Paper No 172 – High-temperature vapor compression heat pump using butane (R600) – development of a prototype and first measurements – 13th IEA Heat Pump Conference, Jeju, Korea
The application of industrial heat pumps for waste heat recovery can reduce the usage of fossil fuels and increase the energy efficiency of industrial processes. Utilizing a trans-critical vapor compression cycle extends the operating range of refrigerants beyond their critical temperature, enabling high heat sink temperatures with natural refrigerants, which are characterized by zero ozone depletion potential and a negligible global warming potential.To prove the concept of a trans-critical vapor compression cycle using butane as refrigerant, a prototype to achieve a nominal heating capacity of 30 kW at heat sink outlet temperatures of up to 160 °C for utilizing waste heat (at 60 °C) was developed. The one-stage cycle with a suction gas cooled reciprocating compressor is equipped with a low-pressure accumulator and an internal heat exchanger (IHX) for suction gas superheating.First measurements of sub-critical and trans-critical operation show remarkable coefficients of performance (COPs) and confirm that optimum high-side pressures yielding the maximum COP exist. In trans-critical operation the optimum pressure can be shifted towards lower pressures by increasing the suction gas superheat in the IHX.