Solar energy-phase change heat storage synergetic parallel evaporator segmented defrosting system and solar energy-phase change heat storage synergetic parallel evaporator segmented defrosting method

Abstract

The invention discloses a solar energy-phase change heat storage collaborative parallel evaporator segmented defrosting system and method, and belongs to the technical field of air source heat pump defrosting and new energy utilization. Comprising evaporator sets (A / B) arranged in parallel, a compressor, a condenser, a four-way reversing valve, a solar heat collecting plate, an electromagnetic valve, a temperature sensor and a connecting pipeline. A phase change material interlayer is embedded in a finned tube of the evaporator set, the phase change material is connected with the solar heat collection plate through a circulation pipeline, the phase change material absorbs or releases a large amount of latent heat in the solid-liquid phase change process, and heat collected by the solar heat collection plate is stored in a high-density mode. When the evaporator is frosted, heat stored by the phase change material can be released directionally, and melting of a frost layer is accelerated. Through the synergistic effect of solar energy and phase change heat storage, the defrosting time is remarkably shortened, indoor temperature fluctuation caused by reverse circulation is reduced, meanwhile, the energy utilization rate is increased, the structure is simple, the cost is controllable, and the efficient defrosting requirement of the air source heat pump in the cold region is met.

Description

Technical Field

[0001] The present invention relates to the technical field of heat pumps, and in particular, to a parallel evaporator segmented defrosting system and method that synergizes solar energy and phase change heat storage. Background Art

[0002] When an air source heat pump operates in a cold region, frosting on the evaporator surface is a key problem restricting its efficient operation. Traditional defrosting methods, such as hot gas bypass defrosting and electric heating defrosting, can relieve frosting temporarily, but have significant drawbacks: when defrosting, high-temperature refrigerant is directly introduced into the evaporator, causing the normal heating cycle to pause, resulting in heating interruption and indoor temperature fluctuations, and increased energy consumption; electric heating defrosting directly relies on high-grade electric energy, with poor economy and difficulty in meeting the low-carbon requirements. In addition, the frosting distribution on the fins of a conventional evaporator is uneven, further reducing the defrosting efficiency and exacerbating energy waste.

[0003] Currently, the defrosting technology of solar-coupled heat pump systems mainly relies on directly heating the evaporator surface by photovoltaic-thermal or using electric heating for auxiliary defrosting. However, such methods have significant drawbacks, including low energy utilization efficiency, independent operation of solar heat collection and the heat pump system without forming efficient synergy, resulting in heat waste; insufficient heat storage capacity and difficulty in meeting the long-term defrosting requirements at night; the risk of energy supply interruption, relying on daytime solar input and being unable to continuously provide defrosting heat under cloudy or night conditions, leading to system performance degradation.

[0004] This solution significantly improves the heat pump defrosting efficiency and energy utilization rate through the deep synergy of high-thermal-conductivity composite phase change materials and solar heat storage. Using paraffin / expanded graphite-nanoaluminum oxide composite materials, the phase change temperature range is extended to 28 - 50 °C. The parallel evaporator group enables seamless connection between defrosting and heating, avoiding shutdown losses. The solar heat collection panel and the phase change material adopt a dynamic coupling control strategy, increasing the solar energy contribution rate to 30% - 35%. At the same time, the phase change material simplifies the process and reduces the manufacturing cost. It can also adjust the fan speed to compensate for uneven heat release and ensure small room temperature fluctuations. It provides an efficient, stable, and low-cost heat pump defrosting solution for severe cold regions. Summary of the Invention

[0005] The object of the present invention is to solve the problems such as serious frosting of the evaporator, low energy efficiency of reverse cycle defrosting, and large indoor temperature fluctuations during the defrosting process when traditional air source heat pumps operate in low-temperature and high-humidity environments. The present invention proposes a solar-phase change heat storage collaborative parallel evaporator segmented defrosting system and method. By deeply combining solar heat storage with the characteristics of phase change materials, a paraffin / expanded graphite-nanoaluminum oxide composite material is used. Heat is stored during the day through a solar collector panel and released when defrosting is required. At the same time, in combination with a parallel evaporator group, seamless switching between the operating state and the defrosting state of the evaporator is achieved. During the defrosting process, the heat stored in the phase change material is directionally transported to the finned tubes of the frosted evaporator, greatly improving the defrosting rate and reducing the reverse cycle time. The system has a simple structure. Only by embedding a phase change material sandwich layer in the existing evaporator and connecting the solar pipeline can continuous energy supply and efficient defrosting be achieved day and night. The comprehensive energy efficiency ratio is improved, and at the same time, it has the dual advantages of energy conservation and consumption reduction and temperature stability, providing a reliable and environmentally friendly heat pump defrosting solution for buildings in cold regions.

