Air source heat pump heat supply method and system based on phase change material

Abstract

The invention provides an air source heat pump heat supply method and system based on a phase change material. The air source heat pump heat supply method comprises the following steps that the environment temperature, the user heat supply demand quantity and the air source heat pump heat supply quantity are obtained; when the environment temperature is larger than or equal to the preset threshold value, excess heat on the surface of the evaporator is transferred to the PCM cold storage unit for heat storage; when the environment temperature is smaller than a preset threshold value, an evaporator in the air source heat pump is heated through the PCM cold storage unit so as to prevent the surface of the evaporator from frosting; the difference value between the heat supply quantity of the air source heat pump and the heat supply demand quantity of the user is calculated, and when the difference value is larger than or equal to a preset heat threshold value, redundant heat of a condenser in the air source heat pump is transmitted to a PCM heat storage unit to be stored; compared with a traditional heat pump system, the heat storage density is greatly improved through the phase change latent heat characteristic of the phase change material, and meanwhile the influence of temperature fluctuation on the heat supply quality is reduced.

Description

Technical Field

[0001] The present invention relates to the field of heating technology, and in particular to an air source heat pump heating method and system based on phase change materials. Background Art

[0002] Air source heat pump heating systems are widely used in building heating, industrial heating and other fields due to their advantages such as energy saving and environmental protection. Traditional air source heat pump systems are mainly composed of components such as compressors, condensers, evaporators, and expansion valves, and transfer heat from the air to the room through the refrigerant circulation. However, when operating in a low temperature environment (such as below -10°C), the system faces a serious frosting problem: the surface temperature of the evaporator is below the freezing point, and the water vapor in the air condenses into frost on its surface, resulting in obstructed air circulation, reduced heat exchange efficiency, and even system failure. Therefore, traditional air source heat pump systems have the following defects: Frost formation leads to reduced efficiency: The frost layer has a high thermal resistance, which reduces the heat exchange efficiency between the evaporator and the air, significantly reducing the heat pump's coefficient of performance (COP). According to statistics, at -15°C, the COP of a heat pump system without defrosting measures can drop by more than 30%.

[0003] Frequent defrosting impacts stability: Traditional defrosting methods (such as reverse cycle defrosting and electric heating) consume a lot of energy, and the system stops supplying heat during the defrost process, causing indoor temperature fluctuations. Reverse cycle defrosting requires switching the refrigerant flow direction, which suddenly increases the compressor load and shortens the equipment lifespan. Electric heating defrost directly increases power consumption, offsetting the energy-saving advantages of heat pumps.

[0004] Poor adaptability to low-temperature environments: The existing system is difficult to operate stably in environments below -20°C and requires auxiliary electric heating devices, further increasing energy consumption and costs. Summary of the Invention

[0005] The object of the present invention is to provide an air source heat pump heating method and system based on phase change materials, which solves the above-mentioned defrosting shortcomings of existing air source heat pumps.

[0006] In order to achieve the above object, the technical solution adopted in the present invention is: In a first aspect, the present invention provides an air source heat pump heating method based on phase change material, comprising the following steps: Obtain ambient temperature, user heating demand, and air source heat pump heating capacity; When the ambient temperature is greater than or equal to the preset threshold, the excess heat on the evaporator surface is transferred to the PCM cold storage unit for heat storage; When the ambient temperature is lower than the preset threshold, the PCM cold storage unit is used to heat the evaporator in the air source heat pump to prevent frost on the evaporator surface; The difference between the heat supply of the air source heat pump and the user's heating demand is calculated. When the difference is greater than or equal to the preset heat threshold, the excess heat of the condenser in the air source heat pump is transferred to the control PCM heat storage unit for storage.

[0007] Preferably, when the PCM cold storage unit is used to heat the evaporator in the air source heat pump, the temperature of the PCM cold storage unit is first obtained, wherein: If the temperature is lower than the preset value, the heat of the PCM thermal storage unit is transferred to the PCM cold storage unit until it reaches the preset value, and the PCM cold storage unit is used to heat the evaporator in the air source heat pump.

[0008] Preferably, before transferring excess heat from the condenser of the air source heat pump to the PCM thermal storage unit for storage, the temperature of the PCM thermal storage unit is first obtained. When the temperature is lower than a preset temperature, the PCM thermal storage unit is preheated to the preset temperature.

