Study of an innovative ejector heat pump-boosted district heating system

An Ejector heat pump-boosted District Heating (EDH) system is proposed to improve the heating capacity of existing district heating systems with Combined Heat and Power (CHP). In the EDH, two ejector heat pumps are installed: a primary heat pump (HP1) at the heating station and a secondary heat pump (HP2) at the heating substation. With the EDH, the low-grade waste heat from circulating cooling water in the CHP is recycled and the temperature difference between the water supply and the return of the primary heating network is increased. A thermodynamic model was provided. An experimental study was carried out for both HP1 and HP2 to verify the predicting performance. The results show that the COP of HP1 can reach 1.5–1.9, and the return water temperature of the primary heating network could be decreased to 35 °C with HP2. A typical case study for the EDH was analyzed.