[0006] A solar-phase change heat storage collaborative parallel evaporator segmented defrosting system includes a compressor (1), a four-way reversing valve (2), a condenser (3), evaporator A (4) and evaporator B (5) arranged in parallel, a solar collector panel (6), a circulation pump (7), temperature sensors (8 - 9), solenoid valves (10 - 13), and connecting pipelines (14); it is characterized in that: a layer of phase change material (16) sandwich layer is arranged inside the finned tubes of evaporator A (4) and evaporator B (5), the phase change material is filled in the annular sandwich area between the copper tube (15) and the fins, supported by a honeycomb aluminum plate (17), and connected to the circulation pump (7) and the solar collector panel (6) through a circulation pipeline to achieve efficient storage and directional release of solar heat.

[0007] The object of the present invention is achieved through the following technical solutions:

[0008] The solar collector panel (6) adopts a copper-aluminum composite plate structure, with a black chromium selective absorption coating on the surface, and is connected to the phase change material (16).

[0009] The ethylene glycol-water solution is used as an antifreeze heat transfer medium, circulating between the solar collector panel (1) and the phase change material (16), absorbing and transferring solar heat to the phase change material (16) for storage, and at the same time ensuring that the pipeline has no freezing risk in extreme low temperatures.

[0010] When the frost layer thickness of evaporator A group (4) reaches a certain level, the solenoid valve (11) is opened to switch to the operation of group B (5); the circulation pump (7) of the solar system operates to provide heat storage for group A. At the same time, a part of the heat is also used to maintain the heat storage of the phase change material (16) in group B.

[0011] The bracket angle of the solar collector panel (6) is adjustable and can be dynamically adjusted by an electric push rod to achieve efficient utilization of solar energy.

[0012] Through the efficient cooperation of solar energy and phase change heat storage, this system provides an innovative solution for heat pump defrosting in cold regions, significantly reducing the energy consumption of traditional reverse cycle defrosting and carbon emissions; the phase change material simplifies the manufacturing process, reduces costs, and promotes the popularization of green technologies; the room temperature fluctuates little and continuous energy supply at night improve user comfort and system reliability. This technology expands the application boundary of heat pumps in extreme environments, contributes to the realization of the "dual carbon" goal, has both ecological and economic benefits, and provides a replicable technical paradigm for the field of building energy conservation.

[0013] Advantages of the present invention:

[0014] 1. A parallel evaporator segmented defrosting system and method that combines solar energy and phase change heat storage. The heat collected by the solar collector panel during the day is stored by the phase change material and used to release heat for defrosting when needed, greatly accelerating the frost melting process, significantly shortening the defrosting time, and greatly improving the defrosting efficiency compared with traditional defrosting methods. Traditional defrosting mostly relies on the reverse cycle of the heat pump itself and takes a long time. This system, with the cooperation of solar energy and the phase change material, directs the heat to the frost layer. For example, on a cold winter night, the defrosting time that originally took several hours can be shortened to about half an hour, efficiently restoring the heat exchange performance of the evaporator and ensuring the continuous and stable heating of the heat pump.

[0015] 2. By combining solar energy and phase change heat storage for defrosting, it avoids a large drop in indoor temperature caused by long-term reverse cycle defrosting. During the defrosting process, it can keep the indoor temperature relatively stable and improve user comfort. In the past, during reverse cycle defrosting, a large amount of indoor heat was extracted and the room temperature dropped suddenly. When this system defrosts, it uses the stored solar energy for heating to maintain the indoor heat balance, and the indoor temperature fluctuates very little, and users can hardly notice the temperature change and enjoy a comfortable and warm environment.

