Evaporator defrosting device, cooling unit and defrosting control method

Abstract

The invention provides an evaporator defrosting device, a cooling unit and a defrosting control method. The evaporator defrosting device comprises an evaporator body, a plurality of different types of phase change material components and a plurality of independently-controlled electric heating units. A plurality of evaporator areas with different frosting characteristics are arranged outside the evaporator body; each phase change material part is arranged in one evaporator area; each electric heating unit is used for heating one phase change material part to trigger phase change of the phase change material and release heat, so that active defrosting is carried out on each evaporator area; according to the frosting characteristics of all the areas of the evaporator, regional defrosting is achieved, the defrosting effect is effectively improved, and energy consumption is remarkably reduced.

Description

Technical Field

[0001] The present invention belongs to the field of refrigeration equipment, and more specifically, relates to an evaporator defrosting device, an air cooling unit and a defrosting control method. Background Art

[0002] The evaporator is a key component of a chiller. Frost easily forms on its surface due to low temperatures, affecting heat transfer efficiency and system performance. While effective, traditional defrosting methods (such as electric heating and hot gas defrosting) have limitations in terms of energy consumption, control accuracy, and dynamic response.

[0003] Existing defrosting methods typically activate the defrost heater when the compressor's operating time reaches a preset threshold, defrosting the entire evaporator. However, existing evaporator defrosting is ineffective, prone to under-defrosting or over-defrosting, and severely wastes energy. Summary of the Invention

[0004] The object of the present invention is to provide an evaporator defrosting device, an air cooling unit and a defrosting control method, so as to improve the defrosting effect of the evaporator.

[0005] To achieve the above object, the technical solution adopted by the present invention is:

[0006] The present invention provides an evaporator defrosting device, comprising:

[0007] an evaporator body, wherein the exterior of the evaporator body has a plurality of evaporator regions with different frosting characteristics;

[0008] a plurality of different types of phase change material components, each of the phase change material components being disposed in one of the evaporator regions;

[0009] A plurality of independently controlled electric heating units, each of which is used to heat one of the phase change material components to trigger phase change of the phase change material and release heat, thereby achieving active defrosting of each of the evaporator areas.

[0010] Furthermore, a refrigeration pipeline for refrigerant circulation is provided inside the evaporator body, and the refrigeration pipeline includes a plurality of branch pipelines. Each branch pipeline is provided with a flow regulating valve for regulating the flow of refrigerant, and each branch pipeline corresponds to an evaporator area and cooperates with a phase change material component, thereby realizing passive defrosting of each evaporator area.

[0011] Furthermore, it also includes: multiple heat flow sensors, each of which is arranged in one of the evaporator areas and is used to detect the heat flux density; the power of each of the electric heating units and the refrigerant flow of each of the branch pipes are adjusted according to the heat flux density.

[0012] Furthermore, the exterior of the evaporator body is divided into an evaporator top area, an evaporator middle area, and an evaporator bottom area along the height direction. A first phase change material component is embedded in the evaporator top area, a second phase change material component is embedded in the evaporator middle area, and a third phase change material component is embedded in the evaporator bottom area. The melting point of the first phase change material component is lower than the melting point of the second phase change material component, and the melting point of the third phase change material component is lower than the melting point of the second phase change material component.

[0013] Furthermore, a first electric heating unit disposed near the first phase change material component, a second electric heating unit disposed near the second phase change material component, and a third electric heating unit disposed near the third phase change material component are installed inside the evaporator body.

[0014] The present invention also provides an air cooling unit, comprising a compressor, a four-way valve, a condenser and an evaporator which are sequentially connected to form a refrigerant circulation loop, wherein the evaporator comprises the evaporator defrosting device as described above.

[0015] The present invention also provides a defrost control method, which is applied to the aforementioned cooling unit, comprising:

[0016] The evaporator is defrosted in different zones according to the load status of the cooling unit and the degree of frost in different zones of the evaporator.

