Solid-solid cross-temperature phase change temperature control device and system for air source heat pump frost suppression

Abstract

The present invention relates to the field of phase change heat storage and heat pump technology, and in particular to a solid-solid cross-temperature phase change temperature control device and system for air source heat pump frost suppression. The present invention proposes a temperature control heat exchange device that combines a solid-solid phase change material in a suitable phase change temperature range with the main body of an outdoor heat exchanger of an air source heat pump, and utilizes the thermal hysteresis phenomenon of the solid-solid phase change material to enable it to store heat at a higher temperature in the scene and release heat at a lower temperature, thereby preventing the heat from being released prematurely, achieving a cross-temperature phase change, and effectively utilizing this part of the energy. At the same time, the invention integrates the above-mentioned temperature control heat exchange device with the air source heat pump frost suppression strategy. The system used stores heat through a variety of methods such as natural heat storage, defrost heat storage, and bypass heat storage. When the surface temperature of the outdoor heat exchanger drops to near the frost temperature, the solid-solid phase change material releases heat, which plays a role in delaying the frost cycle.

Description

Technical Field

[0001] The present invention relates to the technical field of phase change energy storage and heat exchange equipment, and in particular to a solid-solid cross-temperature phase change temperature regulating heat exchange device and system for frost suppression of an air source heat pump. Background Art

[0002] At present, my country's air source heat pump technology is developing rapidly, but the frosting problem has seriously restricted its further promotion. Frosting refers to the phenomenon that when the unit is in winter heating operation, if the surface temperature of the outdoor heat exchanger is lower than the dew point temperature of the outdoor air and the freezing point of water, the water vapor precipitated in the humid air will form ice crystals, resulting in the formation of frost on the surface of the heat exchanger. This phenomenon is particularly obvious in outdoor meteorological conditions between -5℃ and 5℃ and relative humidity above 70%. The appearance of the frost layer increases the thermal resistance of the heat exchanger surface, reduces the area of ​​the air circulation channel, and greatly reduces the heat exchange performance of the unit.

[0003] Today, the main defrosting method for air source heat pumps is thermal defrosting, including reverse cycle method and hot gas bypass method. Reverse cycle defrosting is achieved by switching the heating condition to the cooling condition to melt the frost layer on the surface of the outdoor heat exchanger. During the defrosting period, heat is absorbed from the room in reverse, which takes a long time, and the reversal of the four-way valve and the start and stop of the compressor are relatively frequent, which affects the indoor comfort and the performance and life of the system equipment. The hot gas bypass method is to use a bypass circuit to direct the high-temperature and high-pressure exhaust gas of part of the compressor into the outdoor heat exchanger to achieve the purpose of defrosting. The bypass process has a large energy loss of the refrigerant, and the change of operating parameters may endanger the safety of the compressor.

[0004] In addition, the use of phase change energy storage to achieve defrosting of air source heat pumps has a positive effect on shortening the defrost cycle and improving the winter operating performance of air source heat pumps. Summary of the invention

[0005] The purpose of the present invention is to address the problems existing in the background technology and to propose a solid-solid cross-temperature phase change temperature control device and system for frost suppression of air source heat pumps.

[0006] To solve the problem that the fins of outdoor heat exchangers frost quickly in winter and the defrosting cycle is short, which leads to the decline of unit performance and indoor comfort in the existing common defrosting technology;

[0007] The technical solution of the present invention combines a suitable solid-solid phase change material with the main body of the outdoor heat exchanger of the air source heat pump, and adopts different methods for reasonable filling to realize the integration of materials and devices. In terms of materials, a solid-solid phase change material with an exothermic peak starting temperature near the frosting temperature is initially selected, and the end temperature of the material's endothermic peak is further determined according to the heat storage method, thereby realizing the use of various heat storage methods such as natural heat storage, defrost heat storage, and bypass heat storage. After the heat storage is completed, if the temperature of the outdoor heat exchanger of the air source heat pump drops to near the frosting temperature, the solid-solid phase change material gradually releases heat to inhibit further frosting of the heat exchanger, thereby achieving the effect of reducing the number of defrosting times and improving the performance of the unit;

[0008] Among them, solid-solid phase change materials use organic-inorganic hybrid materials and are synthesized from a variety of materials through chemical methods.

