Thermal modeling and operating tests for a gas-engine driven heat pump working as a water heater in winter

Gas-engine driven heat pump (GEHP) working as water heater has higher energy utilization efficiency and can reduce more environmental pollution than gas-fired (oil-fired, coal-fired) boiler and electric motor driven heat pump (EHP). In the present work, a thermal model of a GEHP system working as water heater was established, and the performances (heating capacity, coefficient of performance (COP) and primary energy ratio (PER) of the GEHP system were also studied both by simulation and experiment. The results showed that the heating capacity increased with the increase of the rotary speed and water flow rate, but decreased with the increase of the hot water temperature. The COP and PER increased with the increase of the water flow rate, but decreased with the increase of the rotary speed and hot water temperature. The simulation results were well agreed with experimental data. The defrost time of the GEHP system was also studied by experiment, the results showed that the defrost time of both using waste heat recovered and reverse cycle defrost (RCD) was the shortest among the three defrost methods used in this paper.

► Modeling of a gas engine driven heat pump working as a water heater is established.
► The gas engine heat pump model is validated by comparing the experimental and simulation data.
► Waste heat recovered from waste heat recovery system is used to defrost in the experiment.