[0017] Furthermore, the performing zoned defrosting on the evaporator according to the load state of the cooling unit and the degree of frost in different areas of the evaporator includes:

[0018] If the cooling unit is in a high-load state, the active defrost mode is activated to defrost the heavily frosted evaporator area, and the passive defrost mode is activated to defrost the evaporator areas with other frosting degrees;

[0019] If the cooling unit is in a low-load state, the passive defrost mode is activated to defrost the evaporator areas with different degrees of frost.

[0020] Furthermore, when the active defrost mode is started to defrost a certain evaporator area, the power of the corresponding electric heating unit is dynamically adjusted according to the change of the heat flux density of the evaporator area.

[0021] Furthermore, when the passive defrost mode is activated to defrost a certain evaporator area, the refrigerant flow rate of the corresponding branch pipeline is dynamically adjusted according to the change of the heat flux density of the evaporator area.

[0022] Furthermore, during the process of starting the passive defrost mode to defrost a certain evaporator area, if the heat flux density of the evaporator area drops to a set threshold, the active defrost mode is switched.

[0023] Compared with the prior art, the beneficial effects of the evaporator defrost device, cold air unit and defrost control method provided by the present invention are: the present invention divides the evaporator into multiple areas in terms of physical structure, selects different types of phase change material components according to the frosting characteristics of different evaporator areas, and uses independently controlled electric heating units to heat each phase change material component, thereby realizing precise defrost control in different areas. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0025] Figure 1 A schematic structural diagram of an evaporator defrosting device provided in a preferred embodiment of the present invention;

[0026] Figure 2 A schematic flow chart of a defrost control method provided in a preferred embodiment of the present invention;

[0027] Among them, the main marks of the drawings in the figure are:

[0028] 11. Evaporator top area;

[0029] 12. Middle area of ​​evaporator;

[0030] 13. Evaporator bottom area;

[0031] 21. First electric heating unit;

[0032] 22. Second electric heating unit;

[0033] 31. First heat flow sensor;

[0034] 32. Second heat flow sensor;

[0035] 33. The third heat flow sensor;

[0036] 41. First flow regulating valve;

[0037] 42. Second flow control valve;

[0038] 43. The third flow regulating valve. DETAILED DESCRIPTION

[0039] In order to make the technical problems, technical solutions and beneficial effects to be solved by the present invention more clearly understood, the present invention is further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0040] The evaporator is a key component of the cooling unit. Its surface is easily frosted due to low temperatures, affecting heat transfer efficiency and system performance. Although traditional defrosting methods (such as electric heating defrosting, hot gas defrosting, etc.) are effective, they have certain limitations in energy consumption, control accuracy and dynamic response. To address this problem, the inventors took advantage of the excellent heat storage and heat release properties of phase change materials and innovatively applied them to refrigeration units. By comprehensively considering the phase change material, the changes in the heat flux density on the evaporator surface and the unit load, precise defrosting control of different areas of the evaporator is achieved.

[0041] The evaporator defrost device provided by the present invention comprises at least an evaporator body, multiple different types of phase change material components, and multiple independently controlled electric heating units. The evaporator body has multiple evaporator zones with different frosting characteristics on its exterior; each phase change material component is disposed within an evaporator zone; and each electric heating unit is configured to heat a phase change material component, triggering a phase change in the phase change material and releasing heat, thereby achieving active defrosting of each evaporator zone.

[0042] It should be noted that each phase change material component contains phase change material, which refers to a material that can absorb or release a large amount of latent heat during the phase change process. The present invention applies phase change material to a refrigeration unit. Phase change material can be used to store and release heat to help regulate the temperature of the evaporator surface. The defrost mode of the present invention includes but is not limited to an active defrost mode. The active defrost mode is set as follows: the phase change of the phase change material is triggered by an external heat source (electric heating), and heat is released to melt the frost layer. An electric heating element is installed near the phase change material, and the heat generated by the current heats the phase change material, causing it to melt and release heat. Increasing the power of the electric heating element can speed up the melting speed of the phase change material and increase the defrost intensity.

[0043] This invention physically divides the evaporator into multiple zones. Different types of phase-change material components are selected based on the frosting characteristics of each evaporator zone. Each phase-change material component is heated using independently controlled electric heating units, thereby achieving precise defrost control in each zone. Based on this, the invention implements regional defrost based on the frosting characteristics of each evaporator zone, effectively improving defrost performance and significantly reducing energy consumption.

