Plate fin-and-tube heat exchangers are employed in a wide variety of engineering applications like air-conditioning apparatus, process gas heaters, and coolers. In plate –fin and tube heat exchangers the fins forms a series of channels that create narrow passages for the external flow. Also the fins act as external surfaces to increase external heat transfer from the tubes in these heat exchangers. The corresponding heat transfer performance of the fin-and-tube heat Exchanger is highly dependent on the pattern of fins for its dominant thermal resistance for typical applications of air-cooled Heat exchangers; the air-side resistance generally comprises over 90% of the total thermal resistance. The fins are extended surfaces which enhance convective heat transfer to the over-tube fluid but at the same time they increase tube to tube conduction. This phenomenon is undesirable because it degrades the performance of heat exchanger.
In this paper the effect of conduction heat transfer between the tubes of a plate-fin and tube heat exchanger by conduction through the fins has been studied. A two dimensional continuum model is developed to evaluate the fin conduction and conditions under which it may or may not be neglected are determined. The effect of parametric variation such as number of tubes and variation of convective heat transfer has been considered detail. Tube-to-tube conduction is found to degrade the performance of the heat exchanger. It is found that the same heat transfer area distributed in a different number of tubes affects its performance.
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