Preparation and characterization of fatty acid eutectic/diatomite filter aid form-stable phase change material for thermal energy storage

Abstract

The aim of this study is to prepare a form-stable phase change material (PCM) with capric and lauric fatty acid (CA-LA) eutectic as the heat absorption material and diatomite filter aid as the supporting matrix. The method of vacuum impregnation was conducted to prepare the composite PCM which has high thermal performance. Its characteristics such as microstructure, thermo-physical propertiesand thermal stability were investigated by SEM, FT-IR, DSC and TG technique. The adsorption capacity of diatomite filter aid to CA-LA eutectic was 49wt%, and the composite PCM kept solid in macro-level even when the CA-LA melted due to the capillary and surface tension forces of diatomite filter aid. DSC analysis showed that phase change temperature and latent heat of the form-stable PCM was 21.8°C and 75.45 J·g-1 respectively. TG analysis indicated that the diatomite filter aid particles absorbed and constrained the CA-LA molecules in the pores and confirmed the form-stable property of the composite. After 100 times thermal cycling, the phase change temperature and latent heat of the form-stable PCM respectively decreased by 0.9% and 1.1%, which can be neglectable in the practical engineering application.