[0044] In addition, in the evaporator defrost device proposed in the present invention, a refrigeration pipeline for refrigerant circulation is arranged inside the evaporator body, and the refrigeration pipeline includes multiple branch pipelines. Each branch pipeline is provided with a flow regulating valve for regulating the refrigerant flow, and each branch pipeline corresponds to an evaporator area and is coordinated with a phase change material component, thereby realizing passive defrosting of each evaporator area.

[0045] It should be noted that the defrost mode of the present invention also includes a passive defrost mode. This passive defrost mode utilizes the refrigerant's evaporative heat absorption properties, combined with the heat storage capacity of the phase change material, to dynamically adjust the evaporator surface temperature to prevent excessive frost formation. The refrigerant flows through the evaporator, absorbing heat and regulating the evaporator surface temperature through its evaporative heat absorption properties. When the evaporator surface temperature drops to a certain level, the phase change material begins to release the stored heat, preventing excessive frost formation. Increasing the refrigerant flow rate can accelerate evaporative heat absorption and reduce frost formation.

[0046] This invention also combines the refrigerant's evaporative heat absorption properties with the heat storage and regulation capabilities of the phase change material to dynamically balance the evaporator surface temperature, preventing excessive frost formation caused by low temperatures or heat imbalance. The synergistic effect of the branch piping and the phase change material components prevents excessive drops in the evaporator surface temperature, slowing frost formation and achieving effective defrosting without the need for external energy.

[0047] In addition, the evaporator defrost device proposed in the present invention also includes: multiple heat flow sensors, each heat flow sensor is arranged in an evaporator area and is used to detect the heat flux density; the power of each electric heating unit and the refrigerant flow of each branch pipeline are adjusted according to the heat flux density.

[0048] It should be noted that heat flux refers to the rate of heat transfer per unit area. Changes in heat flux on the evaporator surface reflect the dynamic process of refrigerant evaporation and heat transfer. When frosted, the heat flux decreases because the frost increases thermal resistance and hinders heat transfer. Conversely, when defrosting occurs, the frost melts and the heat flux increases, restoring or improving heat transfer efficiency. A contact heat flux sensor is installed at the center of each evaporator surface. The heat flux is calculated by directly measuring the rate of change of the evaporator surface temperature over time and combining it with the thermal conductivity and geometric properties of the material.

[0049] Heat flux (q) can be calculated using the following formula: q = C × dT / dt.

[0050] q is the heat flux in watts per square meter (W / m2).

[0051] dT / dt is the rate of change of the evaporator surface temperature with time, expressed in degrees Celsius per second (°C / s).

[0052] C is a proportionality constant that depends on the thermal conductivity (k) and thickness (d) of the evaporator surface material, as well as the sensor response characteristics, and is expressed in watts per square meter Celsius (W / (m 2 ·℃)).

[0053] Moreover, the proportionality constant C can be determined experimentally: C = k × A / d. Where:

[0054] k is the thermal conductivity of the material, measured in watts per meter Celsius (W / (m·°C)).

[0055] A is the area covered by the sensor in square meters (m2).

[0056] d is the thickness of the evaporator surface in meters (m).

[0057] The present invention effectively avoids the problem of inaccurate control of insufficient or excessive defrosting by adjusting the electric heating power and the refrigerant flow rate according to the heat flux density, thereby optimizing the defrosting effect and reducing energy consumption.

[0058] like Figure 1 As shown, in a preferred embodiment of the present invention, the exterior of the evaporator body is divided into an evaporator top area 11, an evaporator middle area 12 and an evaporator bottom area 13 along the height direction. A first phase change material component is embedded in the evaporator top area 11, a second phase change material component is embedded in the evaporator middle area 12, and a third phase change material component is embedded in the evaporator bottom area 13. The melting point of the first phase change material component is lower than the melting point of the second phase change material component, and the melting point of the third phase change material component is lower than the melting point of the second phase change material component.

