Heat exchanger and heat pump water heater
By employing a valve-controlled parallel and series design for refrigerant flow paths in heat pump water heaters, combined with a finned structure, the problem of refrigerant pressure loss is solved, the efficiency of the heat exchanger and the defrosting effect are improved, and the heating performance of the heat pump water heater is enhanced.
Patent Information
- Application Number
- CN202520288732.9
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2025-02-21
- Publication Date
- 2026-02-06
- Estimated Expiration
- 2035-02-21
AI Technical Summary
In existing heat pump water heaters, the refrigerant experiences significant pressure loss after passing through the cold section during heating mode, leading to reduced heat exchange efficiency and impacting heating capacity.
The refrigerant flow path is controlled by a first valve and a second valve. When used as an evaporator, the refrigerant flows into multiple heat exchange tube groups in parallel. When used as a condenser, the refrigerant flows into parallel heat exchange tube groups in series. The fin design is combined to optimize the flow path and increase the heat exchange area.
It improves the heat exchange efficiency and defrosting effect of the heat exchanger, enhances the heating capacity of the heat pump water heater, and reduces the possibility of frosting, especially in low-temperature environments.
Smart Images
Figure CN223882538U_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The utility model relates to heat exchanger technical field, provide a heat exchanger and heat pump water heater specifically. BACKGROUND
[0002] The heat exchanger is one of the components frequently used by the device related to heat exchange such as air conditioner, heat pump water heater, and the performance of the heat exchanger depends on the flow path design of the heat exchanger to a great extent.
[0003] The bottom of the heat exchanger is more likely to frost when the existing heat pump water heater runs in the low temperature environment, so the supercooling section is usually arranged at the bottom of the heat exchanger. In the defrosting mode, the higher temperature refrigerant first enters the supercooling section, defrosts the bottom of the heat exchanger, and then the refrigerant enters the middle and upper part of the heat exchanger. In the heating mode, the low temperature refrigerant first enters the middle and upper part of the heat exchanger, expands into a superheated gas after absorbing heat, and then is collected into the supercooling section.
[0004] The flow path design of the supercooling section can improve the defrosting effect of the bottom of the heat exchanger, but in the heating mode, the pressure loss of the refrigerant flow through the supercooling section is large, which reduces the heat exchange efficiency of the heat exchanger, thereby affecting the heating capacity of the heat pump water heater.
[0005] Therefore, there is a need in the art for a new heat exchanger and heat pump water heater to solve the above problems. SUMMARY
[0006] The utility model aims at solving above-mentioned technical problem, that is, solve the problem that the pressure loss of the refrigerant flow through the supercooling section is large in the heating mode of the existing heat exchanger, which reduces the heat exchange efficiency of the heat exchanger, thereby affecting the heating capacity of the heat pump water heater.
[0007] In a first aspect, the utility model provides a heat exchanger; the heat exchanger comprises a first refrigerant inlet and outlet pipe, a second refrigerant inlet and outlet pipe, a first heat exchange pipe group, a second heat exchange pipe group and a plurality of third heat exchange pipe groups arranged from bottom to top, one end of the first heat exchange pipe group, the second heat exchange pipe group and the third heat exchange pipe group is communicated with the first refrigerant inlet and outlet pipe, and the other end is communicated with the second refrigerant inlet and outlet pipe;
[0008] The heat exchanger further comprises a first valve and a second valve, the first valve is arranged on the first refrigerant inlet and outlet pipe, and is located between the second heat exchange pipe group and the adjacent third heat exchange pipe group, the second valve is arranged on the second refrigerant inlet and outlet pipe, and is located between the first heat exchange pipe group and the second heat exchange pipe group;
[0009] When the heat exchanger is used as an evaporator, the first valve and the second valve allow the refrigerant to flow through;
[0010] When the heat exchanger is used as a condenser, the first valve and the second valve do not allow the refrigerant to flow through.
