The effects of phase change during the stand-by period in latent heat energy storage systems

Abstract

When the boundary condition causing a phase change is interrupted, the phase change process continues until the temperature distribution in the whole system becomes uniform due to the temperature gradients existing in both phases. This continuing phase change during the so called “stand-by solidification” period should be taken into consideration especially at the design and the simulation stages of periodically charged/discharged latent heat energy storage systems. In this work, the effect of this freezing mechanism on the position of interface is analyzed for a semi-infinite region in cartesian coordinates and for both inward and outward solidification in cylindrical coordinates. The effects of both the Stefan number and the interface position at the time of interruption on the last interface position are given in graphical forms. Also, the actual heat removal time to solidify all the phase change material encapsulated in a cylindrical container is given.