[0059] It should be noted that regarding the top area 11 of the evaporator: due to the high density of cold air, it is easy to accumulate at the top, which leads to severe frosting. For this reason, a phase change material with a lower melting point, such as paraffin or fatty acid, can be selected. Regarding the middle area 12 of the evaporator: its temperature and frost amount are between the top and bottom, and the frost distribution is relatively uniform, so it is suitable to use a phase change material with a medium melting point (such as polyol). As for the bottom area 13 of the evaporator: due to the rising hot air, the temperature in this area is higher and the degree of frost is lighter, so a phase change material with a higher melting point (such as salt hydrate) can be selected. In addition, the size of the top, middle and bottom areas of the evaporator can be set according to experiments. Normally, the area of ​​the top area 11 of the evaporator is smaller than that of the middle area 12 of the evaporator, and the area of ​​the middle area 12 of the evaporator is smaller than that of the bottom area 13 of the evaporator.

[0060] This invention physically divides the evaporator into three zones: top, middle, and bottom. Appropriate phase-change materials are selected based on the frost characteristics of each zone to achieve more precise and efficient defrost control. This design not only accounts for temperature differences and frost levels in different evaporator zones, but also optimizes defrost performance and improves the overall evaporator performance through rational zone division and phase-change material selection.

[0061] like Figure 1 As shown, in a preferred embodiment of the present invention, a first electric heating unit 21 arranged near the first phase change material component, a second electric heating unit 22 arranged near the second phase change material component, and a third electric heating unit (not shown in the figure) arranged near the third phase change material component are installed inside the evaporator body.

[0062] The present invention configures three independent electric heating units for the top, middle and bottom areas of the evaporator, respectively. These electric heating units can flexibly adjust the heating power according to the frosting conditions in each area of ​​the evaporator and the type of phase change material.

[0063] In actual use, when the top area 11 of the evaporator is severely frosted, the first electric heating unit 21 is activated to heat the first phase change material component, causing it to melt and release heat. Similarly, when the middle area 12 of the evaporator is severely frosted, the second electric heating unit 22 is activated to heat the second phase change material component, causing it to melt and release heat. Similarly, when the bottom area 13 of the evaporator is severely frosted, the third electric heating unit (not shown) is activated to heat the third phase change material component, causing it to melt and release heat.

[0064] This zone-based control strategy not only effectively avoids energy waste caused by overheating, but also significantly improves defrosting efficiency and evaporator operating stability. Furthermore, by precisely controlling the operating status of each electric heating unit, the present invention can also achieve fine-tuning of the overall evaporator temperature, further improving the energy efficiency of the refrigeration unit.

[0065] like Figure 1 As shown, in a preferred embodiment of the present invention, the refrigerant piping within the evaporator body comprises a first branch line, a second branch line, and a third branch line. A first flow control valve 41 is installed on the first branch line, corresponding to the top area 11 of the evaporator. Similarly, a second flow control valve 42 is installed on the second branch line, corresponding to the middle area 12 of the evaporator. Similarly, a third flow control valve 43 is installed on the third branch line, corresponding to the bottom area 13 of the evaporator. Solenoid valves can be used for the first, second, and third flow control valves 41, 42, and 43.

[0066] The present invention also provides an air cooling unit comprising a compressor, a four-way valve, a condenser, and an evaporator connected in sequence to form a refrigerant circulation loop, wherein the evaporator includes the aforementioned evaporator defrosting device. The evaporator defrosting device proposed in the present invention implements regional defrosting based on the frosting characteristics of each region of the evaporator, effectively improving the defrosting effect and significantly reducing energy consumption, thereby significantly enhancing the safety and adaptability of the air cooling unit.

[0067] The defrost control method provided by the present invention is applied to the aforementioned cooling unit, comprising:

[0068] The evaporator is defrosted in different zones according to the load status of the cooling unit and the degree of frost in different zones of the evaporator.

