Cabinet type heating air conditioner with phase change heat storage function

Abstract

The invention discloses a phase change heat storage cabinet type heating air conditioner, which belongs to indoor heating equipment and comprises an outer shell, an electric heater is mounted in the outer shell, and the electric heater is in contact with a heat exchanger; a plurality of PCM heat storage units are further installed in the outer shell, the PCM heat storage units make contact with a circulating heat exchange pipeline, a circulating pump is installed on the circulating heat exchange pipeline, and the circulating heat exchange pipeline passes through a heat exchanger; the heat exchanger is arranged in an air duct, a fan is installed in the air duct, and the air duct communicates with an air outlet and an air inlet in the outer shell; the PCM heat storage unit packaged by the self-developed phase change material has higher heat storage density and better heat conductivity, so that the electric heater can be used for storing heat at night valley electricity time, and the phase change material is used for phase change heat release and heat supply at daytime peak time, and thus the effectiveness of energy utilization is improved.

Description

Technical Field

[0001] This invention relates to an indoor heating device, and more specifically, to a cabinet-type heating and air conditioning unit with phase change heat storage. Background Technology

[0002] With the continued growth of global energy demand and the fluctuation of power system load, energy efficiency in building heating has become a core issue for energy conservation and emission reduction. Off-peak electricity hours (typically nighttime or periods of low electricity demand) offer cost-effective opportunities for energy storage and load shaving due to lower electricity prices. Phase change materials (PCMs), capable of absorbing or releasing large amounts of latent heat during phase change, possess high heat storage density, isothermal heat release, and long-term thermal stability, making them suitable for applications in building heating, industrial waste heat recovery, and battery thermal management. However, traditional PCMs, often existing as liquids or loose particles, are prone to leakage or phase instability, have unstable thermal conductivity, and are difficult to integrate and encapsulate, making them unsuitable for use in fixed, mobile devices. Therefore, further research and improvement are necessary for indoor heating equipment and the application and encapsulation of the aforementioned PCMs. Summary of the Invention

[0003] One of the objectives of this invention is to address the aforementioned shortcomings by providing a cabinet-type heating and air conditioning unit with phase change heat storage, in order to solve the technical problems in the prior art, such as the large load on the power grid caused by indoor heating, the unstable thermal conductivity and heat storage of phase change materials, and the difficulty in packaging.

[0004] To solve the above-mentioned technical problems, the present invention adopts the following technical solution: This invention provides a cabinet-type heating and air conditioning unit with phase change heat storage, comprising an outer casing, within which an electric heater is installed and in contact with a heat exchanger; multiple PCM heat storage units are also installed within the outer casing, each PCM heat storage unit being in contact with a circulating heat exchange pipeline, on which a circulating pump is installed, and the circulating heat exchange pipeline passes through the heat exchanger; the heat exchanger is placed in an air duct, within which a fan is installed, and the air duct is connected to an air outlet and an air inlet on the outer casing; each PCM heat storage unit includes a metal shell, the metal shell being filled with a phase change material. The phase change material comprises, by mass percentage, 55%-65% lauric acid, 8%-12% expanded graphite, 22%-28% high-density polyethylene, and 4%-6% nano-alumina; the electric heater is used to heat the heat exchanger, and the heat exchange medium is driven by the circulating pump to flow in the circulating heat exchange pipeline, passing through the heat exchanger and multiple PCM heat storage units in sequence, causing the PCM heat storage units to absorb heat and liquefy; the circulating pump is also used to drive the heat exchange medium to flow in the circulating heat exchange pipeline, passing through the PCM heat storage units and the heat exchanger in sequence, causing the PCM heat storage units to solidify and release heat to the heat exchanger, and then the airflow generated by the fan comes into contact with the heat exchanger and is discharged.

[0005] As a preferred embodiment, a further technical solution is that the phase change material is prepared by the following method: Step A: Raw material pretreatment. Weigh a certain amount of lauric acid, expanded graphite, high-density polyethylene and nano-alumina as described in claim 1. Then melt the lauric acid in a water bath at a temperature above 65°C, preheat the high-density polyethylene at a temperature above 130°C, dry the expanded graphite in an environment at 180-200°C, and disperse the nano-alumina by ultrasonication for later use.

