Numerical Research on Shell Side Performance of a Helically Coiled Special-shaped Tube Heat Exchanger
The shape of the helically coiled tube has significant impacts on the heat transfer capacity of helically coiled tube heat exchangers.Eight different helically coiled tubes with different cross-sectional shapes are established in this paper.The effects of different cross-sectional shapes on the shell side heat transfer performance of helically coiled tube heat exchangers are investigated by numerical simulation.Compared with the traditional round tube,the trilobal tube and drop-shaped tube are likely to cause larger perturbation to the shell side,which enhances the comprehensive heat transfer performance of the helically coiled tube heat exchanger.The trilobal tube gets the largest heat transfer performance among the studied eight tubes.The effects of different scouring methods on the shell side performance of helically coiled trilobal and helically coiled drop-shaped tube heat exchangers are further analyzed.The results show that,under the same inlet conditions,the shell side Nusselt number of helically coiled trilobal tube heat ex-changer is increased by 11.8％～15.5％,and the drag coefficient is increased by 41.9％～49.6％compared with the traditional round tube type.The shell side Nusselt number of the helically coiled drop-shaped tube heat exchanger is increased by 2.8％～4.3％,and the drag coefficient is increased by 3.2％～6.8％compared with the traditional round tube type.In the studied range of Reynolds number from 2 603 to 5 206,the comprehensive heat transfer per-formance of the trilobal tube heat exchanger with the angle of 0° between the tube cross-section and the flow direc-tion is the best,while the drop-shaped tube heat exchanger with the tube cross-section and the flow direction of the countercurrent form of the integrated heat transfer performance is the best.The comprehensive heat transfer per-formance of the water drop tube in reverse flow direction is better than that of the layout along the flow direction.
helically coiled tubespiral wound heat exchangerspecial-shaped tubeshell sideheat transfer per-formance
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