Air-side performance of embedded and welded spiral fin and tube heat exchangers

Abstract

This paper presents the air-side performance (ASP) of embedded and welded spiral fin and tube heat exchangers (SFTHXs). Six heat exchangers were tested to investigate the effects of fin-base connections and fin pitch. Test sections were fabricated from steel tubes, with two rows of tubing and a Z-shaped water flow arrangement, and an aluminum fin with various fin pitches. The experiment was done at a high Reynolds number of air flow (4000-18000). The results show that fin pitch had no effect on the ASP of embedded SFTHXs. In contrast, fin pitch influenced the ASP of the welded SFTHX. Moreover, the pressure drop decreased with increasing fin pitch, whereas the friction factor was lower for a smaller fin pitch. Due to better fin base connections, an embedded spiral fin generally provided a higher heat transfer rate than a welded spiral fin did. The pressure drop of the welded spiral fin was greater than that of the embedded spiral fin, possibly because the welded spiral fin had melted slag at the fin base.