[0016] 3. It makes full use of solar energy, a clean energy source, for heat storage, reduces the excessive dependence on other energy sources such as electricity in traditional defrosting methods, realizes the efficient utilization of energy, and reduces the energy consumption cost. Traditional defrosting has high energy consumption, while this system converts free solar energy into heat energy for storage during the day and releases it as needed at night. It not only saves energy and reduces emissions but also reduces the electricity bill expenditure of users, combining economic and environmental benefits.

[0017] 4. A parallel evaporator segmented defrosting system with solar - phase change heat storage collaboration mainly consists of a parallel evaporator group, solar collectors, phase change materials, and a circulation pipeline, etc. It has no complex mechanical structures and components, and the system construction and maintenance are relatively simple. Compared with complex defrosting devices, it does not require precise debugging and professional maintenance. During installation, the connections of each component are clear, and maintenance personnel can easily troubleshoot faults, such as checking for pipeline blockages and inspecting the daylighting condition of the solar collectors, greatly reducing the maintenance difficulty and cost.

[0018] 5. The phase change material sandwich embedded in the evaporator finned tube can efficiently store and release heat. During the phase change process, the temperature remains constant, providing a stable heat source for defrosting and ensuring the stability of the defrosting effect. The temperature of the phase change material remains basically unchanged during heat absorption and release, ensuring a stable output of defrosting heat. Even on cloudy days when solar energy is unstable, the stored heat can continuously melt the frost layer at a constant temperature, avoiding incomplete defrosting caused by heat fluctuations and always maintaining high - efficiency defrosting performance. Brief Description of the Drawings

[0019] Figure 1 is the overall system schematic diagram of the present invention;

[0020] Figure 2 is the partial cross - sectional view of the evaporator of the present invention;

[0021] Figure 3 is the fitting cross - sectional view of the honeycomb aluminum plate and the copper tube of the present invention.

[0022] In the figure: 1 - compressor; 2 - four - way reversing valve; 3 - condenser; 4 - evaporator group; 5 - evaporator group B; 6 - solar collector; 7 - circulation pump; 8 - 9 - temperature sensors; 10 - 13 - solenoid valves; 14 - connecting pipeline; 15 - copper tube; 16 - phase change material; 17 - honeycomb aluminum plate. Detailed Embodiments

[0023] The present invention provides a parallel evaporator segmented defrosting system and method with solar - phase change heat storage collaboration. The following further describes the present invention in conjunction with the drawings and specific embodiments.

[0024] A parallel evaporator segmented defrosting system and method with solar energy - phase change heat storage collaboration, including a compressor (1), a four - way reversing valve (2), a condenser (3), an evaporator A (4) and an evaporator B (5) arranged in parallel, a solar collector panel (6), a circulation pump (7), temperature sensors (8 - 9), solenoid valves (10 - 13) and connecting pipelines (14); it is characterized in that: a layer of phase change material (16) interlayer is arranged inside the finned tubes of the evaporator A (4) and the evaporator B (5), the phase change material (16) is filled in the annular interlayer area between the copper tube (15) and the fins, supported by a honeycomb aluminum plate (17), and the honeycomb aluminum plate (17) is brazed to the copper tube (15) with very small contact thermal resistance to ensure efficient thermal coupling between the phase change material (16) and the refrigerant.

[0025] The parallel evaporator group is composed of group A and group B. Each group of evaporators uses copper corrugated finned tubes, and the two groups are horizontally installed side by side. The evaporator copper tubes (15) are connected to the compressor (1), the four - way reversing valve (2) and the condenser (3). A V - shaped stainless - steel drainage trough is arranged at the bottom of the evaporator to connect a micro - drainage pump to drain the defrosting water. The temperature sensors (8 - 9) are installed at the air inlet and outlet to monitor the evaporator temperature in real time.

[0026] The heat absorbed by the solar collector panel is stored as thermal energy in the composite phase change material (16) inside the evaporator through the connecting pipeline (14). The heat pump refrigerant, driven by the compressor (1), absorbs the heat of outdoor air or solar - preheated air in the non - frosted evaporator, releases heat to the indoor through the condenser, and at the same time stores the waste heat in the phase change material (16).

