Thermal reliability of typical fatty acids as phase change materials based on 10,000 accelerated thermal cycles

The thermal reliability of phase change materials (PCMs) is an important factor for the successful application of latent heat thermal energy storage. In this work, 10,000 thermal cycles have been firstly carried out to investigate the thermal reliability of four typical fatty acids (lauric acid, myristic acid, palmitic acid and stearic acid) as PCMs. The thermal properties before and after cycles were tested by differential scanning calorimeter. It was found that with increasing number of thermal cycles, both the phase transition temperature and the latent heat tended to decrease. In the experiment, the maximum change in the melting temperature was -0.37 degrees C and change rate of latent heat was -7.57%. The freezing temperature decreased obviously with increasing number of thermal cycles, which led to a maximum increase of 4.15 degrees C in the degree of supercooling. In addition, the specific heat and thermal conductivity of the PCMs after 10,000 thermal cycles had no significant change. FT-IR showed that the chemical structure of fatty acids had not changed after thermal cycles. The experimental results showed that these fatty acids can function as admirable PCMs with high thermal reliability for long-term applications.