Numerical investigation of the heat-release performance of a metal hydride reactor-integrated phase change material

Abstract

Metal hydride (MH) heat storage has a relatively high energy density and can be used in concentrated solar power (CSP) plants. However, in this system, the outlet temperature of the heat transfer fluid (HTF) has large fluctuations while discharging heat, which cannot satisfy the requirement of CSP plants. Therefore, this study proposes an MH-based heat storage system integrated with phase change materials (PCMs). A mathematical model was established to investigate the effects of the thickness of PCMs, HTF velocity, and the initial state of PCMs on heat-release performance. The results showed that the fluctuations can be effectively attenuated, and the fluid outlet temperature can be kept stable for a certain period by integrating PCMs. Plateaus in the curves of the MH bed and HTF outlet temperatures were observed, and the platform temperature and time are defined as the average temperature of two inflection points of the curve and their corresponding time difference, respectively. Increasing the thicknesses of PCMs can extend the platform time. Furthermore, the liquid phase of PCMs is conducive to improving the heat-release performance of the MH reactor with PCM.