A cascade heat pump system

Abstract

The utility model provides a kind of cascade heat pump system, it is related to heat pump system field.In first loop (i. e. the low temperature loop described in the foregoing) still be provided with fluorine pump, the fluorine pump is connected to the both ends of first compressor by first branch parallel, so, when the system opens defrosting mode, first compressor in first loop is closed and stops operation, fluorine pump works and it can be combined with the heat provided by second loop, to defrost the heat exchanger in first loop;And because first compressor stops operation, working medium will not backflow to first compressor, i. e. the possibility of first compressor damage is extremely low in the defrosting process of the utility model.

Description

Technical Field

[0001] This application relates to the field of heat pump systems, and more particularly to a cascade heat pump system. Background Technology

[0002] Existing cascade heat pump systems typically include two single loops (i.e., a low-temperature loop and a high-temperature loop), which complete the heat transfer of the two-stage heat pump through a heat exchanger; and the cascade heat pump system is driven by the compressor in the two loops in different operating modes (including cooling, heating and defrosting modes).

[0003] However, the defrosting mode of existing cascade heat pump systems temporarily switches the system from heating to cooling mode by controlling the reversal of the four-way valve in the low-temperature circuit. This involves a brief switch between the condenser and evaporator sides, allowing the high-temperature refrigerant in the low-temperature circuit to flow back to the evaporator to melt the frost layer for defrosting. However, due to the switching of the four-way valve, the evaporator and condenser switch instantaneously (the heat exchanger, which was originally an evaporator in the low-temperature circuit, switches to function as a condenser). A large amount of liquid refrigerant in the low-temperature circuit flows back from the condenser to the compressor, resulting in a higher compressor damage rate during the defrosting process. Furthermore, establishing the compression ratio during defrosting is difficult, potentially leading to insufficient oil supply to the compressor. Utility Model Content

[0004] In view of this, the purpose of this application is to provide a cascade heat pump system to solve the problem that existing cascade heat pump systems are prone to compressor damage in the low-temperature circuit during defrosting.

[0005] To achieve the above objectives, this utility model provides a cascade heat pump system, including a first loop and a second loop, which are connected by a common heat exchanger. The first loop includes a first compressor, the common heat exchanger, and a first heat exchanger arranged sequentially. The first loop also includes a refrigerant pump, which is connected in parallel to both ends of the first compressor via a first branch. When the cascade heat pump system is in normal mode, the first compressor is running and the refrigerant pump is shut down, and the first circuit supplies heat to the second circuit. When the cascade heat pump system is in defrost mode, the first compressor stops and the refrigerant pump runs, and the second circuit supplies heat to the first circuit.

[0006] Preferably, the first circuit includes a first main circuit, on which the first compressor, the first solenoid valve, the common heat exchanger, the first expansion valve, the first heat exchanger and the second solenoid valve are sequentially arranged.

[0007] Preferably, the first end of the first branch is connected between the first solenoid valve and the common heat exchanger; the second end of the first branch is connected between the first heat exchanger and the second solenoid valve.

[0008] Preferably, the first branch is further provided with a third solenoid valve and a fourth solenoid valve, which are located at both ends of the fluorine pump.

[0009] Preferably, when the cascade heat pump system is in the conventional mode, the first compressor operates, and the first and second solenoid valves are open to connect the first compressor to the first main circuit; the refrigerant pump stops, and the third and fourth solenoid valves are closed to disconnect the refrigerant pump from the first main circuit. When the cascade heat pump system is in the defrost mode, the first compressor stops operating, and the first and second solenoid valves close to disconnect the first compressor from the first main circuit; the refrigerant pump operates, and the third and fourth solenoid valves open to connect the refrigerant pump to the first main circuit.

[0010] Preferably, in the first loop, when the cascade heat pump system is in the conventional mode, the working fluid in the first compressor flows sequentially through the common heat exchanger, the first expansion valve, and the first heat exchanger and then flows back to the first compressor; When the cascade heat pump system is in the defrosting mode, the working fluid in the refrigerant pump flows sequentially through the first heat exchanger, the first expansion valve, and the common heat exchanger, and then flows back to the refrigerant pump.

[0011] Preferably, the second circuit includes a second main circuit, which includes the common heat exchanger, the four-way valve, the second heat exchanger, and the second expansion valve arranged in sequence; the common heat exchanger and the second heat exchanger are respectively connected to the first opening and the second opening of the four-way valve.

