Thermodynamic analysis of vapour compression heat pump cycles for high-temperature applications

The implementation of heat pumps (HP) in industrial applications is limited by constraints of technological, thermodynamic, economic, and organisational nature. Reaching high operational efficiency requires the best possible match of the heat pump cycle and the application. Considering the large variety of potential applications and temperature profiles multiple solutions are needed to cover the range at high efficiencies. This study investigates the thermodynamic potential of various HP cycles in terms of Lorenz efficiency. The studied working conditions comprised of supply temperatures of up to 250 °C. The HP configurations included are single-stage, two-stage, and cascade cycles, with natural working fluids. R-718 HPs had the best efficiency at high heat source temperatures while CO₂ showed promise at low heat source temperatures. Hydrocarbons HPs performed well in a broad range of conditions. This suggests that several technologies are necessary to ensure high performance for all industrial applications. However, additional in-depth analysis is needed for each cycle to fully evaluate their potential.