Theoretical analysis of suitable fluids for high temperature heat pumps up to 125 °C heat delivery

Industrial processes with applications such as pasteurization, drying and distillation have heat demand at a temperature between 100–125 °C. Industries with large amounts of waste heat and cooling demand will benefit from the development of high temperature heat pumps (HTHPs) which can replace conventional heating and waste heat disposal systems. This potentially saves both investment and operational cost of a boiler and a cooling tower with a single more efficient and less complex energy system. At the same time, the environmental footprint is reduced. The working fluids for these high temperature heat pumps using the vapour compression technology are often constrained by their high compressor suction and discharge temperature as well as the safety and environmental impact of the fluids. Within these limits, this paper conducts a theoretical analysis to evaluate available and potential fluids with thermodynamic properties that are applicable for HTHPs. The evaluations show that certain hydrocarbons and halocarbons are the most promising fluid candidates for waste heat upgrade from low temperatures to high temperatures, up to 125 °C.