Parametric study of the air-side performance of slit fin-and-tube heat exchangers in wet conditions

Abstract

The air-side performance of three new slit fin-and-tube heat exchangers under dehumidifying conditions is reported. The effects of the number of rows of tubes, the fin pitch and the inlet relative humidity on air-side performance are reported. It is found that for type I slits, which are characterized by a small louvre angle (convex-louvre configuration), the test results show that the sensible heat transfer performances are relatively independent of fin pitch. However, for type III slits, which feature the smallest distance between adjacent slits, a drop of heat transfer performance for N= 1 and Fp = 1.81 mm is observed. It is very likely that this phenomenon is related to the ‘non-recovery wake effect’ caused by the slit geometry. A correlation is proposed for the slit fin configuration; the mean deviations of the proposed heat transfer and friction correlation are 8.0 and 8.1 per cent respectively.