Heat Transfer Enhancement of Partially Serrated Twisted Finned Tube Bank

Abstract

Due to the large thermal resistance on the airside of the air-cooled heat exchangers, it is necessary to improve heat transfer performance and reduce flow resistance by improving the fin structure. In this paper, partially serrated finned tube bank was proposed and numerically investigated. The experimental system of finned tube bank was built to verify the correctness of the numerical simulation. The finned tube bank is twisted and serrated on the windward side to enhance heat transfer. Moreover, the non-grooved sector region on the leeward side reduces the flow resistance and improves the temperature uniformity of the fins. The effects of fin twisting of the windward side and non-grooving angle of the leeward side were explored. Nusselt number and friction factor decrease as the leeward non-grooving sector region increases. The correlations of Nusselt number and friction factor were derived based on the simulation results of partially serrated twisted finned tube banks with 120° non-grooving region on the leeward side. Nusselt number, friction factor and comprehensive heat transfer coefficient of partially serrated twisted finned tube bank are 13.3%, 13.0% and 10.5% higher than that of annular finned tube bank with Reynolds number from 6200 to 20,600, respectively.