[0006] Step B: Add the pretreated lauric acid and high-density polyethylene into the mixing tank and stir thoroughly until uniform. Then add expanded graphite in batches and continue stirring at an increased speed until all the expanded graphite is mixed with it. Finally, add nano alumina and continue stirring to ensure that each component is uniformly dispersed to obtain the intermediate mixture. Step C: Transfer the intermediate mixture to a vacuum drying oven and dry it under vacuum to obtain the final mixture; inject the final mixture into a preheated mold, hot press it, cool it to room temperature, and demold it to obtain the phase change material.

[0007] Step D: Seal the phase change material with aluminum foil to obtain the PCM heat storage unit.

[0008] A further technical solution is that the PCM heat storage unit is in the shape of a flat rectangle.

[0009] A further technical solution is as follows: the electric heater and the heat exchanger are both installed at the lower part of the outer shell, the air outlet and the air inlet are both located on the side of the outer shell, the fan is installed in the air duct formed between the air outlet and the air inlet, and there are multiple air outlets, all of which are connected to the air duct.

[0010] A further technical solution is: the outer casing is also provided with a horizontal mounting frame, the PCM heat storage units are placed in an array on the mounting frame, the circulating heat exchange pipes are in contact with each PCM heat storage unit on the mounting frame, and the PCM heat storage units are all placed on the upper part of the electric heater.

[0011] A further technical solution is that the electric heater, fan, and circulating pump are all connected to a control module. The control module is used to control the start of the electric heater and fan during a preset time period, and to control the start / stop and output power of the circulating pump.

[0012] A further technical solution is that the electric heater is also in contact with a portion of the PCM heat storage unit, and there is a heat-conducting medium between the contact surfaces of the electric heater and the PCM heat storage unit.

[0013] A further technical solution is that a polyurethane foam insulation layer is provided on the inner wall of the outer shell.

[0014] Compared with existing technologies, one of the beneficial effects of this invention is that the PCM thermal storage unit encapsulated by the self-developed phase change material has a higher thermal storage density and better thermal conductivity. This allows for the use of electric heaters to store heat during off-peak hours at night and to release heat through phase change during peak hours in the daytime, thereby improving the efficiency of energy utilization. In addition, the self-developed phase change material of this invention has undergone multiple cycle tests and has a low rate of latent heat and thermal conductivity decay, making it more suitable for integration into portable indoor heating equipment. Attached Figure Description

[0015] Figure 1 This is a schematic diagram illustrating a structural aspect of an embodiment of the present invention.

[0016] Figure 2 for Figure 1 A schematic diagram of the back structure.

[0017] Figure 3 This is a time-series diagram illustrating the cycle of heat storage and release in the PCM thermal storage unit in the embodiments of the present invention.

[0018] In the diagram, 1 is the outer casing, 2 is the electric heater, 3 is the heat exchanger, 4 is the PCM heat storage unit, 5 is the air outlet, 6 is the fan, and 7 is the mounting bracket. Detailed Implementation

[0019] The invention will now be further described with reference to the accompanying drawings.

[0020] refer to Figure 1 As shown, one embodiment of the present invention is a cabinet-type heating and air conditioning unit with phase change heat storage, which includes an outer shell 1. An electric heater 2 is installed inside the outer shell 1. The electric heater is a PTC ceramic resistance heater, and the heating surface of the electric heater 2 is in contact with a heat exchanger 3. The heat exchanger, as the core component of the heating and air conditioning unit, plays an important role in both heat storage and heating. It adopts an aluminum fin structure. More importantly, this embodiment uses phase change material, specifically by installing multiple PCM heat storage units 4 inside the outer shell 1, and making each PCM heat storage unit 4 in contact with a circulating heat exchange pipe. A circulating pump is installed on the circulating heat exchange pipe, and the circulating heat exchange pipe passes through the heat exchanger 3. The aforementioned heat exchanger 3 is placed in an air duct, and a fan 6 is installed in the air duct. The air duct is connected to the air outlet 5 and the air inlet on the outer shell 1, respectively. Preferably, the aforementioned air outlet 5 and air inlet are both located on the side of the outer shell 1, and the fan 6 is installed in the air duct formed between the air outlet 5 and the air inlet. The air outlet 5 is... Figure 1 Multiple units are shown, all of which are connected to the air duct. In the aforementioned structure, in one operating state, the aforementioned electric heater 2 heats the heat exchanger 3, and the heat exchange medium is driven by the circulating pump to flow in the circulating heat exchange pipeline, passing through the heat exchanger 3 and multiple PCM heat storage units 4 in sequence, causing the PCM heat storage units 4 to absorb heat and liquefy; and in another operating state, the circulating pump also drives the heat exchange medium to flow in the circulating heat exchange pipeline, passing through the PCM heat storage units 4 and the heat exchanger 3 in sequence, causing the PCM heat storage units 4 to solidify and release heat to the heat exchanger 3, and then the airflow generated by the fan 6 comes into contact with the heat exchanger 3 and is discharged.

