Heat conduction enhanced molten salt composite phase change material and heat storage device and energy storage method

Abstract

The invention relates to the technical fields of high temperature heat utilization and energy storage, and particularly relates to a heat conduction enhanced molten salt composite phase change material and a heat storage device and an energy storage method; expanded graphite and Hitec ternary molten nitrate salt are selected as the raw materials of a molten salt composite phase change material; the additive amount of the expanded graphite is 20%, and the loose porous expanded graphite is entirely immersed in a saturated nitrate solution; then the mixture is heated at constant temperature of 90DEG C, is stirred all the time with an electric stirrer in the heating period until most water in the saturated nitrate solution is evaporated, and then is heated at constant temperature of 120 DEG C, the rest water is completely evaporated, and finally the mixture is dried to obtain the KNO3-NaNO2-NaNO3 / expanded graphite composite phase change material; according to the invention, the heat conduction performance of the material is enhanced; the heat storage system is formed by stacking in the form of a filling bed, so that the industrial applicability is increased, and the material can be used for heat storage devices of industrial furnaces, iron making hot blast stoves, heat storage subsystems of focusing solar thermal power generation and the like.

Description

technical field [0001] The invention relates to the technical field of high temperature heat utilization and energy storage, in particular to a heat conduction enhanced molten salt composite phase change material, a heat storage device and an energy storage method. Background technique [0002] As an important part of energy utilization, energy storage plays a particularly important role in industrial energy conservation and the utilization of renewable energy. Due to the intermittent and unstable supply of renewable energy, there are often differences in quantity, form and space between the supply and demand of energy, which cannot meet the requirements of industrialized large-scale continuous energy supply; industry is my country's largest The terminal energy consumption sector accounts for about 70% of the total energy consumption in the country, and the energy utilization rate is much lower than that of advanced countries. One of the main reasons is that the intermittent ...

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Problems solved by technology

[0005] Although, the patent number is 01119014.0, and the patent name is the preparation method of energy storage composite materials for heat storage or cold storage, which discloses a graphite matrix prepared by vacuum impregnation of compressed expanded graphite matrix with phase change material (PCM) and PCM impregnated in said matrix and method for thermal or cold storage energy storage composite materials, the method is mainly under atmospheric pressure and partially or completely impregnated in molten PCM or salt solution is fixed in the impregnated Inside the container, then evacuate and impregnate the container until the PCM filled in the matrix reaches the required amount. Although this method is simple and cheap, the residual porosity of graphite is too small, resulting in poor heat storage and cold storage.

[0006] At the same time, the patent application number 02133310.6 discloses a preparation method of a metal-based composite molten salt heat storage material. The method aims to provide a sensible heat heat storage material with a porosity of 25-85%. According to the document, the technical solution is very incomplete, and we have not obtained any substantive technical inspiration from it, how to obtain a sensible heat storage material with a porosity of 25-85%

[0007] In addition, the patent application number 200910074633.6 discloses a metal foam-based high-temperature phase change heat storage composite material and its preparation method. For thermal materials, first of all, "adhesion" is difficult to achieve, and at the same time, "adhesion" is difficult to guarantee. This method is difficult to apply to industrial production

[0008] In addition, the patent application No. 201010527277.1 discloses a method for preparing a porous material matrix. The method mainly involves weighing and mixing calcium-containing raw materials and silicon-containing raw materials at a molar ratio of Ca: Si = 1: 0.4-1. Add water to 20-40 times the weight, stir and keep warm at 180-320°C for 4-12 hours to obtain a porous material slurry; after the slurry is cooled, add 0%-5% nano-metal powder, after drying and molding That is to make a porous material matrix, immerse the porous material matrix in the completely melted inorganic salt phase change material, so that the phase change material is infiltrated into the pores of the porous material matrix; this method is expensive and difficult to process, and the "immersion" method is adopted In fact, it is difficult to ensure whether the method is "uniformly soaked", and the quality is difficult to be guaranteed, which will affect the heat transfer effect

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