Effect of Fin Array Parameters on Variation in Heat Transfer Coefficient for Natural Convection in Fin

摘要

Fins are usually analyzed by assuming uniform heat transfer coefficient model on its surface. However, studies by various investigators revealed that it is not constant but varies along the fin length. It is mainly because of non-uniform resistance experienced by the fluid flow in the inter fin region. Obviously, this variation is functions of fin array parameters such as inter fin spacing (S), fin height (Hf) & fin tip clearance (C) as they largely influence the resistance to the fluid flow. The objective of the present work is to establish experimental relationship between the variations in the heat transfer coefficient along the fin height (Length) with respect to the fin array parameters fin spacing (S), fin height (Hf) & fin tip clearance (C). Experiments were performed for five different values of inter fin spacing (S) and tip clearance (C) and best fit curve of the type h = ax{sup}n was obtained. The values of 'a' and 'n' were then correlated with the appropriate dimensionless fin array parameters thus variation in the heat transfer coefficient with respect to the fin array parameters is obtained It is found that average heat transfer coefficient varies hyperbolically (for constant clearance C= 6) with respect to S/Hf Also the value of n is fairly constant at 0.065 while value of a is decreasing as (S) inter-fin spacing is increasing indicating that the average value of 'h' also decreases with increase in 'S'. It is found that average heat transfer coefficient varies parabolically (for constant inert-fin spacing S= 5.5cm) with respect to C/S with minima occurring around C/S =0.55 Also the value of n is decreasing with increasing clearance and at C=6it again increases indicating rise in heat transfer coefficient