Heating performance of a hybrid power heat pump driven by gas engine and electrical motor

Abstract

The gas engine-driven heat pump (GEHP) has a higher primary energy ratio (PER) than the electric heat pump (EHP) for heating, but has a lower PER than the EHP for cooling. To exploit the advantages of GEHP and EHP, a heat pump system where the compressor could be driven simultaneously by a gas engine and motor was proposed in the paper. An experimental platform was established to investigate the feasibility and performance of the HPHP system. In addition, numerical models were built for further performance analyses. The results indicate that: (1) Increases in the rotation speed of the compressor and engine power ratio lead to an increase in the total heating capacity. The rotation speed should be adjusted first to meet the required heating load, and then the engine power ratio can be adjusted to achieve better performance; (2) Engine power ratio changes the loads of the engine and motor, thus their efficiencies change, leading to different PERs of the HPHP system. Under different local gas and electricity prices, the engine power ratio can also be adjusted to reach a minimum operating cost; (3) For the case-studied commercial building in Beijing, the annual primary energy consumptions for HPHP, GEHP, and EHP are 94.2, 95.7, and 100.0 kWh/m2, respectively. In addition, HPHP saves operating costs by 17.5 % and 35.1 % compared to GEHP and EHP, respectively, with static payback periods of 2.45 and 1.47 years, even if it is only used for heating in winter.