[0012] Preferably, the second circuit further includes a second branch, which is connected to the third opening and the fourth opening of the four-way valve respectively; the second branch is equipped with a second compressor.

[0013] Preferably, inside the four-way valve, the first opening can communicate with the third opening, the third opening can communicate with the second opening, the second opening can communicate with the fourth opening, and the fourth opening can communicate with the first opening.

[0014] Preferably, in the second loop, when the cascade heat pump system is in the conventional mode, the working fluid in the second compressor flows sequentially through the fourth opening and the second opening of the four-way valve through the second heat exchanger and the common heat exchanger, and then flows back to the second compressor through the first opening and the third opening of the four-way valve. When the cascade heat pump system is in the defrost mode, the working fluid in the second compressor flows through the fourth opening and the first opening of the four-way valve sequentially through the common heat exchanger and the second heat exchanger, and then flows back to the second compressor through the second opening and the third opening of the four-way valve.

[0015] According to the cascade heat pump system of this utility model, a refrigerant pump is also provided in the first loop (i.e., the low-temperature loop mentioned above). The refrigerant pump is connected in parallel to both ends of the first compressor through the first branch. Thus, when the defrosting mode of this system is activated, the first compressor in the first loop is shut down, the refrigerant pump works and can combine with the heat provided by the second loop to defrost the heat exchanger in the first loop. Since the first compressor is shut down, the working fluid will not flow back to the first compressor. That is, the possibility of the first compressor being damaged during the defrosting process of this cascade heat pump system is extremely low.

[0016] To make the above-mentioned objectives, features and advantages of this application more apparent and understandable, preferred embodiments are described below in detail with reference to the accompanying drawings. Attached Figure Description

[0017] To more clearly illustrate the technical solutions of the embodiments of this application, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of this application and should not be regarded as a limitation of the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0018] Figure 1 This is a schematic diagram of the cascade heat pump system of this utility model in conventional mode; Figure 2 This is a schematic diagram of the cascade heat pump system of this utility model in defrost mode.

[0019] Icons: 11-First compressor; 121-First solenoid valve; 122-Second solenoid valve; 123-Third solenoid valve; 124-Fourth solenoid valve; 13-First expansion valve; 14-First heat exchanger; 15-Fluorine pump; 21-Second compressor; 22-Four-way valve; 23-Second heat exchanger; 24-Second expansion valve; 3-Common heat exchanger. Detailed Implementation The following detailed embodiments are provided to help the reader gain a comprehensive understanding of the methods, apparatus, and / or systems described herein. However, various changes, modifications, and equivalents of the methods, apparatus, and / or systems described herein will be apparent after understanding the disclosure of this application. For example, the order of operations described herein is merely illustrative and is not limited to the order set forth herein; changes that will be apparent after understanding the disclosure of this application are possible, except for operations that must occur in a specific order. Furthermore, for clarity and brevity, descriptions of features known in the art may be omitted.

[0020] The features described herein may be implemented in different forms and should not be construed as being limited to the examples described herein. Rather, the examples described herein have been provided merely to illustrate some of the many feasible ways of implementing the methods, apparatus, and / or systems described herein that will be apparent upon understanding the disclosure of this application.

[0021] Throughout the specification, when an element (such as a layer, region, or substrate) is described as being "on" another element, "connected to" another element, "bonded to" another element, "on" another element, or "covering" another element, it may be directly "on" another element, "connected to" another element, "bonded to" another element, "on" another element, or "covering" another element, or there may be one or more other elements in between. In contrast, when an element is described as being "directly on" another element, "directly connected to" another element, "directly bonded to" another element, "directly on" another element, or "directly covering" another element, there may be no other elements in between.

[0022] As used herein, the term “and / or” includes any one of the relevant items listed and any combination of any two or more items.

[0023] Although terms such as “first,” “second,” and “third” may be used herein to describe individual components, assemblies, regions, layers, or parts, these components, assemblies, regions, layers, or parts are not limited by these terms. Rather, these terms are used only to distinguish one component, assembly, region, layer, or part from another. Therefore, without departing from the teachings of the examples described herein, the first component, assembly, region, layer, or part referred to as the second component, assembly, region, layer, or part may also be referred to as the second component, assembly, region, layer, or part.

