Heat transfer enhanced box type phase change heat accumulator

Abstract

The invention discloses a heat transfer enhanced box type phase change heat accumulator which comprises a heat accumulator box body, a heat exchange finned tube, a phase change material, compressed superfine steel wool and a heat preservation layer. The box body is coated with a heat preservation layer so as to reduce heat loss; through holes used for erecting heat exchange finned tubes are formed in the two sides of the wall face of the box body, and the heat exchange finned tubes are supported by the wall face of the box body and arranged in the box body. And the phase-change material and the compressed superfine steel wool are jointly filled in the residual space outside the heat exchange finned tube in the box body. When a high-temperature working medium flows in the heat exchange finned tube, the phase change material absorbs heat and is liquefied, so that heat storage is realized; when the low-temperature working medium flows, the phase-change material releases heat and is cured. According to the scheme, under the synergistic effect of the heat exchange finned tubes and the superfine steel wool, the heat transfer performance of the heat accumulator is remarkably improved, the heat accumulation and heat release speed of the phase change material is increased, and the overall working efficiency of the heat accumulator is further improved.

Description

Technical Field

[0001] The invention relates to the technical field of heat accumulators, and in particular to a heat transfer enhanced box-type phase change heat accumulator. Background Art

[0002] In recent years, the implementation of the dual carbon plan has guided my country's energy industry to gradually achieve low-carbon transformation. Among them, energy storage technology, as a key link in energy transformation, has received unprecedented attention. According to different principles, mainstream energy storage technologies can be divided into mechanical energy storage, chemical energy storage, electrochemical energy storage, thermal energy storage, and electromagnetic energy storage. Among the many technical solutions, phase change energy storage, as a type of thermal energy storage, is widely used in thermal energy storage in low-temperature sections due to its advantages of high energy density, small temperature change, high stability and high durability. Using phase change materials to store excess energy and release it when needed can alleviate the peak pressure of energy utilization and improve the flexibility and stability of energy utilization.

[0003] Phase change heat storage is a device based on the principle of phase change energy storage, which absorbs and releases heat by using the phase change of internal phase change materials. Its working effect is directly related to the performance of phase change materials. Commonly used phase change materials include organic paraffin, fatty acids, polymers, etc. and inorganic hydrated salts, alloys, etc. Among them, paraffin, fatty acids and hydrated salts are the most widely used due to their wide temperature range. Although these phase change materials have many advantages, they also have the common problem of poor thermal conductivity, which greatly limits their practicality. Using finned tubes to increase the heat exchange area between hot fluid and phase change materials is a feasible solution, but the layout of finned tubes and the resulting structural complexity need to be considered. It is also a feasible solution to use thermal conductivity enhancing matrices such as graphene, carbon nanotubes, and expanded graphite to enhance their thermal conductivity. At the same time, the resulting cost surge and instability of composite materials hinder the development and deployment of large-scale phase change heat storage. Therefore, it is particularly important to control costs while strengthening the thermal conductivity of phase change materials, enhance operational stability, and reduce the difficulty of maintenance caused by the complexity of the device. Summary of the invention

[0004] In view of the problems in the prior art, the present invention aims to provide a phase change heat accumulator with relatively lower cost, higher stability, lower maintenance difficulty and excellent working effect.

[0005] A heat transfer enhanced box-type phase change heat storage device comprises a heat accumulator box, heat exchange fin tubes, phase change material, ultrafine steel wool, and a thermal insulation layer. Holes are reserved on the side of the heat accumulator box for installing the heat exchange fin tubes. The remaining space in the heat accumulator box except the heat exchange fin tubes is used to accommodate the phase change material and the ultrafine steel wool. After the ultrafine steel wool is compressed to 1 / 2 of its original volume, it is filled into the box together with the composite phase change material, and a thermal insulation layer is laid outside the box.

[0006] Furthermore, the heat accumulator box and the heat exchange fin tubes are made of 304 steel.

[0007] Furthermore, a discharge port is provided at the bottom of the side wall of the heat accumulator box.

[0008] Furthermore, the bottom plate of the heat storage tank body has an inclined angle to facilitate pouring out the phase change material after it melts.

[0009] Furthermore, the surface of the heat storage tank is coated with a heat insulation layer to reduce heat loss.