[0011] In the above technical solution, when the heat exchanger is used as an evaporator, the first valve and the second valve allow the refrigerant to flow through, so that the first heat exchange pipe group, the second heat exchange pipe group and each third heat exchange pipe group are connected in parallel. The low-temperature refrigerant flowing through the first refrigerant inlet and outlet pipe can flow into the first heat exchange pipe group, the second heat exchange pipe group and each third heat exchange pipe group at the same time, thereby reducing the pressure drop of the refrigerant in the heat exchanger and improving the heat exchange efficiency and the heating efficiency of the heat pump water heater. At the same time, the surface temperature of the heat exchanger can be improved, and the possibility of frost formation on the heat exchanger in a low-temperature environment can be reduced. When the heat exchanger is used as a condenser, the first valve and the second valve do not allow the refrigerant to flow through, so that the first heat exchange pipe group is connected in series with the second heat exchange pipe group and the third heat exchange pipe group, and the third heat exchange pipe groups are connected in parallel. The high-temperature refrigerant flowing through the second refrigerant inlet and outlet pipe first flows through the first heat exchange pipe group located below, preferentially removes the thick frost layer at the bottom, then flows into the second heat exchange pipe group, and then flows into the plurality of third heat exchange pipe groups at the same time, thereby removing the frost layer on the upper part of the heat exchanger and improving the defrosting effect of the heat exchanger. By changing the flow path of the refrigerant in the heat exchanger through the first valve and the second valve, the heat exchanger can improve the heat exchange efficiency and the defrosting effect, and the overall heating effect of the heat pump water heater can be improved.
[0012] In the above preferred technical solution of the heat exchanger, the first valve is a first one-way valve, and the first one-way valve only allows the refrigerant flowing out of the first heat exchange pipe group to flow into the second heat exchange pipe group.
[0013] The second valve is a second one-way valve, and the second one-way valve only allows the refrigerant flowing into the first heat exchange pipe group from the second refrigerant inlet and outlet pipe.
[0014] In the above technical solution, the first one-way valve is used to allow only the refrigerant flowing out of the first heat exchange pipe group to flow into the second heat exchange pipe group, and the second one-way valve is used to allow only the refrigerant flowing into the first heat exchange pipe group from the second refrigerant inlet and outlet pipe.
[0015] In the above preferred technical solution of the heat exchanger, the first valve and the second valve are both shut-off valves.
[0016] In the above technical solution, the opening and closing of the first valve and the second valve are controlled to realize the on-off of the refrigerant flow path.
[0017] In the above preferred technical solution of the heat exchanger, the first heat exchange pipe group and the first refrigerant inlet and outlet pipe are connected through a first left connecting pipe, and a temperature detection member is arranged on the first left connecting pipe.
[0018] In the technical scheme, the temperature detecting member is installed on the first left connecting pipe, so that the temperature of the first heat exchange pipe group at the bottom can be detected, and whether to enter or exit the defrosting mode can be determined more accurately.
[0019] In the preferred technical scheme of the heat exchanger, the third heat exchange pipe group and the first refrigerant inlet and outlet pipe are connected through at least one third left connecting pipe, the third heat exchange pipe group and the second refrigerant inlet and outlet pipe are connected through at least one third right connecting pipe, and the number of the third left connecting pipes is less than the number of the third right connecting pipes.
[0020] In the technical scheme, when the heat pump water heater operates in the heating mode, the refrigerant enters the third heat exchange pipe group through the third left connecting pipes with a smaller number, and flows out through the third right connecting pipes with a larger number, so that the pressure drop of the gaseous refrigerant is reduced, and the heat exchange efficiency of the heat exchanger is improved.
[0021] In the preferred technical scheme of the heat exchanger, each third heat exchange pipe group is connected with one third left connecting pipe and two third right connecting pipes.
[0022] In the technical scheme, the one-in-two-out design can reduce the pressure drop of the gaseous refrigerant, and improve the heat exchange efficiency of the heat exchanger.
[0023] In the preferred technical scheme of the heat exchanger, the outer circumferential walls of the first heat exchange pipe group, the second heat exchange pipe group and the third heat exchange pipe group are sleeved with fins.