[0009] Among them, the performance of solid-solid phase change materials remains stable, the phase change range needs to be appropriate, and the starting temperature of the exothermic peak is between -5°C and 0°C.

[0010] The solid-solid phase change material may be a composite phase change material containing a high thermal conductivity additive or other forms.

[0011] Among them, the heat storage performance of solid-solid phase change materials should not be affected by the appearance, and should be processed into different types according to different application modes to reduce the difficulty of forming the device during packaging.

[0012] The present invention provides a device, a frost suppression heat exchanger including temperature regulating fins, wherein corresponding types of solid-solid phase change materials are applied inside the fins.

[0013] The end point temperature of the endothermic peak of the solid-solid phase change material should be between 10°C and 15°C.

[0014] Among them, the anti-frost heat exchanger has a fin-tube heat exchange structure or a microchannel heat exchange structure.

[0015] Among them, the system using the anti-frost heat exchanger includes: a compressor and a gas-liquid separator connected in series in sequence, and the two ends of the series are respectively connected to the two ends of the four-way valve; an indoor ordinary heat exchanger, an electronic expansion valve, and an outdoor anti-frost heat exchanger connected in series in sequence, and the two ends of the series are respectively connected to the other two ends of the four-way valve.

[0016] The system switches to a refrigeration cycle for defrosting. During the defrosting period, the temperature of the outdoor anti-frost heat exchanger rises, and the solid-solid phase change material in the temperature-regulating fins stores heat. After the defrosting is completed, the system switches to a heating cycle for heating, and the temperature of the fins in the outdoor anti-frost heat exchanger decreases. When the temperature reaches the starting temperature of the exothermic peak of the solid-solid phase change material, the material gradually releases heat, inhibiting the further decrease of the outdoor heat exchanger temperature and delaying the frosting cycle.

[0017] Another frost suppression device provided by the present invention and applying the above frost suppression scheme is: a frost suppression heat exchanger comprising a temperature-regulating heat exchange tube, wherein a solid-solid phase change material of a type corresponding to the application is encapsulated inside the heat exchange tube.

[0018] Among them, the end point temperature of the endothermic peak of the solid-solid phase change material should be lower than 50°C.

[0019] Among them, the anti-frost heat exchanger is a fin-tube heat exchange structure.

[0020] Among them, the anti-frost heat exchanger is provided with two heat exchange channels, one channel adopts ordinary heat exchange copper tubes, and the other channel adopts temperature-regulating heat exchange tubes.

[0021] The temperature-regulating heat exchange tube is a concentric copper tube, the refrigerant is bypassed in the small inner tube, and the annular area between the two tubes is filled with solid-solid phase change material. Fins are welded between the inner small tube and the outer large tube to enhance the heat transfer effect of the solid-solid phase change material.

[0022] Among them, ordinary heat exchange copper tubes serve as the main heat exchange channels and are arranged at intervals with temperature regulating heat exchange tubes.

[0023] Among them, the system using the anti-frost heat exchanger includes: a system used by an anti-frost heat exchanger with a thermostatic fin, on the basis of which a defrost heat storage bypass pipeline is added, one end of the pipeline is connected to the pipeline between the indoor heat exchanger outlet and the electromagnetic expansion valve inlet, and the other end is connected to the thermostatic heat exchange pipe inlet of the outdoor anti-frost heat exchanger. A parallel pipeline is added to the pipeline connecting the anti-frost heat exchanger and the four-way valve, and the other end of the pipeline is connected to the thermostatic heat exchange pipe outlet.

[0024] Among them, a solenoid valve is arranged on the defrost heat storage bypass pipeline, and a flow distributor is arranged between the solenoid valve and the frost suppression heat exchanger.

[0025] Wherein, a capillary throttling element is arranged on the parallel pipeline, and a one-way valve is arranged between the capillary and the outlet of the parallel pipeline.

