Simulation Study on the Effect of Heat Exchanger Area on the Performance of Dual Evaporating Temperature Air Conditioning System

In response to the issue of heat exchanger design in a dual evaporating temperature air conditioning system, in this study, a simulation model is established for a dual evaporating temperature air conditioning system to evaluate the impact of the heat exchanger area on the system performance. A dual evaporating temperature air conditioning system experimental platform is built, and the compressor frequency (30-120 Hz) and supply air volumetric flow rate (400-1000 m³/h) under experimental conditions are used to obtain the cooling capacity Q_c, sensible heat cooling capacity Q_s, and sensible heat ratio (SHR) of the air conditioning unit. These performance metrics are used to verify the accuracy of the established model. The range of the system operation adjustment is studied by changing the heat exchanger area (48, 60, and 72 coils) in the model. The results show that with an increase in the heat exchanger area, the adjustment ranges of systems Q_c, Q_s, and SHR expand generally, with maximum increases of 5.0%, 13.8%, and 11.8%, respectively. When the heat exchange area increased from 48 to 60 coils and 72 coils, at an air supply volumetric flow rate of 1000 m³/h and the compressor frequency of 30 Hz, the increase in Q_s was 9.8% and 13.8%, respectively, indicating that when the heat exchange area increased to 60 coils, the increase in Q_s was obvious. When the heat exchange area was further increased, although Q_s increased, the growth rate decreased. Finally, a method was proposed to design the heat exchanger area according to the ambient temperature and humidity adjustment range, with the required cooling capacity as the target.