Phase change heat storage device with high heat storage density and heat exchange rate
By using a honeycomb-arranged cylindrical phase change thermal storage unit and a screen structure design, the problem of insufficient thermal storage density and heat exchange rate in existing technologies has been solved, achieving high-efficiency thermal storage performance and simple processing technology.
Patent Information
- Application Number
- CN202423317548.7
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-12-31
- Publication Date
- 2025-12-09
- Estimated Expiration
- 2034-12-31
AI Technical Summary
Existing phase change thermal storage devices have limitations in improving heat exchange rate and thermal storage density. In particular, thermally conductive composite phase change materials lead to a decrease in thermal storage density, reduced fluidity, and increased cost. Existing optimized structures are complex and have limited effectiveness.
The system employs cylindrical phase change thermal storage units arranged in a honeycomb pattern, combined with thermal storage unit shelves with a screen structure, to form a tightly arranged and uniform heat exchange channel. This optimizes the flow of heat exchange fluid, enhances the heat exchange area and channel design, and reduces the reliance on thermally conductive materials.
It achieves high heat storage density and high heat exchange rate, has a simple structure, is easy to process, reduces costs, and improves heat exchange efficiency.
Smart Images
Figure CN223649767U_ABST
Abstract
Description
Technical Field
[0001] This utility model relates to the field of thermal energy storage technology, specifically to a phase change thermal energy storage device that combines high thermal energy storage density and heat exchange rate. Background Technology
[0002] Phase change materials (PCMs) are widely used in various fields such as solar thermal storage, industrial waste heat recovery, and mobile heating due to their high-density heat storage capacity. The key to PCM thermal storage technology lies in the timely absorption or release of sufficient latent heat during the phase change process, achieving energy storage and release. However, most PCMs have low thermal conductivity, limiting the rate of heat transfer within the PCM, resulting in a low heat exchange rate during the storage and release processes of PCM thermal storage devices. The industry typically employs two methods to improve the heat exchange rate of thermal storage devices.
[0003] One approach involves preparing thermally conductive composite phase change materials (PCCs), which is achieved by adding highly thermally conductive fillers, such as metal particles, carbon nanotubes, or graphene, to a PCC. These fillers form thermally conductive channels that penetrate the interior of the PCC, effectively enhancing its thermal conductivity. However, this method has certain limitations, such as:
[0004] 1) Decreased heat storage density of phase change materials: The introduction of thermally conductive fillers occupies space that could otherwise be used for heat storage. Since these highly thermally conductive materials typically do not possess phase change heat storage capabilities, the overall heat storage density of the composite material is significantly lower than that of pure phase change materials. In practical applications, the volume of the heat storage device needs to be increased to achieve the same amount of heat storage, thereby increasing the overall space occupied and cost of the system.
[0005] 2) Convective heat transfer is suppressed: After the preparation of composite phase change materials, the viscosity of the material increases during melting, the fluidity decreases or even loses fluidity, the convective heat transfer capacity decreases, and may reduce the heat transfer rate of the thermal storage device.
[0006] 3) Increased Costs: The relatively high cost of high thermal conductivity fillers (such as carbon nanotubes and graphene) leads to an increase in the cost of composite phase change materials. Cost-effectiveness is particularly critical for large-scale applications (such as industrial waste heat recovery or building heating systems).
[0007] The second method is to improve the heat exchange rate of the thermal storage device by optimizing its internal heat exchange structure. Existing optimization approaches include: First, increasing the contact area between the phase change material and the heat exchange fluid to accelerate heat transfer; for example, designing a honeycomb structure, a sandwich design, or adding heat exchange fins. Second, optimizing the flow path of the heat exchange fluid to ensure that the fluid flows evenly through all phase change material areas within the thermal storage device; for example, adding guide vanes or using a spiral flow channel structure to make the fluid flow more uniform and sufficient within the thermal storage device. While both of these measures can improve the heat exchange rate to some extent, the current optimized structures also have significant drawbacks, such as:
[0008] (1) The structure is complex and difficult to process; most optimization designs require fine structural processing of the internal structure of the thermal storage device, which greatly increases the processing difficulty of the device.