[0026] The system defrosts by bypassing the refrigerant at the outlet of the indoor evaporator to the temperature-controlled heat exchange tube of the outdoor anti-frost heat exchanger, and the solid-solid phase change material filled inside stores heat at the same time. When the bypass stops, the temperature of the fins in the outdoor anti-frost heat exchanger gradually decreases. When the temperature reaches the starting temperature of the exothermic peak of the solid-solid phase change material, the material gradually releases heat, inhibiting the further decrease of the outdoor heat exchanger temperature and delaying the frosting cycle.

[0027] Compared with the prior art, the present invention has the following beneficial technical effects:

[0028] 1. The thermal hysteresis of phase change materials is fully utilized. Most phase change materials are restricted in practical application due to the large thermal hysteresis. The present invention utilizes this characteristic to realize cross-temperature heat storage and release. The stored heat will not be released in advance, and this part of the heat can be better utilized, expanding the application concept and applicable occasions of phase change materials.

[0029] 2. Combining the temperature control method with frost suppression can curb the rapid frost formation of the outdoor heat exchanger during winter operation, reduce the defrosting frequency, extend the life of equipment such as four-way valves and engines that frequently change operating conditions due to defrosting, improve the COP of the unit, and reduce indoor thermal comfort fluctuations.

[0030] 3. There are various ways to store heat in the anti-frost strategy. When the ambient temperature is high, the phase change material can directly absorb heat from the environment to achieve natural heat storage. When the air conditioner performs reverse cycle defrosting, the outdoor anti-frost heat exchanger releases heat to the outside, and the phase change material filled inside can absorb the released heat to achieve defrosting heat storage. When defrosting by bypass, the phase change material filled in the temperature-regulating heat exchange tube can absorb the heat of the refrigerant in the internal small circular tube to achieve bypass heat storage.

[0031] 4. In the example of combining bypass technology with heat storage solution, the system can realize indoor heating, defrosting and heat storage simultaneously. The application of phase change materials can reduce the frequency of bypass, thereby reducing the negative impact of bypass on system operation and improving the operating performance of the unit.

[0032] 5. The solid-solid phase change rather than solid-liquid phase change filling material is used, which will not produce phase separation phenomenon, the material volume changes little, there is no leakage risk, no complex packaging is required and it is easy to process into various shapes, with stable performance, long service life, and easier to combine with the outdoor heat exchanger body. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 This is a schematic diagram of the system structure using an outdoor frost suppression heat exchanger;

[0034] Figure 2 It is a schematic diagram of the structure of an outdoor frost suppression heat exchanger combining a temperature regulating fin and a fin-tube heat exchanger;

[0035] Figure 3 It is a schematic diagram of the structure of an outdoor frost suppression heat exchanger combining temperature regulating fins with a microchannel heat exchanger;

[0036] Figure 4 It is a three-dimensional structural schematic diagram of an outdoor anti-frost heat exchanger including a temperature-regulating heat exchange tube;

[0037] Figure 5 It is a schematic diagram of the side layout and partial cross-section of an outdoor anti-frost heat exchanger containing temperature-regulating heat exchange tubes.

[0038] Figure numerals: 1. compressor; 2. four-way valve; 3. gas-liquid separator; 4. indoor heat exchanger; 5. electronic expansion valve; 6. outdoor anti-frost heat exchanger; 7. solenoid valve; 8. flow distributor; 9. capillary tube; 10. one-way valve; 11. straight fins; 12. straight temperature-regulating fins; 14. solid-solid phase change material; 15. collector; 16. flat tube; 17. corrugated temperature-regulating fins; 18. heat exchange copper tube; 19. temperature-regulating heat exchange tube; 20. inner circular tube; 21. outer circular tube; 22. fins inside the tube. DETAILED DESCRIPTION

[0039] Example 1

[0040] See also Figure 2 This embodiment is specifically an outdoor anti-frost heat exchanger that combines a temperature-regulating fin filled with solid-solid phase change material with a common fin-tube heat exchanger. The end temperature of the heat absorption peak of the solid-solid phase change material used should be between 10°C and 15°C, and the starting temperature of the heat release peak should be between -5°C and 0°C. In the anti-frost heat exchanger, the thickness of the straight temperature-regulating fin 12 is increased compared with the ordinary fin, and the solid-solid phase change material 14 is encapsulated inside. The straight ordinary fin 11 is used as the main heat exchange fin, and the straight temperature-regulating fin 12 is arranged at intervals therefrom, taking into account the heat exchange and anti-frost effects of the heat exchanger.