[0024] For ease of description, spatial relation terms such as “above,” “upper,” “below,” and “lower” are used herein to describe the relationship between one element and another, as shown in the accompanying drawings. Such spatial relation terms are intended to include not only the orientation depicted in the drawings but also different orientations of the device during use or operation. For example, if the device in the drawings is flipped, an element described as being “above” or “upper” relative to another element will subsequently be “below” or “lower” relative to that other element. Therefore, the term “above” includes both “above” and “below” orientations depending on the spatial orientation of the device. The device may also be positioned in other ways (e.g., rotated 90 degrees or in other orientations), and the spatial relation terms used herein will be interpreted accordingly.

[0025] The terminology used herein is for the purpose of describing various examples only and is not intended to limit this disclosure. Unless the context clearly indicates otherwise, the singular form is also intended to include the plural form. The terms “comprising,” “including,” and “having” enumerate the stated features, quantities, operations, components, elements, and / or combinations thereof, but do not exclude the presence or addition of one or more other features, quantities, operations, components, elements, and / or combinations thereof.

[0026] Variations in the shapes shown in the accompanying drawings may occur due to manufacturing techniques and / or tolerances. Therefore, the examples described herein are not limited to the specific shapes shown in the accompanying drawings, but include changes in shape that may occur during manufacturing.

[0027] The features of the examples described herein can be combined in various ways that will be apparent upon understanding the disclosure of this application. Furthermore, although the examples described herein have a wide variety of constructions, other constructions are possible, as will be apparent upon understanding the disclosure of this application.

[0028] This utility model provides a cascade heat pump system, such as Figures 1 to 2 As shown, the cascade heat pump system in this embodiment includes a first loop and a second loop, which are connected by a common heat exchanger 3. The common heat exchanger 3 enables heat transfer between the two loops; that is, at the common heat exchanger 3, the first loop can provide heat to supply the second loop (when the system is in normal mode), or the second loop can provide heat to supply the first loop (when the system is in defrost mode). The specific structure and connection relationships of the above-mentioned parts of the cascade heat pump system according to this invention will be described in detail below.

[0029] In this embodiment, as Figures 1 to 2As shown, the first circuit includes a first main circuit and a first branch circuit, with the first branch circuit connected in parallel with the first main circuit. Specifically, the first main circuit is sequentially equipped with a first compressor 11, a first solenoid valve 121, the aforementioned common heat exchanger 3, a first expansion valve 13, a first heat exchanger 14, and a second solenoid valve 122. Furthermore, the first end of the first branch circuit is connected between the first solenoid valve 121 and the common heat exchanger 3, and the second end of the first branch circuit is connected between the first heat exchanger 14 and the second solenoid valve 122. The first branch circuit is sequentially equipped with a third solenoid valve 123, a refrigerant pump 15, and a fourth solenoid valve 124.

[0030] Thus, by controlling the opening and closing of the first solenoid valve 121, the second solenoid valve 122, the third solenoid valve 123, and the fourth solenoid valve 124, it is possible to control whether the first compressor 11 and the refrigerant pump 15 are connected to the first main circuit.

[0031] Furthermore, in this embodiment, such as Figures 1 to 2 As shown, the second circuit includes a second main circuit, which sequentially includes a common heat exchanger 3, a four-way valve 22, a second heat exchanger 23, and a second expansion valve 24. The common heat exchanger 3 and the second heat exchanger 23 are respectively connected to the first opening and the second opening of the four-way valve 22. Further, the second circuit also includes a second branch, the two ends of which are respectively connected to the third opening and the fourth opening of the four-way valve 22, and a second compressor 21 is installed on the second branch. Even further, inside the four-way valve 22, the first opening can connect to the third opening, the third opening can connect to the second opening, the second opening can connect to the fourth opening, and the fourth opening can connect to the first opening.

[0032] Thus, when this system is in normal mode, such as Figure 1 As shown, in the first circuit, the first compressor 11 operates, and the first solenoid valve 121 and the second solenoid valve 122 are opened to connect the first compressor 11 to the first main circuit; the refrigerant pump 15 is stopped, and the third solenoid valve 123 and the fourth solenoid valve 124 are closed to disconnect the refrigerant pump 15 from the first main circuit. The low-temperature, low-pressure gaseous working fluid enters the first compressor 11 and is compressed into a high-temperature, high-pressure gaseous working fluid; the high-temperature, high-pressure gaseous working fluid then enters the common heat exchanger 3 to release heat and form a high-pressure, medium-temperature liquid working fluid (i.e., the first circuit supplies heat to the second circuit); the high-pressure, medium-temperature liquid working fluid is throttled by the first expansion valve 13 into a low-temperature, low-pressure liquid working fluid, and then evaporates through the first heat exchanger 14 (at this time, the first heat exchanger 14 is equivalent to an evaporator) to form a low-temperature, low-pressure gaseous working fluid; finally, the low-temperature, low-pressure gaseous working fluid enters the first compressor 11 again and is compressed to complete the working fluid cycle of the first circuit.

