Measured Performance of a High Temperature Heat Pump with HFO-1336mzz-Z as the Working Fluid (ST-16-C063)

Industrial heating consumes a significant fraction of the energy consumed globally. Heating at temperatures higher than about 100°C is predominantly provided through combustion of fossil fuels with uncertain prices and well recognized environmental impacts. A significant fraction of industrial input energy is lost as low temperature waste heat (e.g. warm exhaust gases or cooling water) that could be lifted by high temperature heat pumps to process relevant temperatures. This paper assesses the potential for providing heating at temperatures between 100^oC and 150^oC through electrically-driven mechanical compression heat pumps. It reports the measured performance of a lab-scale reciprocating heat pump with HFO-1336mzz-Z (CF₃CH=CHCF₃; previously referred to as DR-2) as the working fluid over a range of conditions representative of intended applications (e.g. drying or steam generation). HFO-1336mzz-Z has attractive safety, environmental and thermodynamic properties and high chemical stability at high temperatures. Various compressor technologies, compressor lubricants, heat exchanger designs, expansion valve types and cycles with and without an internal heat exchanger were considered. Suitable equipment components were selected to meet the requirements for testing at evaporating temperatures between 30°C and 115°C and condensing temperatures in the range of 75°C to 150°C. Test results are compared with predictions based on ideal cycle thermodynamic modeling and the advantages of HFO-1336mzz-Z over other refrigerants are discussed. HFO-1336mzz-Z could enable more environmentally sustainable industrial heat pumps for the utilization of abundantly available low temperature heat to meet heating duties at higher temperatures, with higher energy efficiencies and lower environmental impacts than with incumbent working fluids.