[0041] The structure of the frost suppression heat exchanger application system can be found in Figure 1 In the solid part of the system, the solid arrows in the figure indicate the flow direction of the refrigerant in the cooling mode, and the dotted arrows indicate the flow direction of the refrigerant in the heating mode. The system includes a compressor 1 and a gas-liquid separator 3 connected in series, and the two ends of the series are respectively connected to the two ends of the four-way valve 2; an indoor heat exchanger 4, an electronic expansion valve 5, and an outdoor anti-frost heat exchanger 6 connected in series, and the two ends of the series are respectively connected to the other two ends of the four-way valve 2. The specific implementation process of each working condition of the system during winter heating is as follows:

[0042] 1. Normal heating conditions. The low-temperature, low-pressure refrigerant is converted into high-temperature, high-pressure gas by the compressor 1, and is sent to the indoor heat exchanger 4 through the four-way valve 2 to exchange heat with the indoor air, and becomes a normal-temperature, high-pressure refrigerant liquid. After throttling and reducing the pressure by the electronic expansion valve 5, it is sent to the outdoor anti-frost heat exchanger 6 to absorb the heat of the outdoor air, and is converted into a low-temperature, low-pressure refrigerant gas. Finally, it is passed into the gas-liquid separator 3 and sent to the compressor 1 for compression, completing a heating cycle.

[0043] 2. Natural heat storage condition: When the air conditioner is in shutdown state in winter and the outdoor ambient temperature is higher than the phase change temperature corresponding to the type of solid-solid phase change material 14 used in this example, the material absorbs ambient heat and the phase change enthalpy is stored.

[0044] 3. Defrosting and heat storage working condition: During the heating operation, if the system detects that the outdoor anti-frost heat exchanger 6 is in a frosted state, the four-way valve 2 is reversed, and the system is converted to the refrigeration operation condition for defrosting and heat storage. The specific process of the working condition is as follows: the refrigerant passes through the compressor 1 and becomes a high-temperature and high-pressure gas. After passing through the four-way valve 2, it is sent to the outdoor anti-frost heat exchanger 6 to exchange heat with the outdoor air and the solid-solid phase change material 14. At this time, the material absorbs the heat discharged by the refrigerant and stores the phase change enthalpy. The refrigerant becomes a normal temperature and high-pressure refrigeration liquid. After throttling and reducing the pressure by the electronic expansion valve 5, it is sent to the indoor heat exchanger 4 to absorb the heat of the coil and the indoor air, and is converted into a low-temperature and low-pressure refrigerant gas. Finally, it is passed into the gas-liquid separator 3 and sent to the compressor 1 for compression to complete a refrigeration cycle. When the system temperature sensor detects that the fin temperature of the outdoor anti-frost heat exchanger 6 is higher than the end temperature of the endothermic peak of the phase change material used in this embodiment, the working condition stops running.

[0045] 4. Heat release and frost suppression conditions: During the heating operation of the system, the fin temperature of the outdoor frost suppression heat exchanger 6 gradually decreases. When the surface temperature of the straight temperature regulating fin 12 is lower than the crystallization temperature of the solid-solid phase change material 14, the phase change heat stored in the material begins to be continuously released, suppressing frost on the surface of the heat exchanger.

[0046] Example 2

[0047] See also Figure 3 This embodiment is specifically an outdoor anti-frost heat exchanger that combines temperature-regulating fins filled with solid-solid phase change materials with common microchannel heat exchangers. The phase change temperature range of the solid-solid phase change material used is the same as that in Example 1. The thickness of the corrugated temperature-regulating fins 17 in the anti-frost heat exchanger is slightly increased compared with the corrugated ordinary fins, and the solid-solid phase change material 14 is encapsulated inside. When the refrigerant passes through the flat tubes 16, the corrugated temperature-regulating fins 17 between adjacent flat tubes exchange heat with it. The structure of the anti-frost heat exchanger application system and the various operating conditions of the system operation are consistent with those in Example 1.

