A Two-stage Vertical Absorption Heat Exchanger for District Heating System

Abstract The absorption heat exchanger (AHE) is designed to decrease the temperature of outlet primary water. A two-stage vertical absorption heat exchanger for district heating system is designed and tested in this research. The system consists of two stages absorption heat pump with different vapor pressure in generator and evaporator, while the two stages are only connected with primary and secondary water. The system is designed to a vertical structure in order to reduce the covered area, which consists of condenser, generator, evaporator and absorber from top to bottom. A simulation model is put up and verified to predict the performance of the system. The performance of this system with 6000 kW heating capacity is tested in Taiyuan with the load rate ranges from 4.7% to 50.0%. The outlet water temperature of primary network is below 20°C in the past heating seasons, which is 15 – 25 K lower than inlet water temperature of secondary network. The tested temperature efficiency is 1.250 - 1.420, while the tested temperature efficiency of single-stage system is 1.140 - 1.200. The two-stage vertical AHE system has higher temperature efficiency and better performance compared with traditional AHE according to field test.