Phase change material heat exchanger with heat energy transfer elements extending through the phase change material

Abstract

A heat exchanger for a phase change material including a container holding the phase change material, a tube surrounding the container to define an annular space therebetween, and preferably divider walls within that annular space to create a circuitous path for heat exchange fluid to be routed in multiple passes along the length of the container when passing from the top of the annular space to the bottom of the annular space. When the heat exchanger is operated in a melt cycle, multiple heat energy transfer elements positioned within the lower portion of the container and extending through the phase change material are heatable to a sufficiently high temperature to initiate melting of the phase change material. The heat energy transfer elements are preferably electrical resistance heated rods or coils, or tubes through which is routed high temperature fluid. When the heat exchanger is operated in a freeze cycle, heat exchange fluid at a low enough temperature to initiate freezing of the phase change material typically is introduced into the top of the annular space. In an alternate embodiment in which water is employed as a phase change material, the heat energy transfer elements are used in the freezing cycle, and heat exchange fluid flowing through the annular space is used in the melting cycle.