[0009] (2) The effect of structural optimization on improving heat exchange efficiency is usually limited; since the thermal conductivity of phase change materials is a bottleneck, even if the flow channel design is optimized, the room for improvement in heat exchange efficiency is relatively limited. Therefore, in practical applications, the two structurally complex and costly optimization schemes mentioned above are often disproportionate to the increase in heat exchange rate they bring. Utility Model Content
[0010] To address the shortcomings of the existing technology, this utility model provides a phase change thermal energy storage device that combines high thermal energy storage density and high heat exchange rate. Through reasonable arrangement of thermal energy storage units and optimization of heat exchange channels, it achieves both high thermal energy storage density and high thermal energy storage and release rate, and has a simple structure that is easy to process.
[0011] To achieve the above objectives, the present invention adopts the following technical solution:
[0012] A phase change thermal energy storage device with both high thermal energy storage density and high heat exchange rate includes a housing shell. The housing shell has a cavity inside, and several phase change thermal energy storage units are vertically arranged in a honeycomb pattern inside the cavity. The phase change thermal energy storage units have circular cross-sections and are closely arranged. The gaps between adjacent phase change thermal energy storage units and between the phase change thermal energy storage units and the inner wall of the cavity form heat exchange fluid channels.
[0013] As a further implementation, a heat storage unit shelf is provided at the bottom of the cavity, and the phase change heat storage unit is placed on the heat storage unit shelf; the heat storage unit shelf is a screen structure, and the aperture of the screen is smaller than the outer diameter of the phase change heat storage unit.
[0014] As a further implementation, the shelf of the thermal storage unit is a stainless steel screen made of several steel wires, with the spacing between adjacent steel wires being smaller than the outer diameter of the phase change thermal storage unit.
[0015] As a further implementation, the heat storage unit shelf is welded to the outer shell of the housing.
[0016] As a further implementation, the phase change thermal storage unit is a cylindrical structure, and the interior of the phase change thermal storage unit is filled with a phase change material with a phase change temperature of 40-90℃.
[0017] As a further implementation, the diameters of several phase change thermal storage units may be the same or different; the volume of the phase change material accounts for 70%-90% of the total volume of the phase change thermal storage device.
[0018] As a further implementation, the outer shell of the phase change thermal storage unit is made of aluminum alloy, and the phase change material is one of paraffin wax, polyethylene glycol, n-octadecyl alcohol, lauric acid, and stearic acid.
[0019] As a further implementation, the outer layer of the enclosure is covered with thermal insulation cotton.
[0020] As a further implementation, the bottom and top of the housing are respectively provided with a heat exchange fluid inlet and a heat exchange fluid outlet, and the heat exchange fluid inlet and the heat exchange fluid outlet are respectively connected to the heat exchange fluid flow channel.
[0021] As a further implementation, a water pump is provided at the heat exchange fluid inlet to provide circulation power for the heat exchange fluid.
[0022] As a further implementation, temperature sensors are respectively installed at the heat exchange fluid inlet and heat exchange fluid outlet. The temperature sensors are connected to the control system and can feed back the temperature of the heat exchange fluid to the control system to control the working status of the water pump.
[0023] As a further implementation, flow meters are installed at the heat exchange fluid inlet and outlet to monitor the flow rate of the heat exchange fluid.
[0024] By adopting the above technical solution, the beneficial effects of this utility model are as follows:
[0025] 1. This utility model maximizes the space utilization inside the housing by closely arranging several phase change thermal storage units with circular cross-sections inside the housing, thereby greatly increasing the volume ratio of the phase change material, achieving high thermal storage density, and enhancing the heat exchange effect. At the same time, the gaps between adjacent phase change thermal storage units and between the phase change thermal storage units and the inner wall of the cavity form a uniform and continuous heat exchange channel, allowing the heat exchange fluid to exchange heat with all phase change thermal storage units simultaneously along the way when passing through the thermal storage device, significantly improving the heat exchange rate.
