A Multi‐Criteria Study of Optimal Working Fluids for High Temperature Heat Pumps

Abstract

A bi-objective optimization with respect to coefficient of performance (COP) and volumetric heating capacity (VHC) is performed for a high temperature heat pump. For fixed temperature levels of the heat source and sink, the values for temperature in the evaporator and condenser as well as the degree of vapor super-heating and condensate sub-cooling are optimized. Constraints are placed on the minimal pressure in the evaporator, the maximal pressure in the condenser and the compressor discharge temperature. Results are presented for a one-stage and a two-stage heat pump cycle. Cyclobutane and several butene isomers are identified as working fluids with a good compromise between COP and VHC from a CoMT-CAMD approach based on PC-SAFT and a realistic model for the ideal gas heat capacity.