Application of Hydroturbine Pump in Water Source Heat Pump Drainage Gravitational Potential Energy Recovery System

In this study, an energy recovery water source heat pump (ERWSHP) system has been developed and evaluated for feasibility, parameter efficiency and energy saving potential in comparison to conventional water source heat pump (WSHP) systems. The water discharged from the heat exchanger at a height, with an elevation difference of approximately 30 m in some areas of the mountainous city of Chongqing, was utilised as gravitational potential energy (GPE) which is converted into mechanical shaft power to drive the hydroturbine pump. A prototype of the system was set up, characterised, parameter tested and optimised in the laboratory at Chongqing University. MATLAB curve tool (cftool) was utilised to fit the characteristic curves under different water heads. The test data obtained were compared with the standard supplied data to ensure that the measurement was consistent with the performance expected. The system was validated by application to an off-site office development where the hourly cooling load during summer and heating load during winter was assessed using DeST-c (Designer’s Simulation Toolkits). The influence of the parameters was also evaluated. The energy-saving rates of ERWSHP systems in summer and winter were 37.5% and 60.1%, respectively, an equivalent to a fuel reduction of 14.7 tons of coal in summer and 31.8 tons during the winter. The use of GPE would also reduce water intake and increase the total transfer efficiency from 60% to 75% for the hydroturbine pump. A saving of 1131.01 kJ per year, a peak saving rate of 20.8%, in energy consumption could be achieved using the system.