Development And Optimization Of New Double Torsional Flow Heat Exchanger Based On Orthogonal Baffles

With the continuous improvement of China's economic and social development,more and more attention has been paid to the efficient use of energy and environmental protection.As an important energy-using equipment in the industrial field,the enhanced technology of shell and tube heat exchangers has received widespread attention at home and abroad.The torsional flow heat exchanger is a new type shell and tube heat exchanger with high efficient.The orthogonal structure of the baffle plate promotes the fluid form periodic torsional flow in the shell side.Compared with the traditional bow-shaped baffle heat exchanger,the shell-side pressure drop of the torsional flow heat exchanger is effectively reduced,and the heat transfer coefficient is higher than that of the spiral flow heat exchanger.But this new type of heat exchanger still has room for optimization and improvement.Based on the study of shell-side flow pattern and heat transfer performance of torsional flow heat exchangers and spiral flow heat exchangers,this paper proposes three new tube bundle support structures,and optimizes their performance.The main research contents and conclusions are as follows:1.Numerical simulations of torsional flow heat exchanger and spiral flow heat exchanger are performed in this paper.The distribution of velocity field and temperature field in the shell side of two heat exchangers were studied respectively,and the influence of baffle structure on the physical field in the shell side was compared and analyzed,as well as the relationship between the physical field distribution and the heat exchanger performance.The results show that compared with the spiral flow heat exchanger,the heat transfer coefficient,resistance factor and comprehensive performance of the torsional flow heat exchanger are increased by 49-78%,88-94%,and 22-44% respectively under the same Re.The heat transfer performance of the heat exchanger is better than that of the spiral flow heat exchanger.2.A cold-state experimental platform of torsional flow heat exchanger was set up.The velocity components in the two directions of the shell-side fluid of the heat exchanger were measured by LDV,and the corresponding numerical simulation data was extracted.The accuracy of the numerical simulation results was verified by experimental comparison method.The comparison result between experimental data and simulation data shows that the maximum error is 21%,and the remaining data errors are controlled within 16%.The simulation results agree well with the experimental data.In view of the inevitable scale differences and boundary condition differences between experiments and numerical simulations,the accuracy of the simulation results is within an acceptable range.3.According to the relationship between the shell-side structure and performance of torsional flow and spiral flow heat exchangers,and combined with the geometrical characteristics of the high heat transfer performance areas of the them,a double torsional flow heat exchanger structure was designed and developed.The physical distribution,heat transfer performance and field synergy characteristics of the shell-side physical field of the double torsional flow heat exchanger were compared and analyzed.The comparison results show that the fluid in the shell side of the double torsional flow heat exchanger has longer streamlines than the original structure,and the flow field distributed more uniformly.4.The response surface optimization method is used to optimize the baffle parameters of the new double torsional flow heat exchanger.The optimization results show that the overall optimization results of the heat exchanger are moving in the direction of decreasing the baffle inclination angle,increasing the plate width,and decreasing the baffle spacing.The prediction accuracy of the response surface optimization results is verified.The errors between the predicted values of the heat transfer coefficient,pressure drop,comprehensive performance evaluation values and the numerical calculation results are small,which proves the accuracy of using the response surface to optimize the structure of the heat exchanger.