[0069] By monitoring the load condition of the cooling unit and the degree of frost in each zone of the evaporator, the present invention achieves zoned defrosting of the evaporator, significantly improving the defrosting effect and reducing energy consumption. However, existing technologies fail to optimize the frosting characteristics of different zones of the evaporator, resulting in poor defrosting effect, severe energy waste, and an inability to adapt to diverse operating conditions and load changes, making the defrosting effect unstable, which in turn affects the efficiency and reliability of the system and results in poor system adaptability. The present invention can also improve the adaptability and efficiency of the unit, enabling it to effectively cope with different operating conditions and load changes, while also enhancing the unit's reliability and stability.

[0070] In some embodiments of the present invention, the defrost control method specifically includes:

[0071] If the cooling unit is in a high-load state, the active defrost mode is activated to defrost the heavily frosted evaporator area, and the passive defrost mode is activated to defrost the evaporator areas with other frosting degrees;

[0072] If the cooling unit is in a low-load state, the passive defrost mode is activated to defrost the evaporator areas with different degrees of frost.

[0073] It should be noted that when determining the load status of the air conditioner, the compressor frequency range is generally between 40Hz and 60Hz. The compressor frequency threshold is set at around 55Hz. If the compressor frequency is higher than 55Hz, the air conditioner is in a high load state; if the compressor frequency is lower than or equal to 55Hz, the air conditioner is in a low load state.

[0074] The principle of unit load detection is as follows: In a variable-frequency compressor, the operating frequency is directly related to the unit load. Specifically, the higher the frequency, the greater the load. The air cooler uses a frequency converter to drive the compressor, which outputs a corresponding frequency signal. By connecting to the frequency output port of the frequency converter, the compressor frequency data can be obtained in real time. Under high load conditions, the air cooler operates with high cooling demand, resulting in rapid evaporator frosting and a thicker frost layer. Under low load conditions, the air cooler operates with low cooling demand, resulting in slower evaporator frosting and a thinner frost layer.

[0075] Furthermore, the degree of frost in the evaporator region can be determined based on heat flux density. When the heat flux density in the evaporator region drops to a set threshold (e.g., 40%), it is determined to be severely frosted. The present invention preferably categorizes the degree of frost in the evaporator region into three levels: severe frosting, moderate frosting, and light frosting.

[0076] The present invention dynamically selects an active defrost mode or a passive defrost mode according to the load state of the cold air unit and the degree of frost in each area of ​​the evaporator, thereby achieving a better defrost effect and significantly improving the applicability of the unit.

[0077] Furthermore, when the active defrost mode is activated to defrost a specific evaporator area, the power of the electric heating unit in that area is dynamically adjusted based on changes in the heat flux density of the evaporator area. By detecting changes in the heat flux density on the evaporator surface in real time and adjusting the electric heating power for active defrost, the present invention optimizes the defrosting effect and significantly reduces energy consumption.

[0078] Furthermore, when passive defrosting is activated for a specific evaporator zone, the refrigerant flow rate in the corresponding branch line is dynamically adjusted based on the heat flux density changes in that evaporator zone. By detecting changes in heat flux density on the evaporator surface in real time and adjusting the refrigerant flow rate for passive defrosting, the present invention optimizes the defrosting effect and significantly reduces energy consumption.

[0079] Furthermore, when the passive defrost mode is activated to defrost a certain evaporator area, if the heat flux density of the evaporator area drops to a set threshold, the system switches to the active defrost mode. The present invention can automatically switch to the active defrost mode if the passive defrost effect is unsatisfactory, thereby ensuring the defrost effect.

[0080] It should be noted that in actual application scenarios, active defrost mode and passive defrost mode can be used at the same time. When the defrost effect of a single mode is not ideal, the other mode can be activated to assist defrost and ensure the desired defrost effect.

[0081] For ease of understanding, the evaporator defrost device and the defrost control method thereof shown in the preferred embodiment of the present invention are now described in detail.

[0082] like Figure 1 As shown, in the evaporator defrosting device, the exterior of the evaporator body is divided into an evaporator top area 11 , an evaporator middle area 12 and an evaporator bottom area 13 .

[0083] The entire surface of the evaporator top region 11 is embedded with a first phase change material component, the entire surface of the evaporator middle region 12 is embedded with a second phase change material component, and the entire surface of the evaporator bottom region 13 is embedded with a third phase change material component.

