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CN-122012030-A - Chloride-based high-temperature composite phase-change heat storage material and preparation method thereof

CN122012030ACN 122012030 ACN122012030 ACN 122012030ACN-122012030-A

Abstract

The invention discloses a chloride-based high-temperature composite phase-change heat storage material and a preparation method thereof, belonging to a phase-change heat storage material, and comprising, by weight, 45-47 parts of sodium chloride, 38-40 parts of potassium chloride, 15-17 parts of magnesium chloride, 5-10 parts of expanded graphite and 1-3 parts of aluminum oxide. The chloride eutectic matrix in the phase change material provides the advantages of high latent heat and low cost, the expanded graphite is shaped to reduce leakage risk, the safety of a system in application is improved, the aluminum oxide can inhibit a corrosion mechanism to form a protective layer, the corrosion depth is large, the moisture absorption rate is low, the problem of durability of chloride salt at high temperature is solved, the stability of heat conductivity is ensured, the heat transmission efficiency is improved, and the phase change material is suitable for a high-pressure heat storage device, so that the heat release power is improved, the heat loss rate is reduced, the flexibility of power grid energy storage can be supported, and the economic benefit is remarkable.

Inventors

  • LEI XIANZHANG
  • XIAO YAN
  • Gao Dengzhao
  • LAN TIAN

Assignees

  • 成都相变科技有限公司

Dates

Publication Date
20260512
Application Date
20260206

Claims (6)

  1. 1. The chloride-based high-temperature composite phase-change heat storage material is characterized by comprising, by weight, 45-47 parts of sodium chloride, 38-40 parts of potassium chloride, 15-17 parts of magnesium chloride, 5-10 parts of expanded graphite and 1-3 parts of aluminum oxide.
  2. 2. The chloride-based high-temperature composite phase-change heat storage material according to claim 1, wherein the weight ratio of sodium chloride to potassium chloride to magnesium chloride is 46:39:15.
  3. 3. A method of preparing the material of claim 1 or 2, said method comprising the steps of: weighing corresponding amounts of sodium chloride, potassium chloride and magnesium chloride, mixing, heating to 500-600 ℃ in a vacuum furnace for melting, and uniformly stirring to obtain eutectic melt; Weighing a corresponding amount of expanded graphite, preheating to 200-300 ℃, then immersing in the eutectic melt, and performing dispersion treatment to promote permeation; and weighing a corresponding amount of aluminum oxide, adding the aluminum oxide into the eutectic melt, uniformly stirring, carrying out vacuum degassing, and cooling and forming to obtain the chloride-based high-temperature composite phase change heat storage material to be packaged.
  4. 4. A method of preparing according to claim 3, characterized in that the method further comprises the steps of: mechanically crushing the cooled chloride-based high-temperature composite phase change heat storage material into particles, and sealing and packaging the particles into a tubular module shape by adopting a metal film.
  5. 5. The method according to claim 4, wherein the mechanically broken particles have a particle diameter of 20 to 50nm and the filling ratio of the space of the particles in the metal film is more than 90%.
  6. 6. The method of manufacturing a heater according to claim 4 or 5, wherein the tubular module is shaped to fit outside the insulated heater.

Description

Chloride-based high-temperature composite phase-change heat storage material and preparation method thereof Technical Field The invention relates to a phase-change heat storage material, in particular to a chloride-based high-temperature composite phase-change heat storage material and a preparation method thereof. Background The high-temperature phase change heat storage material (PCM) plays an important role in stable transmission and distribution and grid connection of renewable energy sources, and provides necessary heat energy storage flexibility so as to buffer intermittent output of solar energy or wind energy. However, existing high temperature PCM often face a number of technical challenges including insufficient insulation, severe corrosion, moisture absorption problems, and poor cycling stability, which directly result in potential safety hazards and performance decay in high voltage grid applications. For example, traditional nitrate-based PCMs (e.g., naNO 3-KNO3 mixtures), while having moderate melting points (about 220-300 ℃) are susceptible to thermal decomposition and oxidation above 400 ℃, resulting in latent heat decay rates as high as 10-20%. Carbonate-based materials (e.g., K 2CO3-Li2CO3) have relatively high melting points (about 500-700 ℃) and high latent heat (> 200 kJ/kg), but are prone to moisture absorption (moisture absorption up to 20% or more) and corrosion to metal substrates, forming corrosion products such as Fe 3O4 and NiO, and the like, which can have corrosion depths in excess of 50 μm/month after contact with stainless steel at 500 ℃. The current prior art also discloses related attempts, but has limitations. For example, shaped PCM using a carbonate matrix, shape stabilization is achieved by classifying porous calcium magnesium carbonates, but the high temperature compatibility and corrosion problems of chloride systems, especially the long term stability at >500 ℃, are not solved. In another example, a preparation method of inorganic salt composite PCM is adopted, so that melting and compounding are emphasized to improve heat conduction, but optimization for high-voltage insulation (dielectric strength <5 kV/mm) and cyclic attenuation (> 10% after 500 cycles) is lacked, and the severe requirement of power grid energy storage cannot be met. Therefore, although the melting point regulation and nano enhancement of the chloride PCM in the prior art are explored, the shaping structure and corrosion inhibition are not effectively integrated, so that the heat loss rate of the material in the practical CSP or power grid application is more than 10%, and the economical efficiency and the reliability are limited. There is therefore a need to develop a new phase change material to support reliable application of the grid energy storage system. Disclosure of Invention The invention aims to provide a chloride-based high-temperature composite phase-change heat storage material and a preparation method thereof, aiming at the defects, so as to solve the technical problems of insufficient insulation, serious corrosion, moisture absorption, poor cycling stability, high-temperature compatibility of a chloride system, corrosion and the like of similar materials in the prior art. In order to solve the technical problems, the invention adopts the following technical scheme: the invention provides a chloride-based high-temperature composite phase-change heat storage material which is characterized by comprising, by weight, 45-47 parts of sodium chloride, 38-40 parts of potassium chloride, 15-17 parts of magnesium chloride, 5-10 parts of expanded graphite and 1-3 parts of aluminum oxide. Preferably, the further technical scheme is that the weight ratio of the sodium chloride to the potassium chloride to the magnesium chloride is 46:39:15. In another aspect, the present invention provides a method for preparing the above material, which includes the steps of: And step A, weighing corresponding amounts of sodium chloride, potassium chloride and magnesium chloride, mixing, heating to 500-600 ℃ in a vacuum furnace for melting, and uniformly stirring to obtain a eutectic melt. And B, weighing a corresponding amount of expanded graphite, preheating to 200-300 ℃, immersing in the eutectic melt, and performing dispersion treatment to promote permeation. And C, weighing a corresponding amount of aluminum oxide, adding the aluminum oxide into the eutectic melt, uniformly stirring, performing vacuum degassing, and cooling and forming to obtain the chloride-based high-temperature composite phase change heat storage material to be packaged. Preferably, the method further comprises the step D of mechanically crushing the cooled chloride-based high-temperature composite phase-change heat storage material into particles, and sealing and packaging the particles into a tubular module shape by adopting a metal film. The further technical scheme is that the particle size of mechanically crushed particles is 20-50