Effect of Inclination Angle on the Airside Hydrothermal Performance of the Rectangular Plain Fin Heat Exchangers Operating Under Wet Conditions

Condensate retention occurs in heat exchangers operating under wet conditions. The retained condensate could bridge two consecutive fins and narrow the air flow passage resulting in an increased airside pressure drop, and more energy consumption accordingly. This study experimentally investigated the effect of inclination angle on condensate drainage in rectangular plain fin heat exchangers. The inlet air temperature was 27 °C and the fin base temperature was fixed at 7 ° C. The experimentation was conducted with different fin spacings of 1, 2.5, and 4 mm, flow depth (25 and 16 mm), face velocities (1 to 2.5 m s^-1), and relative humidities (50% and 90%). The results showed that the effect of inclination and relative humidity on sensible heat transfer coefficient is negligible, whereas the shorter flow depth (16 mm), compared to the 25 mm flow depth, offers a significant improvement in the sensible heat transfer coefficient which is about 30-82%. Due to gravitational force, the inclined fin arrangement can offer a 5-65%reduction in pressure drop compared to the horizontal fin arrangement.