Air source heat pump system, control method of air source heat pump system and design method of heat exchanger

Abstract

The embodiment of the invention provides an air source heat pump system, a control method of the air source heat pump system and a design method of a heat exchanger, the air source heat pump system comprises a controller, an air cooling evaporator, a compressor, a throttling device and the heat exchanger, and a phase change material is arranged in the heat exchanger; the controller collects system state parameters, switching of system modes is achieved through an algorithm, when the frosting information is that frosting is not carried out, the controller is configured to control the air cooling evaporator to communicate with the heat exchanger, and the air cooling evaporator heats first fluid and then flows to the heat exchanger; and when the frosting information is frosting, the controller is configured to control the air cooling evaporator and the heat exchanger to be disconnected, and the phase change material releases heat in the heat exchanger. And in the time period when the first fluid does not heat the third fluid, the phase change material releases heat to heat the third fluid, and it is guaranteed that the temperature of the third fluid is constant.

Description

Technical Field

[0001] The present application relates to the field of heat exchange technology, and in particular to an air source heat pump system and a control method thereof, and a design method for a heat exchanger. Background Art

[0002] Air source heat pump systems are widely used due to their flexible installation and compact structure. However, in complex usage environments, the air source heat pump system may stop supplying heat for a certain period of time due to various reasons, causing the temperature of the heated fluid in the heat exchanger in the system to not remain constant and unable to meet the user's heating needs. Summary of the invention

[0003] The embodiments of the present application provide an air source heat pump system and a control method thereof, and a design method of a heat exchanger, which are intended to solve the problem that the heat supply to the heated fluid cannot be kept constant.

[0004] An embodiment of the first aspect of the present application provides an air source heat pump system, including a controller, an air-cooled evaporator, a compressor, a throttling device and a heat exchanger, wherein a phase change material is arranged in the heat exchanger; the controller is used to obtain frost information of the air-cooled evaporator, and when the frost information is that there is no frost, the controller is configured to control the air-cooled evaporator, the compressor, the heat exchanger and the throttling device to be connected end to end in sequence for circulating a first fluid, and the air-cooled evaporator heats the first fluid and then circulates it to the heat exchanger; when the frost information is that there is frost, the controller is configured to control the compressor and the heat exchanger to be disconnected, and the phase change material releases heat in the heat exchanger.

[0005] In some embodiments of the present application, when the frosting information indicates that frosting has occurred, the controller is further configured to control the air-cooled evaporator to heat the first fluid, and the first fluid is passed into the air-cooled evaporator for defrosting.

[0006] In some embodiments of the present application, the controller is also configured to obtain ambient temperature information, determine frosting information based on the ambient temperature information, calculate the alternatingly distributed first time and second time based on the ambient temperature information, and determine that the frosting information in the first time is frosted and the frosting information in the second time is not frosted.

[0007] In some embodiments of the present application, the heat exchanger includes a cylinder, a first heat exchange part and a first fluid heat exchange tube, the cylinder includes a first accommodating chamber; the first heat exchange part includes a second accommodating chamber and a second fluid heat exchange tube, the second fluid heat exchange tube is located in the first accommodating chamber, a phase change material is arranged in the second accommodating chamber, the second fluid heat exchange tube and the second accommodating chamber are connected to each other and are used for circulating the second fluid; the first fluid heat exchange tube is arranged in the first accommodating chamber, the two ends of the first fluid heat exchange tube are respectively connected to the compressor and the throttling device for circulating the first fluid, and the first fluid heat exchange tube is used to heat the second fluid heat exchange tube.

[0008] In some embodiments of the present application, the air source heat pump system further includes a plurality of heat storage heat exchangers, each heat storage heat exchanger includes a third accommodating chamber and a second heat exchange portion, and the third accommodating chambers of each heat storage heat exchanger are sequentially connected and communicated with the first accommodating chamber;

[0009] The second heat exchange part includes a fourth accommodating chamber and a fourth fluid heat exchange tube. The fourth fluid heat exchange tube is located in the third accommodating chamber. Phase change material is arranged in the fourth accommodating chamber. The fourth fluid heat exchange tube and the fourth accommodating chamber are interconnected and used for circulating the fourth fluid.

[0010] An embodiment of the second aspect of the present application provides a control method for an air source heat pump system, wherein the air source heat pump system is the air source heat pump system in any embodiment of the first aspect above, and the air source heat pump system includes an air-cooled evaporator, a compressor, a throttling device and a heat exchanger, and a phase change material is arranged in the heat exchanger; the control method includes: obtaining frost information of the air-cooled evaporator, the frost information includes frosted and unfrosted; when the frost information is unfrosted, controlling the air-cooled evaporator, the compressor, the heat exchanger and the throttling device to be connected end to end in sequence for circulating a first fluid, so that the first fluid heated by the air-cooled evaporator flows to the heat exchanger; when the frost information is frosted, controlling the air-cooled evaporator and the heat exchanger to be disconnected, so that the phase change material in the heat exchanger releases heat in the heat exchanger.

[0011] In some embodiments of the present application, when the frosting information indicates that frosting has occurred, the first fluid heated by the air-cooled evaporator is controlled to continue to flow to the air-cooled evaporator for defrosting.