[0033] In the second circuit, the fourth opening and the second opening inside the four-way valve 22 are connected, and the first opening and the third opening of the four-way valve 22 are also connected. For example... Figure 1 As shown, the low-temperature, low-pressure gaseous working fluid is compressed into a high-temperature, high-pressure gaseous working fluid by the second compressor 21. The high-temperature, high-pressure gaseous working fluid enters the second heat exchanger 23 (which acts as a condenser at this time) through the fourth and second openings of the four-way valve 22, releasing heat to form a high-pressure, medium-temperature liquid working fluid. This heat pump system is connected to the user end through the second heat exchanger 23, meaning that the high-temperature, high-pressure gaseous working fluid releases heat at the second heat exchanger 23 to provide heat energy to the outside. Then, the high-pressure, medium-temperature liquid working fluid is throttled into a medium-temperature, low-pressure two-phase working fluid through the second expansion valve 24. These working fluids then enter the common heat exchanger 3 to exchange heat with the high-temperature, high-pressure gaseous working fluid in the first loop. That is, the medium-temperature, low-pressure two-phase working fluid in the second loop absorbs heat to form a low-temperature, low-pressure gaseous working fluid, which then returns to the second compressor 21 through the first and third openings of the four-way valve 22 to be compressed again, thus completing the working fluid cycle of the second loop.

[0034] When this system operates in normal mode for an extended period, frost may form on the first heat exchanger 14, requiring the defrosting mode to be activated. Figure 2 As shown, in the first loop, when the control module (not shown) detects that the first heat exchanger 14 has reached the condition requiring defrosting, the control module controls the first compressor 11 to stop and closes the first solenoid valve 121 and the second solenoid valve, so that the first compressor 11 is disconnected from the first main loop; the control module controls the refrigerant pump 15 to run, and the third solenoid valve 123 and the fourth solenoid valve 124 are opened so that the refrigerant pump 15 is connected to the first main loop. At this time, high-temperature liquid working fluid is injected from the common heat exchanger 3 into the refrigerant pump 15, and the refrigerant pump 15 transports the high-temperature liquid working fluid to the first heat exchanger 14, so that the frost layer on the surface of the first heat exchanger 14 melts. Then, after heat exchange, the high-temperature liquid working fluid flows back to the common heat exchanger 3 through the first expansion valve 13, and exchanges heat with the heat source in the second loop (i.e., the second loop supplies heat to the first loop), so that the temperature of the liquid working fluid rises, and then enters the refrigerant pump 15 to complete a defrosting cycle.

[0035] In the second loop, when the control module detects that the first heat exchanger 14 has reached the condition requiring defrosting, the control module controls the second compressor 21 to reduce its frequency and controls the four-way valve 22 to switch (i.e., the fourth opening inside the four-way valve 22 is connected to the first opening, and the second opening and the third opening of the four-way valve 22 are connected), and the second loop switches from heating mode to cooling mode. Figure 2As shown, the second compressor 21 compresses the low-temperature, low-pressure gaseous working fluid into a high-temperature, high-pressure gaseous working fluid. The high-temperature, high-pressure gaseous working fluid enters the common heat exchanger 3 through the fourth and first openings of the four-way valve 22. In the common heat exchanger 3, it releases heat and condenses into a medium-temperature, high-pressure liquid working fluid, thus providing heat to the first loop. The medium-temperature, high-pressure liquid working fluid is then throttled by the second expansion valve 24 into a low-pressure liquid working fluid. Then, it absorbs heat and evaporates into a low-temperature, low-pressure gaseous working fluid through the second heat exchanger 23. The low-temperature, low-pressure gaseous working fluid flows back to the second compressor 21 through the second and third openings of the four-way valve 22 to complete one cycle.

[0036] It should be noted that the above-mentioned control module is a conventional setup in this field, and its working principle and specific form will not be described in detail (for example, it can be formed as a PCB board and communicate with the above-mentioned related components).

