There are two serious problems in the combined heat and power system: with the increase of heating area and quality

the heating is insufficient; the heavy discharge of low-grade thermal energy in the circulating cooling water wastes energy seriously. A novel system is presented based on ejector heat pumps (EDH-CHP) to solve the two problems by improving the heating capacity of the district heating system. It recycles the waste heat from circulating cooling water for district heating

and increases the heating capacity of the existing heating network by increasing the temperature difference between the water streams supplying and returning the original heating network. Compared with a traditional system

the new one has an additional ejector heat pump in the heating station

named HP1

and another ejector heat pump in the heating substation

named HP2. Thermodynamic analysis and experimental study are carried out for the two ejector heat pumps. The results show that both HP1 and HP2 can improve the performance of district heating under normal working conditions. Experimental results show that the COP of HP1 can reach 1.4—1.9 and the temperature of returning water in the original network can be decreased to 35℃ in HP2. A typical case study shows that the EDH-CHP system can improve the heating capacity of the existing heating network by 50% by adding 30% steam consumption

or improve the heating capacity of the existing heating network by 9% at the same steam consumption

or decrease the energy consumption by 6% at the same heating capacity.