which in its entirety are herein incorporated by reference.

TECHNICAL FIELD OF INVENTION

The present invention relates to the field of heat pumps, in particular to a heat pump system with an economizer capable of operating in both cooling and heating modes.

BACKGROUND OF THE INVENTION

In order to improve the comfort of air conditioning systems, common air conditioning systems have the heating mode. Air conditioning systems with both cooling and heating modes are also referred to as heat pump systems. In order to improve the capacity of the heat pump system in the heating mode, the Enhanced Vapor Injection (EVI) compressor and the economizer located in front of the throttling device are often used. This structure can increase the heating capacity of the system by about 10%.
In order to enable the EVI compressor and the economizer to also operate in the cooling mode, i.e., to improve the capacity of the system in the cooling mode, it is usually necessary to employ a complicated pipeline structure with four check valves and one expansion valve, which challenges the reliability of the check valves.

SUMMARY OF THE INVENTION

The object of the present application is to solve or at least alleviate the problems existing in the prior art.
According to one aspect, a heat pump system is provided, which comprises: a compressor having a compressor inlet and a compressor outlet; a reversing valve configured to selectively connect the compressor inlet and the compressor outlet to a first flow path and a second flow path; a heat source-side heat exchanger on the first flow path; a user-side heat exchanger on the second flow path; a first branch and a second branch between the first flow path and the second flow path, wherein the first branch is provided with a first valve and a second valve, and the second branch is provided with a first throttling device and a second throttling device; and an economizer connected between a first position between the first valve and the second valve on the first branch and a second position between the first throttling device and the second throttling device on the second branch.
Optionally, in an embodiment of the heat pump system, the compressor is an EVI compressor, wherein the EVI compressor further comprises an air supplement port, and the economizer comprises a port connected with the air supplement port.
Optionally, in an embodiment of the heat pump system, the economizer is a flash tank, wherein the inlet of the flash tank is connected to the first position, the gas-phase outlet of the flash tank is connected to the air supplement port, and the liquid-phase outlet of the flash tank is connected to the second position.
Optionally, in an embodiment of the heat pump system, the economizer is a heat exchanger comprising a first pipeline and a second pipeline. The first pipeline is connected between the first position and the second position, and a branch path is branched out at a third position between the first position or the second position and the economizer, wherein the branch path is provided with an additional throttling device, and is connected to the air supplement port of the compressor through the second pipeline of the economizer.
Optionally, in an embodiment of the heat pump system, the first valve is a check valve that only allows refrigerant fluid to flow from the first flow path to the first position, and the second valve is a check valve that only allows refrigerant fluid to flow from the second flow path to the first position.
Optionally, in an embodiment of the heat pump system, the first throttling device and the second throttling device are expansion valves.
Optionally, in an embodiment of the heat pump system, the heat pump system further comprises a controller that controls the first throttling device and the second throttling device. The controller is configured to turn off the first throttling device and allow the second throttling device to play a throttling role in a cooling mode, and turn off the second throttling device and allow the first throttling device to play a throttling role in a heating mode.
Optionally, in an embodiment of the heat pump system, the first valve and the second valve are cut-off valves. The controller is configured to control the first valve and the second valve, so that the first valve is turned on and the second valve is turned off in the cooling mode, and the second valve is turned on and the first valve is turned off in the heating mode.
According to another aspect, a control method of a heat pump system is provided, which is for use in the heat pump system according to the various embodiments. The method comprises: turning off the first throttling device and allowing the second throttling device to play a throttling role in the cooling mode, so that the refrigerant passes through the first valve, the economizer and the second throttling device in turn; and turning off the second throttling device and allowing the first throttling device to play a throttling role in the heating mode, so that the refrigerant passes through the second valve, the economizer and the first throttling device in turn.
Optionally, the method further comprises: using a flash tank as an economizer, so that after the refrigerant enters the flash tank, gas-phase refrigerant is delivered to the air supplement port of the compressor, and liquid-phase refrigerant is delivered to the first throttling device or the second throttling device; or using a heat exchanger comprising a first pipeline and a second pipeline as the economizer, and dividing the refrigerant into a first part and a second part before it enters the first pipeline or after it leaves the first pipeline, wherein the first part of the refrigerant is delivered to the first throttling device or the second throttling device, and the second part of the refrigerant is delivered to the air supplement port of the compressor after passing through an additional throttling device and then through the second pipeline of the economizer.
The system and method according to the embodiments of the present invention improves the system capacity using the economizer in the cooling and heating modes, and has stronger reliability.