[0009] In a second aspect, the present invention provides an air source heat pump heating system based on phase change materials, comprising an intelligent defrost device, a PCM cold storage unit, and a PCM heat storage unit, wherein the PCM heat storage unit is connected to the condenser of the air source heat pump to cool the condenser; the PCM cold storage unit is installed on the evaporator of the air source heat pump to heat the evaporator; The intelligent defrosting device is used to control the PCM cold storage unit and the PCM heat storage unit to defrost and store heat for the air source heat pump.

[0010] Preferably, the PCM heat storage unit is also connected to a PCM cold storage unit to supplement the heat source to the PCM cold storage unit.

[0011] Preferably, the PCM cold storage unit includes a first shell, in which a honeycomb porous structure is provided, and each hole is filled with HT-PCM; heat transfer medium flow channels are provided on the symmetrical side walls of the first shell and on the bottom of the shell, and the three heat transfer medium flow channels are connected in sequence to form a first U-shaped flow channel; the inlet and outlet of the first U-shaped flow channel are connected to the PCM heat storage unit.

[0012] Preferably, the PCM thermal storage unit includes a second shell, wherein a honeycomb porous structure is provided in the second shell, and each hole is filled with LT-PCM; heat transfer medium flow channels are provided on both symmetrical side walls and the bottom of the second shell, and the three heat transfer medium flow channels are connected in sequence to form a second U-shaped flow channel; the inlet and outlet of the second U-shaped flow channel are connected to the PCM cold storage unit; A third U-shaped flow channel is further provided in the second shell, and the third U-shaped flow channel is arranged in parallel with the second U-shaped flow channel; The third U-shaped flow channel is communicated with the circulating medium flow channel provided on the condenser in the air source heat pump.

[0013] Preferably, a plurality of serrated fins are arranged on the outer surface of the U-shaped flow channel along its circumference, and each serrated fin is arranged along the axial direction of the U-shaped flow channel.

[0014] Preferably, the PCM thermal storage unit is further connected to an external electric auxiliary heating device.

[0015] Preferably, the intelligent defrosting device includes a plurality of temperature sensors and a controller, wherein: The plurality of temperature sensors are used to collect the ambient temperature, the PCM heat storage unit temperature, and the PCM cold storage unit temperature respectively; The controller is used to control the PCM cold storage unit and the PCM thermal storage unit to defrost and store heat for the air source heat pump according to the ambient temperature, the temperature of the PCM thermal storage unit, and the temperature of the PCM cold storage unit.

[0016] Compared with the prior art, the present invention has the following beneficial effects: The present invention provides an air source heat pump heating method based on phase change materials, which dynamically controls the working mode of the PCM cold storage unit by the ambient temperature, effectively solving the problem of frosting of the evaporator of the traditional air source heat pump in a low temperature environment. When the ambient temperature is lower than the preset threshold, the PCM cold storage unit actively releases the stored heat to heat the evaporator, which not only avoids the interruption of heating caused by the defrosting process, but also reduces the additional energy consumption caused by conventional electric auxiliary heating. At the same time, the system adopts dual PCM modules to collaboratively manage energy, and realizes the cascade utilization of heat by calculating the difference in heating demand in real time. When the heating amount exceeds the user's demand, the excess heat is stored in the PCM heat storage unit and released during the peak heating period or extreme weather conditions, so that the heating stability of the system is improved, while reducing the start and stop frequency of the compressor and extending the service life of the equipment.

[0017] Furthermore, the use of a honeycomb porous structure filled with paraffin wax-expanded graphite (HT-PCM) and decanoic acid-graphene (LT-PCM) composite phase change materials significantly increases the heat transfer area and improves the material's thermal conductivity, increasing the phase change rate of the heat storage / cold unit by over 30%. The combined design of the U-shaped flow channel and serrated fins enhances the convection-conduction synergistic heat exchange between the heat transfer medium and the PCM. Through the intelligent control of the first and second electric valves, the system can achieve three operating modes: heat replenishment from the heat storage unit to the cold storage unit, condenser waste heat recovery mode, and combined defrost mode. In particular, the direct connection between the third U-shaped flow channel and the condenser enables the system to recover high-temperature refrigerant waste heat in real time for defrosting or heat storage, solving the problem of indoor heat supply interruption during conventional heat pump defrosting.