[0026] 2. In this utility model, the phase change thermal storage unit adopts a cylindrical structure, and multiple phase change thermal storage units with the same or different diameters are arranged closely, so that the volume ratio of phase change material can reach 90%, which significantly increases the heat exchange area and thus enhances the heat exchange effect.
[0027] 3. This utility model improves the heat exchange area by designing the structure and arrangement of the phase change thermal storage unit, and optimizes the design of the heat exchange fluid flow channel, which effectively enhances the heat exchange effect and reduces the dependence on the thermal conductivity of the thermal storage material. It can reduce the thermal conductivity requirements of the phase change material, so it can use a lower-cost phase change material. It does not need to rely on high thermal conductivity composite phase change materials, and can also significantly improve the heat storage and heat release rate. Thus, while achieving a high thermal storage density, it avoids the manufacturing difficulty and cost increase caused by complex structures.
[0028] 4. This utility model adopts cylindrical phase change thermal storage units arranged in a honeycomb pattern. Multiple cylindrical phase change thermal storage units can be fixed by thermal storage unit shelves, which can ensure that the heat exchange fluid flows evenly. The structure is simple and easy to process. Attached Figure Description
[0029] The accompanying drawings, which form part of this specification, are used to provide a further understanding of this utility model. The illustrative embodiments of this utility model and their descriptions are used to explain this utility model and do not constitute an improper limitation of this utility model.
[0030] Figure 1 This is a schematic diagram of the phase change thermal storage device in an embodiment of the present invention.
[0031] Figure 2 This is a schematic diagram of the horizontal cross-section of the phase change thermal storage device in an embodiment of this utility model.
[0032] Figure 3 This is a schematic diagram of the heat storage unit shelf structure in an embodiment of the present invention.
[0033] In the diagram: 1. Metal casing; 2. Phase change thermal storage unit; 3. Thermal storage unit shelf; 4. Heat exchange fluid inlet; 5. Heat exchange fluid outlet; 6. Heat exchange fluid flow channel; 7. Temperature sensor; 8. Water pump; 9. Flow meter. Detailed Implementation
[0034] It should be noted that the following detailed description is illustrative and intended to provide further explanation of the present invention. Unless otherwise specified, all technical and scientific terms used in this invention have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains.
[0035] It should be noted that the terminology used herein is for descriptive purposes only and is not intended to limit the exemplary embodiments according to this invention. As used herein, the singular form is intended to include the plural form as well, unless the context clearly indicates otherwise. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without inventive effort are within the scope of protection of this invention.
[0036] Example 1
[0037] In one typical embodiment of this application, a phase change thermal storage device with both high thermal storage density and high heat transfer rate is provided, such as... Figure 1-3 As shown, the device includes a housing 1, and the interior of the housing has a cavity. Several phase change thermal storage units 2 are vertically arranged in a honeycomb pattern inside the cavity. The phase change thermal storage units have a circular cross-section and are closely arranged. The gaps between adjacent phase change thermal storage units and between the phase change thermal storage units and the inner wall of the cavity form heat exchange fluid channels 6.
[0038] Specifically, the outer shell 1 is a cylindrical structure with a main diameter of 40-80cm and a height of 40-100cm, made of metal, with several phase change heat storage units 2 arranged inside, and covered with insulation cotton on the outside. In this embodiment, as... Figure 1 As shown, the outer shell 1 is a cylindrical shell with an inner diameter of 40cm, a height of 70m, and a wall thickness of 2mm, made of 304 stainless steel. Several phase change thermal storage units 2 are arranged in a honeycomb pattern within the cavity inside the outer shell 1, which can greatly increase the heat exchange area and enhance the heat exchange effect.
