Study on the heating performance and optimal intermediate temperature of a series gas engine compression-absorption heat pump system

To upgrade the heating performance of gas engine heat pump (GEHP) system at low air temperature and achieve cascade utilization of waste heat of gas engine, a series gas engine compression-absorption heat pump (GECAHP) system combining a GEHP and an absorption heat pump is proposed and modeled. The GEHP is driven by the gas engine motive power and the absorption subsystem is activated by gas engine waste heat. Based on a mathematical model, the heating performance of the series GECAHP system at low air temperature and the optimal intermediate temperature are investigated. The simulation results show that the heating capacity of the series GECAHP system has an evident tendency to augment with the increase of gas engine speed and water inlet temperature, while the primary energy ratio just have a little degradation. Compared with the GEHP system, the series GECAHP system can effectively improve the heating capacity at the low air temperature, but the primary energy ratio is relatively low, only between 1.0 and 1.1. In addition, the optimal intermediate temperature increases with the growth of gas engine speed, ambient air temperature and water inlet temperature as well as with the decrease of recovery water temperature.