Evaluation of PCM thermophysical properties on a compressed air energy storage system integrated with packed-bed latent thermal energy storage

Abstract

Compressed air energy storage (CAES) is a promising large-scale energy storage technology to mitigate the fluctuations and intermittence of renewable energies. The application of latent thermal energy storage (LTES) using phase change materials (PCM) to recover compressed waste heat can further improve the energy storage density and round-trip efficiency of CAES. However, there are very few guidelines of PCM selection for a CAES system. In view of the challenge, this study first conducts orthogonal experiments to analyze the effects of the thermophysical properties of PCMs on the performance of the packed-bed LTES and CAES system. Then a PCM selection procedure for CAES is developed based on the orthogonal experiment design and TOPSIS method. The results of range analysis indicate that each thermophysical property of PCM has quite different relative importance to the performance indicators of the CAES system. From the aspect of packed-bed LTES, the density (40.8 %) and latent heat (32.8 %) of PCMs are the top two impact factors for the heat storage rate, while the melting temperature (45.7 %) and thermal conductivity (22.4 %) are the top two impact factors for the residual heat. From the aspect of the CAES system, the density (31.9 %) and melting temperature (24.4 %) are the top two impact factors for the round-trip efficiency, while the density (42.2 %) and latent heat (35.2 %) rank the top two impact factors for the air storage capacity.