[0084] A first heat flow sensor 31 is installed in the middle of the top area 11 of the evaporator, a second heat flow sensor 32 is installed in the middle of the middle area of ​​the evaporator, and a third heat flow sensor 33 is installed in the middle of the bottom area 13 of the evaporator.

[0085] The evaporator body is internally installed with a first electric heating unit 21 arranged near the first phase change material component, a second electric heating unit 22 arranged near the second phase change material component, and a third electric heating unit (not shown in the figure) arranged near the third phase change material component.

[0086] The refrigerant piping within the evaporator body consists of a first branch line, a second branch line, and a third branch line. A first flow control valve 41 is installed on the first branch line, corresponding to the top area 11 of the evaporator. A second flow control valve 42 is installed on the second branch line, corresponding to the middle area 12 of the evaporator. A third flow control valve 43 is installed on the third branch line, corresponding to the bottom area 13 of the evaporator.

[0087] like Figure 2 As shown, the specific process of the defrost control method is as follows:

[0088] Determine the load status of the cooling unit;

[0089] If the chiller is under high load, the active defrost mode is activated for the top evaporator zone 11. For the middle evaporator zone 12, the defrost mode is dynamically adjusted, and active defrost mode is activated when necessary. For the bottom evaporator zone 13, passive defrost mode is activated. Furthermore, the electric heating power in active defrost mode and the refrigerant flow in passive defrost mode are dynamically adjusted based on changes in heat flux. Specifically, the defrost process for the top, middle, and bottom evaporator zones is as follows:

[0090] The evaporator's top area 11 is severely frosted, and the first flow control valve 41 is closed. The first electric heating unit 21 is activated to rapidly melt the frost layer through active defrosting. The power of the first electric heating unit 21 is dynamically adjusted based on the changes in the heat flux density in the evaporator's top area 11. When the heat flux density drops rapidly, the power of the first electric heating unit 21 is increased. When the heat flux density recovers, the power of the first electric heating unit 21 is appropriately reduced. This rapidly melts the frost layer and maintains heat transfer efficiency.

[0091] If frost is common in the central evaporator area 12, the defrost mode is dynamically adjusted, and active defrost mode is activated when necessary. During the initial high-load operation, the central evaporator area 12 uses passive defrost mode, with only the second flow control valve 42 open. The refrigerant flow in the second branch line is dynamically adjusted based on changes in the heat flux density in the central evaporator area 12. When the heat flux density drops significantly, the opening of the second flow control valve 42 is increased to increase the refrigerant flow rate and enhance heat transfer. When the heat flux density stabilizes, the opening of the second flow control valve 42 is decreased to reduce the refrigerant flow rate and save energy. When the heat flux density drops to a set threshold (e.g., 50%), it is determined that the frost has worsened and the passive defrost effect is insufficient. The second electric heating unit 22 is activated, and active defrost mode is activated to assist in clearing the frost layer. When the heat flux density drops rapidly, the power of the second electric heating unit 22 is increased. When the heat flux density recovers, the power of the second electric heating unit 22 is appropriately reduced. This rapidly melts the frost layer and maintains heat transfer efficiency.

[0092] The evaporator bottom area 13 is lightly frosted, relying primarily on passive defrosting. The third flow control valve 43 is opened. The refrigerant flow in the third branch line is dynamically adjusted based on changes in the heat flux density in the evaporator bottom area 13. When the heat flux density drops significantly, the opening of the third flow control valve 43 is increased to increase the refrigerant flow rate and enhance heat transfer. When the heat flux density stabilizes, the opening of the third flow control valve 43 is decreased to reduce the refrigerant flow rate and save energy.

