Performance Research And Structural Optimization Of Vertical Fin And Flat Tube Heat Exchangers

The development and manufacturing technology of new and highly efficient heat exchanger has been a hot research in the field of energy use.It is directly related to the energy efficiency in chemical industry, electric power, petrochemical and other industries.Because heat exchangers which are widely used in high temperature and corrosive gas with dust of chemical industry, electric power, petrochemical and other industries have some shortcomings such as large gas-side resistance, cleaning difficulties and low heat transfer efficiency, as well as vertical fins and flat tubes have the unique advantages, the paper propose a new type of heat exchanger - the vertical fin and flat tube heat exchanger.Due to gas flowing along axial direction of the flat tube, paralleling to the direction of water flow, the design can enhance heat transfer, reduce air-side resistance and desposit, and be easy to maintain.Based on fluid mechanics theory and heat transfer theory, this paper treated the vertical fin and flat tube heat exchanger as the research object to analyze its characteristics of flow and heat transfer to identify the main factors impacting its performance in numerical simulation methods, and to optimize fin structure and the flat tube.In the numerical simulation, fluent software was used to study the effect of the length, height and pitch of fin on flow and heat transfer performance of the rectangle plain-fin. On this basis, the 400mm-long fin structure when the import speed of wind is 2m/s was optimized by orthogonal experiments, and got a group of better fin parameters (height of 25mm, fin pitch of 2.7mm). By comparing and analyzing heat transfer and flow characteristics of the optimized structure and the original structure, the conclusion that fin tubes had different optimized structure at different speeds was got. Aslo the paper Proposed and studied the ameliorating method - fin-hole to improve its performance.In the fin-tube optimization, the original fin structure was optimizated by Qfin software, and got better fin structures at different speeds. This is a reference for the vertical fin and flat tube heat exchanger in engineering applications. By analyzing two kinds of optimization process in Qfin, the conclusions were as follows: Effect of fin pitch (fin number) on the thermal resistance and the average convective heat transfer coefficient was greater than fin high's impact. In the optimization process, fin pitch played a decisive role; the effect of heat source on the average convective heat transfer coefficient was very small, and it almost had no effect on the thermal resistance, as well as pressure drop decreased as the heat source temperature's increase.In engineering applications, according to the special requirements of transformers and the shortcoming of the traditional heat exchanger - plate-fin heat exchanger used in transformers, this paper proposed the vertical fin and flat tube heat exchanger that was used to cool transformer. Taking a small transformer for example and based on the research findings of vertical fin and flat-tube heat exchanges, the author designed matching heat transfer equipment for transformers, and this also provides a reference for vertical fin and flat tube heat exchangers used in practical engineering in the future.