[0024] In the technical scheme, the fins increase the heat exchange area of the first heat exchange pipe group, the second heat exchange pipe group and the third heat exchange pipe group, so that the heat exchange efficiency of the heat exchanger is improved.
[0025] In the preferred technical scheme of the heat exchanger, the cross section of the fin is rectangular or corrugated.
[0026] In the technical scheme, the fin is corrugated, so that the heat exchange area of the fin is increased.
[0027] In the preferred technical scheme of the heat exchanger, at least one vertical flow guide groove is arranged on the fin with a rectangular cross section.
[0028] In the technical scheme, the flow guide groove can increase the heat exchange area of the fin, and guide the condensation water on the fin, so that the condensation water is timely dripped from the fin, and the frost amount of the fin is reduced.
[0029] In a second aspect, the utility model provides a heat pump water heater; the heat pump water heater comprises the heat exchanger.
[0030] In the preferred technical scheme of the heat exchanger, the flow path of the refrigerant in the heat exchanger is changed through the first valve and the second valve, so that the heat exchanger can improve the heat exchange efficiency and the defrosting effect, and the overall heating effect of the heat pump water heater can be improved.
[0031] In summary, the utility model has at least the following beneficial effects:
[0032] 1. When the heat exchanger is used as an evaporator, the first valve and the second valve allow the refrigerant to pass through, so that the first heat exchange pipe group, the second heat exchange pipe group and each third heat exchange pipe group are connected in parallel. The low-temperature refrigerant flowing in through the first refrigerant inlet and outlet pipe can flow into the first heat exchange pipe group, the second heat exchange pipe group and each third heat exchange pipe group at the same time, so that the pressure drop of the refrigerant in the heat exchanger can be reduced, the heat exchange efficiency and the heating efficiency of the heat pump water heater can be improved. At the same time, the surface temperature of the heat exchanger can be improved, and the possibility of frosting of the heat exchanger in a low-temperature environment can be reduced.
[0033] 2. When the heat exchanger is used as a condenser, the first valve and the second valve do not allow the refrigerant to pass through, so that the first heat exchange pipe group is connected in series with the second heat exchange pipe group and the third heat exchange pipe group, and the multiple third heat exchange pipe groups are connected in parallel. The high-temperature refrigerant flowing in through the second refrigerant inlet and outlet pipe first passes through the first heat exchange pipe group located at the bottom, preferentially removes the thick frost layer at the bottom, then flows into the second heat exchange pipe group, and then flows into the multiple third heat exchange pipe groups at the same time, so that the frost layer on the upper part of the heat exchanger can be removed, and the defrosting effect of the heat exchanger can be improved. BRIEF DESCRIPTION OF DRAWINGS
[0034] The preferred embodiments of the utility model will be described below with reference to the accompanying drawings, in which:
[0035] Figure 1 is a schematic view of a heat pump water heater of the utility model;
[0036] Figure 2 is a flow path diagram of refrigerant in a heat exchanger when the heat pump water heater of the utility model is running in a heating mode;
[0037] Figure 3 is a flow path diagram of refrigerant in a heat exchanger when the heat pump water heater of the utility model is running in a defrosting mode;
[0038] Figure 4 is a schematic view of a fin of the heat exchanger of the utility model;
[0039] Reference signs:
[0040] 1, first refrigerant inlet and outlet pipe; 2, second refrigerant inlet and outlet pipe; 3, first heat exchange pipe group; 4, second heat exchange pipe group; 5, third heat exchange pipe group; 61, first left connecting pipe; 62, first right connecting pipe; 71, Second left connecting pipe; 72, second right connecting pipe; 81, third left connecting pipe; 82, third right connecting pipe; 9, first check valve; 10, second check valve; 11, temperature detection piece; 12, fin; 121, flow guide groove; 13, heat preservation water tank; 14, fan; 15, compressor; 16, four-way valve; 17, condenser; 18, heat exchanger. DETAILED DESCRIPTION
[0041] The preferred embodiments of the present application will be described below with reference to the accompanying drawings. Those skilled in the art should understand that these embodiments are only used to explain the technical principles of the present application, and are not intended to limit the protection scope of the present application. Those skilled in the art can make adjustments as needed in order to adapt to specific application occasions.
