A biomimetic thermocline phase change heat accumulator based on solid waste steel slag

Abstract

This invention relates to the field of solar thermal power generation and energy storage, specifically to a biomimetic thermocline phase change accumulator based on solid waste steel slag. The accumulator has several equally spaced leaf veins, each including a portion perpendicular to the top surface of the accumulator and a portion parallel to the top surface. The other parts of the accumulator are leaf mesophyll portions arranged at the same equal intervals as the leaf veins. Each leaf mesophyll portion consists of multiple rings of phase change capsules arranged circumferentially around the steel slag, with the steel slag as the center. Similarly, each leaf vein portion consists of multiple rings of steel slag arranged circumferentially around the steel slag. In this design, a accumulator structure combining leaf biomimetic principles is adopted. The steel slag, acting as leaf veins, reduces the cost of filling materials, while the phase change capsules, acting as leaf mesophyll, increase the heat storage density. The combination of these two elements achieves the effect of improving heat storage efficiency while reducing costs.

Description

Technical Field

[0001] This invention relates to the field of solar thermal power generation and energy storage, specifically to a biomimetic thermocline phase change heat storage device based on solid waste steel slag. Background Technology

[0002] The intermittency and volatility of renewable energy sources are the main constraints to achieving stable energy supply. Currently, one of the primary objectives of optimizing the layout of large-scale concentrated solar power (CSP) plants is to improve the heat storage and release efficiency of thermal accumulators, reduce the cost of filling materials, and increase the density of thermal storage materials. Spherical thermal accumulators absorb or release sensible and latent heat to store energy, transforming fluctuating energy input into relatively stable energy output. They offer advantages such as high heat storage density, high heat storage and release efficiency, and low cost of thermal storage materials. Applying them to renewable energy systems can effectively alleviate the asynchrony and mismatch between energy supply and demand in terms of time, space, and intensity, thereby improving the stability and reliability of renewable energy.

[0003] The task of bionics is to study the superior capabilities of biological systems and the principles underlying them, to model these capabilities, and then to apply these principles to design and manufacture new technological devices. Mevi-Schutz et al. demonstrated through experiments that heat permeation gas transport within lotus roots can drive air flow from the leaves to the roots. Wei Wang et al. established a two-dimensional transient model using simulation methods, drawing on the structural characteristics of lotus roots through bionics, and verified the effect of the radial gradient arrangement of phase change material capsules on the thermal behavior of a packed bed latent heat storage system. Zheng et al. created a synthetic material that follows Murray's law, similar to a plant stem. The pore size of this material is reduced at multiple scales, which enhances the capacity for mass exchange and transfer. Dong et al. optimized the thermal performance of phase change capsules by designing the diameter to vary along the flow direction, while keeping the surface cells of the mesophyll at the same porosity. Generally, leaves consist of an epidermis, mesophyll, and veins; veins are responsible for transporting nutrients, while the mesophyll is responsible for storing them.

[0004] The above research suggests that the veins and mesophyll structure of leaves can be applied to the energy storage system of thermal accumulators to improve the thermal storage efficiency and density of the accumulators, and reduce the cost of filling materials. Summary of the Invention

[0005] To address the shortcomings of existing technologies, such as relatively high accumulator costs and low heat storage density, the present invention aims to provide a biomimetic thermocline phase change accumulator based on solid waste steel slag with high heat storage efficiency.

[0006] To solve the above-mentioned technical problems, the technical solution provided by the present invention is: the biomimetic inclined thermocline phase change accumulator based on solid waste steel slag, wherein the accumulator is provided with a plurality of equally spaced leaf veins, the leaf veins including a portion arranged perpendicular to the top surface of the accumulator and a portion parallel to the top surface of the accumulator, and the other portions on the accumulator are leaf mesophyll portions arranged at the same equal intervals as the leaf veins;

[0007] Each individual leaf mesophyll portion is composed of multiple rings of phase change capsules arranged in a circumferential array around the steel slag, with the steel slag as the center. Similarly, each individual leaf vein portion is composed of multiple rings of steel slag arranged in a circumferential array around the steel slag, with the steel slag as the center.

[0008] In the above technical solution, a heat storage structure design combining blade bionics is adopted. The steel slag, which serves as the leaf vein, can reduce the cost of filling materials, while the phase change capsule, which serves as the leaf mesophyll, can increase the heat storage density. The combination of the two can achieve the effect of improving heat storage efficiency while reducing costs.

[0009] Furthermore, the porosity of the leaf vein is 0.32, the average diameter of the steel slag is 45 mm, the porosity of the leaf mesophyll is 0.22, and the diameter of the phase change capsule is 30 mm. The diameters of the phase change capsule and the steel slag affect the porosity; the smaller the porosity, the greater the energy consumed by the pump.

[0010] Furthermore, the heat accumulator uses solar salt (60% NaNO3-40% KNO3) as the heat transfer fluid.

[0011] Furthermore, steel slag and phase change capsules are laid layer by layer, which facilitates the formation of an alternating arrangement.

[0012] Furthermore, the heat accumulator is connected to a central receiver and a generator set, and the central receiver is electrically connected to a heliostat.