[0027] As Figure 3 The phase change material (16) interlayer is supported by a honeycomb aluminum plate (17) and vacuum - infused and encapsulated in the annular area between the copper tube (15) and the fins. The circulating medium is ethylene glycol - aqueous solution, which releases heat to the frosting part directionally during the defrosting stage, and realizes efficient heat transfer and room - temperature stability by combining the switching of the four - way reversing valve (2).

[0028] The phase change material interlayer (16) is connected in a closed loop with the solar collector panel (6) through the connecting pipeline (14). The connecting pipeline is covered with a polyurethane thermal insulation layer, and a fluororubber sealing ring is used at the interface to prevent leakage.

[0029] The surface of the solar collector panel (6) is coated with a black chromium selective absorption coating. The internal copper - aluminum composite plate is heated by sunlight. After the antifreeze flows through the collector panel to absorb heat, it is transported to the phase change material (16) interlayer of the evaporator through the connecting pipeline (14) for storage; a circulation pump (7) is arranged in the pipeline to realize efficient dynamic coupling between solar energy heat and the phase change material (16).

[0030] For the parallel evaporator segmented defrosting system with solar energy - phase change heat storage synergy, solenoid valves (10 - 13) are installed at the refrigerant inlets and outlets of evaporators A / B and are independently switched by the controller.

[0031] The working modes of a parallel evaporator segmented defrosting system with solar energy - phase change heat storage synergy can be divided into the following three types, and the operating logic and component states of each mode are as follows:

[0032] Mode 1 (normal heating mode): In the normal heating mode, when heating is required indoors and the evaporator is not frosted, the system starts the heating cycle. The four - way reversing valve (2) is in the heating position. Evaporator groups A / B operate as evaporators simultaneously, absorbing heat from the air to supply heat to the room. The phase - change material (16) sandwich embedded in its finned tubes is in a heat - storage standby state. At this time, the solar collector panel (6) transports the collected heat to the phase - change material (16) sandwich of the evaporator through the connecting pipeline (14) and stores it efficiently in the form of latent heat to reserve energy for subsequent defrosting. The solar circulation loop adjusts dynamically according to the light conditions - the circulation pump (7) is turned on during the day to maximize heat storage and turned off at night to reduce energy consumption. The compressor operates to maintain the refrigerant circulation pressure and drive the heating process to proceed stably. Through the synergy of solar heat storage and heat pump heating, while meeting the heating demand, the system accumulates energy for potential defrosting conditions, achieving efficient energy utilization and fast response capabilities.

[0033] Mode 2 (single - evaporator segmented defrosting mode): When a certain evaporator (such as A) is frosted while the other evaporator B (5) still has heating capacity, the system switches to the single - evaporator segmented defrosting mode. At this time, the four - way reversing valve (2) switches to the defrosting position, and the refrigerant flow direction is reversed, causing evaporator A (4) to operate as a condenser. The high - temperature refrigerant flows into its pipeline to release condensation heat. At the same time, the phase - change material (16) sandwich embedded in evaporator A (4) transports the stored solar heat to the fin surface through the circulation loop, forming a dual - heat - source synergy of reverse - cycle condensation heat + latent heat of the phase - change material to accelerate the melting of the frost layer. Evaporator B (5) maintains its original heating state, and the refrigerant pipeline circulates normally, independently undertaking the indoor heating demand to reduce temperature fluctuations. The solenoid valve (10) synchronously closes the refrigerant inlet of evaporator A and opens its phase - change material (16) circulation loop to ensure that the defrosting energy is concentratedly supplied, while the pipeline solenoid valve (11) of evaporator B (5) remains fully open. The compressor (1) continues to operate and dynamically adjusts the output power according to the single - evaporator load to balance the system pressure and energy efficiency. This mode, through zone control and energy synergy, maintains heating continuity while quickly defrosting, significantly reducing the energy waste and room - temperature fluctuations caused by traditional reverse - cycle defrosting.

