Super High Performance Compressor-Driven Heat Pump, High Temperature Output Type for Low Temperature Heat Source

Development of a large-scale screw compression heat pump which recovers sensible heat from around 50°C range of low temperature waste water discharged from petrochemical plants and which generate general-purpose use 150°C high-temperature water with a heat profitability of COP 3 or more. The working fluid used is Trifluoro-Ethanol and water, having good properties for cycling efficiency and thermal stability at high temperature. Because of the large temperature range, the heat pump system employs a two-stage compression system and utilizes a bi-phase power recovery expander in place of a conventional expansion valve. Normally, the COP of a conventional single-stage compression heat pump operating under the same conditions with a Trifluoro-Ethanol-water system is 2.9 (provided mechanical efficiency is 100%, thus it is not possible to realize the COP 3 level at which heat profitability is achieved. This system makes it possible to achieve a level of efficiency nearly the same as the 3.89 of the reverse Carnot cycle. Thrust offset structured rotors are used in the compressor to improve efficiency by cancelling out axial load and decreasing friction loss at the thrust bearing.