[0021] For ease of installation, in this embodiment, both the electric heater 2 and the heat exchanger 3 are designed to be installed at the lower part of the outer casing 1. To further facilitate the installation of the core component, the PCM heat storage unit, a horizontally positioned mounting bracket 7 is provided inside the outer casing 1. These mounting brackets 7 are designed with a sealed layer, allowing the multiple PCM heat storage units 4 to be placed in an array on the mounting brackets 7. This facilitates the contact between the circulating heat exchange pipes and each PCM heat storage unit 4 on the mounting brackets 7, thereby enabling heat conduction. Furthermore, to facilitate heat conduction, all the PCM heat storage units 4 can be placed above the electric heater 2. Based on this approach, to accelerate heat conduction and heat storage in the PCM heat storage units 4, the electric heater 2 can be placed in contact with some of the lower-layered PCM heat storage units 4, and a thermally conductive medium, such as thermal grease, is placed between the contact surfaces of the electric heater 2 and the PCM heat storage units 4.

[0022] In this embodiment, to facilitate heat preservation, a polyurethane foam insulation layer can be provided on the inner side of the outer shell 1 to improve the heat storage speed of the device and the concentration of the heat source during the heat release process. On the other hand, to facilitate the control of the electric heater 2 to heat the phase change material in the PCM heat storage unit 4 during off-peak electricity hours, the electric heater 2, fan 6, and circulation pump can all be connected to the control module. The control module can control the electric heater 2 and fan 6 to start at preset time periods, and control the start / stop and output power of the circulation pump. This enables the use of phase change material to store heat during off-peak electricity hours at night and to release heat during peak electricity hours in the daytime to heat the room, thereby improving energy utilization and reducing the pressure on the power grid.

[0023] As mentioned above, the PCM heat storage unit 4 has a metal shell, which is filled with a phase change material, including 55%-65% lauric acid, 8%-12% expanded graphite, 22%-28% high-density polyethylene and 4%-6% nano-alumina by mass percentage; the PCM heat storage unit 4 is designed as a flat rectangular shape.

[0024] The self-developed polymer-based composite PCM is packaged into 10mm×10mm×2mm micro-modules. The preferred formulation consists of 60wt% lauric acid, 10wt% expanded graphite, 25wt% high-density polyethylene, and 5wt% nano-alumina, totaling 600 modules (approximately 12kg in total weight). These modules are fixed to the aluminum fins of a fan coil heat exchanger using a 6061 aluminum alloy mesh frame, employing a two-layer staggered layout (300 modules per layer, 4mm spacing). The total heat storage reaches 215.28MJ. The heat transfer coefficient reaches 55W / (m²·K). Each module is encapsulated with 0.05mm thick aluminum foil for moisture and corrosion protection, with a cycle life ≥5000 cycles.

[0025] As mentioned above, the main heat storage component of the self-developed phase change material of this invention is lauric acid (C12H24O2, melting point 24-26℃, latent heat 190kJ / kg) accounting for 60wt%, providing high heat storage density suitable for indoor heating needs of 20-30℃. The thermal conductivity enhancer is expanded graphite (EG, particle size 50-100μm, thermal conductivity 200W / (m·K)) accounting for 10wt%, increasing the thermal conductivity of the PCM from 0.2W / (m·K) to 2.5W / (m·K) and shortening the charging and discharging time by 50%. The stabilizer is high-density polyethylene (HDPE, density 0.95g / cm³, melting point 130℃) accounting for 25wt%, serving as a shape-stabilizing matrix to ensure no leakage of the liquid PCM, with deformation ≤1.5% after 1000 cycles. The additive is 5wt% nano-alumina (Al2O3, particle size 20nm, thermal conductivity 30W / (m·K)), which further improves the thermal conductivity to 2.4W / (m·K), reduces the supercooling to 0.8℃, and improves the thermal stability by 20%. Based on this, the above-mentioned PCM heat storage unit 4 can be prepared by the following process.