[0093] If the chiller is in a low-load state, the active defrost mode is activated for the top evaporator area 11 only when frost is severe. The passive defrost mode is activated for the middle evaporator area 12, and the passive defrost mode is activated for the bottom evaporator area 13. Furthermore, the electric heating power in active defrost mode and the refrigerant flow in passive defrost mode are dynamically adjusted based on changes in heat flux density. Specifically, the defrost process for the top, middle, and bottom evaporator areas is as follows:

[0094] The active defrost mode is activated only when severe frost forms in the top area 11 of the evaporator. During the initial low-load operation, the top area 11 of the evaporator adopts the passive defrost mode, with only the first flow control valve 41 open. The refrigerant flow rate in the first branch line is dynamically adjusted based on changes in the heat flux density in the top area 11 of the evaporator. When the heat flux density drops significantly, the opening of the first flow control valve 41 is increased to increase the refrigerant flow rate and enhance heat transfer. When the heat flux density stabilizes, the opening of the first flow control valve 41 is decreased to reduce the refrigerant flow rate and save energy. When the heat flux density drops to a set threshold (e.g., 40%), the frost is judged to be severe and the passive defrost effect is insufficient. The first electric heating unit 21 is turned on, and the active defrost mode is activated to assist in clearing the frost layer. When the heat flux density drops rapidly, the power of the first electric heating unit 21 is increased. When the heat flux density recovers, the power of the first electric heating unit 21 is appropriately reduced. This rapidly melts the frost layer and maintains heat transfer efficiency.

[0095] The central evaporator area 12 relies primarily on passive defrosting. The second electric heating unit 22 is off, and the second flow control valve 42 is open. When the heat flux drops significantly, the opening of the second flow control valve 42 is increased to increase the refrigerant flow rate and enhance heat transfer. When the heat flux stabilizes, the opening of the second flow control valve 42 is decreased to reduce the refrigerant flow rate and save energy.

[0096] The evaporator bottom area 13 relies primarily on passive defrosting. Open the third flow control valve 43. When the heat flux drops significantly, increase the opening of the third flow control valve 43 to increase the refrigerant flow rate and enhance heat transfer. When the heat flux stabilizes, decrease the opening of the third flow control valve 43 to reduce the refrigerant flow rate and save energy.

[0097] It can be seen that the present invention achieves precise defrosting control in different regions by subdividing the evaporator into multiple regions (such as the top, middle, and bottom) in terms of physical structure and selecting corresponding phase change materials according to the frosting characteristics of each region. The present invention dynamically selects active defrosting mode or passive defrosting mode based on the load of the unit and the degree of frost in each region of the evaporator, effectively improving the adaptability and operating efficiency of the unit, being applicable to a variety of working conditions and load changes, and enhancing the reliability and stability of the unit. In addition, the present invention monitors the changes in the heat flux density on the surface of the evaporator in real time, accurately adjusts the electric heating power of active defrosting and the refrigerant flow of passive defrosting, optimizes the defrosting effect, and significantly reduces energy consumption.

[0098] In summary, the present invention divides the evaporator into multiple areas in terms of physical structure, and selects corresponding phase change materials according to the frosting characteristics of each area. In addition, the active or passive defrosting mode is intelligently selected in combination with the unit load and the degree of frost in different areas of the evaporator, which effectively solves the problems of energy waste caused by the unified defrosting mode of the traditional defrosting method, as well as the inability to adapt to different working conditions and load changes, unstable defrosting effect, impact on system efficiency and reliability, and poor system adaptability. In addition, by adjusting the electric heating power and refrigerant flow according to the heat flux density, the problem of the traditional defrosting method being unable to dynamically adjust the defrosting intensity according to the degree of frost and the unit load, and the problem of inaccurate control of insufficient defrosting or excessive defrosting, is solved.

[0099] In the description of the present invention, it should be understood that, unless otherwise expressly specified or limited, when an element is referred to as being “fixed to” or “disposed on” another element, it may be directly on the other element or indirectly on the other element. When an element is referred to as being “connected to” another element, it may be directly connected to the other element or indirectly connected to the other element.

[0100] In addition, the orientations or positional relationships indicated by terms such as “center”, “length”, “width”, “thickness”, “up”, “down”, “front”, “back”, “left”, “right”, “vertical”, “horizontal”, “top”, “bottom”, “inside” and “outside” are based on the orientations or positional relationships shown in the accompanying drawings and are only for the convenience of describing the present invention and simplifying the description. They do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operate in a specific orientation, and therefore should not be understood as limiting the present invention.