BRIEF DESCRIPTION OF THE DRAWINGS

With reference to the accompanying drawings, the disclosure of the present application will become easier to understand. Those skilled in the art would readily appreciate that these drawings are for the purpose of illustration, and are not intended to limit the protection scope of the present application. In addition, in the figures, similar numerals are used to denote similar components, where:

FIG. 1 shows a partial schematic diagram of a heat pump system according to an embodiment of the present invention;

FIG. 2 shows a schematic diagram of a heat pump system according to an embodiment of the present invention;

FIG. 3 shows a schematic diagram of a heat pump system according to another embodiment of the present invention; and

FIG. 4 shows a schematic diagram of a heat pump system according to another embodiment of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 1 shows a partial schematic diagram of a heat pump system according to an embodiment of the present invention. The heat pump system comprises: a first flow path 31 and a second flow path 32 selectively connected with the compressor inlet and the compressor outlet; a heat source-side heat exchanger 4 on the first flow path 31; a user-side heat exchanger 5 on the second flow path 32; a first branch 62 and a second branch 61 between the first flow path 31 and the second flow path 32, wherein the first branch 62 and the second branch 61 are connected to the end 311 of the first flow path 31 and the end 321 of the second flow path 32 respectively, and the first branch 62 is provided with a first valve 72 and a second valve 71, and the second branch 61 is provided with a first throttling device 82 and a second throttling device 81; and an economizer 9 connected between a first position 621 between the first valve 72 and the second valve 71 on the first branch 62 and a second position 611 between the first throttling device 82 and the second throttling device 81 on the second branch 61. The heat pump system according to the embodiments of the present invention utilizes the four valve elements that are the first valve 72, the second valve 71, the first throttling device 82 and the second throttling device 81 to realize the application of the economizer 9 in the cooling and heating modes, thereby improving the capacity and stability of the heat pump system.
With continued reference to FIG. 2 , the application of the heat pump system according to the embodiment of the present invention combined with an EVI compressor is shown. The EVI compressor 1 comprises a compressor inlet 12, a compressor outlet 11 and an air supplement port 13. Compressor 1 is connected with the portion of the heat pump system shown in FIG. 1 through a reversing valve 2, and the economizer is also connected to the air supplement port of compressor 1. More specifically, the compressor outlet 11 and the compressor inlet 12 of the EVI compressor 1 are selectively connected with the first flow path 31 and the second flow path 32 through the reversing valve 2 to execute the cooling mode and the heating mode. In the embodiment shown in FIG. 2 , the economizer is in the form of a flash tank 90, the inlet 91 of which is connected to a first position 621 on the first flow path 62, the gas-phase outlet 92 of which is connected to the air supplement port 13 of the compressor 1, and the liquid-phase outlet 93 of which is connected to a second position 611 on the second flow path 61. In this embodiment, in the cooling mode, the refrigerant leaving from the compressor outlet 11 enters through the port a and leaves from the port b of the reversing valve 2, enters the heat source-side heat exchanger 4 which serves as a condenser, passes through a first valve 72 (the first throttling device 82 is turned off), and then enters the economizer in the form of the flash tank 90. Wherein, the gas-phase refrigerant returns to the air supplement port 13 of the compressor 1 from the gas-phase outlet 92 of the flash tank, the liquid-phase refrigerant leaves from the liquid-phase outlet 93 of the flash tank, passes through the second throttling device 81 for throttling, then passes through the user-side heat exchanger 5 which serves as an evaporator, then passes through the second flow path 32, enters from the port c and leaves from the port d of the reversing valve 2, and finally returns to the compressor inlet 12. In the heating mode, the refrigerant leaving from the compressor outlet 11 enters through the port a and leaves from the port c of the reversing valve 2, enters the user-side heat exchanger 5 which serves as a condenser, passes through a second valve 71 (the second throttling device 81 is turned off), and then enters the economizer in the form of the flash tank 90. Wherein, the gas-phase refrigerant returns to the air supplement port 13 of the compressor 1 from the gas-phase outlet 92 of the flash tank, and the liquid-phase refrigerant leaves from the liquid-phase outlet 93 of the flash tank, passes through the first throttling device 82 for throttling, then passes through the heat source-side heat exchanger 4 which serves as an evaporator, passes through the first flow path 31, enters from the port b and leaves from the port d of the reversing valve 2, and finally returns to the compressor inlet 12. It can be seen that the heat pump system according to the embodiments of the present invention realizes the application of the economizer in the cooling and heating modes through four valves, thus improving the system capacity and stability.
In some embodiments, the first valve 72 is a check valve that only allows refrigerant fluid to flow from the first flow path 31 to the first position 621, and the second valve 71 is a check valve that only allows refrigerant fluid to flow from the second flow path 32 to the first position 621. In some embodiments, the first throttling device 82 and the second throttling device 81 are both expansion valves, such as electronic expansion valves. In some embodiments, the heat pump system also comprises a controller that controls the first throttling device 82 and the second throttling device 81. The controller is configured to turn off the first throttling device 82 and allow the second throttling device 81 to play a throttling role in the cooling mode, and to turn off the second throttling device 81 and allow the first throttling device 82 to play a throttling role in the heating mode. In some embodiments, the first valve 72 and the second valve 71 can also be cut-off valves. The controller is configured to control the first valve 72 and the second valve 71, so that the first valve 72 is turned on and the second valve 71 is turned off in the cooling mode, and the second valve 71 is turned on and the first valve 72 is turned off in the heating mode. In some embodiments, other suitable types of valves can also be utilized to achieve the above functions.