[0012] In some embodiments of the present application, the step of obtaining frost information of the air-cooled evaporator also includes: obtaining ambient temperature information; calculating the duration of the alternating first time period and the second time period based on the ambient temperature information, and determining that the frost information in the first time period is frosted and the frost information in the second time period is not frosted.

[0013] An embodiment of the third aspect of the present application provides a design method for a heat exchanger, wherein the air source heat pump system is the air source heat pump system in any embodiment of the first aspect above, the air source heat pump system comprises an air-cooled evaporator and a heat exchanger which are interconnected, and a phase change material is arranged in the heat exchanger, and the design method comprises: obtaining the ambient temperature; determining the maximum defrost time of the air-cooled evaporator according to the ambient temperature; obtaining the heating amount per unit time of the air source heat pump system; and determining the heat storage amount of the phase change material in the heat exchanger according to the heating amount and the maximum defrost time.

[0014] In some embodiments of the present application, the maximum defrost time satisfies the following relationship:

[0015]

[0016] Among them, t maxis the maximum defrost time, in minutes; abs(T air ) is the absolute value of the ambient temperature in degrees Celsius.

[0017] In some embodiments of the present application, the heat storage capacity of the phase change material satisfies the following relationship:

[0018] Q v =60×Q h ×t max

[0019] Among them, Q V Q is the heat storage capacity of the phase change material required for the heat exchanger, in kilojoules; h is the heating capacity of the air source heat pump system per second, in kilowatts; t max It is the maximum defrost time in minutes.

[0020] In some embodiments of the present application, the design method further includes:

[0021] After the step of determining the heat storage capacity of the phase change material in the heat exchanger according to the heating amount and the maximum defrosting time, the method further includes: determining the storage volume of the phase change material in the heat exchanger according to the latent heat value, density, comprehensive expansion coefficient and heat storage capacity of the phase change material.

[0022] In some embodiments of the present application, the storage volume of the heat exchanger storing the phase change material satisfies the following relationship:

[0023]

[0024] Where V is the storage volume in m 3 ; C V is the comprehensive expansion coefficient, which is 1.1 to 1.2; r hp is the latent heat value of the phase change material, in kJ / kg; ρ t is the density of the phase change material in the solid state, in kg / m 3 .

[0025] In some embodiments of the present application, the air source heat pump system includes a plurality of heat exchangers connected to each other, and the total volume of the phase change material stored in the plurality of heat exchangers is equal to the storage volume.

[0026] In an embodiment of the present application, when the frosting information is not frosted, the controller is configured to control the air-cooled evaporator and the heat exchanger to be connected, and the air-cooled evaporator heats the first fluid and then flows to the heat exchanger to heat the third fluid in the heat exchanger. When the frosting information is frosted, the controller controls the air-cooled evaporator and the heat exchanger to be disconnected, and the phase change material releases heat in the heat exchanger. During the period when the first fluid does not heat the third fluid, the phase change material releases heat to heat the third fluid, ensuring that the temperature of the third fluid is constant. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Other features, objects and advantages of the present application will become more apparent by reading the following detailed description of non-limiting embodiments with reference to the accompanying drawings, in which the same or similar reference numerals represent the same or similar features.

[0028] Figure 1 It is a structural schematic diagram of an air source heat pump system provided in an embodiment of the present application;

[0029] Figure 2 is a structural schematic diagram of another air source heat pump system provided in an embodiment of the present application;

[0030] Figure 3 is a structural schematic diagram of a heat exchanger provided in an embodiment of the present application;

[0031] Figure 4 It is a structural schematic diagram of a heat storage heat exchanger provided in an embodiment of the present application;

[0032] Figure 5 is a flow chart of a control method of an air source heat pump system provided in an embodiment of the present application;

[0033] Figure 6 This is another control method flow chart of an air source heat pump system provided in an embodiment of the present application.

[0034] Figure 7 It is a flow chart of a design method for a heat exchanger provided in an embodiment of the present application.

[0035] Explanation of the reference numerals: 10, heat exchanger; 20, air-cooled evaporator; 30, compressor; 40, first three-way valve; 50, second three-way valve; 60, defrost solenoid valve; 70, throttling device; 80, controller; 90, heat storage heat exchanger; 100, cylinder; 110, first accommodating chamber; 200, first heat exchange part; 210, second accommodating chamber; 220, second fluid heat exchange tube; 230, phase change material; 300, first fluid heat exchange tube; 400, third accommodating chamber; 500, second heat exchange part; 510, fourth accommodating chamber; 520, fourth fluid heat exchange tube. DETAILED DESCRIPTION

[0036] The features and exemplary embodiments of various aspects of the present application will be described in detail below. In the detailed description below, many specific details are proposed to provide a comprehensive understanding of the present application. However, it is obvious to those skilled in the art that the present application can be implemented without the need for some of these specific details. The following description of the embodiments is only to provide a better understanding of the present application by illustrating examples of the present application. In the accompanying drawings and the following description, at least some of the known structures and technologies are not shown to avoid unnecessary ambiguity in the present application; and, for clarity, the size of some structures may be exaggerated. In addition, the features, structures or characteristics described below may be combined in one or more embodiments in any suitable manner.

[0037] In the description of the present application, it should be noted that, unless otherwise specified, "multiple" means more than two; the terms "upper", "lower", "left", "right", "inner", "outer", etc., indicating directions or positional relationships, are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific direction, be constructed and operated in a specific direction, and therefore cannot be understood as limiting the present application. In addition, the terms "first", "second", etc. are only used for descriptive purposes and cannot be understood as indicating or implying relative importance.

