Influence of inlet water temperature on heat transfer and pressure drop of dehumidifying air coil using analytical and experimental methods

Abstract

A model, which used the enthalpy potential method, was formulated and an experimental apparatus was established to investigate a dehumidifying air coil with a continuous plate finned tube. The effects of the air face velocity, water flow rate and water temperature on the cooling load and air pressure drop were analysed. The face velocity, water flow rate and water temperature ranged from 1-4 m/s, 14–18 L/min and 12–18 °C, respectively. Moreover, the inlet air temperature and relative humidity were maintained at approximately 30 °C and 68%, respectively. The experimental results showed that the air pressure drop increased when the inlet water temperature decreased. This phenomenon occurred because of the development of condensed water on the coil surface, which caused a transition from fully dry conditions to fully wet conditions. Therefore, a linear correlation was proposed to predict the air pressure drop in the partially wet zone. The results also showed that both the latent load and the sensible load increased when the water temperature decreased. To provide the same cooling capacity, the water flow rate can be reduced by approximately 22% when the water temperature decreases by 1 °C.