Numerica Simulation And Structural Optimization Based On FLUENT For Corrugated Tube Heat Exchanger

With the development of society and the improvement of living standard, the contradictions that energy demand increases with the earth resource exhaustion are constantly increasing. Developing all kinds of efficient heat exchanger and rational use of energy is one of main ways to ease the conflict. Corrugated tube heat exchanger is a new type of heat exchanger. It has good performance of heat transfer. The flow and heat transfer characteristics of corrugated tube heat exchanger is studied by FLUENT in this thesis. The main works of this paper are summarized as follows:Firstly, the3D modeling of corrugated tube heat exchanger tube was simulated by FLUENT, and water was used as a medium in the study. In the flow characteristics, the comparative analysis of the corrugated tube and corresponding straight was carried out for velocity filed, velocity vectors, flow charts and pressure filed. Research shows that, under the influence of the structure, the velocity of the fluid in the corrugated tube is periodic distribution. And the recirculation zones are formed in the peaks. The pressure drop of the corrugated tube is much greater than the straight tube. In the heat transfer characteristics, the temperature field was compared between the corrugated tube and straight tube, and the field synergy principle was used to analysis the both of heat transfer performance. The local Nu number of the corrugated tube was studied and the average Nu number of the two kinds of tubes was compared. The min and max values of local Nu number were seen respectively in the upstream and contraction section of a peak. The average Nu number of the corrugated tube is greater than straight tube.Secondly, the no baffle shell (KC_BJG32and KC_GG_Y) and baffle shell (KC_GG_Y) were modeled and simulated. In the flow characteristics, the comparative analysis of the no baffle shell and baffle shell was carried out for velocity filed, velocity vectors and pressure filed. Result show that the baffle plate is the main factor to affect the flow characteristics of the shell side. It can greatly improve the shell-side flow conditions, but the pressure loss will increase rapidly too. In the heat transfer characteristics, the temperature fields of the3shells were comparative analyzed. And the comprehensive performance assessment of the3 shells was carried out with the standard of heat flow per pressure drop. We can find that the comprehensive performance of KC_GG_Y is the worst.Thirdly, the corrugated tube geometry parameter (D1,S1,S2,S) as variables,3series of15corrugated tubes were designed to optimization analyze. The results show that D1and S are most important parameters for enhanced performance of the corrugated tube. The dimensionless number ε0=(D1-D2)/S was introduced to link the D1and S. When ε0=O.28O, the corrugated tube has the best performance.At last, the simulation results of the straight tube such as△P, Nu and△P' were verified by engineering formula and experimental correlations. The maximum deviations of the three respectively are13.5%,22.57%,13.81%, with the flow velocity increasing, the deviation decreases gradually. And the reliability of simulation results was verified.