[0010] Furthermore, the heat exchange fin tubes are composed of a plurality of groups of serpentine fin tubes connected in parallel.

[0011] Furthermore, the fin height of the heat exchange fin tube is 3-15 mm.

[0012] Furthermore, when the heat exchange fin tube stores heat, one side thereof is a hot fluid inlet, and the other side thereof is a cold fluid outlet; when releasing heat, one side thereof is a cold fluid inlet, and the other side thereof is a hot fluid outlet.

[0013] Furthermore, the phase change material is a phase change material such as fatty acid or paraffin which has a low thermal conductivity and does not react with steel wool.

[0014] Furthermore, the total volume of the ultra-fine steel wool is fixed by a metal wire mesh arranged in the heat accumulator box after being compressed.

[0015] Beneficial effects of the present invention: The heat transfer enhanced box-type phase change heat accumulator provided by the present invention fully increases the heat exchange area and improves the performance of the phase change heat accumulator through a reasonable layout of heat exchange fin tubes, and has the following advantages and beneficial effects: steel wool with high porosity, high thermal conductivity and low cost is used to compound with phase change material, thereby enhancing the thermal conductivity of the phase change material and shortening the heat storage time while ensuring the high energy density of the phase change heat accumulator.

[0016] The fixed structure designed in the box can prevent the compressed steel wool from rebounding, thereby enhancing the stability of the composite material.

[0017] The structure designed by the present invention is convenient for assembly and disassembly, effectively reduces the difficulty of later maintenance, and is widely applicable to various organic phase change materials.

[0018] The bottom of the heat storage box is designed with an inclination and a discharge port, so that the phase change material can be easily collected after absorbing heat and melting into liquid in the box.

[0019] The box body is covered with a thermal insulation layer, which can reduce the loss of heat stored in the heat storage box and extend the heat storage time. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1This is a schematic structural diagram of a heat transfer enhanced box-type phase change heat accumulator according to an embodiment of the present invention; Figure 2 The relationship between the compression degree of the filled steel wool and the physical properties of the composite phase change material; Figure 3 Comparison of the charging speed of the phase change heat accumulator before and after enhanced heat transfer. Attached photos

[0021] 1. Heat accumulator box; 2. Heat exchange fin tubes; 3. Phase change material; 4. Ultrafine steel wool; 5. Insulation layer; 6. Discharge port. DETAILED DESCRIPTION

[0022] In the description of this application, unless otherwise clearly specified and limited, the terms "setting", "parallel", "layout", "compound", etc. should be understood in a broad sense. For example, it can be an integrally formed parallel connection, a welded parallel connection, or a detachable parallel connection of multiple parts. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to specific circumstances. In order to enable those skilled in the art to better understand the scheme of this application, the technical scheme in the embodiment of this application will be clearly and completely described below in conjunction with the drawings in the embodiment of this application.

[0023] The heat storage device of this embodiment is as follows Figure 1 As shown, it mainly includes components such as a heat accumulator box 1, heat exchange fin tubes 2, phase change material 3 and ultra-fine steel wool 4. The surface of the heat accumulator box 1 is coated with a 30-50mm thick insulation layer to reduce heat loss. The bottom is provided with a discharge port 6 with an inclined angle to facilitate the discharge of the phase change material 3, and the top is provided with a groove for installing the heat exchange fin tube 2. The key process is: first fill the gap between the heat exchange fin tube 2 and the box with compressed dense ultra-fine steel wool 4 and fix it with a fixing part, then inject the molten phase change material 3 to fully penetrate the ultra-fine steel wool 4 gap, and after cooling and solidification, form a composite phase change material with steel wool as the skeleton, and finally cover and package it. This structural design not only ensures the efficient storage of heat, but also prolongs the insulation time.

[0024] The working principle of the present invention is as follows: the heat exchange fin tube 2 is connected to the fluid passage, and in the heat storage mode and heat release mode, the heat exchange fin tube 2 draws heat from the hot fluid and transfers it to the composite of the phase change material 3 and the ultra-fine steel wool 4, and draws heat from the composite of the phase change material 3 and the ultra-fine steel wool 4 and transfers it to the cold fluid. The phase change material 3 undergoes a solid-liquid phase change during the heat storage process and a liquid-solid phase change during the heat release process.