[0018] The present invention provides an air-source heat pump heating system based on phase change materials. Through the synergistic effect of a composite energy storage module and an intelligent defrost device, it significantly improves the operating efficiency and reliability of traditional heat pumps in low-temperature environments. The core innovation of the system lies in the construction of a two-way energy circulation system: the PCM heat storage unit absorbs the waste heat of the condenser to achieve phase change heat storage, which not only reduces the condensation temperature to improve the COP (energy efficiency ratio) of the heat pump, but also reserves a stable heat source for subsequent defrosting; at the same time, the PCM cold storage unit forms a controllable thermal barrier on the evaporator surface, slowing the frosting rate through phase change heat release, and can quickly melt the frost layer when the intelligent defrost device is triggered. The heat source replenishment channel between the two units forms an energy dynamic allocation mechanism, allowing the cold storage unit to quickly recover its activity through the heat storage unit after continuous heat release, solving the response speed bottleneck caused by the thermal hysteresis of a single PCM material. The intelligent defrost device accurately schedules the phase change energy release timing of the two modules based on real-time frost layer monitoring data. This solution, which deeply integrates phase change energy storage technology with active defrost strategy, not only breaks through the technical bottleneck of poor low-temperature adaptability of air source heat pumps, but its modular design also provides a scalable solution for the carbon-neutral transformation of building heating systems.

[0019] In summary, this method couples the PCM cold storage unit with the evaporator heat exchange process. The cold energy stored in the high-temperature period can be converted into a heat source in the low-temperature period, realizing the spatiotemporal transfer of energy. Compared with the traditional heat pump system, this technology greatly improves the heat storage density through the phase change latent heat characteristics of the phase change material, while reducing the impact of temperature fluctuations on the heating quality. DETAILED DESCRIPTION

[0020] In the following description, specific details such as specific system structures and techniques are provided for purposes of illustration rather than limitation to facilitate a thorough understanding of the embodiments of the present application. However, it will be apparent to those skilled in the art that the present application may be implemented in other embodiments without these specific details. In other cases, detailed descriptions of well-known systems, devices, circuits, and methods are omitted to avoid obscuring the description of the present application with unnecessary detail.

[0021] It should be understood that when used in the present specification and the appended claims, the term "comprising" indicates the presence of described features, integers, steps, operations, elements and / or components, but does not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components and / or collections thereof.

[0022] It will also be understood that the term "and / or" used in this specification and the appended claims refers to and includes any and all possible combinations of one or more of the associated listed items.

[0023] As used in this specification and the appended claims, the term "if" can be interpreted as "when" or "upon" or "in response to determining" or "in response to detecting," depending on the context. Similarly, the phrase "if it is determined" or "if [described condition or event] is detected" can be interpreted as meaning "upon determination" or "in response to determining" or "upon detection of [described condition or event]" or "in response to detecting [described condition or event]," depending on the context.

[0024] In addition, in the description of the present application specification and the appended claims, the terms "first", "second", "third", etc. are only used to distinguish the descriptions and cannot be understood as indicating or implying relative importance.

[0025] References to "one embodiment" or "some embodiments" in this specification mean that a particular feature, structure, or characteristic described in conjunction with that embodiment is included in one or more embodiments of the present application. Thus, phrases such as "in one embodiment," "in some embodiments," "in other embodiments," and "in other embodiments" appearing in various places in this specification do not necessarily refer to the same embodiment, but rather mean "one or more but not all embodiments," unless otherwise specifically emphasized. The terms "including," "comprising," "having," and variations thereof all mean "including but not limited to," unless otherwise specifically emphasized.

[0026] Example 1 This embodiment provides an air source heat pump heating method based on phase change material, comprising the following steps: Obtain ambient temperature, user heating demand, and air source heat pump heating capacity; When the ambient temperature is greater than or equal to 0°C, the excess heat on the evaporator surface is transferred to the PCM cold storage unit for heat storage; When the ambient temperature is below 0°C, the PCM cold storage unit is used to heat the evaporator in the air source heat pump to prevent frost on the evaporator surface.