[0038] The directional words appearing in the following description are all directions shown in the figures, and do not limit the specific structure of the embodiments of the present application. In the description of the present application, it should also be noted that, unless otherwise clearly specified and limited, the terms "installation" and "connection" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be directly connected or indirectly connected. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to the specific circumstances.

[0039] like Figure 1 and Figure 2 As shown, the first embodiment of the present application proposes an air source heat pump system, including a controller 80, an air-cooled evaporator 20, a compressor 30, a throttling device 70 and a heat exchanger 10, wherein a phase change material 230 is provided in the heat exchanger 10;

[0040] The controller 80 is used to obtain the frost information of the air-cooled evaporator 20, and when the frost information is not frosted, the controller 80 is configured to control the air-cooled evaporator 20, the compressor 30, the heat exchanger 10 and the throttling device 70 to be connected end to end in sequence; when the frost information is frosted, the controller 80 is configured to control the compressor and the heat exchanger 10 to be disconnected, and the phase change material 230 releases heat in the heat exchanger 10.

[0041] In this embodiment, when the frosting information is not frosted, the controller 80 is configured to control the air-cooled evaporator 20, the compressor 30, the heat exchanger 10 and the throttling device 70 to be connected end to end in sequence, the air-cooled evaporator 20 heats the first fluid and then flows to the compressor 30, the first fluid enters the heat exchanger 10 after being compressed and pressurized by the compressor 30, and heats the third fluid in the heat exchanger 10, the first fluid flows from the heat exchanger 10 to the throttling device 70 to be throttled to a low-temperature and low-pressure first fluid, and finally enters the air-cooled evaporator 20, absorbs heat from the air, becomes a saturated or superheated gas, and then works through the compressor 30 to become a high-temperature and high-pressure state, and so on, providing continuous heat for the third fluid. When the frosting information is frosted, the controller 80 controls the compressor 30 and the heat exchanger 10 to be disconnected, the phase change material 230 releases heat in the heat exchanger 10, and during the period when the first fluid does not heat the third fluid, the phase change material 230 releases heat to heat the third fluid, ensuring that the temperature of the third fluid is constant.

[0042] Optionally, the throttling device 70 may be an expansion valve.

[0043] In some optional embodiments, when the frosting information indicates that frosting has occurred, the controller 80 is further configured to control the air-cooled evaporator 20 to heat the first fluid, and the first fluid is passed into the air-cooled evaporator 20 for defrosting.

[0044] In these optional embodiments, the controller 80 controls the first fluid heated by the air-cooled evaporator 20 to flow back into the air-cooled evaporator 20, and the air-cooled evaporator 20 is defrosted by the heat of the first fluid.

[0045] In some optional embodiments, the controller 80 is also configured to obtain ambient temperature information, determine frosting information based on the ambient temperature information, calculate the alternatingly distributed first time and second time based on the ambient temperature information, and determine that the frosting information in the first time is frosted and the frosting information in the second time is not frosted.

[0046] In these optional embodiments, the ambient temperature information is an important factor affecting the frosting information, and different ambient temperatures are also accompanied by different ambient humidity. The ambient temperature reflects the degree of frosting of the air-cooled evaporator 20 within a certain period of time. The defrosting time and the defrosting interval time of the air-cooled evaporator 20 can be calculated by the ambient temperature. Among them, the first time corresponds to the defrosting time, and defrosting is performed within the first time. After the defrosting of the first time, the defrosting of the air-cooled evaporator 20 is completed, and the second time is reached. The second time is the defrosting interval time, and the frosting information during the defrosting interval is not frosted. The air-cooled evaporator 20 gradually frosts in the second time period, so after the second time ends, it is the first time, and the frosting information in the first time is frosted, then defrosting is performed again, so that the air-cooled evaporator 20 can be automatically defrosted.

[0047] like Figure 3 As shown, in some optional embodiments, the heat exchanger 10 includes a cylinder 100, a first heat exchange part 200 and a first fluid heat exchange tube 300, the cylinder 100 includes a first accommodating chamber 110; the first heat exchange part 200 includes a second accommodating chamber 210 and a second fluid heat exchange tube 220, the second fluid heat exchange tube 220 is located in the first accommodating chamber 110, a phase change material 230 is arranged in the second accommodating chamber 210, the second fluid heat exchange tube 220 and the second accommodating chamber 210 are interconnected and used for circulating the second fluid; the first fluid heat exchange tube 300 is arranged in the first accommodating chamber 110, and both ends of the first fluid heat exchange tube 300 are respectively connected to the compressor 30 and the throttling device 70 for circulating the first fluid, and the first fluid heat exchange tube 300 is used to heat the second fluid heat exchange tube 220.