With continued reference to FIG. 3 , the economizer in the form of a heat exchanger is adopted. The heat exchanger 900 comprises a first pipeline 901 and a second pipeline 902, where the fluids in the first pipeline 901 and the second pipeline 902 exchange heat in the economizer 900. The first pipeline 901 is connected between the first position 621 of the first branch 62 and the second position 611 of the second branch 61. A branch path is branched out at a third position 903 between the first position 621 and the economizer 900. The branch path is provided with an additional throttling device 904. The branch path is connected to the air supplement port 13 of the compressor through the second pipeline 902 of the economizer 900. The additional throttling device 904 can be an expansion valve, such as an electronic expansion valve. The proportion of refrigerant delivered to the air supplement port 13 can be adjusted by adjusting the opening degree of the additional throttling device 904.
In an alternative embodiment, as shown in FIG. 4 , the third position 903 can also be arranged between the second position 611 and the economizer 900, and the branch path can also be branched out from a third position 903 between the second position 611 and the economizer 900. The branch path can also be provided with an additional throttling device 904, and connected to the air supplement port 13 of the compressor through the second pipeline 902 of the economizer 900.
In this embodiment, in the cooling mode, the refrigerant leaving from the compressor outlet 11 enters from port a and leaves from port b of the reversing valve 2, enters the heat source-side heat exchanger 4 which serves as a condenser, and then passes through the first valve 72 (the first throttling device 82 is turned off). Then, at the third position 903, the refrigerant is divided into a first part that passes through the first pipeline 901 of the economizer and a second part that enters the second pipeline 902 of the economizer 900 after passing through the additional throttling device 904. After the first part and the second part of the refrigerant exchange heat in the economizer 900, the second part of the refrigerant returns to the air supplement port 13 of the compressor 1. The first part of the refrigerant passes through the second throttling device 81 for throttling, then passes through the user-side heat exchanger 5 which serves as an evaporator, passes through the second flow path 32, enters from the port c and leaves from port d of the reversing valve 2, and finally returns to the compressor inlet 12. In the heating mode, the refrigerant leaving from the compressor outlet 11 enters from the port a and leaves from port c of the reversing valve 2, enters the user-side heat exchanger 5 which serves as a condenser, and then passes through the second valve 71 (the second throttling device 81 is turned off). Then, at the third position 903, the refrigerant is divided into a first part that passes through the first pipeline 901 of the economizer and a second part that enters the second pipeline 902 of the economizer 900 after passing through the additional throttling device 904. After the first part and the second part of the refrigerant exchange heat in the economizer 900, the second part of the refrigerant returns to the air supplement port 13 of the compressor 1. The first part of the refrigerant passes through the first throttling device 82 for throttling, then passes through the heat source-side heat exchanger 4 which serves as an evaporator, passes through the first flow path 31, enters from the port b and leaves from port d of the reversing valve 2, and finally returns to the compressor inlet 12. It can be seen that in the heat pump system according to the embodiment in FIG. 3 , the application of the economizer in the cooling and heating modes is also realized through four valves, thus improving the system efficiency and stability. In the heat pump system according to the embodiments of the present invention, two check valves and two electronic expansion valves are used to realize the application of the economizer in the cooling and heating modes. Compared with the existing structure with four check valves and a single expansion valve, the number of valves is reduced, and the number of check valves with relatively poor stability is reduced, so that the system stability is improved.
According to another aspect, the embodiments of the present invention also provide a control method of a heat pump system, the method comprising: turning off the first throttling device and allowing the second throttling device to play a throttling role in the cooling mode, so that the refrigerant passes through the first valve, the economizer and the second throttling device in turn; and turning off the second throttling device and allowing the first throttling device to play a throttling role in the heating mode, so that the refrigerant passes through the second valve, the economizer and the first throttling device in turn.
In some embodiments, the method further comprises: using a flash tank as an economizer, so that after the refrigerant enters the flash tank, gas-phase refrigerant is delivered to the air supplement port of the compressor, and liquid-phase refrigerant is delivered to the first throttling device or the second throttling device; or using a heat exchanger comprising a first pipeline and a second pipeline as the economizer, and dividing the refrigerant into a first part and a second part before it enters the first pipeline or after it leaves the first pipeline, wherein the first part of the refrigerant is delivered to the first throttling device or the second throttling device, and the second part of the refrigerant is delivered to the air supplement port of the compressor after passing through an additional throttling device and then through the second pipeline of the economizer.
The specific embodiments of the present application described above are merely intended to describe the principles of the present application more clearly, wherein various components are clearly shown or described to facilitate the understanding of the principles of the present invention. Those skilled in the art may, without departing from the scope of the present application, make various modifications or changes to the present application. Therefore, it should be understood that these modifications or changes should be included within the scope of patent protection of the present application.

