Properties of wood-based composite phase change heat storage materials with Cu particles to enhance heat conduction

  Objective  Although high thermal conductivity fillers can improve the heat storage and release rate of wood-based phase change heat storage composite materials. The agglomeration of nanoparticles is not conducive to their uniform dispersion in the material. The purpose of this paper is to use the solution reduction method to in-situ generate monodisperse copper particles in the balsa wood (Ochroma pyramidale) matrix from the inside to outside, so as to develop a green and economic way to improve the heat storage and release properties of phase change heat storage wood-based composite materials.

  Method  Firstly, the balsa wood was delignified with acid sodium chlorite solution to improve the packaging efficiency of phase change materials. Then, the monodisperse Cu particles were prepared by the solution reduction method in delignified balsa wood with CuSO₄ solution and ascorbic acid solution by cyclic reaction, and the paraffin wax (PW) was added to the wood-based composite by vacuum impregnation method. Field emission electron microscope (SEM), infrared spectroscopy (FTIR), X-ray diffraction (XRD), differential scanning calorimeter (DSC), thermal conductivity tester and temperature inspection instrument were used to evaluate the microstructure, crystallization, chemical structure and heat storage and release properties of the materials.

  Result  After delignification, the encapsulation efficiency of balsa wood increased from 64.9% to 82.6%. After the reduction of Cu²⁺ by ascorbic acid, Cu was produced in-situ in the balsa wood matrix. However, if the number of cycles was too small, Cu can not be evenly distributed in the wood matrix, and if the number of cycles was too large, the packaging effect of balsa wood on phase change materials will be excessively affected. The three cycles were the most appropriate. The thermal conductivity of the composite phase change heat storage material prepared by this method was increased by 1.76 times, the melting and solidification latent heat were as high as 143.7 and 142.9 J/g, respectively, and the heat storage and heat release time were shortened by 23.7% and 32.6%, respectively, showing a better potential for temperature regulation.

  Conclusion  The solution reduction method can effectively prepare Cu particles uniformly in the balsa wood matrix, and the wood-based composite phase change heat storage material with Cu particles prepared by three cycles to enhance heat conduction has good heat storage and release performance.