Investigation On The Performance Of One New Small Shell-and-Tube Heat Exchanger With Vortex-Shaped Tubes

Heat exchangers are widely used in many fields.Among all types of heat exchangers,shell-and-tube heat exchangers are more common in industrial applications due to their reliable structure,wide application range.The different flow patterns on the shell side have a significant effect on the performance of the shell-and-tube heat exchanger.The longitudinal flow heat exchanger has become the focus of scholars at home and abroad due to its small flow resistance and high heat transfer performance.In order to improve the comprehensive performance of the heat exchangers,baffles are added to the shell side of heat exchangers which will lead to a significant increase in pressure loss and power consumption in the shell side of heat exchangers.In this paper,one new type of shell and tube heat exchanger with vortex-shaped tube is proposed.Vortex tube can significantly improve the thermal efficiency of the heat exchanger without causing excessive pressure loss by drawing on the enhanced heat transfer performance and flow resistance reduction characteristics of the dimple tube.In this paper,a counter-current-flow smooth tube heat exchanger,a counter-current-flow vortex tube heat exchanger,and three smooth tube heat exchangers with different baffle spacing,vortex tube heat exchanger with a baffle spacing of 187.5 mm are established under certain simplifying assumptions.The three-dimensional numerical simulations are carried out by the realizable k-? turbulence model.The results show that compared with the smooth tube,the vortex structure can improve the heat transfer coefficient of the heat exchanger tube and shell side,and the heat transfer coefficient and pressure loss in the tube increase more.The comprehensive performance of the tube side is better than the shell side.Compared with the heat exchangers with different baffle spacing,at Re_in>5000,the heat transfer performance of the counter-current-flow vortex tube heat exchanger is better than that of the smooth tube heat exchanger with the smallest baffle spacing.The shell-side heat transfer performance of the counter-current-flow vortex tube heat exchanger is poor,indicating that the factors affecting the shell-side heat transfer and flow characteristics in this paper are the baffles rather than the wall shape changes.In order to further improve the shell-side heat transfer performance of the counter-current vortex tube heat exchanger,baffles are provided in the shell side of the counter-current-flow vortex tube heat exchanger.In this paper,the shell side flow and heat transfer characteristics of a vortex tube heat exchanger with a baffle spacing of 187.5 mm are studied in case of where there are gaps and no gaps in the vortex tubes and the baffles.The results show that the shell-side heat transfer performance of the vortex tube heat exchanger with a baffle spacing of 187.5 mm is improved and the shell-side pressure loss is effectively reduced.If the heat transfer performance is equivalent,the number of baffles can be reduced,and the pressure loss and power consumption can be reduced.At the same time,the flow field and temperature field distribution are more uniform,which makes the operation of the heat exchange equipment more safe and stable,and improves the usage time.When there are no gap between the vortex tubes and the baffles,the shell-side heat transfer performance of the vortex tube heat exchanger is more significant.When there are gaps between the vortex tubes and the baffles,the shell-side pressure drop loss of the vortex tube heat exchanger is significantly reduced.