The elliptical finned tube is a heat exchange element composed of a elliptical base tube and outer fins. The common ones are elliptical tube with rectangular fins finned tubes, elliptical tube with elliptical finned tubes, elliptical tube with round finned tubes, spiral elliptic flat tubes, elliptical H-shaped finned tubes and so on. Oval finned tubes are receiving attention due to their superior performance to round finned tubes. Oval finned tubes have been widely used in industrial fields such as ethylene and oil refining. The elliptical finned tube is used as a high-efficiency heat exchange element in heat exchange equipment. The small flow resistance outside the tube and high heat exchange efficiency make the heat exchange equipment compact, lightweight, efficient and miniaturized.
According to the fin arrangement, there are two types of finned tubes: longitudinal finned tubes and horizontal finned tubes. According to the shape of the base tube, the finned tube includes round finned tube, elliptical finned tube and flat tube finned tube. On the market, round finned tube heat exchangers play a leading role, but a large number of experiments have shown that, compared with round finned tubes, the backflow area and windward area of the elliptical tube are much smaller, which effectively reduces the air side. When the number of tube bundles is the same, the elliptical tube and the flat tube are more compact than the round tube structure, and the volume of the heat exchanger is smaller, which reduces the cost.
Features of elliptical finned tube
(1) Compared with round-tube finned tubes, elliptical finned tubes are easier to achieve compact layout, which reduces the overall volume of the entire heat exchanger, thereby reducing the footprint.
(2) Due to the shape characteristics of the elliptical finned tube, the air side resistance is small, and the heat transfer coefficient between the fluids is increased; the thermal resistance in the tube is relatively small, which increases the heat transfer of the fluid in the tube.
(3) The heat transfer area of an elliptical finned tube is larger than that of a round tube with the same cross-sectional area. This is because the heat transfer periphery of the elliptical tube is relatively long under the same cross-sectional area.
(4) The most commonly used elliptical fin tube is rectangular steel fin, which has high strength, and the base tube is not suitable for freezing and cracking in winter and has a long service life.
(5) Since the elliptical finned tube can be arranged more compactly, the front row tube has a greater impact on the rear row. The fin spacing of the rear row tube can be increased to reduce the flow resistance outside the tube, but the number of tube rows should not be too large.