[0048] In these optional embodiments, the heat exchanger 10 is used to heat the third fluid, the third fluid is arranged in the first accommodating chamber 110, a first fluid heat exchange tube 300 is arranged in the first accommodating chamber 110, the two ends of the first fluid heat exchange tube 300 are respectively connected to the compressor 30 and the throttling device 70 for passing the first fluid into the first fluid heat exchange tube 300, and the third fluid absorbs the heat of the first fluid heat exchange tube 300 in the first accommodating chamber 110. After the first fluid heat exchange tube 300 heats the third fluid, the third fluid transfers the heat to the second fluid in the second fluid heat exchange tube 220 in the first accommodating chamber 110, the second fluid circulates in the second accommodating chamber 210 and the second fluid heat exchange tube 220, transfers the heat to the phase change material 230, and the phase change material 230 absorbs the heat of the second fluid to realize heat storage. During the defrosting stage, the phase change material 230 undergoes a phase change to release heat and transfer it to the second fluid. After the second fluid flows to the second fluid heat exchange tube 220, the heat is released into the first accommodating chamber 110 to heat the third fluid, thereby achieving a constant temperature of the third fluid in the first accommodating chamber 110.

[0049] The heat exchanger 10 in this embodiment can achieve continuous and stable heating of the third fluid, and at the same time can transfer excess heat to the phase change material 230 to achieve heat storage. When the air-cooled evaporator 20 is defrosted, the first fluid is used for defrosting, so that the first fluid heat exchange tube 300 stops heating, and the phase change material 230 undergoes a phase change to release the stored heat to heat the third fluid, thereby preventing the temperature of the third fluid from dropping significantly and alleviating the problem that the heat supply to the third fluid cannot be kept constant.

[0050] Optionally, the phase change material 230 may include paraffin, which can store and release energy through the phase change of the material. Among them, paraffin has the advantages of high storage density, stability, safety, environmental protection, etc. The application principle of paraffin is to use it in a solid state at room temperature. When the temperature rises to a certain level, it will change phase while maintaining the solid state, and store the absorbed heat. On the contrary, when the temperature drops, the paraffin will release the previously stored heat. This phase change process is a reversible process, so it can be continuously recycled.

[0051] Optionally, the second fluid may be liquid or gas, which is conducive to circulation in the second accommodating chamber 210 and the second fluid heat exchange tube 220 , and the second fluid may include water.

[0052] like Figure 2 As shown, in some optional embodiments, a first tee 40 is arranged between the compressor 30 and one end of the first fluid heat exchange tube 300, and a second tee 50 is arranged between the air-cooled evaporator 20 and the other end of the first fluid heat exchange tube 300; the first end of the first tee 40 is connected to the compressor 30, the second end of the first tee 40 is connected to one end of the first fluid heat exchange tube 300, the third end of the first tee 40 is connected to the first end of the second tee 50, the second end of the second tee 50 is connected to the air-cooled evaporator 20, and the third end of the second tee 50 is connected to the throttling device 70.

[0053] In these optional embodiments, a first tee 40 is provided between the compressor 30 and one end of the first fluid heat exchange tube 300, a second tee 50 is provided between the air-cooled evaporator 20 and the throttling device 70, and the third end of the first tee 40 is connected to the first end of the second tee 50 so that the air-cooled evaporator 20 and the compressor 30 form a circulation loop. When the air source heat pump system works in a low temperature and high humidity environment, the evaporator frosts, resulting in a decrease in heating capacity and system energy efficiency ratio. In severe cases, it may cause the system to shut down. In order to ensure the continuous and normal operation of the unit, the evaporator needs to be periodically defrosted. The air-cooled evaporator 20 and the compressor 30 form a circulation loop so that at least part of the first fluid is heated and then circulated back to the air-cooled evaporator 20 by the compressor 30 through the first tee 40 for heating and defrosting. During the heating and defrosting stage, since at least part of the first fluid circulates back to the air-cooled evaporator 20 through the first tee 40, the temperature of the first fluid heat exchange tube 300 in the heat exchanger 10 is reduced. In order to ensure that the heat exchanger 10 supplies heat to the third fluid at a constant temperature, the second fluid absorbs the heat released by the phase change material 230 in the second accommodating chamber 210 and circulates to the second fluid heat exchange tube 220 to release the heat to the first accommodating chamber 110 to heat the third fluid, thereby ensuring constant heat supply to the third fluid.

[0054] like Figure 2As shown, in some optional embodiments, a defrost solenoid valve 60 is provided between the third end of the first tee 40 and the first end of the second tee 50 .

[0055] In these optional embodiments, the defrost solenoid valve 60 is disposed between the third end of the first three-way connection 40 and the first end of the second three-way connection 50. When the defrost solenoid valve 60 is opened, at least part of the first fluid is heated and then circulated back to the air-cooled evaporator 20 through the first three-way connection 40 by the compressor 30 for heating and defrosting. When the defrost solenoid valve 60 is closed, the first fluid can be prevented from entering the pipeline between the third end of the first three-way connection 40 and the first end of the second three-way connection 50 to cause heat waste, thereby improving thermal efficiency.

[0056] like Figure 2 As shown, the air source heat pump system may include a plurality of heat exchangers 10 connected to each other, and the plurality of heat exchangers 10 are interconnected for circulating a third fluid. The phase change material 230 may be respectively arranged in the plurality of heat exchangers 10 to reduce the volume of each heat exchanger 10. When the volume of the heat exchanger 10 is large, it will lead to an increase in manufacturing cost and transportation cost, and will also lead to a larger occupied space volume. By setting up a plurality of heat exchangers 10, the third fluid absorbs the heat of the phase change material 230 through the plurality of heat exchangers 10, and each heat exchanger 10 can ensure a suitable volume, thereby reducing manufacturing cost and transportation cost, and the installation method and installation position can also be more flexible.