[0026] Step 1, Raw material pretreatment: Lauric acid is melted in a 65℃ water bath, high-density polyethylene is preheated in a 130℃ oven for 30 minutes, expanded graphite is dried in a 200℃ vacuum oven for 2 hours (moisture removal ≤0.1%), and nano-alumina is pretreated by ultrasonic dispersion (600W, 40 minutes, solvent ethanol) to prevent agglomeration.

[0027] Step 2, Mixing and Stirring: In a stainless steel mixing tank (temperature controlled at 65℃), mix molten lauric acid with high-density polyethylene at a stirring speed of 350 rpm for 40 minutes until homogeneous. Add expanded graphite in batches (2 wt% each time), increasing the stirring speed to 600 rpm for 1 hour. Then add nano-alumina and stir for 30 minutes to ensure uniform dispersion of the components (particle distribution uniformity ≥95%).

[0028] Step 3, Vacuum Degassing: Transfer the mixture to a vacuum drying oven (85℃, -0.1MPa), evacuate for 40 minutes to remove air bubbles, and the material density reaches 1.1g / cm³.

[0029] Step 4, Compression Molding: Inject the mixture into a preheated mold (size 10mm×10mm×2mm, preheated to 75℃), and mold it for 6 minutes at 6MPa pressure on a 10-ton hydraulic press. Cool it to 25℃ (cooling rate 2℃ / minute), and demold to obtain the PCM heat storage element.

[0030] Step 5, Packaging and Testing: The PCM module is packaged using 0.05mm thick aluminum foil via a heat sealer (180℃, 2 seconds), achieving an IP65 sealing performance. Differential scanning calorimetry (DSC, heating rate 5℃ / min) testing reveals: melting point 25.2℃, latent heat 185kJ / kg, thermal conductivity 2.4W / (m·K). After 1500 cycles, latent heat decay ≤4.5%, and thermal conductivity decay ≤3%.

[0031] During the preparation of phase change materials as described above, 15% of each batch can be randomly sampled for testing, including melting point (deviation ±0.5℃), latent heat (≥180kJ / kg), and thermal conductivity (≥2.0W / (m·K)). Non-conforming products are reworked or discarded, with a waste recycling rate of ≥90%.

[0032] Furthermore, the inventors optimized the preparation of the phase change material filled in the aforementioned PCM heat storage unit, specifically through raw material quality control: lauric acid purity ≥ 99.5%, high-density polyethylene molecular weight ≥ 100,000, expanded graphite expansion rate ≥ 200 times, and nano-alumina purity ≥ 99.9%. Each batch of raw materials was tested by GC-MS and XRD to ensure the absence of impurities. Stirring optimization: A dual-shaft stirrer (main shaft 350 rpm, auxiliary shaft 100 rpm) was used to reduce particle settling and improve uniformity to 98%. The inner wall of the stirring tank was coated with PTFE to prevent adhesion, extending the cleaning cycle to one month. Molding accuracy: The mold was CNC machined with a dimensional tolerance of ±0.05 mm. The molding machine was equipped with a pressure sensor (accuracy ±0.1 MPa) to ensure uniform pressure of 6 MPa. Cooling was achieved using circulating water cooling (15℃) with a precisely controlled rate of 2℃ / minute to reduce internal stress. Encapsulation enhancement: After heat sealing with aluminum foil, an airtightness test was performed (0.2 MPa, 10 seconds, no leakage). Five modules were randomly selected from every 100 modules for corrosion resistance verification via salt spray testing (48 hours). Performance verification: DSC testing (heating rate 5℃ / min, nitrogen atmosphere) was repeated three times, with melting point deviation ±0.3℃ and latent heat deviation ±2kJ / kg. Thermal conductivity was determined by laser scintillation, with an error of ±0.05W / (m·K). After 1500 cycles, SEM analysis confirmed no phase separation.

