New waste heat district heating system with combined heat and power based on absorption heat exchange cycle in China

A new waste heat district heating system with combined heat and power based on absorption heat exchange cycle (DHAC) was developed to increase the heating capacity of combined heat and power (CHP) through waste heat recovery, and enhance heat transmission capacity of the existing primary side district heating network through decreasing return water temperature by new type absorption heat exchanger (AHE). The DHAC system and a conventional district heating system based on CHP (CDH) were analyzed in terms of both thermodynamics and economics. Compared to CDH, the DHAC increased heating capacity by 31% and increased heat transmission capacity of the existing primary side district heating network by 75%. The results showed that the exergetic efficiency of DHAC was 10.41% higher and the product exergy monetary cost was 36.6¥/GJ less than a CHD. DHAC is an effective way to increase thermal utilization factor of CHP, and to reduce district heating cost.

► Absorption heat pumps are used to recover waste heat in CHP.
► Absorption heat exchanger can reduce exergy loss in the heat transfer process.
► New waste heat heating system (DHAC) can increase heating capacity of CHP by 31%.
► DHAC can enhance heat transmission capacity of the primary pipe network by 75%.
► DHAC system has the higher exergetic efficiency and the better economic benefit.