U.S. patent application 20180340738 (applicant Alliance for Sustainable Energy LLC, Golden, Colo.):
"Disclosed herein are multi-circuit thermal energy storage (TES) systems connected in heating, ventilation, and air conditioning (HVAC) systems. The two circuits (a refrigeration circuit and a secondary fluid circuit) are designed to work together, but they might contain separate units. In certain configurations, the TES system may use a phase change composite (PCC) with high thermal conductivity, which allows for efficient heat transfer within the PCC. Thus, the PCC itself may be used as the heat transfer media between a refrigerant and a secondary fluid, allowing the refrigerant/secondary fluid heat exchanger in typical configurations of HVAC systems to be removed."