Page No 272 – High-efficiency low temperature lift heat pump with novel oil-free, gas-bearing turbo compressor – 13th IEA Heat Pump Conference, Jeju, Korea
The Coefficient of Performance (COP) of a heat pump and the Energy Efficiency Ratio (EER) of a chiller are strongly dependent on the internal temperature lift, which corresponds to the difference between the condensation and evaporation temperatures. In modern and efficient building heating and cooling systems, low temperature lifts can be achieved. Turbo compressors have high efficiencies at low pressure ratios during full and part-load operation, thus suiting low temperature lift building heating/cooling applications well. This paper presents the results of experimental investigations on a prototype low temperature lift heat pump/chiller with a heating capacity of 500 kW. The heat pump/chiller is equipped with four novel oil-free turbo compressors built with patented, self-acting gas bearings. High efficiency values during full and part-load operation were measured. Second-law efficiencies for building heating applications of up to 62% were determined. F urther increases in efficiency during part-load operation are possible by implementing inlet guide vanes or by shifting the design point of the compressor to lower capacities.