[0042] It should be noted that in the description of the present application, the terms "up", "down", "left", "right" and the like indicate the direction or positional relationship of the terms based on the direction or positional relationship shown in the drawings, which is only for the convenience of description, and does not indicate or imply that the device or element must have a specific orientation, be constructed and operated in a specific orientation, therefore cannot be understood as a limitation on the present application. In addition, the terms "first", "second", "third", "fourth" are only for descriptive purposes, and cannot be understood as indicating or implying relative importance.
[0043] In addition, it should be noted that in the description of the present application, unless otherwise specified and limited, the terms "connected", "connected", "communicated" should be understood broadly, for example, it can be fixedly connected, or it can be detachably connected; it can be directly connected, or it can be indirectly connected through an intermediate medium; it can be the communication between two elements inside. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.
[0044] In order to solve the problem that the existing heat exchanger has large pressure loss after the refrigerant flows through the cold section in heating mode, which reduces the heat exchange efficiency of the heat exchanger, thereby affecting the heating capacity of the heat pump water heater.
[0045] As Figure 1As shown, the embodiment discloses a heat exchanger, which comprises a shell, a heat preservation water tank 13 located in the shell, a fan 14, a refrigerant circulation pipeline, a compressor 15 installed on the refrigerant circulation pipeline, a four-way valve 16, a heat exchanger and a condenser 17 installed in the heat preservation water tank 13 for heating water in the heat preservation water tank 13. The shell is provided with an air inlet and an air outlet, the heat exchanger is located on one side of the air inlet, and the fan 14 is located on one side of the heat exchanger to exchange heat with air through the heat exchanger.
[0046] As shown in Figure 2 and Figure 3 , specifically, the heat exchanger comprises a first refrigerant inlet and outlet pipe 1, a second refrigerant inlet and outlet pipe 2, a first valve, a second valve, a temperature detection piece 11, a first heat exchange pipe group 3, a second heat exchange pipe group 4 and a plurality of third heat exchange pipe groups 5. The first refrigerant inlet and outlet pipe 1 is connected with the condenser 17 through the refrigerant circulation pipeline, and the second refrigerant inlet and outlet pipe 2 is connected with the compressor 15 through the refrigerant circulation pipeline.
[0047] The first heat exchange pipe group 3, the second heat exchange pipe group 4 and the plurality of third heat exchange pipe groups 5 are arranged from bottom to top. The first heat exchange pipe group 3 is connected with the first refrigerant inlet and outlet pipe 1 through a first left connecting pipe 61 and connected with the second refrigerant inlet and outlet pipe 2 through a first right connecting pipe 62. The temperature detection piece 11 is installed on the first left connecting pipe 61, which can better detect the temperature of the first heat exchange pipe group 3 located at the bottom, so as to more accurately judge whether the heat pump water heater enters or exits the defrosting mode. The second heat exchange pipe group 4 is connected with the first refrigerant inlet and outlet pipe 1 through a second left connecting pipe 71 and connected with the second refrigerant inlet and outlet pipe 2 through a second right connecting pipe 72. The third heat exchange pipe group 5 is connected with the first refrigerant inlet and outlet pipe 1 through a third left connecting pipe 81 and connected with the second refrigerant inlet and outlet pipe 2 through a third right connecting pipe 82, and the number of the third left connecting pipe 81 is less than that of the third right connecting pipe 82.
