Effect of fin pitches on the air-side performance of L-footed spiral fin-and-tube heat exchangers

The purpose of this experimental investigation is to investigate the effects of fin pitch (i.e., fp of 2.4, 3.2, and 4.2 mm) on the air-side heat transfer performance and frictional characteristics of L-footed spiral fin-and-tube heat exchangers at high Reynolds numbers (Redc) of 4000–15,000. A determinant of the parallel cross-flow and the counter cross-flow is the flow arrangement of the test heat exchangers. Ambient air and hot water are used as a working fluid on the air- and the tube-side, respectively. The results indicate that the air-side heat transfer coefficient and Colburn factor are independent of fin pitch. However, fin pitch does have an influential effect on the average heat transfer rate, pressure drop, and friction factor. In terms of industrial applications, the correlation of the Colburn factor and friction factor are proposed for practical applications.