[0048] Example 3

[0049] See also Figure 4 and Figure 5This embodiment is specifically manifested as an outdoor anti-frost heat exchanger that combines a thermostatic heat exchange tube filled with solid-solid phase change material with a common tube-fin heat exchanger. The end temperature of the heat absorption peak of the solid-solid phase change material used should be lower than 50°C, and the starting temperature of the heat release peak should be between -5°C and 0°C. The anti-frost heat exchanger is provided with two heat exchange channels. The first heat exchange channel is an ordinary heat exchange copper tube 18, and the second heat exchange channel is a thermostatic heat exchange tube 19, and the two are arranged at intervals in a certain form. The thermostatic heat exchange tube 19 is a concentric circle sleeve copper tube structure, and the refrigerant is bypassed in the internal small circular tube 20. The annular area in the two circular sleeves is encapsulated with solid-solid phase change material. An inner tube fin 22 is welded between the internal small circular tube 20 and the external large circular tube 21 to enhance the heat transfer effect of the solid-solid phase change material.

[0050] The structure of the frost suppression heat exchanger application system can be found in Figure 1 , the pipeline represented by the dotted line is a newly added structure based on the system of Example 1. The system newly adds a defrost heat storage bypass pipeline and a parallel pipeline. One end of the bypass pipeline is connected to the channel between the outlet of the indoor heat exchanger 4 and the inlet of the electronic expansion valve 5, and the other end is connected to the inlet of the temperature-regulating heat exchange pipe of the outdoor anti-frost heat exchanger 6. A solenoid valve 7 is provided on the bypass pipeline, and a flow distributor 8 is provided between the solenoid valve 7 and the outdoor anti-frost heat exchanger 6. One section of the parallel pipeline is connected to the channel between the outdoor anti-frost heat exchanger 6 and the four-way valve 2, and the other end is connected to the outlet of the temperature-regulating heat exchange pipe 19. A capillary tube 9 is provided on the parallel pipeline, and a one-way valve 10 is provided between the capillary tube 9 and the outlet of the parallel pipeline. The specific implementation process of each working condition when the system is heating in winter is as follows:

[0051] 1. Normal heating condition: the solenoid valve 7 is closed, the system does not bypass the refrigerant, and all the refrigerant is passed into the first heat exchange channel of the outdoor anti-frost heat exchanger 6. The overall cycle process is consistent with the normal heating condition in Example 1.

[0052] 2. Bypass heat storage working condition: During the heating operation, if the system detects that the outdoor anti-frost heat exchanger 6 is in a frosted state, the solenoid valve 7 is opened, and the high-temperature and high-pressure refrigerant discharged from the compressor 1 is partially bypassed to the second heat exchange channel of the outdoor anti-frost heat exchanger 6 for defrosting after heat exchange in the indoor heat exchanger 4. At the same time, the phase change material in the temperature-adjusting heat exchange tube 19 absorbs part of the heat and stores the phase change enthalpy. After the refrigerant flows out of the temperature-adjusting heat exchange tube 19, it is depressurized through the capillary 9, merges with the refrigerant discharged from the first heat exchange channel, passes through the four-way valve 2, and enters the gas-liquid separator 3, and is finally sent back to the compressor 1 for compression. When the system detects that the frost layer disappears and the surface temperature of the temperature-adjusting heat exchange tube 19 is higher than the end temperature of the endothermic peak of the phase change material used in this embodiment, the solenoid valve 7 is closed, and this working condition stops running.