[0057] like Figures 2 to 4 As shown, in some other optional embodiments, the air source heat pump system also includes a plurality of heat storage heat exchangers 90, each heat storage heat exchanger 90 includes a third accommodating chamber 400 and a second heat exchange part 500, the third accommodating chamber 400 of each heat storage heat exchanger 90 is sequentially connected and connected to the first accommodating chamber 110; the second heat exchange part 500 includes a fourth accommodating chamber 510 and a fourth fluid heat exchange tube 520, the fourth fluid heat exchange tube 520 is located in the third accommodating chamber 400, the fourth accommodating chamber 510 is provided with a phase change material 230, the fourth fluid heat exchange tube 520 and the fourth accommodating chamber 510 are connected to each other and are used to circulate the fourth fluid.

[0058] In these optional embodiments, the third accommodating chambers 400 of each heat storage heat exchanger 90 are connected in sequence and connected to the first accommodating chamber 110 for circulating the third fluid. When the third fluid passes through the heat storage heat exchanger 90, the third fluid heats the fourth fluid heat exchange tube 520 in the third accommodating chamber 400. After being heated, the fourth fluid in the fourth fluid heat exchange tube 520 enters the fourth accommodating chamber 510 to heat the phase change material 230 to achieve heat storage. During the defrosting process of the air source heat pump system, the phase change material 230 releases heat to heat the fourth fluid. The fourth fluid circulates to the fourth fluid heat exchange tube 520, and releases heat to the third accommodating chamber 400 through the fourth fluid heat exchange tube 520 to heat the third fluid. When the heat exchanger 10 and the heat storage heat exchanger 90 are large in size, the manufacturing cost and transportation cost will increase, and the space occupied will be larger. By setting up multiple heat storage heat exchangers 90, the phase change material 230 can be respectively set in the heat exchanger 10 and multiple heat storage heat exchangers 90 to reduce the volume of the heat exchanger 10 and each heat storage heat exchanger 90. The third fluid absorbs the heat of the phase change material 230 through the heat exchanger 10 and the heat storage heat exchanger 90. The heat exchanger 10 and the heat storage heat exchanger 90 can both ensure a suitable volume, thereby reducing manufacturing cost and transportation cost, and the installation method and installation position can also be more flexible.

[0059] like Figure 5 As shown, the second aspect of the present application proposes a control method for an air source heat pump system, wherein the air source heat pump system may be the air source heat pump system in any embodiment of the first aspect, the air source heat pump system comprises an air-cooled evaporator 20, a compressor 30, a throttling device 70 and a heat exchanger 10, and a phase change material 230 is provided in the heat exchanger 10; the control method comprises:

[0060] Step S10: obtaining frosting information of the air-cooled evaporator 20, where the frosting information includes frosted and unfrosted.

[0061] When the frost information indicates that there is no frost, step S20 is executed: the air-cooled evaporator 20 , the compressor 30 , the heat exchanger 10 and the throttling device 70 are controlled to be connected end to end in sequence for circulating the first fluid, so that the first fluid heated by the air-cooled evaporator 20 flows to the heat exchanger 10 .

[0062] When the frost information indicates that frost has occurred, step S30 is executed: the air-cooled evaporator 20 and the heat exchanger 10 are controlled to be disconnected, so that the phase change material 230 in the heat exchanger 10 releases heat in the heat exchanger 10 .

[0063] In this embodiment, when the frost information is no frost, the air-cooled evaporator 20 and the heat exchanger 10 are controlled to be connected, so that the first fluid heated by the air-cooled evaporator 20 flows to the heat exchanger 10 to heat the third fluid. At the same time, part of the heat of the third fluid will be absorbed and stored by the phase change material 230. After the air-cooled evaporator 20 heats the first fluid, it flows to the compressor 30. After being compressed and pressurized by the compressor 30, the first fluid enters the heat exchanger 10, heats the third fluid in the heat exchanger 10, flows from the heat exchanger 10 to the throttling device 70 to be throttled to a low-temperature and low-pressure first fluid, and finally enters the air-cooled evaporator 20, absorbs heat from the air, becomes a saturated or superheated gas, and then works through the compressor 30 to become a high-temperature and high-pressure state. This cycle provides continuous heat for the third fluid.

[0064] When the frost information indicates that frosting has occurred, the air-cooled evaporator 20 and the heat exchanger 10 are controlled to be disconnected. At this time, the first fluid cannot enter the heat exchanger 10 to heat the third fluid. At this time, the phase change material 230 in the heat exchanger 10 releases heat in the heat exchanger 10. The heat is the heat stored in the phase change material 230 in the unfrosted stage. The heat is released in the heat exchanger 10 to heat the third fluid, so that the third fluid absorbs heat from the heat released by the phase change material 230 when the air-cooled evaporator 20 stops supplying heat to ensure a constant temperature.

[0065] In some optional embodiments, when the frosting information indicates that frosting has occurred, the first fluid heated by the air-cooled evaporator 20 is controlled to continue to flow to the air-cooled evaporator 20 for defrosting.

[0066] In these optional embodiments, the first fluid heated by the air-cooled evaporator 20 flows back into the air-cooled evaporator 20, and the air-cooled evaporator 20 is defrosted by the heat of the first fluid.

[0067] like Figure 6 As shown, in some optional embodiments, in step S10, it also includes:

[0068] Step S011: Acquire ambient temperature information.

