Effects of the shape of tube and flow field on fluid flow and heat transfer

Abstract

The arc tube is an innovative heat exchange device that has the advantages of high heat exchange efficiency, which slows down the damage thermal stress to the pipeline and high mass transfer rate, in comparison to the traditional straight wall tubes. Therefore, it is widely applied in the field of heat and mass transfer, particularly in heat exchanger. To study the influence of the ratio of the circumscribed arc radius of the arc tube on the heat transfer and flow resistance characteristics of the fluid inside the tube, geometric models of sine wave wall tubes with various radius ratio i, and the same size parameters have been established. The flow field and temperature field in the tube have been analyzed by numerical simulation and experiment, and the comprehensive heat transfer performance of different wave-wall tubes has been evaluated using the performance evaluation factor PEC. The results show that the heat transfer capacity is stronger for the smaller i. Further, Nu decreases with increasing i, and the reduction decreases with increasing Re. The frictional resistance coefficient at 1 is proportional to i at radius ratio between 0.1 and 1, and the frictional resistance coefficient is inversely proportional to i at 1 < i < 10. When i = 1, the frictional resistance coefficient appears to be the maximum, PEC increases as Re increases and the PEC of external tangential arc wave wall tube is higher than the sine wave wall tube. To improve the heat transfer efficiency of the sine wave wall tube, a pulsating flow field has been applied to the flowing fluid in the wave wall tube. It has been found that the application of the pulsating flow field can improve the heat transfer coefficient of the fluid in the wave wall tube, and the pulsation parameter has a greater impact on the heat transfer coefficient.