Experimental Study of the Air Side Performance of Fin-and-Tube Heat Exchanger with Different Fin Material in Dehumidifying Conditions

Abstract

Under dehumidifying conditions, the condensed water will directly affect the heat transfer and resistance characteristics of a fin-and-tube heat exchanger. The geometrical form of condensed water on fin surfaces of three different fin materials (i.e., copper fin, aluminum fin, and aluminum fin with hydrophilic layer) in a fin-and-circular-tube heat exchanger was experimentally studied in this paper. The effect of the three different fin materials on heat transfer and friction performance of the heat exchanger was researched, too. The results show that the condensation state on the surface of copper fin and aluminum fin are dropwise condensation. The condensation state on the surface of the aluminum fin with the hydrophilic layer is film condensation. For the three different material fins, increasing the air velocity (ua,in) and relative humidity (RHin) of the inlet air can enhance the heat transfer of the heat exchanger. Friction factor (f) of the three different material fins decreases with the increase of ua,in, however, increases with the increase of RHin. At the same ua,in or RHin, Nusselt number (Nu) of the copper fin heat exchanger is the largest and Nu of the aluminum fin with hydrophilic layer is the smallest, f of the aluminum fin heat exchanger is the largest and f of the aluminum fin with hydrophilic layer is the smallest. Under the identical pumping power constrain, the comprehensive heat transfer performance of the copper fin heat exchanger is the best for the studied cases.

Keywords

• condensate droplet
• dehumidifying conditions
• fin-and-tube heat exchanger
• fin material