[0039] Specifically, the phase change thermal storage unit 2 is a cylindrical structure filled with an organic phase change material with a phase change temperature of 40-90℃, allowing heat exchange as the heat exchange fluid passes through. During the manufacturing process, the phase change material is first heated and melted, then encapsulated within the phase change thermal storage unit. These units are then arranged vertically and tightly on a storage unit shelf. When the thermal storage device is storing or releasing heat, the heat exchange fluid flows through all the heat exchange fluid channels formed by the gaps between adjacent phase change thermal storage units and between the phase change thermal storage unit and the inner wall of the cavity, exchanging heat with the phase change material within the storage unit.
[0040] To increase the space occupied by the phase change material, phase change thermal storage units of different diameters can be combined and arranged, achieving a volume of 70%-90% for the phase change material in the total volume of the phase change thermal storage device. In this embodiment, combined with... Figure 1 , 2As shown, the interior of the outer casing 1 contains 76 phase change thermal storage units 2 with an outer diameter of 4 cm and 8 with an outer diameter of 3 cm, all with a height of 65 cm, slightly less than the height of the outer casing 1. The outer casing of the phase change thermal storage unit 2 is made of aluminum alloy, and the phase change material filled inside can be one of paraffin wax, polyethylene glycol, n-octadecyl alcohol, lauric acid, or stearic acid. Considering material costs, in this embodiment, paraffin wax with a phase change temperature of 58-60℃ and a latent heat of phase change of 170-180 J / g is filled inside the phase change thermal storage unit. During manufacturing, the paraffin wax is first melted in an 80℃ heating furnace and poured into a sealed section of the phase change thermal storage unit. After the paraffin wax has completely solidified, a rubber stopper is used to seal the other end of the phase change thermal storage unit to ensure airtightness. The total volume of the phase change thermal storage unit is calculated to account for 72.9% of the internal space of the entire thermal storage device.
[0041] Specifically, such as Figure 1 As shown, the bottom and top of the outer casing 1 are respectively provided with a heat exchange fluid inlet 4 and a heat exchange fluid outlet 5, which are connected to the heat exchange fluid flow channel 6. The heat exchange fluid flows in from the heat exchange fluid inlet 4 at the bottom and flows out from the heat exchange fluid outlet 5 at the top, and can exchange heat with all phase change heat storage units 2 simultaneously along the way, significantly improving the heat exchange rate. In this embodiment, a water pump 8 is provided at the heat exchange fluid inlet 4 to provide circulation power for the heat exchange fluid. Temperature sensors 7 are respectively provided at the heat exchange fluid inlet 4 and the heat exchange fluid outlet 5. The temperature sensors 7 are connected to the control system and can feed back the temperature of the heat exchange fluid to the control system to control the working state of the water pump. Specifically, during heat storage, the water pump stops working when the outlet temperature is higher than the set value; during heat release, the water pump stops working when the outlet temperature is lower than the set value. At the same time, flow meters 9 are respectively provided at the heat exchange fluid inlet 4 and the heat exchange fluid outlet 5 to monitor the flow rate of the heat exchange fluid in real time.
[0042] Optionally, the heat exchange fluid can be one of water, ethylene glycol, or silicone oil. In this embodiment, the heat exchange fluid is water, the inlet temperature is 85°C, the flow rate is 5.5 L / min, and the initial temperature of the phase change thermal storage unit is 30°C. When the outlet temperature of the heat exchange fluid exceeds 80°C, the control system issues a command to shut down the water pump.
