Effects of Wall Fins Patterns on the Flue Gas Performance of Condensing Heat Exchanger

Abstract

Heat exchanger is an important element of thermal systems. The wall fins patterns with different shape have strong effects on flue gas flow, which affects the performance of heat exchanger. A numerical model of heat exchanger was established based on computational fluid mechanics theory and the flow and heat transfer characteristics of flue gas were studied by the method of CFD and experiment. The optimal form of the wall fins patterns of flue gas channel was proposed. The results showed that the traditional circular fins reduce the effective contact time and lower the heat transfer efficiency between the flue gas and fin. When the optimal elliptical fins were used, the location of the detachment point was postponed, the effective heat transfer area was increased by 7.6% and the average heat transfer coefficient was increased by 12.1%. At the end, the fitting formula of convective heat transfer coefficient of Nu number was obtained in the optimized conditions.