Numerical analysis for thermo-hydraulic performance of staggered cross flow tube bank with longitudinal tapered fins

Abstract

Cross flow tube bank is an important constituent in most of the industrial heat exchanging systems such as Heating Ventilation and Air Conditioning (HVAC) systems, Waste Heat Recovery systems and Industrial Boilers. Considering the depletion of fossil fuels and allied environmental concerns, there is a huge need for improving the performance of the cross flow tube bank. The present numerical study investigates the effect of longitudinal taper fins on external flow over staggered cross flow tube bank. The longitudinal fins of various length (0.50 ≤ L/D ≤ 1.50), base thickness (0.40 ≤ T/D ≤ 0.80) and end thickness (t/D = 0.12 and 0.28) are used to evaluate the thermal performance of the tube bank. The thermal hydraulic performance is evaluated considering the effects on rate of heat transfer along with pressure drop characteristics across the tube bank. The results shows that the use of longitudinal taper fins significantly enhances the thermal hydraulic performance of cross flow tube banks. Moreover, the increase in length of fin results in an appreciable enhancement in Nusselt number, which overrules the increase in pressure drop penalty. Whereas, the increase in the fin base thickness, results in a significant reduction in pressure drop capable of compensating the reduction in Nusselt number. Hence, increase in both these dimensions results in higher thermal hydraulic performance than the bare tube bank. On the other hand, fin end thickness plays only a minor role in the finned tube bank performance. Lowering the value of fin end thickness slightly increase the thermal performance by suppressing the friction factor.