[0069] Step S012: Calculate the duration of the alternating first time period and the second time period according to the ambient temperature information, and determine that the frosting information in the first time period is frosted, and the frosting information in the second time period is not frosted.

[0070] In these optional embodiments, the ambient temperature information is an important factor affecting the frosting information, and different ambient temperatures are also accompanied by different ambient humidity. The ambient temperature reflects the degree of frosting of the air-cooled evaporator 20 within a certain period of time. The defrosting time and the defrosting interval time of the air-cooled evaporator 20 can be calculated by the ambient temperature. Among them, the first time period and the second time period are alternately distributed. The first time period corresponds to the defrosting time. Defrosting is performed in the first time period. After defrosting in the first time period, the defrosting of the air-cooled evaporator 20 is completed, that is, it reaches the second time period. The second time period is the defrosting interval time, and the frosting information in the defrosting interval time is no frost. In the second time period, the air-cooled evaporator 20 gradually frosts, so after the second time period ends, it is the first time period. The frosting information in the first time period is frosted, and then defrosting is performed again, so that the air-cooled evaporator 20 can be automatically defrosted.

[0071] like Figure 7 As shown, a design method of a heat exchanger 10 is provided in a third aspect of an embodiment of the present application, wherein the heat exchanger 10 may be a heat exchanger 10 of an air source heat pump system in any embodiment of the first aspect above, and a phase change material 230 is provided in the heat exchanger 10. The design method includes:

[0072] Step S41: Acquire the ambient temperature.

[0073] Step S42: Determine the maximum defrosting time of the air-cooled evaporator 20 according to the ambient temperature.

[0074] Step S43: Obtain the heating capacity per unit time of the air source heat pump system.

[0075] Step S44: determining the heat storage amount of the phase change material 230 in the heat exchanger 10 according to the heating amount and the maximum defrosting time.

[0076] In this embodiment, the heat emitted by the air-cooled evaporator 20 in the air source heat pump system heats the third fluid in the heat exchanger 10, and the phase change material 230 in the heat exchanger 10 absorbs a portion of the heat of the third fluid to store heat. Frosting will occur during the heating process of the air-cooled evaporator 20, wherein the ambient temperature is an important factor for the frosting of the air-cooled evaporator 20, and different ambient temperatures are also accompanied by different ambient humidity. The ambient temperature reflects the degree of frosting of the air-cooled evaporator 20 within a certain period of time, and the maximum defrosting time of the air-cooled evaporator 20 can be determined by the ambient temperature.

[0077] The air source heat pump system is used to defrost the air-cooled evaporator 20, and the heating capacity per unit time of the air source heat pump system is obtained, so that the total heating capacity of the air source heat pump system within the maximum defrosting time can be obtained. During the defrosting stage, the heat storage of the phase change material 230 in the heat exchanger 10 is released to heat the third fluid, so that the third fluid can also receive heat during the defrosting stage to ensure constant temperature. The heat storage capacity of the phase change material 230 is equal to the total heating capacity of the air source heat pump system within the maximum defrosting time.

[0078] In this embodiment, by calculating the maximum defrost time of the air-cooled evaporator 20 at different temperatures, and by making the total heating capacity of the air source heat pump system during the maximum defrost time equal to the heat storage capacity of the phase change material 230, it is possible to ensure that the heat received by the third fluid during the maximum defrost time remains unchanged and the temperature of the third fluid is constant. This design method can calculate the heat storage capacity of the phase change material 230 at different ambient temperatures.

[0079] In some optional embodiments, the maximum defrost time satisfies the following relationship:

[0080]

[0081] Among them, t max is the maximum defrost time, in minutes; abs(T air ) is the absolute value of the ambient temperature in degrees Celsius.

[0082] In these optional embodiments, the maximum defrost time is the time it takes to completely clear the frost in the air-cooled evaporator 20. When the ambient temperature is closer to 0 degrees Celsius, the degree of frost is smaller, and the maximum defrost time t is obtained. max The smaller the temperature, the defrosting can be completed after a preset time, for example, 15 minutes. When the ambient temperature is lower than 0 degrees Celsius, the lower the temperature, the easier it is for the air-cooled evaporator 20 to frost. When the ambient temperature is higher than 0 degrees Celsius, the higher the temperature, the greater the ambient humidity, and the easier it is for the air-cooled evaporator 20 to frost.

[0083] In some optional embodiments, the heat storage capacity of the phase change material 230 satisfies the following relationship:

[0084] Q v =60×Q h ×t max

[0085] Among them, Q V Q is the heat storage capacity of the phase change material 230 required by the heat exchanger 10, in kilojoules; h is the heating capacity of the air source heat pump system per second, in kilowatts; t max It is the maximum defrost time in minutes.

[0086] In these optional embodiments, an air source heat pump system is used to defrost the air-cooled evaporator 20. The heating capacity per second of the air source heat pump system multiplied by the maximum defrost time is the total heating capacity of the air source heat pump system during the defrost stage. During the defrost stage, the heat required by the third fluid in the heat exchanger 10 can only be obtained through the phase change material 230. The heat storage of the phase change material 230 in the heat exchanger 10 is released to heat the third fluid. The heat storage of the phase change material 230 is equal to the total heating capacity of the air source heat pump system within the maximum defrost time, which can ensure that the third fluid can also receive heat during the defrost stage to ensure constant temperature.

