Non-mechanical heat transfer systems include cooling systems that do not rely on a vapor compression cycle, such as those using convection to remove heat from an area. Two types of such systems are recirculating coolers, i.e., systems with fluid pumps, and thermosiphons, i.e., those that rely on natural convection currents. This end-use also includes Organic Rankine Cycle (ORC) devices that typically pump refrigerant to recover and utilize energy from lower-temperature heat rejected from other processes.