Conference article

Engine waste heat recovery represents one of the main advantages of a gas engine heat pump (GEHP) as compared to conventional heat pump system. Engine waste heat can be recovered to heat the supply water (at high ambient air temperature) or to evaporate the refrigerant in the refrigerant circuit (at low air ambient temperature). At the middle range of ambient air temperature (10:15°C); the two possibilities are valid but the GEHP performance is different. The present work is aimed at comparing the performance characteristics of the gas engine heat pump with waste heat recovery subsystems for supplying the hot water demands. In order to achieve this objective; a test facility was developed and then experiments were performed over a wide range of condenser water inlet temperature (34°C to 48°C) and at ambient temperature of 13°C. Performance of the gas engine heat pump was characterized by the supply water outlet temperature; heating capacity; gas engine energy consumption and primary energy ratio. The results showed that a water outlet temperature up to 70°C is obtained when the recovered engine heat is transferred to the supply water circuit. On the contrary; a higher condenser heating capacity (13%) and higher gas engine energy consumption (12.8%) are obtained when the recovered engine heat is transferred to the refrigerant circuit. Furthermore; primary energy ratio of the gas engine heat pump is increased by 17.5% when recovered engine heat is transferred to the supply water circuit. Also; GEHP incorporated with heat recovery subsystems can be used for utilizing the waste heat to provide efficient supply of hot water.

Gas engine heat pump; Heating mode; Water heating; Primary energy ratio; Engine waste heat recovery.