[0033] The PCM heat storage unit 4 made of the aforementioned material can be integrated into a heating and air conditioning unit as follows: The PCM heat storage elements are fixed to the heat exchanger fins via aluminum slots (0.5mm thick), with a spacing of 4mm, and 300 modules are arranged on one side to ensure airflow resistance ≤10Pa. Figure 1As shown, the PCM module and fins are bonded together with thermally conductive adhesive (thermal conductivity 3 W / (m·K)), with a contact thermal resistance ≤0.005 m²·K / W. The heater is fixed to the bottom of the heat exchanger by a stainless steel bracket, 2 mm away from the PCM module, and the contact surface is filled with thermally conductive silicone. The power cord is a flame-retardant silicone cable, resistant to 200℃. The control module is installed in a separate cavity at the top of the unit, with an IP54 protection rating and equipped with a cooling fan (5W power).

[0034] In a preferred embodiment of the invention, the device employs a modular frame with dimensions of 800mm × 400mm × 1200mm and a total weight of approximately 50kg. The exterior is a rectangular vertical cabinet, with a 1.2mm thick high-strength stainless steel shell coated with a corrosion-resistant layer. A U-shaped handle at the top facilitates manual operation and movement. Two spherical air outlets (80mm in diameter) are located at the top and center, respectively, for air circulation and heat release. The cabinet interior is filled with a 5cm thick polyurethane foam insulation layer (thermal conductivity ≤0.02W / (m·K)), resulting in a heat loss rate of less than 1% / hour. Four locking casters (150kg load capacity) are installed at the bottom of the unit for easy movement and securing. Each PCM module (10mm × 10mm × 2mm) is precision injection molded with a surface roughness Ra ≤ 1.6μm, enhancing the adhesion of the thermally conductive adhesive. The module fixing frame is made of 6061 aluminum alloy, weighing only 200g and exhibiting strong corrosion resistance. The PCM modules are arranged in two layers (300 modules per layer) with a staggered layout, increasing the heat exchange area by 10%. This optimized layout reduces airflow resistance to 8 Pa and improves heat exchange efficiency by 5%. The PCM modules support quick assembly and disassembly, with a single module replacement time of ≤3 minutes. The heater features a new temperature control feedback loop, achieving 0.1kW step power adjustment with a response time of ≤1 second through PWM (Pulse Width Modulation) technology. The thickness of the thermally conductive silicone layer between the heater and the PCM heat storage unit has been optimized to 0.5mm, increasing the thermal conductivity to 6W / (m·K). The copper tube diameter of the heat exchanger has been optimized to 8mm, with a fin spacing of 1.5mm, increasing the heat exchange area to 1.8m². The fan supports five fan speeds (200 / 300 / 500 / 650 / 800m³ / h), reducing energy consumption by 10% through frequency conversion control. A new deflector has been added to the air outlet, optimizing airflow distribution and expanding the coverage angle to 70° vertically and 100° horizontally, improving heating uniformity by 15%. The HEPA filter features a washable design, extending its lifespan to 1 year.

[0035] The working process of this application example is as follows: Thermal storage operation: The heater starts at 5kW, heating to 50℃ within 30 seconds, then maintains the PCM temperature at 25-35℃ at 3.5-4.5kW. Real-time display of stored heat capacity (MJ) shows 215.28MJ after 13 hours. If the outdoor temperature is ≤-5℃, the system automatically extends thermal storage by 30 minutes. During thermal storage, the fan operates at a low speed of 200m³ / h to assist in heat dissipation and prevent localized overheating. Figure 3 As shown, the thermal storage efficiency is 92% and the electrical energy conversion rate is ≥95%.

[0036] Thermal insulation management: After thermal storage is completed, the system shuts down the heater and starts the insulation mode. The heat loss rate is controlled to be ≤0.8% / hour through the insulation layer and low-speed fan (50m³ / h). The PCM temperature drops by ≤0.5℃ per hour, extending the effective thermal storage time to 12 hours.

[0037] When the indoor temperature is 0.5℃ lower than the set value, the fan starts with an initial airflow of 800m³ / h, and the temperature rises to the target value within 30 minutes. The airflow is then adjusted according to the temperature difference (ΔT): 800m³ / h for ΔT ≥ 5℃; 500m³ / h for 2℃ ≤ ΔT < 5℃; and 300m³ / h for ΔT < 2℃.

