Numerical investigation on the application of elliptical tubes in a spiral-wound heat exchanger used in LNG plant

The elliptical tubes were proposed to use in a spiral-wound heat exchanger to boost the shell-side transfer rate with the decrease of shell-side pressure drop. The effects of major axis and minor axis of elliptical tubes on thermal hydraulic performance are numerically investigated. The results show that, compared with the circular tube, the SWHE with elliptical tubes have a better heat transfer ability when the shell-side pressure drop is equal to that with circular tubes. With the increase of the major axis of the elliptical tube, the friction factor f decrease firstly and then increase. While with the increase of the minor axis, the variations of the f have an opposite trend with the increase of the major axis. For the heat transfer, the Nu decreases firstly with the increase of major axis and then increases. However, Nu number increases monotonously with the minor axis because elliptical tube bundle promotes the shell-side turbulent mixing. Based on the numerical data, the multi-objective optimization is performed by genetic algorithm. The optimal results show that, by contrast with the original structure, the comprehensive performance (K/△P) of the optimized structures increases by an average of 315.4% and the pumping consumption decreases by an average of 65.5%.