[0087] like Figure 7 As shown, in some optional embodiments, after step S44, the method further includes:

[0088] Step S45 : determining the storage volume of the heat exchanger 10 for storing the phase change material 230 according to the latent heat value, density, comprehensive expansion coefficient and heat storage capacity of the phase change material 230 .

[0089] In these optional embodiments, the maximum volume of the phase change material 230, that is, the storage volume of the heat exchanger 10 for storing the phase change material 230, can be calculated based on the latent heat value, density, comprehensive expansion coefficient and heat storage of the phase change material 230. The latent heat value of the phase change material 230 refers to the heat absorbed or released from one phase to another under isothermal and isobaric conditions. The comprehensive expansion coefficient refers to the volume change of the phase change material 230 during the phase change process.

[0090] In some optional embodiments, the storage volume of the heat exchanger 10 storing the phase change material 230 satisfies the following relationship:

[0091]

[0092] Where V is the storage volume in m 3 ; C V is the comprehensive expansion coefficient, which is 1.1 to 1.2; r hp is the latent heat value of the phase change material, in kJ / kg; ρ t is the density of the phase change material 230 in the solid state, in kg / m 3 , Q V is the heat storage capacity of the phase change material 230 required by the heat exchanger 10, in kilojoules.

[0093] In these optional embodiments, the product of the comprehensive expansion coefficient and the heat storage capacity of the phase change material 230 divided by the latent heat value of the phase change material 230 and the density of the phase change material 230 in the solid state is the storage volume of the phase change material 230. The storage volume is the minimum storage volume of the heat exchanger 10 for storing the phase change material 230. When the storage volume of the heat exchanger 10 for storing the phase change material is greater than or equal to the minimum storage volume, the heat storage capacity of the phase change material 230 can be released to heat the third fluid during the defrost stage. The heat storage capacity of the phase change material 230 is equal to or greater than the total heating capacity of the air source heat pump system within the maximum defrost time, which can ensure that the third fluid can also receive heat during the defrost stage to ensure constant temperature.

[0094] In some optional embodiments, the air source heat pump system includes a plurality of heat exchangers 10 connected to each other, and the total volume of the plurality of heat exchangers 10 storing the phase change material 230 is equal to the storage volume.

[0095] In these optional embodiments, when the volume of the heat exchanger 10 is large, it will lead to an increase in manufacturing cost and transportation cost, and at the same time, it will lead to a larger space volume. By setting multiple heat exchangers 10, the total volume of the phase change material 230 stored in the multiple heat exchangers 10 is equal to the above-mentioned storage volume. The multiple heat exchangers 10 are interconnected to circulate the third fluid. The third fluid absorbs the heat of the phase change material 230 through the multiple heat exchangers 10, and the phase change material 230 can heat the third fluid during the defrosting process. The total volume of the phase change material 230 contained in the multiple heat exchangers 10 is equal to the storage volume, that is, each heat exchanger 10 can ensure a suitable volume, thereby reducing the manufacturing cost and transportation cost, and the installation method and installation position can also be more flexible.

[0096] Optionally, the multiple heat exchangers 10 may also be replaced by one heat exchanger 10 and multiple heat accumulators in the first aspect, and the total volume of the phase change material 230 contained in the one heat exchanger 10 and the multiple heat accumulators is equal to the storage volume.

[0097] The air source heat pump system is an air source transcritical CO2 heat pump system as an example. In the heating mode, the first fluid is CO2. After passing through the air-cooled evaporator 20 and the compressor 30, the CO2 pressure is 10MPa and the temperature is 114.9°C. After passing through the heat exchanger 10 as the third fluid, the CO2 temperature drops to 40°C, and the evaporation temperature is 0°C; the temperature of the third fluid entering the heat exchanger 10 is 30°C, and after being heated in the heat exchanger 10, it reaches 65°C, and the flow rate is 0.136kg / s; the phase change material 230 in the heat exchanger 10 is loaded with 100kg, the latent heat mass is 280kJ / kg, and the heat storage Q1=28000kJ. The defrost time is set to 20min. During the defrost time, the third fluid in the heat exchanger 10 requires heat Q2=24000kJ to keep the temperature at 65°C after heating. The results show that: Q1>Q2, therefore, the heat exchanger 10 and the air source heat pump system in the present application can achieve stable and continuous heating in the defrost mode.

[0098] Although the present application has been described with reference to preferred embodiments, various modifications may be made thereto and parts thereof may be replaced with equivalents without departing from the scope of the present application. In particular, the various technical features mentioned in the various embodiments may be combined in any manner as long as there are no structural conflicts. The present application is not limited to the specific embodiments disclosed herein, but includes all technical solutions falling within the scope of the claims.

Claims

1. An air source heat pump system, characterized in that: It includes a controller, an air-cooled evaporator, a compressor, a throttling device and a heat exchanger, wherein the heat exchanger is provided with a phase change material; The controller is used to obtain frosting information of the air-cooled evaporator, and when the frosting information indicates that there is no frosting, the controller is configured to control the air-cooled evaporator, the compressor, the heat exchanger and the throttling device to be connected end to end in sequence for circulating a first fluid; When the frosting information indicates that frosting has occurred, the controller is configured to control the compressor and the heat exchanger to be disconnected, and the phase change material releases heat in the heat exchanger.