[0034] Mode III (segmented defrosting pure phase change heat storage mode): When solar energy is unavailable at night or on cloudy days and the evaporator (such as B) is frosted, the system ensures continuous indoor heating by closing the refrigerant passage of the frosted evaporator B (5) and maintaining the continuous heating of evaporator A (4). At this time, the heat stored in the phase change material (16) becomes the sole heat source, and the high-density latent heat stored in the phase change material (16) is directionally transported to the fin surface of evaporator B (5), and the latent heat released by the solid-liquid phase change is used to quickly melt the frost layer. This mode fully relies on the energy storage of the phase change material (16), without the need to switch the four-way valve (2) or start the reverse cycle, avoiding the energy consumption loss and temperature fluctuation caused by traditional defrosting. Thanks to the efficient heat storage and release characteristics of the phase change material (16), the frost layer can be completely removed in a short time, and then evaporator B (5) immediately restarts and resumes parallel operation, significantly shortening the downtime and ensuring the stability and energy efficiency of the system under solar energy-free conditions, especially suitable for rapid defrosting scenarios under continuous heating requirements in cold regions.

[0035] This invention patent provides a parallel evaporator segmented defrosting system and method that synergizes solar energy and phase change heat storage, designed specifically for the problem of low-temperature operation of heat pumps in severe cold regions. The system efficiently collects heat energy through a solar collector panel, and uses the ethylene glycol-water solution cycle to store the heat in the high-thermal conductivity composite phase change material (16) inside the evaporator fin tube, abandoning the reverse cycle power consumption mode. It provides an efficient, stable, and green integrated solution for heating and defrosting in alpine regions.

[0036] The above-described embodiments are only descriptions of the preferred embodiments of the present invention, and do not limit the scope of the present invention. Without departing from the design spirit of the present invention, various deformations and improvements made by those of ordinary skill in the art to the technical solutions of the present invention shall fall within the protection scope determined by the claims of the present invention.

Claims

1. A solar energy-phase change thermal storage synergistic parallel evaporator segmented defrosting system, characterized by: The system comprises a compressor (1), a four-way reversing valve (2), a condenser (3), an evaporator A (4) and an evaporator B (5) arranged in parallel, a solar heat collecting plate (6), a circulation pump (7), temperature sensors (8-9), solenoid valves (10-13) and a connecting pipeline (14).

2. A solar energy-phase change thermal storage synergistic parallel evaporator segmented defrosting system according to claim 1, characterized in that: A layer of phase change material (16) is provided inside the finned tubes of the evaporator A (4) and the evaporator B (5), and the phase change material (16) is filled in the annular interlayer area between the copper tube (15) and the fin, supported by a honeycomb aluminum plate (17), and connected to a circulation pump (7) and a solar thermal collector (6) through a connecting pipeline (14), thereby realizing efficient storage and directional release of solar heat.

3. The solar energy-phase change thermal storage coordinated parallel evaporator segmented defrosting system according to claim 1, characterized in that: The evaporator A (4) and the evaporator B (5) are connected in parallel to the refrigerant circuit, and a layer of phase change material (16) is embedded in the fins of each group of evaporators; the evaporator group is connected in parallel to the refrigerant circuit through a copper tube (15), and forms a closed-loop system with the compressor (1) and the condenser (3) through a four-way reversing valve (2).

4. The solar energy-phase change thermal storage coordinated parallel evaporator segmented defrosting system according to claim 1, characterized in that: The phase change material (16) is connected to the solar heat collecting plate (6) via a connecting pipe (14), and is wrapped around the outer wall of the copper tube (15). A paraffin / expanded graphite-nano-alumina composite material is used to store solar heat through a photothermal cycle, and is used to release heat in a directional manner for defrosting.

5. The solar energy-phase change thermal storage coordinated parallel evaporator segmented defrosting system according to claim 3, characterized in that: The solar energy connection pipeline (14) is coated with a polyurethane foam insulation layer, a copper-aluminum composite pipe is used as a heat transfer channel, the circulating medium is ethylene glycol-water solution, and a fluororubber sealing ring is used at the flange interface to prevent leakage; the flow rate is controlled by a circulating pump (7).

6. A solar energy-phase change thermal storage synergistic parallel evaporator segmented defrosting system according to claims 2 and 3, characterized in that: The phase change temperature range of the phase change material (16) is 28-50°C.

7. The solar energy-phase change thermal storage coordinated parallel evaporator segmented defrosting system according to claim 1, characterized in that: A V-shaped stainless steel condensate water guide groove is provided at the bottom of the evaporator, which is connected to a drain pipe and a micro centrifugal pump.

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