[0013] Compared with existing technologies, the significant advantages of this solution are:

[0014] This solution combines biomimetic blade design, using steel slag as leaf veins to reduce the cost of filling materials, and phase change capsules as leaf mesophyll to increase heat storage density. Combined with the layered biomimetic blade structure, it effectively controls the overall heat storage density and heat storage efficiency, solving the problems existing in the prior art. Attached Figure Description

[0015] The accompanying drawings are provided to further illustrate the invention and form part of the specification. They are used in conjunction with embodiments of the invention to explain the invention and do not constitute a limitation thereof. In the drawings:

[0016] Figure 1This is a schematic diagram of the heat accumulator in an embodiment of the present invention;

[0017] Figure 2 This is a structural schematic diagram of the heat accumulator installation and connection method in an embodiment of the present invention;

[0018] In the diagram: 1 - leaf vein, 2 - leaf mesophyll. Detailed Implementation

[0019] The preferred embodiments of the present invention will be described below with reference to the accompanying drawings. It should be understood that the preferred embodiments described herein are for illustration and explanation only and are not intended to limit the present invention.

[0020] like Figure 1 and 2 As shown, the biomimetic inclined thermocline phase change accumulator based on solid waste steel slag of the present invention is a cylindrical body. The accumulator is provided with a number of equally spaced leaf veins 1. The leaf veins 1 include a part arranged perpendicular to the top surface of the accumulator and a part parallel to the top surface of the accumulator. The other parts on the accumulator are leaf mesophyll parts 2 arranged at the same intervals as the leaf veins 1.

[0021] The individual leaf mesophyll 2 is composed of multiple rings of phase change capsules arranged in a circular array around the steel slag, with the steel slag as the center. The individual leaf vein 1 is also composed of multiple rings of steel slag arranged in a circular array around the steel slag, with the steel slag as the center.

[0022] Furthermore, the porosity of the leaf vein 1 is 0.32, the average diameter of the steel slag is 45 mm, the porosity of the leaf mesophyll 2 is 0.22, and the diameter of the phase change capsule is 30 mm. Overall, the steel slag and the phase change capsule are laid layer by layer. It should be noted that the purpose is to maintain the steel slag and the phase change capsule in an alternating arrangement.

[0023] As can be seen from the diagram, the heat storage unit is connected to a central receiver and a generator set, and the central receiver is electrically connected to a heliostat.

[0024] The working principle of this solution is as follows:

[0025] The solar accumulator uses 60% NaNO3-40% KNO3 as the heat transfer fluid and can operate in the range of 300℃-600℃. Steel slag is used as the leaf veins, and phase change capsules containing NaNO3 and with a phase change temperature of 308℃ are used as the leaf mesophyll. The height of the thermocline accumulator is 10m and the diameter is 3m.

[0026] Heat storage process:

[0027] In the initial state of the heat storage process, the temperature inside the accumulator is 290℃. A heat transfer fluid (solar salt) at 320℃ enters the accumulator from the top, and the fluid that has completed the heat exchange flows out from the bottom. The temperature difference causes stratification between the hot and cold fluids due to their density difference, achieving the effect of heat storage. The cutoff temperature for the heat storage process is 290℃. Initially, the temperature of the heat transfer fluid, steel slag, and phase change capsule contained in the accumulator is all 290℃, slightly lower than the melting point of the phase change capsule. The cutoff temperature is slightly higher than the melting point of the phase change capsule to ensure sufficient storage of latent heat.

[0028] Exothermic process:

[0029] In the initial state of the heat release process, the temperature inside the heat accumulator is 320℃. The heat transfer fluid (solar salt) at 290℃ enters the heat accumulator from the bottom, and the fluid that has completed the heat exchange process flows out from the top. The cutoff temperature of the heat release process is 320℃. In the initial state, the temperature of the heat transfer fluid, steel slag, and phase change capsule contained in the heat accumulator is all 320℃, which is slightly higher than the melting point of the phase change capsule. The cutoff temperature is slightly lower than the melting point of the phase change capsule to ensure the full release of latent heat.

[0030] Finally, it should be noted that the above descriptions are merely preferred embodiments of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A biomimetic thermocline phase change regenerator based on solid waste steel slag, characterized in that, The heat accumulator is provided with a number of leaf veins arranged at equal intervals. The leaf veins include a portion arranged perpendicular to the top surface of the heat accumulator and a portion parallel to the top surface of the heat accumulator. The other parts of the heat accumulator are leaf mesophyll portions arranged at the same equal intervals as the leaf veins. Each individual leaf mesophyll portion is composed of multiple rings of phase change capsules arranged in a circumferential array around the steel slag, with the steel slag as the center. Similarly, each individual leaf vein portion is composed of multiple rings of steel slag arranged in a circumferential array around the steel slag, with the leaf vein portion and the leaf mesophyll portion laid out layer by layer.

2. The biomimetic thermocline phase change regenerator based on solid waste steel slag according to claim 1, characterized in that, The porosity of the leaf vein is 0.32, the average diameter of the steel slag is 45 mm, the porosity of the leaf mesophyll is 0.22, and the diameter of the phase change capsule is 30 mm.

3. The biomimetic thermocline phase change regenerator based on solid waste steel slag according to claim 1, characterized in that, The heat storage device uses solar salt as the heat transfer fluid, and the solar salt contains 60% NaNO3-40% KNO3.

4. The biomimetic thermocline phase change regenerator based on solid waste steel slag according to claim 1, characterized in that, The heat storage device is connected to a central receiver and a generator set, and the central receiver is electrically connected to a heliostat.

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