Thermal storage heat exchanger structures employing phase change materials

A heat exchanger includes at least one conduit configured to carry a working fluid. The heat exchanger also includes a plurality of chambers in proximity to the at least one conduit, each chamber configured to contain a phase change material (PCM) that expands upon freezing. The at least one conduit and the plurality of chambers are thermally coupled for transfer of thermal energy between the working fluid and the PCM in each chamber. One wall of each chamber is formed of a compliant layer configured to deform to increase a volume of the chamber as the PCM expands upon freezing.