[0043] Specifically, the phase change thermal storage unit 2 is placed on the thermal storage unit shelf 3 inside the cavity, combined with Figure 1 , 3 As shown, the heat storage unit shelf 3 is made of a circular stainless steel mesh, which is made of several stainless steel wires. The outer diameter of the heat storage unit shelf 3 is the same as the inner diameter of the outer shell 1 of the box, and it is welded to the bottom of the inner shell 1 of the box. The spacing between adjacent wires in the heat storage unit shelf 3 is slightly smaller than the outer diameter of the phase change heat storage unit, which can fix the phase change heat storage unit and allow the heat exchange fluid to flow through. This ensures that the heat exchange fluid can flow evenly across the surface of all phase change heat storage units, which significantly improves the heat exchange rate.
[0044] The phase change thermal storage device in this embodiment has a simple structure, a high volume ratio of phase change material, a large heat exchange area, and low requirements for the thermal conductivity of phase change material. It can be used in building heating, waste heat recovery, solar energy storage and other fields.
[0045] It should be noted that the above embodiments are only used to illustrate the technical solution of this utility model, and are not intended to limit it. Those skilled in the art should understand that this utility model can have various modifications and variations. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this utility model should be included within the protection scope of this utility model.
Claims
1. A phase change thermal energy storage device with both high thermal energy storage density and high heat transfer rate, characterized in that, The device includes an outer shell, inside which is a cavity. Several phase change thermal storage units are vertically arranged in a honeycomb pattern within the cavity. The phase change thermal storage units have a circular cross-section and are closely arranged. The gaps between adjacent phase change thermal storage units and between the phase change thermal storage units and the inner wall of the cavity form heat exchange fluid channels.
2. The phase change thermal energy storage device with both high thermal storage density and heat transfer rate as described in claim 1, characterized in that, The bottom of the cavity is provided with a heat storage unit shelf, and the phase change heat storage unit is placed on the heat storage unit shelf; the heat storage unit shelf is a screen structure, and the aperture of the screen is smaller than the outer diameter of the phase change heat storage unit.
3. A phase change thermal energy storage device with both high thermal storage density and heat transfer rate as described in claim 2, characterized in that, The shelf of the thermal storage unit is a stainless steel screen made of several steel wires, with the spacing between adjacent steel wires being smaller than the outer diameter of the phase change thermal storage unit.
4. A phase change thermal energy storage device with both high thermal energy storage density and high heat transfer rate as described in claim 1, characterized in that, The phase change thermal storage unit has a cylindrical structure, and the interior of the phase change thermal storage unit is filled with a phase change material with a phase change temperature of 40-90℃.
5. A phase change thermal energy storage device with both high thermal energy storage density and high heat transfer rate as described in claim 4, characterized in that, The diameters of the several phase change thermal storage units may be the same or different; the volume of the phase change material accounts for 70%-90% of the total volume of the phase change thermal storage device.
6. A phase change thermal energy storage device with both high thermal energy storage density and high heat transfer rate as described in claim 4, characterized in that, The outer shell of the phase change thermal storage unit is made of aluminum alloy, and the phase change material is one of paraffin wax, polyethylene glycol, n-octadecyl alcohol, lauric acid, and stearic acid.
7. A phase change thermal energy storage device with both high thermal energy storage density and high heat transfer rate as described in claim 1, characterized in that, The bottom and top of the housing are respectively provided with a heat exchange fluid inlet and a heat exchange fluid outlet, which are respectively connected to the heat exchange fluid flow channel.
8. A phase change thermal energy storage device with both high thermal energy storage density and high heat transfer rate as described in claim 7, characterized in that, A water pump is installed at the inlet of the heat exchange fluid to provide circulation power for the heat exchange fluid.
9. A phase change thermal energy storage device with both high thermal energy storage density and high heat transfer rate as described in claim 7, characterized in that, Temperature sensors are installed at the heat exchange fluid inlet and heat exchange fluid outlet, and the temperature sensors are connected to the control system.
10. A phase change thermal energy storage device with both high thermal energy storage density and high heat transfer rate as described in claim 7, characterized in that, Flow meters are installed at the heat exchange fluid inlet and heat exchange fluid outlet, respectively.