Abstract: A thermal energy storage system (TESS) that enables the discharge of refrigerated air for cooling cargo or passengers in large compartments, such as the trailer of a semi-truck, for a period of time well in excess of several hours. The TES system is able to provide refrigeration without operating a conventional VCC unit, the truck engine, or the TRU diesel APU engine during all or a significant portion of the period of the typical range of time that a 53 foot refrigerated the truck is traveling over the road. The TES system includes a phase change material (PCM) reservoir, a cooling system-to-WF heat exchanger in fluid communication with the PCM reservoir, and a PCM-to-target heat exchanger in fluid communication with the PCM reservoir. The PCM reservoir contains a phase change material, a working fluid (WF) and a working fluid-to-PCM heat exchanger.