[0038] Heat release control: The PCM heat storage unit releases heat in zones (prioritizing the upper layers, with heat transferred downwards), distributing the heat evenly through a heat exchanger. The heating power is 4kW, with indoor temperature fluctuations of ±0.8℃, lasting for 13 hours. The system calibrates the remaining heat storage of the PCM every 15 minutes; if it falls below 20%, the airflow is reduced to 200m³ / h, extending the heating time by 2 hours. Figure 3 As shown, the heat release efficiency is 88%, and the indoor temperature rise rate is 2.5℃ / hour.

[0039] As can be seen from the above embodiments, this invention encapsulates polymer-based composite PCM into a 10mm×10mm×2mm micro-module, which transfers heat through heat exchange pipes and the surface of heat exchanger fins, achieving seamless integration of heat storage function and heating equipment. The micro-PCM module significantly reduces the system volume (overall dimensions only 800mm×400mm×1200mm) and improves heat exchange efficiency (heat transfer coefficient reaches 55W / (m²·K)). Furthermore, the aluminum foil encapsulation technology of the micro-module (IP65 protection rating) ensures the dimensional stability and long-term stability of the PCM in its liquid state, with performance degradation ≤4.5% after 5000 cycles.

[0040] This invention relates to a composite phase change material that, compared to traditional paraffin-based PCM (latent heat approximately 150 kJ / kg, thermal conductivity 0.2 W / (m·K)), exhibits a 23% increase in heat storage capacity and a 12-fold increase in thermal conductivity. The manufacturing process utilizes vacuum degassing and molding techniques to ensure material density and uniformity. Furthermore, optimized coordination between the fan, heat exchanger, and PCM heat storage unit achieves highly efficient thermal energy management. The isothermal heat release characteristics of the PCM (temperature fluctuation ±0.8℃) ensure heating comfort, while the combination of the high thermal conductivity PCM and the copper tube aluminum fin heat exchanger results in an overall system coefficient of performance (COP) of 3.8.

[0041] like Figure 3 As shown in the timing diagram of the heat charging and discharging cycle, during off-peak hours, the electric heating device operates at 5kW for 13 hours, heating the PCM heat storage unit to above its melting point of 25.2℃, increasing the stored heat to 215.28MJ with a heat storage efficiency of 92%. It then enters a heat preservation phase with a heat loss rate ≤0.8% / hour, maintaining a stable stored heat. During peak hours, the PCM releases heat energy, providing heating at an average power of 4kW for 13 hours (7:00-20:00, considering a 24-hour cycle adjustment), releasing 187.2MJ of heat, meeting the required 212.73MJ (heat release efficiency 88%), and maintaining the indoor temperature at 20±0.8℃. The stored heat gradually decreases from 215.28MJ to approximately 28MJ, completing one full cycle. This invention directly verifies that by extending off-peak hours and increasing heating power, a stored heat of 215.28MJ can be achieved, supporting 13 hours of heat release and ensuring the economy and stability of efficient heating during peak hours.

[0042] In addition to the above, it should be noted that the terms "one embodiment," "another embodiment," and "embodiment" used in this specification refer to specific features, structures, or characteristics described in connection with that embodiment, which are included in at least one embodiment described in the general description of this application. The appearance of the same expression in multiple places in the specification does not necessarily refer to the same embodiment. Furthermore, when a specific feature, structure, or characteristic is described in connection with any embodiment, the intention is to suggest that implementing such a feature, structure, or characteristic in conjunction with other embodiments also falls within the scope of this invention.

[0043] Although the invention has been described herein with reference to several illustrative embodiments, it should be understood that many other modifications and implementations can be devised by those skilled in the art, which will fall within the scope and spirit of the principles disclosed herein. More specifically, various variations and modifications can be made to the components and / or layout of the subject matter arrangement within the scope of the disclosure, drawings, and claims. Besides variations and modifications to the components and / or layout, other uses will be apparent to those skilled in the art.