[0025] The phase change material 3 is an organic phase change material such as paraffin wax or fatty acid. Depending on the working conditions, materials with different phase change temperatures that do not react with steel wool can be selected. The thermal conductivity and phase change enthalpy of lauric acid after combining with steel wool of different compression degrees are as follows: Figure 2 The results show that the material exhibits the best comprehensive performance when the compression ratio is 2.0, and the thermal conductivity is increased to 0.3846 W·m - ¹·K - ¹, the volumetric energy storage density remains at 132.32 J·cm - ³.

[0026] Example 1 of the present invention combines Figure 1 As shown, the heat accumulator case 1 and the heat exchange fin tube 2 are made of 304 stainless steel, the wall thickness of the heat accumulator case 1 is 3 mm, the heat exchange fin tube 2 has a tube diameter of 32 mm, a wall thickness of 3 mm, and a fin height of 10 mm, the phase change material 3 is lauric acid, and the steel wool material is 316 stainless steel and the steel wire diameter is about 0.025 mm.

[0027] The comparative example of the present invention refers to Example 1, the difference between the two is that the box is filled with pure lauric acid and is not composited with steel wool to enhance heat transfer. The other results and dimensions are the same as those of Example 1.

[0028] like Figure 3 As shown, in the heat storage stage, the latent heat accumulation time of Example 1 is shortened to 201 minutes compared with the control example, and the phase change completion time at the front and rear ends of the heat accumulator is advanced by 11.57% and 33.88%, respectively, confirming that the composite structure significantly improves the uniformity of the temperature field and effectively suppresses the local thermal resistance effect during the phase change process.

[0029] The above-described embodiments are merely descriptions of preferred implementations of the present invention, and are not intended to limit the concept and scope of the present invention. All other embodiments obtained by ordinary technicians in this field without creative work without departing from the design concept of the present invention shall fall within the scope of protection of this application. The scope of protection claimed by the present invention is defined by the attached claims and their equivalents.

Claims

1. A heat transfer enhanced box-type phase change heat accumulator, characterized in that: The device comprises a heat accumulator case (1), a heat exchange fin tube (2), a phase change material (3), ultrafine steel wool (4), and a heat insulation layer (5); a hole is provided on the side of the heat accumulator case (1), and the heat exchange fin tube (2) is installed in the heat accumulator case (1) through the hole; the heat accumulator case (1) is also provided with a phase change material (3) and ultrafine steel wool (4); and the heat insulation layer (5) is laid on the outside of the heat accumulator case (1).

2. The heat transfer enhanced box-type phase change heat accumulator according to claim 1, characterized in that: The heat storage tank body (1) and the heat exchange fin tube (2) are both made of 304 steel.

3. The heat transfer enhanced box-type phase change heat accumulator according to claim 1, characterized in that: A discharge port (6) is provided at the bottom of the side wall of the heat accumulator box (1).

4. The heat transfer enhanced box-type phase change heat accumulator according to claim 3, characterized in that: The bottom plate of the heat storage tank body (1) has a certain inclination angle, and the phase change material is poured out from the discharge port (6) after being melted.

5. The heat transfer enhanced box-type phase change heat accumulator according to claim 1, characterized in that: The heat exchange fin tube (2) is composed of a plurality of groups of serpentine fin tubes connected in parallel.

6. The heat transfer enhanced box-type phase change heat accumulator according to claim 5, characterized in that: The height of the fins is 3-15 mm.

7. The heat transfer enhanced box-type phase change heat accumulator according to claim 6, characterized in that: During the heat storage process, one side of the heat exchange fin tube (2) is a hot fluid inlet, and the other side is a cold fluid outlet; during the heat release process, one side of the heat exchange fin tube (2) is a cold fluid inlet, and the other side is a hot fluid outlet.

8. The heat transfer enhanced box-type phase change heat accumulator according to claim 1, characterized in that: The phase change material (3) is fatty acid, paraffin or other phase change materials with low thermal conductivity and that do not react with steel wool.

9. The heat transfer enhanced box-type phase change heat accumulator according to claim 1, characterized in that: After being compressed to 1 / 2 of its original volume, the ultrafine steel wool (4) is fixed in the heat accumulator box (1) by means of a metal mesh, the phase change material (3) is filled around the ultrafine steel wool (4) in the heat accumulator box (1), and the heat exchange fin tube (2) is wrapped in the phase change material (3) and the ultrafine steel wool (4).

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