[0048] As shown in Figure 2 and Figure 3 , the first valve is installed on the first refrigerant inlet and outlet pipe 1 and located between the second heat exchange pipe group 4 and the adjacent third heat exchange pipe group 5, i.e. between the second left connecting pipe 71 and the adjacent third left connecting pipe 81. The second valve is installed on the second refrigerant inlet and outlet pipe 2 and located between the first heat exchange pipe group 3 and the second heat exchange pipe group 4, i.e. between the first right connecting pipe 62 and the second right connecting pipe 72. The first valve is a first one-way valve 9, which only allows the refrigerant flowing out of the first heat exchange pipe group 3 to flow into the second heat exchange pipe group 4. The second valve is a second one-way valve 10, which only allows the refrigerant flowing into the first heat exchange pipe group 3 from the second refrigerant inlet and outlet pipe 2.
[0049] As shown in Figure 2As shown, when the heat pump water heater runs in the heating mode, the heat exchanger works as an evaporator, the refrigerant flowing into the first refrigerant inlet pipe can flow through the first one-way valve 9, enter the first heat exchange pipe group 3 and the second heat exchange pipe group 4, and the refrigerant flowing out of the second heat exchange pipe group 4 can flow through the second one-way valve 10, so that the first heat exchange pipe group 3, the second heat exchange pipe group 4 and each third heat exchange pipe group 5 are in parallel. The low-temperature liquid flowing out of the condenser 17 enters the first refrigerant inlet pipe 1, and then flows into the first heat exchange pipe group 3, the second heat exchange pipe group 4 and each third heat exchange pipe group 5 through the first left connecting pipe 61, the second left connecting pipe 71 and each third left connecting pipe 81 for heat exchange, changes from liquid state to gaseous state, and then flows into the second refrigerant inlet pipe 2 through the first right connecting pipe 62, the second right connecting pipe 72 and each third right connecting pipe 82, flows into the compressor 15, and the high-temperature and high-pressure refrigerant enters the condenser 17 to heat the water in the heat preservation water tank 13.
[0050] The first heat exchange pipe group 3, the second heat exchange pipe group 4 and the third heat exchange pipe group 5 are connected in parallel through the first one-way valve 9 and the second one-way valve 10, the refrigerant flows into the first heat exchange pipe group 3, the second heat exchange pipe group 4 and the third heat exchange pipe group 5 at the same time, compared with the refrigerant flowing into the upper pipe group of the heat exchanger first and then flowing into the supercooling section, the pressure drop of the refrigerant in the heat exchanger can be reduced, the heat exchange efficiency of the heat exchanger can be improved, and thus the heating efficiency of the heat pump water heater can be improved. Moreover, the surface temperature of the heat exchanger can be improved, and the possibility of frost formation on the surface of the heat exchanger can be reduced when the heat pump water heater runs in a low-temperature environment.
[0051] As shown, Figure 3 As shown, when the heat pump water heater runs in the defrosting mode, the heat exchanger works as a condenser 17, the refrigerant flowing into the second refrigerant inlet pipe 2 can only flow into the first heat exchange pipe group 3 and cannot flow into the second heat exchange pipe group 4 through the second one-way valve 10, and the refrigerant flowing out of the first heat exchange pipe group 3 can only flow into the second heat exchange pipe group 4 and cannot flow into the third heat exchange pipe group 5 through the first one-way valve 9, so that the first heat exchange pipe group 3 is connected in series with the second heat exchange pipe group 4 and the third heat exchange pipe group 5, and the third heat exchange pipe groups 5 are connected in parallel. The high-temperature and high-pressure gas flowing out of the compressor 15 flows into the second refrigerant inlet pipe 2, the first heat exchange pipe group 3 and the second heat exchange pipe group 4 in sequence, flows into each third heat exchange pipe group 5 at the same time, and then flows into the first refrigerant inlet pipe 1, flows into the condenser 17 and returns to the compressor 15.