Claims

1. A cabinet type heating and air conditioning machine having a phase change heat accumulator, comprising an outer casing, characterized in that: The outer shell is internally provided with an electric heater, which is in contact with a heat exchanger; the outer shell is also internally provided with a plurality of PCM heat storage units, which are in contact with circulating heat exchange pipelines, the circulating heat exchange pipelines are provided with a circulating pump, and the circulating heat exchange pipelines pass through the heat exchanger; The heat exchanger is arranged in an air duct, the air duct is internally provided with a fan, and the air duct is in communication with air outlets and air inlets on the outer shell; The PCM heat storage unit comprises a metal shell, the metal shell is internally filled with a phase change material, the phase change material comprises lauric acid in a mass percentage of 55%-65%, expanded graphite in a mass percentage of 8%-12%, high-density polyethylene in a mass percentage of 22%-28%, and nano-aluminum oxide in a mass percentage of 4%-6%; The electric heater is used for heating the heat exchanger, the circulating pump is used for driving the heat exchange medium to flow in the circulating heat exchange pipeline, and the heat exchange medium sequentially passes through the heat exchanger and the plurality of PCM heat storage units, so that the PCM heat storage units absorb heat and liquefy; the circulating pump is also used for driving the heat exchange medium to flow in the circulating heat exchange pipeline, and the heat exchange medium sequentially passes through the PCM heat storage units and the heat exchanger, so that the PCM heat storage units solidify and release heat to the heat exchanger, and the fan generates air flow, which is in contact with the heat exchanger and then discharged.

2. The cabinet-type heating and air conditioning machine with phase change heat accumulation according to claim 1, characterized in that The phase change material is prepared by the following method: The raw materials are pretreated, the lauric acid, the expanded graphite, the high-density polyethylene, and the nano-aluminum oxide are weighed according to claim 1, then the lauric acid is melted in a water bath above 65 DEG C, the high-density polyethylene is preheated at a temperature above 130 DEG C, the expanded graphite is dried in an environment of 180-200 DEG C, and the nano-aluminum oxide is dispersed by ultrasonic, and then is ready for use; The pretreated lauric acid and high-density polyethylene are added into a stirring tank, and are fully stirred until uniform, then the expanded graphite is added in batches, and the stirring speed is continuously increased until all the expanded graphite is mixed, finally the nano-aluminum oxide is added, and the stirring is continuously carried out, so that the components are uniformly dispersed, and a middle mixture is obtained; The middle mixture is transferred to a vacuum drying box, and is dried under vacuum to obtain a final mixture; The final mixture is injected into a preheated mold, and is heat-pressed, cooled to room temperature, demolded to obtain the phase change material; The phase change material is sealed by an aluminum foil to obtain the PCM heat storage unit.

3. The cabinet-type heating and air conditioning machine with phase change heat accumulation according to claim 1 or 2, characterized in that: The PCM heat storage unit is in the shape of a flat rectangular body.

4. The cabinet-type heating and air conditioning machine having a phase change heat accumulator according to claim 1, wherein: The electric heater and the heat exchanger are both arranged in the lower part of the outer shell, the air outlets and the air inlets are both arranged on the side surface of the outer shell, the fan is arranged in the air duct formed between the air outlets and the air inlets, and the air outlets are a plurality of air outlets and are in communication with the air duct.

5. The cabinet-type heating and air conditioning machine with phase change heat accumulation according to claim 1 or 3, characterized in that: The outer shell is also provided with a transversely arranged mounting rack, the PCM heat storage units are arranged in an array on the mounting rack, the circulating heat exchange pipelines are in contact with the PCM heat storage units on the mounting rack, and the PCM heat storage units are arranged above the electric heater.

6. The cabinet-type heating and air conditioning machine having a phase change heat accumulator according to claim 1, wherein: The electric heater, the fan, and the circulating pump are connected to a control module, and the control module is used for controlling the electric heater and the fan to start at a preset time period, controlling the start-stop and output power of the circulating pump.

7. The cabinet-type heating and air conditioning machine with phase change heat accumulation according to claim 1 or 6, characterized in that: The electric heater is also in contact with part of the PCM heat storage unit, and a heat conducting medium is arranged between the contact surface of the electric heater and the PCM heat storage unit.

8. The cabinet-type heating and air conditioning machine having a phase change heat accumulator according to claim 1, wherein: The inner wall of the outer shell is provided with a polyurethane foam heat insulation layer.

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