A new ejector heat exchanger based on an ejector heat pump and a water-to-water heat exchanger

As urban construction has been developing rapidly in China, urban heating load has been increasing continually. Heating capacity of the existed primary heating network (PHN) cannot meet district heating requirements of most metropolises in northern China. A new type of ejector heat exchanger (EHE) based on an ejector heat pump and a water-to-water heat exchanger (WWHE) was presented to increase the heating capacity of the existed PHN, and the EHE was also analyzed in terms of laws of thermodynamics. A new parameter, the exergy distribution ratio (EDR), is introduced, which is adopted to analyze regulation characteristics of the EHE. We find that the EHE shows better performance when EDR ranges from 44% to 63%. EHE can decrease the temperature of return water in the PHN to 35 °C, therefore, this can increase the heating capacity of existed PHN by about 43%. The return water with lower temperature in the PHN could recover more low-grade waste heat in industrial systems. Because of its smaller volume and lower investment, EHEs could be applied more appropriately in district heating systems for long-distance heating and waste heat district heating systems.