LAUSR

Water refrigerant heat pump system with a water vapour turbo compressor is developed. Water (R718) is an ideal refrigerant that is considered perfectly environment friendly. Although water refrigerant heat pump is studied extensively, the development of turbo compressors of high pressure ratio is still a technical challenge, in terms of both aerodynamics of the impellers and high-speed rotordynamics. In this study, the high-speed rotor is supported by journal bearings lubricated with water refrigerant. Additionally, other system components such as sprayed direct intercooler heat exchanger and anti-cavitation flow control valve have to be designed and developed with the new requirements as well. An experimental test rig of closed-loop heat pump is constructed which achieves the cooling capacity of 100 kW on the rated condition with COP = 5. The experimental results and the experienced challenges and their undertaken solutions are discussed in terms of the efficiency and the vibrations of the turbo compressor and the heat pump system.