PNNL

Abstract

Thermal energy storage materials are becoming increasingly important as a renewable energy source. Several types of phase change material (PCM) have been evaluated for thermal energy storage application [1-6]. The solid-liquid PCM including paraffin and salt hydrates [7-10] have been extensively studied and solid-gas PCM in the form of metal hydrides have also been investigated [11, 12]. The solid-solid PCM (SSPCM) are the most promising ones as they undergo changes in crystal structure (well below their melting points) releasing or absorbing a large amount of maintaining almost constant temperature during heat absorption and release cycles. The SSPCM store the latent heat of transformation in addition to the sensible heat, thus making the overall storage capacity per unit mass far greater than for materials such as concrete storing sensible heats only [13].