[0053] 3. Heat release and frost suppression condition: After the bypass heat storage condition stops, the system enters the normal heating condition. At this time, the high-temperature and high-pressure refrigerant passes through the indoor heat exchanger 4 and then enters the electronic expansion valve 5 for throttling and pressure reduction, and then enters the first heat exchange channel of the outdoor frost suppression heat exchanger 6 to absorb heat. During operation, the fin temperature of the outdoor frost suppression heat exchanger 6 gradually decreases. When the fin surface temperature is lower than the exothermic peak starting temperature of the solid-solid phase change material 14, the phase change heat stored in the material begins to be continuously released, inhibiting frost on the heat exchanger surface.

[0054] The above specific implementation methods are only for illustrating the technical concept and structural features of the present invention, and the purpose is to enable relevant persons familiar with this technology to implement it. However, the above content does not limit the protection scope of the present invention. Any equivalent changes or modifications made according to the spirit of the present invention should fall within the protection scope of the present invention.

Claims

1. A solid-solid cross-temperature phase change temperature control system for air source heat pump frost suppression, characterized in that: The invention comprises a compressor (1) and a gas-liquid separator (3) connected in series in sequence; the other end of the compressor (1) and the other end of the gas-liquid separator (3) are respectively connected to the two ends of a four-way valve (2); the invention also comprises an indoor heat exchanger (4), an electronic expansion valve (5), and an outdoor anti-frost heat exchanger (6) connected in series in sequence; the other end of the indoor heat exchanger (4) and the other end of the outdoor anti-frost heat exchanger (6) are respectively connected to the other two ends of the four-way valve (2); the outdoor anti-frost heat exchanger (6) encapsulates a solid-solid phase change material; the outdoor anti-frost heat exchanger (6) is a fin-tube heat exchange structure, and two heat exchange channels are arranged therein, one of which is a heat exchange copper tube (18) and the other is a temperature regulating heat exchange tube (19); The heat exchange copper tube (18) is a main heat exchange channel and is arranged at intervals with the temperature regulating heat exchange tube (19); the temperature regulating heat exchange tube (19) is a concentric circle sleeve copper tube, including an inner circle tube (20) and an outer circle tube (21); the annular region between the two circle sleeve copper tubes is encapsulated with a solid-solid phase change material (14); An inner tube fin (22) is welded between the inner tube (20) and the outer tube (21); a refrigerant is introduced into the inner tube (20); The temperature control system also includes a defrost heat storage bypass pipeline and a parallel pipeline, one end of the defrost heat storage bypass pipeline is connected to the channel between the outlet of the indoor heat exchanger (4) and the inlet of the electronic expansion valve (5), and the other end is connected to the inlet of the temperature control heat exchange pipe of the outdoor frost suppression heat exchanger (6); A solenoid valve (7) is provided on the defrost heat storage bypass pipeline, and a flow distributor (8) is provided between the solenoid valve (7) and the outdoor frost suppression heat exchanger (6); One end of the parallel pipeline is connected to the channel between the outdoor frost suppression heat exchanger (6) and the four-way valve (2), and the other end is connected to the outlet of the temperature regulating heat exchange pipe (19); A capillary tube (9) is provided on the parallel pipeline, and a one-way valve (10) is provided between the capillary tube (9) and the outlet of the parallel pipeline; The system has three operating modes in winter: normal heating, bypass heat storage, and heat release and frost suppression.

2. A solid-solid cross-temperature phase change temperature control device for air source heat pump frost suppression, applied to the system as claimed in claim 1, characterized in that: The outdoor anti-frost heat exchanger (6) is a fin-tube structure, and a straight temperature regulating fin (12) and a straight temperature regulating fin (11) are arranged inside; the straight temperature regulating fin (11) serves as a main body, and the straight temperature regulating fin (12) is arranged at intervals therefrom; the thickness of the straight temperature regulating fin (12) is greater than that of the straight temperature regulating fin (11), and a cavity for accommodating a solid-solid phase change material is formed inside the straight temperature regulating fin (12); the solid-solid phase change material is encapsulated in the straight temperature regulating fin (12).

3. The solid-solid cross-temperature phase change temperature control device for air source heat pump frost suppression according to claim 2, characterized in that: The end point temperature of the endothermic peak of the solid-solid phase change material (14) used is lower than 50°C, and the starting temperature of the exothermic peak is between -5°C and 0°C.

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