This article relates to a type of H-type finned tube, particularly focusing on an axially penetrating H-type finned tube and its heat exchange tube bundle, which is applicable to various types of heat exchange and heating equipment in industries such as power, petroleum, chemical engineering, refrigeration, metallurgy, etc.

 

 

With the sustained rapid development of Chinas economy, issues related to energy supply shortages are becoming increasingly prominent, making energy conservation, emission reduction, and consumption reduction inevitable requirements for the countrys economic and social development. Heat exchangers, as important components of industrial processes in fields such as power, petroleum, chemical engineering, refrigeration, metallurgy, and even aerospace/rocketry, hold significant importance for safe and efficient operation. Among various heat exchange equipment, increasing heat transfer area through fins is a common method to enhance heat transfer efficiency.

 

H-type finned tubes, also known as H-type fins or ribbed tubes, are also referred to as butterfly fin tubes. They are formed by symmetrically welding two steel plates with arcs in between onto a bare tube, hence named for their frontal shape resembling the letter "H". Research and practice have shown that H-type finned tubes can significantly increase heat transfer area, enlarge the cross-section of flue gas flow, reduce flue gas velocity, and decrease ash accumulation and wear. However, despite their good resistance to ash accumulation and wear, in the presence of ash-laden gas flow, due to the viscous effect of the fluid itself and the presence of adverse pressure gradients, flow separation inevitably occurs, forming a vortex stagnation zone on the lee side of the finned tube. This leads to continuous ash accumulation on the lee side, causing localized heavy ash deposition, which severely affects the heat transfer efficiency of the finned tube and the safe and efficient operation of the heat exchanger. Through structural analysis of H-type finned tubes, it has been found that in the passage of ash-laden gas flow through H-type finned tubes, there is almost no gas disturbance in the local space between each pair of fins, and the gas flow in this local space approximates laminar flow, making it difficult for ash particles to flow between different fins, further exacerbating ash accumulation. Therefore, it is an effective method to reduce ash accumulation by taking necessary structural optimization to decrease the area of vortex stagnation zone. This is proposed under such circumstances.

 

From the existing situation, this article proposes an elliptical H-type finned tube. The elliptical tube does indeed reduce flow resistance to some extent compared to a circular tube, but because the overall structure does not undergo significant changes, it does not disrupt the vortex stagnation zone, thus providing limited improvement in ash accumulation. Various s have suggested enhancing heat transfer by installing certain longitudinal vortex generators, but compared to this , the longitudinal vortex generators disclosed in those s have insufficient height in the direction perpendicular to the fins, leading to a decrease in heat transfer and ash accumulation resistance when the distance between fins is large. H-type finned tubes are all achieved by various deformations to the outer edge of the fins of conventional H-type finned tubes, allowing heat exchange on discontinuous surfaces. Although this structure can effectively increase the finning ratio of heat exchange tubes and reduce fin spacing, the wear on the outer edge of the fins will be more severe under high-speed ash-laden airflow, reducing the lifespan of the finned tubes.

 

 

To address the problems existing in the prior art, the purpose of this article is to provide an axially penetrating H-type finned tube and its heat exchange tube bundle, by adding guide vanes overall to reduce flow separation, decrease the area of vortex stagnation zone, thereby reducing ash accumulation on the lee side of the H-type finned tube, and improving the operation of the heat exchanger.