[0052] The first heat exchange pipe group 3 is connected in series with the second heat exchange pipe group 4 and the third heat exchange pipe group 5 through the first one-way valve 9 and the second one-way valve 10, and the third heat exchange pipe groups 5 are connected in parallel, so that the high-temperature and high-pressure refrigerant first flows into the first heat exchange pipe group 3 located at the bottom, preferentially removes the thick frost layer at the bottom, then flows into the second heat exchange pipe group 4, and then flows into the third heat exchange pipe groups 5 at the same time, so that the frost layer at the upper part of the heat exchanger is removed, and the defrosting effect of the heat exchanger is improved. Thus, the influence of the frost layer on the heat exchange effect of the heat exchanger is reduced, and the heating capacity of the heat pump water heater is improved.
[0053] Especially for the heat pump water heater using the refrigerant R290, near the saturation temperature 0℃, as the pressure drop increases, the saturation temperature of R290 decreases more than that of other refrigerants such as R410A, that is, at the same pressure drop, the heat exchanger using the refrigerant R290 is more likely to frost than other refrigerants, thereby causing insufficient heating capacity of the heat pump water heater. The heat exchanger in the present application can have better defrosting effect and heating efficiency for the heat pump water heater using the refrigerant R290.
[0054] As another preferred embodiment, the first valve and the second valve can also be shut-off valves. When the heat pump water heater operates in the heating mode, the first valve and the second valve are opened, so that the first heat exchange pipe group 3, the second heat exchange pipe group 4, and the third heat exchange pipe groups 5 are connected in parallel. When the heat pump water heater operates in the defrosting mode, the first valve and the second valve are closed, so that the first heat exchange pipe group 3 is connected in series with the second heat exchange pipe group 4 and the third heat exchange pipe groups 5, and the third heat exchange pipe groups 5 are connected in parallel. Through the first valve and the second valve, the flow path of the refrigerant in the heat exchanger is changed, so that the heat exchanger can improve the heat exchange efficiency and the defrosting effect, and the overall heating effect of the heat pump water heater can be improved.
[0055] As shown in FIG. 1, Figure 2 and Figure 3As shown, the flow path of the refrigerant in the first heat exchange tube group 3, the second heat exchange tube group 4 and the third heat exchange tube group 5 is in the shape of "N", which prolongs the path of the refrigerant in the heat exchanger, increases the contact area with the heat exchanger, and reduces the resistance of fluid flow, thereby improving the heat exchange efficiency. In the embodiment, the number of the first heat exchange tube group 3 and the second heat exchange tube group 4 is one, the number of the first left connecting tube 61 and the first right connecting tube 62 is one, and the number of the third heat exchange tube group 5 is four. Each of the third heat exchange tube groups 5 is connected with one third left connecting tube 81 and two third right connecting tubes 82. The flow path of the heat exchanger is in the shape of "N" with six inlets and ten outlets. When the heat pump water heater operates in the heating mode, the design of fewer inlets and more outlets can reduce the pressure drop of the gaseous refrigerant, improve the heat exchange efficiency of the heat exchanger, and also reduce the possibility of frost formation on the surface of the heat exchanger under low temperature conditions. Of course, each of the third heat exchange tube groups 5 can also be connected with one third left connecting tube 81 and three or four third right connecting tubes 82, or each of the third heat exchange tube groups 5 can be connected with two third left connecting tubes 81 and three or four third right connecting tubes 82. The specific number is not limited, as long as the number of the third left connecting tube 81 is less than the number of the third right connecting tube 82, and the design of fewer inlets and more outlets can reduce the pressure drop of the gaseous refrigerant, improve the heat exchange efficiency of the heat exchanger, and also reduce the possibility of frost formation on the surface of the heat exchanger under low temperature conditions.
