Simulation Study on Convective Heat Transfer of Flue Gas in Fin-and-tube Heat Exchangers

Taking spiral fin-and-tube heat exchanger as the research object, the inlet and outlet pressure drop and Nusselt number (Nu) were selected to characterize the flow resistance of flue gas and strength of convective heat exchange. Fluent software was used to simulate and analyze the influence of fin structure parameters on the flow resistance and heat exchange effect of heat exchanger under different flue gas flow rates. The performance factors were introduced to evaluate the influence of fin structure parameters on heat exchange performance. The results show that the inlet and outlet pressure drop and Nu increase with the increasing of fin height, thickness and spacing when the flue gas flow rate is constant, and the heat transfer effect is enhanced with the increasing of flow resistance. The variation of fin structure parameters and performance factors is contrary to Nu, The comprehensive performance of heat exchanger is better when selecting the fin parameters with lower height, thinner thickness and sparse spacing. In addition, different from the structure parameters, both Nu and performance factor increase when the flue gas flow rate increases, which can improve the comprehensive heat-transfering performance of the fin-and-tube heat exchanger.