[0037] According to the cascade heat pump system of this utility model, a refrigerant pump 15 is also provided in the first loop. The refrigerant pump 15 is connected in parallel to both ends of the first compressor 11 through the first branch. Thus, when the defrosting mode of this system is activated, the first compressor 11 in the first loop is shut down, and the refrigerant pump 15 works and can combine with the heat provided by the second loop to defrost the heat exchanger in the first loop. Since the first compressor 11 is shut down, the working fluid will not flow back to the first compressor 11. That is, the possibility of the first compressor 11 being damaged during the defrosting process of this cascade heat pump system is extremely low.

[0038] Finally, it should be noted that the above-described embodiments are merely specific implementations of this application, used to illustrate the technical solutions of this application, and not to limit them. The protection scope of this application is not limited thereto. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that any person skilled in the art can still modify or easily conceive of changes to the technical solutions described in the foregoing embodiments, or make equivalent substitutions for some of the technical features, within the technical scope disclosed in this application. Such modifications, changes, or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this application, and should all be covered within the protection scope of this application. Therefore, the protection scope of this application should be determined by the protection scope of the claims.

Claims

1. A cascade heat pump system, comprising a first loop and a second loop, wherein the first loop and the second loop are connected via a common heat exchanger, characterized in that, The first circuit includes a first compressor, a common heat exchanger, and a first heat exchanger arranged in sequence; the first circuit also includes a refrigerant pump, which is connected in parallel to both ends of the first compressor via a first branch. When the cascade heat pump system is in normal mode, the first compressor is running and the refrigerant pump is shut down, and the first circuit supplies heat to the second circuit. When the cascade heat pump system is in defrost mode, the first compressor stops and the refrigerant pump runs, and the second circuit supplies heat to the first circuit.

2. The cascade heat pump system of claim 1, wherein, The first circuit includes a first main circuit, on which the first compressor, the first solenoid valve, the common heat exchanger, the first expansion valve, the first heat exchanger, and the second solenoid valve are sequentially arranged.

3. The cascade heat pump system of claim 2, wherein, The first end of the first branch is connected between the first solenoid valve and the common heat exchanger; the second end of the first branch is connected between the first heat exchanger and the second solenoid valve.

4. The cascade heat pump system according to claim 3, characterized in that, The first branch is also equipped with a third solenoid valve and a fourth solenoid valve, which are located at both ends of the fluorine pump.

5. The cascade heat pump system of claim 4, wherein, When the cascade heat pump system is in the conventional mode, the first compressor operates, and the first and second solenoid valves are open to connect the first compressor to the first main circuit; the refrigerant pump stops, and the third and fourth solenoid valves are closed to disconnect the refrigerant pump from the first main circuit. When the cascade heat pump system is in the defrost mode, the first compressor stops operating, and the first and second solenoid valves close to disconnect the first compressor from the first main circuit; the refrigerant pump operates, and the third and fourth solenoid valves open to connect the refrigerant pump to the first main circuit.

6. The cascade heat pump system according to claim 5, characterized in that, In the first loop, when the cascade heat pump system is in the conventional mode, the working fluid in the first compressor flows sequentially through the common heat exchanger, the first expansion valve, and the first heat exchanger and then flows back to the first compressor. When the cascade heat pump system is in the defrosting mode, the working fluid in the refrigerant pump flows sequentially through the first heat exchanger, the first expansion valve, and the common heat exchanger, and then flows back to the refrigerant pump.

7. The cascade heat pump system of claim 1, wherein, The second circuit includes a second main circuit, which includes a common heat exchanger, a four-way valve, a second heat exchanger, and a second expansion valve arranged in sequence; the common heat exchanger and the second heat exchanger are respectively connected to the first opening and the second opening of the four-way valve.

8. The cascade heat pump system of claim 7, wherein, The second circuit also includes a second branch, which is connected to the third and fourth openings of the four-way valve respectively; the second branch is equipped with a second compressor.

9. The cascade heat pump system according to claim 8, characterized in that, Inside the four-way valve, the first opening can communicate with the third opening, the third opening can communicate with the second opening, the second opening can communicate with the fourth opening, and the fourth opening can communicate with the first opening.

10. The cascade heat pump system according to claim 9, characterized in that, In the second loop, when the cascade heat pump system is in the conventional mode, the working fluid in the second compressor flows through the fourth opening and the second opening of the four-way valve sequentially through the second heat exchanger and the common heat exchanger, and then flows back to the second compressor through the first opening and the third opening of the four-way valve. When the cascade heat pump system is in the defrost mode, the working fluid in the second compressor flows through the fourth opening and the first opening of the four-way valve sequentially through the common heat exchanger and the second heat exchanger, and then flows back to the second compressor through the second opening and the third opening of the four-way valve.

Images