[0027] The difference between the heat supply of the air source heat pump and the user's heating demand is calculated. When the difference is greater than or equal to the preset heat threshold, the excess heat of the condenser in the air source heat pump is transferred to the control PCM heat storage unit for storage.

[0028] In this embodiment, the operating mode of the PCM cold storage unit is dynamically controlled by the ambient temperature, effectively solving the problem of evaporator frosting in traditional air-source heat pumps in low-temperature environments. When the ambient temperature falls below a preset threshold, the PCM cold storage unit actively releases stored heat to heat the evaporator, not only avoiding heating interruptions caused by the defrosting process but also reducing the additional energy consumption associated with conventional electric auxiliary heating. Simultaneously, this method couples the PCM cold storage unit with the evaporator heat exchange process, converting the cold stored during high-temperature periods into a heat source during low-temperature periods, achieving spatiotemporal energy transfer. Compared to traditional heat pump systems, this technology significantly improves heat storage density through the latent heat properties of phase change materials, while also reducing the impact of temperature fluctuations on heating quality.

[0029] Example 2 Based on Example 1, this embodiment provides a phase change material-based air source heat pump heating method. When the PCM cold storage unit is used to heat the evaporator in the air source heat pump, the temperature of the PCM cold storage unit is first obtained, wherein: If the temperature is lower than the preset value, the heat of the PCM thermal storage unit is transferred to the PCM cold storage unit until it reaches the preset value, and the PCM cold storage unit is used to heat the evaporator in the air source heat pump.

[0030] Example 3 Based on Example 1, this embodiment provides an air source heat pump heating method based on phase change material. Before transferring excess heat from the condenser of the air source heat pump to the PCM thermal storage unit for storage, the temperature of the PCM thermal storage unit is first obtained. When the temperature is lower than a preset temperature, the PCM thermal storage unit is preheated to the preset temperature.

[0031] Example 4 This embodiment provides an air source heat pump heating system based on phase change materials, including a composite PCM cold / heat storage module and an intelligent defrost device, wherein: The composite PCM cold / heat storage module includes a PCM cold storage unit and a PCM heat storage unit, wherein the PCM heat storage unit is connected to the condenser of the air source heat pump to cool the condenser; the PCM cold storage unit is installed on the evaporator of the air source heat pump to heat the evaporator; The intelligent defrosting device is used to control the PCM cold storage unit and the PCM heat storage unit to defrost and store heat for the air source heat pump.

[0032] The PCM heat storage unit is also connected to the PCM cold storage unit to supplement the heat source to the PCM cold storage unit.

[0033] In this embodiment, the synergistic effect of a composite energy storage module and an intelligent defrost device significantly improves the operating efficiency and reliability of a traditional heat pump in low-temperature environments. The system's core innovation lies in the construction of a bidirectional energy circulation system: the PCM thermal storage unit absorbs waste heat from the condenser to achieve phase change heat storage, which not only lowers the condensing temperature to improve the heat pump's COP (energy efficiency ratio) but also reserves a stable heat source for subsequent defrosting. Simultaneously, the PCM cold storage unit forms a controllable thermal barrier on the evaporator surface, releasing heat through phase change to slow frost formation and rapidly melting the frost layer when the intelligent defrost device is triggered. The heat source replenishment channel between the two units creates a dynamic energy allocation mechanism, allowing the cold storage unit to quickly recover through the thermal storage unit after continuous heat release, thus resolving the response speed bottleneck caused by the thermal hysteresis of a single PCM material. The intelligent defrost device accurately schedules the phase change energy release timing of the two modules based on real-time frost layer monitoring data. This solution, which deeply integrates phase change energy storage technology with active defrost strategy, not only breaks through the technical bottleneck of poor low-temperature adaptability of air source heat pumps, but its modular design also provides a scalable solution for the carbon-neutral transformation of building heating systems.

[0034] Example 5 Based on Example 4, this embodiment provides an air source heat pump heating system based on phase change material, wherein the PCM heat storage unit includes a first shell, wherein a honeycomb porous structure is provided in the first shell, and each hole is filled with HT-PCM; heat transfer medium flow channels are provided on the symmetrical side walls of the first shell and on the bottom of the shell, and the three heat transfer medium flow channels are connected in sequence to form a first U-shaped flow channel; the inlet and outlet of the first U-shaped flow channel are connected to the PCM cold storage unit.

