Abstract
The purpose of this study is to develop the internal finned tube for the shell-type fire-tube boiler. The parallel plate fins are made by the aluminum hot extrusion. The fin units are installed into the boiler tubes by the pressure welding, thus, the thermal resistance is vanished. On this experiment, the plate fin was 24mm of the maximum height and 2mm of the thickness, and arranged in 6mm pitch. The local heat-transfer coefficient is estimated by the inverse problem of the heat conduction problem. The high heat transfer coefficient appears at the inlet region, and decreases rapidly. By cutting the fin unit in 100mm length and reconstructing the finned-tube with the 15mm clearance between the fin units, the heat transfer coefficient is increased by the edge effect. The heat transfer rate becomes about 17 times to that of the bare tube.
