Modeling and experimental investigation on a gas engine-driven heat pump for space-heating and sanitary hot water

Utilization of gas engine-driven heat pumps (GEHP) can reduce the heavy loads on the power grid when electric heat pumps operate during the heating season. This study is to examine the performance of GEHP as a water heater with different engine speeds and water flow rates providing space-heating and sanitary hot water. When the engine speed rises from 1400 rpm to 1900 rpm, the temperature rise of water increases by 37% from 25.7 °C to 35.3 °C. Moreover, the system heat capacity rises from 71.8 kW to 97.7 kW with an increase of 36%, while the COP decreases from 3.6 to 3.0. As the inlet water flow rate an increase from 2.5 m3/h to 4.0 m3/h, the temperature rise decreases from 44.3 °C to 24.1 °C, with decreasing heat capacity from 128.8 kW to 112.1 kW. Additionally, the primary energy ratio (PER) initially increases from 1.46 to 1.50 at the engine speed of 1800 rpm, followed by a slight decrease to 1.48 when the engine speed reaches 1900 rpm. With an increasing water flow rate, the PER achieves its highest value of 1.64 at 3 m3/h and its lowest value of 1.49 at 3.5 m3/h.