Experimental investigation on the airside performance of fin-and-tube heat exchangers having herringbone wave fins and proposal of a new heat transfer and pressure drop correlation

The heat transfer and friction characteristics of fin-and-tube heat exchangers having herringbone wave fins were experimentally investigated. Eighteen samples having different fin pitches (1.34 mm to 2.54 mm) and tube rows (one to four) were tested. For all the samples, the waffle depth and the corrugation angle of the fin was 1.14 mm and 11.7 o respectively. Results showed that the j factors were insensitive to fin pitch, while f factors increased as the fin pitch increased. As the number of tube rows increased, both the j and f factors decreased. However, the effect of tube row diminished as the Reynolds number increased, at least for j factors. Existing correlations failed to adequately predict the present data. A new correlation was developed based on existing data, which significantly improved the predictions of the present data.