Claims

What is claimed is:

1. A heat pump system, comprising:

a compressor having a compressor inlet and a compressor outlet;

a reversing valve configured to selectively connect the compressor inlet and the compressor outlet to a first flow path and a second flow path;

a heat source-side heat exchanger on the first flow path;

a user-side heat exchanger on the second flow path;

a first branch and a second branch between the first flow path and the second flow path, wherein the first branch is provided with a first valve and a second valve, and the second branch is provided with a first throttling device and a second throttling device; and

an economizer connected between a first position between the first valve and the second valve on the first branch and a second position between the first throttling device and the second throttling device on the second branch.

2. The heat pump system according to claim 1, wherein the compressor is an Enhanced Vapor Injection compressor, where the Enhanced Vapor Injection compressor further comprises an air supplement port, and the economizer comprises a port connected with the air supplement port.

3. The heat pump system according to claim 2, wherein the economizer is a flash tank, an inlet of the flash tank being connected to the first position, a gas-phase outlet of the flash tank being connected to the air supplement port, and a liquid-phase outlet of the flash tank being connected to the second position.

4. The heat pump system according to claim 2, wherein the economizer is a heat exchanger comprising a first pipeline and a second pipeline, where the first pipeline is connected between the first position and the second position, and a branch path is branched out at a third position between the first position or the second position and the economizer, wherein the branch path is provided with an additional throttling device, and is connected to the air supplement port of the compressor through the second pipeline of the economizer.

5. The heat pump system according to claim 1, wherein the first valve is a check valve that only allows refrigerant fluid to flow from the first flow path to the first position, and the second valve is a check valve that only allows refrigerant fluid to flow from the second flow path to the first position.

6. The heat pump system according to claim 1, wherein the first throttling device and the second throttling device are expansion valves.

7. The heat pump system according to claim 6, wherein the heat pump system further comprises a controller that controls the first throttling device and the second throttling device, where the controller is configured to turn off the first throttling device and allow the second throttling device to play a throttling role in a cooling mode, and to turn off the second throttling device and allow the first throttling device to play a throttling role in a heating mode.

8. The heat pump system according to claim 7, wherein the first valve and the second valve are cut-off valves, and the controller is configured to control the first valve and the second valve, so that the first valve is turned on and the second valve is turned off in the cooling mode, and the second valve is turned on and the first valve is turned off in the heating mode.

9. A control method of a heat pump system for use in the heat pump system according to claim 1, the method comprising:

turning off the first throttling device and allowing the second throttling device to play a throttling role in the cooling mode, so that refrigerant passes through the first valve, the economizer and the second throttling device in turn; and

turning off the second throttling device and allowing the first throttling device to play a throttling role in the heating mode, so that refrigerant passes through the second valve, the economizer and the first throttling device in turn.

10. The method according to claim 9, further comprising:

using a flash tank as an economizer, so that after refrigerant enters the flash tank, gas-phase refrigerant is delivered to the air supplement port of the compressor, and liquid-phase refrigerant is delivered to the first throttling device or the second throttling device; or

using a heat exchanger comprising a first pipeline and a second pipeline as the economizer, and dividing the refrigerant into a first part and a second part before it enters the first pipeline or after it leaves the first pipeline, wherein the first part of the refrigerant is delivered to the first throttling device or the second throttling device, and the second part of the refrigerant is delivered to the air supplement port of the compressor after passing through an additional throttling device and then through the second pipeline of the economizer.