[0101] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the quantity of the technical features being referred to. Thus, a feature specified as "first" or "second" may explicitly or implicitly include one or more of such features. In the description of the present invention, "plurality" means two or more, unless otherwise specifically defined.

[0102] Furthermore, the terms "mounted," "connected," and "connected" should be interpreted broadly. For example, they can refer to fixed, detachable, or integral connections; mechanical or electrical connections; direct or indirect connections through an intermediary; and internal communication between two components or interaction between two components. Those skilled in the art will understand the specific meanings of these terms in the present invention based on specific circumstances.

[0103] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. An evaporator defrosting device, characterized in that: include: an evaporator body, wherein the exterior of the evaporator body has a plurality of evaporator regions with different frosting characteristics; a plurality of different types of phase change material components, each of the phase change material components being disposed in one of the evaporator regions; A plurality of independently controlled electric heating units, each of which is used to heat one of the phase change material components to trigger phase change of the phase change material and release heat, thereby achieving active defrosting of each of the evaporator areas.

2. The evaporator defrosting device according to claim 1, characterized in that: A refrigeration pipeline for refrigerant circulation is provided inside the evaporator body, and the refrigeration pipeline includes a plurality of branch pipelines. A flow regulating valve for regulating the flow of refrigerant is provided on each branch pipeline, and each branch pipeline corresponds to an evaporator area and cooperates with a phase change material component, thereby realizing passive defrosting of each evaporator area.

3. The evaporator defrosting device according to claim 2, characterized in that: Also includes: a plurality of heat flow sensors, each of the heat flow sensors being disposed in one of the evaporator regions and configured to detect heat flux density; The power of each of the electric heating units and the refrigerant flow rate of each of the branch pipelines are adjusted according to the heat flux density.

4. The evaporator defrosting device according to any one of claims 1 to 3, characterized in that: The exterior of the evaporator body is divided into an evaporator top area, an evaporator middle area, and an evaporator bottom area along the height direction. A first phase change material component is embedded in the evaporator top area, a second phase change material component is embedded in the evaporator middle area, and a third phase change material component is embedded in the evaporator bottom area. The melting point of the first phase change material component is lower than the melting point of the second phase change material component, and the melting point of the third phase change material component is lower than the melting point of the second phase change material component.

5. The evaporator defrosting device according to claim 4, characterized in that: A first electric heating unit disposed close to the first phase change material component, a second electric heating unit disposed close to the second phase change material component, and a third electric heating unit disposed close to the third phase change material component are installed inside the evaporator body.

6. A cooling unit comprising a compressor, a four-way valve, a condenser and an evaporator connected in sequence to form a refrigerant circulation loop, characterized in that: The evaporator includes the evaporator defrosting device according to any one of claims 1 to 5.

7. A defrost control method, applied to the cooling unit according to claim 6, characterized in that: include: The evaporator is defrosted in different zones according to the load status of the cooling unit and the degree of frost in different zones of the evaporator.

8. The defrost control method according to claim 7, wherein: The performing zoned defrosting on the evaporator according to the load state of the cooling unit and the degree of frost in different areas of the evaporator comprises: If the cooling unit is in a high-load state, the active defrost mode is activated to defrost the heavily frosted evaporator area, and the passive defrost mode is activated to defrost the evaporator areas with other frosting degrees; If the cooling unit is in a low-load state, the passive defrost mode is activated to defrost the evaporator areas with different degrees of frost.

9. The defrost control method according to claim 8, characterized in that: When the active defrost mode is started to defrost a certain evaporator area, the power of the corresponding electric heating unit is dynamically adjusted according to the change of the heat flux density of the evaporator area.

10. The defrost control method according to claim 8, wherein: When the passive defrost mode is started to defrost a certain evaporator area, the refrigerant flow rate of the corresponding branch pipeline is dynamically adjusted according to the change of the heat flux density of the evaporator area.

11. The defrost control method according to claim 8, wherein: During the process of starting the passive defrost mode to defrost a certain evaporator area, if the heat flux density of the evaporator area drops to a set threshold, it switches to the active defrost mode.

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