해양플랜트용 휜-튜브 형 방열기 전열특성

Abstract

A fin-tube radiator is a type of compact heat exchanger, where the fluid to be cooled is flowing inside of bundles of round pipe, at which thin plate fins are arranged vertically at regular pitches. The air for cooling is blown parallel to the plate fins, transversely to the bundles of pipe so that the hot fluid in the pipes might be cooled. Due to the densely arranged plate fins, the heat transfer area is extended and the fin-tube radiator shows good cooling performance. In this paper, both numerical and experimental studies have been conducted to estimate the heat transfer characteristics of the fin-tube radiator, with changing the geometric shape of the fin or the supported air velocity. Air is used as a working fluid; the air side thermal resistance occupies about 70 % of the whole thermal resistance, so the inlet air velocity condition takes significant role. Also the surface heat transfer characteristics on the fin is largely affected by geometrical shape of the fin. Different parameters of (i) shape of the plate fin (flat or wavy), (ii) fin pitch, (iii) punching shapes on the surface of the fin and (iv) the inlet air velocity are used to compare the heat transfer characteristics of the fin tube radiator. The results show that the wavy type plate fin is the optimal shape due to its better performance when it comes to heat transfer characteristics compared to the flat plate fin. Moreover, as the inlet air velocity becomes faster, the heat transfer performance also increases. This can be seen in both the flat and wavy type plate fins. And for the punching shapes on the surface of the fin, the case with long and thin punching shapes arranged like a vertical pyramid in the flow direction shows the best performance, regarding the heat transfer and pressure drop together.