[0035] The HT-PCM is a paraffin-expanded graphite composite phase change material.

[0036] The PCM cold storage unit includes a second shell, which is provided with a honeycomb porous structure, and each hole is filled with LT-PCM; heat transfer medium flow channels are provided on the symmetrical side walls of the second shell and the bottom of the shell, and the three heat transfer medium flow channels are connected in sequence to form a second U-shaped flow channel; the inlet and outlet of the second U-shaped flow channel are connected to the PCM thermal storage unit.

[0037] The LT-PCM is a decanoic acid-graphene composite phase change material.

[0038] A third U-shaped flow channel is further provided in the second shell, and the third U-shaped flow channel is arranged in parallel with the second U-shaped flow channel.

[0039] The third U-shaped flow channel is communicated with the circulating medium flow channel provided on the condenser in the air source heat pump.

[0040] A plurality of serrated fins are arranged along the circumference of the outer surface of the U-shaped flow channel, and each serrated fin is arranged along the axial direction of the U-shaped flow channel.

[0041] A first electric valve is provided on the connecting pipe between the first U-shaped flow channel and the second U-shaped flow channel.

[0042] A second electric valve is provided on the connecting pipe between the third U-shaped flow channel and the circulating medium flow channel.

[0043] In this embodiment, a honeycomb porous structure filled with paraffin wax-expanded graphite (HT-PCM) and decanoic acid-graphene (LT-PCM) composite phase change materials significantly increases the heat transfer area and improves the material's thermal conductivity, increasing the phase change rate of the heat storage / cooling unit by over 30%. The combined design of the U-shaped flow channel and serrated fins enhances the synergistic convection-conduction heat exchange between the heat transfer medium and the PCM. Through the intelligent control of the first and second electric valves, the system can achieve three operating modes: heat replenishment from the heat storage unit to the cold storage unit, condenser waste heat recovery, and combined defrost mode. In particular, the direct connection between the third U-shaped flow channel and the condenser enables the system to recover high-temperature refrigerant waste heat in real time for defrosting or heat storage, resolving the problem of indoor heat supply interruption during conventional heat pump defrosting.

[0044] Example 6 On the basis of Example 4, this embodiment provides an air source heat pump heating system based on phase change material, wherein the PCM cold storage unit is embedded in the fin gap of the evaporator.

[0045] Example 7 On the basis of Example 4, this embodiment provides an air source heat pump heating system based on phase change material, wherein the second U-shaped flow channel is further connected to an external electric auxiliary heating device.

[0046] Example 8 Based on Example 4, this embodiment provides an air source heat pump heating system based on phase change materials, wherein the intelligent defrosting device includes a temperature sensor and a controller, wherein: The temperature sensors are provided in plurality, and are used to collect the ambient temperature, the temperature of the PCM heat storage unit, and the temperature of the PCM cold storage unit respectively; The output end of the controller is connected to a first electric valve and a second electric valve, which are used to control the PCM cold storage unit and the PCM thermal storage unit to defrost and store heat for the air source heat pump according to the ambient temperature, the PCM thermal storage unit temperature, and the PCM cold storage unit temperature.

[0047] Example 9 Based on Example 4, this embodiment provides an air source heat pump heating system based on phase change materials. The working process of the air source heat pump is as follows: The compressor compresses the refrigerant (R410A) into a high-temperature, high-pressure gas (75°C, 1.8 MPa). This gas then enters the condenser, releasing heat to the terminal heat exchanger, heating the circulating water (supply temperature 50°C, return temperature 45°C), which is then supplied to the fan coil unit. The refrigerant condenses into a liquid, which is then reduced in pressure to 0.6 MPa and temperature to 10°C by the expansion valve before entering the evaporator. The evaporator absorbs heat from the air, evaporating the refrigerant into a gas (temperature 5°C, pressure 0.6 MPa).

[0048] The above-described embodiments are only used to illustrate the technical solutions of the present application, rather than to limit them. Although the present application has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. These modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the various embodiments of the present application, and should all be included in the scope of protection of the present application.