[0056] As shown in the drawings, Figure 4 Further, as shown, the outer peripheral wall of the first heat exchange tube group 3, the second heat exchange tube group 4 and the third heat exchange tube group 5 is sleeved with fins 12, and the cross section of the fins 12 is in the shape of rectangle or corrugation. The fins 12 increase the heat exchange area of the first heat exchange tube group 3, the second heat exchange tube group 4 and the third heat exchange tube group 5, thereby improving the heat exchange efficiency of the heat exchanger. In the embodiment, the first heat exchange tube group 3, the second heat exchange tube group 4 and the third heat exchange tube group 5 share one set of heat exchange fins 12. The cross section of the fins 12 is in the shape of rectangle, and at least one vertical flow guide groove 121 is arranged on the fins 12. The flow guide groove 121 can increase the heat exchange area of the fins 12, thereby further improving the heat exchange efficiency of the heat exchanger. Meanwhile, the flow guide groove 121 can also guide the condensation water on the fins 12, so that the condensation water can drop from the fins 12 in time, thereby reducing the frost amount on the fins 12, and it is also easier to remove the frost in the flow guide groove 121 during defrosting.
[0057] The technical scheme of the present application has been described in combination with the preferred embodiments shown in the drawings, but those skilled in the art can easily understand that the protection scope of the present application is obviously not limited to these specific embodiments. Those skilled in the art can make equivalent changes or replacements to the related technical features without deviating from the principles of the present application, and the technical schemes after the changes or replacements will all fall within the protection scope of the present application.
Claims
1. A heat exchanger, characterized by, The heat exchanger comprises a first refrigerant inlet and outlet pipe (1), a second refrigerant inlet and outlet pipe (2), a first heat exchange pipe group (3) arranged from bottom to top, a second heat exchange pipe group (4), and a plurality of third heat exchange pipe groups (5), one end of the first heat exchange pipe group (3), the second heat exchange pipe group (4), and the third heat exchange pipe group (5) is communicated with the first refrigerant inlet and outlet pipe (1), and the other end is communicated with the second refrigerant inlet and outlet pipe (2); The heat exchanger further comprises a first valve and a second valve, the first valve is arranged on the first refrigerant inlet and outlet pipe (1) and located between the second heat exchange pipe group (4) and the adjacent third heat exchange pipe group (5), and the second valve is arranged on the second refrigerant inlet and outlet pipe (2) and located between the first heat exchange pipe group (3) and the second heat exchange pipe group (4); When the heat exchanger is used as an evaporator, the first valve and the second valve allow the refrigerant to flow through; When the heat exchanger is used as a condenser (17), the first valve and the second valve do not allow the refrigerant to flow through.
2. The heat exchanger of claim 1, wherein The first valve is a first one-way valve (9), which only allows the refrigerant flowing out of the first heat exchange pipe group (3) to flow into the second heat exchange pipe group (4); and / or The second valve is a second one-way valve (10), which only allows the refrigerant flowing into the first heat exchange pipe group (3) from the second refrigerant inlet and outlet pipe (2).
3. The heat exchanger of claim 1, wherein The first valve and the second valve are both shut-off valves.
4. The heat exchanger of claim 1, wherein The first heat exchange pipe group (3) and the first refrigerant inlet and outlet pipe (1) are communicated through a first left connecting pipe (61), and a temperature detection member (11) is arranged on the first left connecting pipe (61).
5. The heat exchanger of claim 1, wherein The third heat exchange pipe group (5) and the first refrigerant inlet and outlet pipe (1) are communicated through at least one third left connecting pipe (81), the third heat exchange pipe group (5) and the second refrigerant inlet and outlet pipe (2) are communicated through at least one third right connecting pipe (82), and the number of the third left connecting pipes (81) is less than the number of the third right connecting pipes (82).
6. The heat exchanger of claim 5, wherein Each third heat exchange pipe group (5) is communicated with one third left connecting pipe (81) and two third right connecting pipes (82).
7. The heat exchanger of claim 1, wherein The first heat exchange pipe group (3), the second heat exchange pipe group (4), and the third heat exchange pipe group (5) are provided with fins (12) on the outer peripheral wall.
8. The heat exchanger of claim 7, wherein The cross section of the fin (12) is rectangular or corrugated.
9. The heat exchanger of claim 8, wherein, The fin (12) with a rectangular cross section is provided with at least one vertical flow guide groove (121).
10. A heat pump water heater, characterized by, The heat pump water heater comprises the heat exchanger according to any one of claims 1-9.