Effects of fin shape and parameter on the flow and heat transfer performance of finned tube heat exchangers

Three-dimensional numerical simulations are conducted by using Fluent software to investigate the effect of rectangular fin length to span ratio (L/W), fin thickness and Reynolds number (Re) on fluid flow and heat transfer as well as fin efficiency (eta(f)). The comparison of rectangular fins with circular fin having the same heat transfer area is performed. The steady laminar flow model is adopted for Re = 500 similar to 5000. The flow visualization shows that the proper L/W and Re can make recirculation zone behind the tube disappear, and thus enhance the heat transfer (Nusselt number Nu(f,t)) as well as detract the friction factor (f). The eta(f) decreases with increasing L/W vand Re. The influence of fin thickness on the Nu(f,t) is related to the range of Re, and its increase causes an increase in pressure drop (Delta P) and fin efficiency. By comparison, it is found that the circular fin has the highest eta(f), the lowest Delta P and the smallest Nu(f,t).