A kind of polylactic acid gradient phase change heat storage material and preparation method thereof

Abstract

The invention relates to a gradient phase change heat storage material and a preparation method thereof, belonging to the technical field of phase change materials and heat storage. The present invention adopts a biodegradation method to degrade polylactic acid in multiple stages to obtain low molecular weight polylactic acid with various molecular weights or melting points, and forms a gradient phase change heat storage material with multiple liquid transition point.

Description

technical field [0001] The invention relates to a gradient phase change heat storage material and a preparation method thereof. Specifically, two or more phase change materials with different solid-liquid phase transition points are used to form a composite phase change material with multiple phase change points, which belongs to phase change materials and Its thermal storage technology field. Background technique [0002] Phase change heat storage uses the heat absorption and release of materials at the melting point to achieve isothermal heat storage, which is more efficient than sensible heat storage. [0003] The sunlight intensity of solar energy is different in different seasons, different regions, and different hours, and the temperature generated by solar heat storage materials is also different. If a single phase change material is used to absorb heat, it is difficult to achieve the same temperature value in each period. It can be as close as possible to the phase ...

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Problems solved by technology

[0003] The sunlight intensity of solar energy is different in different seasons, different regions, and different hours, and the temperature generated by solar heat storage materials is also different. If a single phase change material is used to absorb heat, it is difficult to achieve the same temperature value in each period. It can be as close as possible to the phase change point, so that it is difficult for phase change materials to work at the phase change point, and more often the heat storage has to be done in a low-efficiency sensible heat method. If the composite phase change material is a composite phase change material, each phase change component can be as close as possible to the phase change working state, minimize the proportion of sensible heat, and store heat with the highest efficiency. At present, such technical methods at home and abroad are relatively rare

[0004] Chinese patent CN106221676A discloses a "phase-change heat storage material with multiple phase-change points and its preparation process", the principle of which is to mix a variety of phase-change materials with different phase-change points to form a heat storage material with multiple phase-change temperatures Hierarchical phase-change materials; Chinese patent CN106634856A discloses a "two-gradient phase-change heat storage material and its preparation method". The purpose of the invention is to achieve the purpose of complementary performance by combining two phase-change materials with different properties. The patent does not mention the completion of phase change heat exchange at various temperature points through different phase change temperatures

Chinese patent CN106675525A discloses a "phase-change cold storage material with dual-phase transition point and its preparation method". The purpose of this invention is to use the dual-phase-transition point composite material to keep its working temperature between the two phase-transition temperatures. , the patent also does not mention the completion of phase change heat exchange at various temperature points through different phase change temperatures

Chinese patent CN106940148A discloses a "Variable Gradient Fractal Lattice Sandwich Strengthened Phase Change Heat Sink", the principle is to arrange the phase change cores in sequence in an array according to the gradient method to improve the heat exchange efficiency, and its basic structure is also in accordance with the heat flow direction; none of the above-mentioned patents modified the phase change material to change the phase change point

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