Claims

1. An air source heat pump heating method based on phase change material, characterized in that: The following steps are involved: Obtain ambient temperature, user heating demand, and air source heat pump heating capacity; When the ambient temperature is greater than or equal to the preset threshold, the excess heat on the evaporator surface is transferred to the PCM cold storage unit for heat storage; When the ambient temperature is lower than the preset threshold, the PCM cold storage unit is used to heat the evaporator in the air source heat pump to prevent frost on the evaporator surface; The difference between the heat supply of the air source heat pump and the user's heating demand is calculated. When the difference is greater than or equal to the preset heat threshold, the excess heat of the condenser in the air source heat pump is transferred to the control PCM heat storage unit for storage.

2. The air source heat pump heating method based on phase change material according to claim 1, characterized in that: When using the PCM cold storage unit to heat the evaporator in the air source heat pump, first obtain the temperature of the PCM cold storage unit, where: If the temperature is lower than the preset value, the heat of the PCM thermal storage unit is transferred to the PCM cold storage unit until it reaches the preset value, and the PCM cold storage unit is used to heat the evaporator in the air source heat pump.

3. The air source heat pump heating method based on phase change material according to claim 1, characterized in that: Before transferring the excess heat of the condenser in the air source heat pump to the PCM thermal storage unit for storage, the temperature of the PCM thermal storage unit is first obtained. When the temperature is lower than the preset temperature, the PCM thermal storage unit is preheated to the preset temperature.

4. An air source heat pump heating system based on phase change material, characterized in that: It includes an intelligent defrost device, a PCM cold storage unit and a PCM heat storage unit, wherein the PCM heat storage unit is connected to the condenser of the air source heat pump to cool the condenser; the PCM cold storage unit is installed on the evaporator of the air source heat pump to heat the evaporator; The intelligent defrosting device is used to control the PCM cold storage unit and the PCM heat storage unit to defrost and store heat for the air source heat pump.

5. The air source heat pump heating system based on phase change material according to claim 4, characterized in that: The PCM heat storage unit is also connected to the PCM cold storage unit to supplement the heat source to the PCM cold storage unit.

6. The air source heat pump heating system based on phase change material according to claim 5, characterized in that: The PCM cold storage unit includes a first shell, which is provided with a honeycomb porous structure, and each hole is filled with HT-PCM; heat transfer medium flow channels are provided on the symmetrical side walls of the first shell and the bottom of the shell, and the three heat transfer medium flow channels are connected in sequence to form a first U-shaped flow channel; the inlet and outlet of the first U-shaped flow channel are connected to the PCM thermal storage unit.

7. The air source heat pump heating system based on phase change material according to claim 5, characterized in that: The PCM thermal storage unit includes a second shell having a honeycomb-shaped porous structure, each pore of which is filled with LT-PCM; heat transfer medium flow channels are provided on both symmetrical side walls of the second shell and on the bottom of the shell, and the three heat transfer medium flow channels are connected in sequence to form a second U-shaped flow channel; the inlet and outlet of the second U-shaped flow channel are connected to the PCM cold storage unit; A third U-shaped flow channel is further provided in the second shell, and the third U-shaped flow channel is arranged in parallel with the second U-shaped flow channel; The third U-shaped flow channel is communicated with the circulating medium flow channel provided on the condenser in the air source heat pump.

8. An air source heat pump heating system based on phase change material according to claim 6 or 7, characterized in that: A plurality of serrated fins are arranged along the circumference of the outer surface of the U-shaped flow channel, and each serrated fin is arranged along the axial direction of the U-shaped flow channel.

9. The air source heat pump heating system based on phase change material according to claim 7, characterized in that: The PCM heat storage unit is also connected to an external electric auxiliary heating device.

10. The air source heat pump heating system based on phase change material according to claim 1, characterized in that: The intelligent defrosting device includes a plurality of temperature sensors and a controller, wherein: The plurality of temperature sensors are used to collect the ambient temperature, the PCM heat storage unit temperature, and the PCM cold storage unit temperature respectively; The controller is used to control the PCM cold storage unit and the PCM thermal storage unit to defrost and store heat for the air source heat pump according to the ambient temperature, the temperature of the PCM thermal storage unit, and the temperature of the PCM cold storage unit.