Theoretical and experimental study of combined heat and power (CHP) system integrated with ground source heat pump (GSHP)

A new power and heat generation system is suggested and studied for better exploitation of the heat content of flue gases with sulfur compounds from CHP (Combined Heating and Power) systems at low temperature, and solve the heat balance problem (the heat absorbed is always unequal to that released to soil) in GSHP (Ground Source Heat Pump system). Experimental and theoretical methodologies are selected to investigate the operating performance (including heat resistance performance, heat transfer coefficient and sulfur reduction) of the key unit- a novel heat exchanger underground made of polyethylene material which can face acid environment, and a comparison is made between experimental and theoretical results. The experimental results show that the PE heat exchanger underground can support the operating temperature and bear the presence of acid. A higher amount of heat in the flue gas can be recovered because of the reduced final temperature of the exhaust gases (from 140 °C to 50 °C) and most of the emission of sulfur to the environment can be eliminated. The simulation results of the whole system indicate that the novel system makes better use of the flue gases, with total thermal (First law efficiency) and exergy (Second law efficiency) efficiencies equal to 82.7% and 28.8%, respectively, much higher than those of the reference system (73.8% and 25.8%, respectively).