Embedded Fin Tubes for Air Cooled Heat Exchanger

Air-cooled finned tube heat exchangers generally use embedded fin tubes as the main heat dissipation components. The heat transfer coefficient of the finned tubes is influenced by factors such as fin height, spacing, thickness, shape, material, and manufacturing process. When the fin height increases beyond a certain point, further increases can reduce the heat dissipation capacity, lowering fin efficiency. Fins should not be too densely spaced, as this can lead to ash accumulation, difficulty in cleaning, increased process complexity, and higher processing costs.

In embedded fin tubes air coolers, since the convective heat transfer coefficient of air is far lower than that of water, under the conditions of absorbing the same amount of heat and achieving the same temperature rise, the temperature rise of air is 4.2 times that of water, and the volume of air is 830 times that of water. Therefore, air coolers require large air volumes and extensive heat exchange area on the air side.

To improve the heat exchange efficiency of air coolers, the vast majority of them employ finned tubes as the heat transfer components. Because air passing over the fins causes almost no pollution or corrosion, and under most operating conditions, surface ash accumulation and structural issues are not severe, the fin density of the finned tubes used in air coolers is very high, with a fin ratio that can exceed 20. The fin material is mostly aluminum, while the base tube material is typically carbon steel or stainless steel, with embedded fin tubes being the most widely used.

The contact thermal resistance of embedded fin tubes is very small. Additionally, the integral aluminum fins completely isolate the base tube from the air, and they are easy to process and have low manufacturing costs, making them the preferred choice in the air cooler industry.

Commonly used specifications for embedded fin tubes are: base tube outer diameter: D = 20–25 mm; fin height: 10–15 mm; fin spacing: 2.5–4 mm; fin thickness: 0.3–0.6 mm; and fin ratio: 15–25.