Multi-objective optimization on shell-side performance of rod-baffle heat exchangers with twisted oval tubes

Based on genetic aggregation response surface models and multi-objective genetic algorithms, the effects of key structural parameters and inlet velocities on the shell-side flow and heat transfer of rod-baffle heat exchangers (RBHXs) with twisted oval tubes were investigated. The performance of twisted-oval-tube RBHXs was optimized. The results show that the heat transfer coefficient h decreases by 9.38% firstly and then remains constant with the increase of the pitch and it increases with the ratio of long axis to short axis under lower inlet velocities and decreases firstly and then increases when inlet velocities are higher. When the inlet velocity is 0.1 m/s, the heat transfer coefficient increases by 45.92% with the ratio of long axis to short axis. When the inlet velocity is 0.5 m/s, the heat transfer coefficient decreases by 12.96% firstly and increases by 7.74% then. The pressure drop Δp is constant with the increase of the pitch; the increase with the ratio of the long and short axes is reduced by 36.67%. The sensitivity analysis shows that inlet velocities influence the heat transfer coefficient and pressure drop more than structural parameters and the ratio of long axis to short axis of structural parameters influences output parameters more than the pitch, which provides theoretical guides for structure improvement and inlet velocities selection of RBHE given structure and inlet velocities. Three sets of optimal results were obtained by employing multi-objective genetic algorithms to maximize the heat transfer coefficient and minimize the pressure drop simultaneously on response surfaces. Compared with the original structure, the heat transfer coefficient increases averagely by 19.17%; the pressure drop decreases by an average of 5.74%; the comprehensive performance h/Δp is enhanced by 26.42%. © All Right Reserved.