An Empirical Investigation of a Modified Gas Engine Heat Pump in Heating and Cooling Mode for the Residential Application

Abstract

Gas Engine Heat Pump (GEHP) is found as an effective machine among energy conversion systems. However, further improvement of GEHP performance is still indispensable. In the current study, to recycle efficiently the flue gases waste heat of GEHP unit, it is suggested to utilize a condensing heat exchanger. To assess the performance of the proposed GEHP, an equipped test room was designed. The nominal capacity of the current GEHP is about 80 kW for heating and 71 kW for cooling. The experimental investigation was implemented for two common strategies, i.e. heating and cooling modes. The effect of outlet dry bulb temperature of 0 °C, 5 °C, 10 °C and 15 °C for heating, and 25 °C, 30 °C, 35 °C and 40 °C for cooling as well as water outlet temperature of 40 °C, 45 °C and 50 °C for heating and 8.5 °C, 11 °C, 14 °C for cooling on the performance of the GEHP is investigated. The 95% confidence interval has been considered in statistical analysis. In heating mode, results show that the efficiency of the condensing heat exchanger increases during the reduction of water out temperature and it leads to a Coefficient of Performance (COP) enhancement. Additionally, observation indicates that the decrement of the ambient air temperature from 5 to 0 ° C leads to the severe enhancement of fuel consumption of the gas engine. The performance indicators are re-evaluated using the non-condensing heat exchanger. It is concluded that the COP of GEHP with the condensing heat exchanger decreases by the steeper slope versus the reduction of the ambient dry bulb temperature compared to the non-condensing heat exchanger.

Keywords

• gas engine heat pump
• condensing heat exchanger
• heating and cooling mode
• performance map