2. The air source heat pump system according to claim 1, characterized in that: When the frosting information indicates that frosting has occurred, the controller is further configured to control the air-cooled evaporator to heat the first fluid, and the first fluid is passed into the air-cooled evaporator for defrosting.

3. The air source heat pump system according to claim 1, characterized in that: The controller is also configured to obtain ambient temperature information, determine the frosting information according to the ambient temperature information, calculate the alternatingly distributed first time and second time according to the ambient temperature information, and determine that the frosting information in the first time is frosted and the frosting information in the second time is not frosted.

4. The air source heat pump system according to claim 1, characterized in that: The heat exchanger comprises a cylinder, a first heat exchange part and a first fluid heat exchange tube, and the cylinder comprises a first accommodating cavity; The first heat exchange part comprises a second accommodating chamber and a second fluid heat exchange tube, the second fluid heat exchange tube is located in the first accommodating chamber, the second accommodating chamber is provided with the phase change material, the second fluid heat exchange tube and the second accommodating chamber are interconnected and used for circulating the second fluid; The first fluid heat exchange tube is arranged in the first accommodating chamber, and both ends of the first fluid heat exchange tube are respectively connected to the compressor and the throttling device for circulating the first fluid, and the first fluid heat exchange tube is used to heat the second fluid heat exchange tube.

5. The air source heat pump system according to claim 4, characterized in that: The air source heat pump system further comprises a plurality of heat storage heat exchangers, each of the heat storage heat exchangers comprises a third accommodating chamber and a second heat exchange portion, and the third accommodating chamber of each of the heat storage heat exchangers is sequentially connected and communicated with the first accommodating chamber; The second heat exchange part includes a fourth accommodating chamber and a fourth fluid heat exchange tube. The fourth fluid heat exchange tube is located in the third accommodating chamber. The phase change material is arranged in the fourth accommodating chamber. The fourth fluid heat exchange tube and the fourth accommodating chamber are interconnected and used for circulating the fourth fluid.

6. A control method for an air source heat pump system, characterized in that: The air source heat pump system includes an air-cooled evaporator, a compressor, a throttling device and a heat exchanger, wherein a phase change material is arranged in the heat exchanger; the control method includes: Acquire frosting information of the air-cooled evaporator, wherein the frosting information includes frosted and unfrosted; When the frosting information indicates that there is no frosting, the air-cooled evaporator, the compressor, the heat exchanger and the throttling device are controlled to be connected end to end in sequence for circulating the first fluid, so that the first fluid heated by the air-cooled evaporator flows to the heat exchanger; When the frosting information indicates that frosting has occurred, the air-cooled evaporator and the heat exchanger are controlled to be disconnected, so that the phase change material in the heat exchanger releases heat in the heat exchanger.

7. The control method of the air source heat pump system according to claim 6, characterized in that: When the frost information indicates that frost has occurred, the first fluid heated by the air-cooled evaporator is controlled to continue to flow to the air-cooled evaporator for defrosting.

8. The control method of the air source heat pump system according to claim 6, characterized in that: The step of obtaining the frosting information of the air-cooled evaporator further includes: Get ambient temperature information; The duration of the alternating first time period and the second time period is calculated according to the ambient temperature information, and it is determined that the frosting information in the first time period is frosted, and the frosting information in the second time period is not frosted.

9. A method for designing a heat exchanger, characterized in that: The air source heat pump system includes an air-cooled evaporator and a heat exchanger which are interconnected, and a phase change material is arranged in the heat exchanger. The design method includes: Get the ambient temperature; determining a maximum defrost time of the air-cooled evaporator according to the ambient temperature; Obtaining the heating capacity per unit time of the air source heat pump system; The heat storage amount of the phase change material in the heat exchanger is determined according to the heating amount and the maximum defrosting time.

10. The method for designing a heat exchanger according to claim 9, characterized in that: The maximum defrost time satisfies the following relationship: Among them, t max is the maximum defrosting time, in minutes; abs(T air ) is the absolute value of the ambient temperature, in degrees Celsius.

11. The method for designing a heat exchanger according to claim 9, characterized in that: The heat storage capacity of the phase change material satisfies the following relationship: Q v =60×Q h ×t max Among them, Q V is the heat storage capacity of the phase change material required by the heat exchanger, in kilojoules; Q h is the heating capacity of the air source heat pump system per second, in kilowatts; t max The maximum defrost time is expressed in minutes.

12. The method for designing a heat exchanger according to claim 9, characterized in that: Also includes: After the step of determining the heat storage of the phase change material in the heat exchanger according to the heating amount and the maximum defrosting time, the method further includes: The storage volume of the heat exchanger for storing the phase change material is determined according to the latent heat value, density, comprehensive expansion coefficient and the heat storage capacity of the phase change material.

13. The method for designing a heat exchanger according to claim 12, characterized in that: The storage volume of the heat exchanger storing the phase change material satisfies the following relationship: Wherein, V is the storage volume, in m 3 ; C V is the comprehensive expansion coefficient, which is 1.1 to 1.2; r hp is the latent heat value of the phase change material, in kJ / kg; ρ t is the density of the phase change material in the solid state, in kg / m 3 .

14. The method for designing a heat exchanger according to claim 12, characterized in that: The air source heat pump system includes a plurality of the heat exchangers connected to each other, and the total volume of the phase change material stored in the plurality of heat exchangers is equal to the storage volume.

Images