Optimization Research On Structured Packing And Offset Strip Fin

In the process of mass transfer and heat transfer,the performance of the tower equipment and the plate fin heat exchanger are greatly depended on the internal components,such as the packing and the fin.Because of the excellent mass transfer performance of the structured packings and excellent heat transfer performance of offset strip fins,they are widely used in the actual industrial production,and it has practical application value to optimize them.In order to improve the performance of mass transfer and heat transfer,the CFD numerical simulation is used to optimize the structured packings and offset strip fins.For structured packings,Mass transfer occurs on the wall,two stands of gas collide in the middle of channels,that forms many vortexes,which can strengthen mass transfer to some extent,while consume lots of energy,and increase pressure drop.To decrease press drop,a baffle was added in the middle of each mass transfer unit without valleys.This structured packing is Mon-JKB-250 Y.CFD numerical simulation was used,when the length(?)of baffle was 12.6mm,F=0.9~2.7,pressure drop decreased by(28~32)%,gas-side total mass transfer efficiency increased by(3.1~5.5)% and mass transfer coefficient at per pressure drop increased by(29~38)%.With the increase of ?(0~21mm),pressure drop decreased remarkably,gas-side total mass transfer efficiency improved,mass transfer coefficient at per pressure drop increased first and then decreased.And when the length was 16 mm,mass transfer coefficient at per pressure drop was best.When the length was longer than 16 mm,the changes of pressure drop and gas-side total mass transfer efficiency were small.So Mon-JKB-250 Y with a baffle of length about 16 mm was the best optimization.A chromochemical reactive flow visualization technique was employed to verify the data from CFD,average relative error was about 10%,so CFD numerical simulation results were reliable.For offset strip fins,heat transfer coefficient is maldistribution along the direction of fluid flow,and more uneven on the perpendicular to the direction of flow.Heat transfer coefficient in central is greater than the edge.In order to increase the heat transfer coefficient,the uniformity of heat transfer coefficient of offset strip fins was improved.To strengthen the heat transfer in the edge,V shaped corrugations were add on the center of the surface of offset strip fins,part of fluid in the central region was led to the edge of the fins.At the same time,V shaped corrugations increased the disturbance in the boundary layer of the central region,so the heat transfer in the center region of the fin was further strengthened.CFD numerical simulation was used,it showed that under the conditions of this paper,the pressure drop of offset strip fins increased along the increase of the height and span of the V shaped corrugations;The heat transfer coefficient was maximum when the height of V-corrugation is 0.2mm,and the heat transfer coefficient increased along the increase of the span of V-corrugation;V-corrugation,V-arc-corrugation and arc-corrugation can increase the uniformity of heat transfer coefficient of offset strip fins and increase the heat transfer coefficient,the optimization effect of V-corrugation and V-arc-corrugation was better than arc-corrugation.So,V-corrugation or V-arc-corrugation whose height is 0.2mm added on the center of the surface of offset strip fins has the best heat transfer enhancement effect.