Sensitivity and stress analysis of serrated fin structure in plate-fin heat exchanger on cryogenic condition

Abstract

The effects and interaction effects of fin height, fin space, fin thickness and fin interrupted length on flow resistance, heat transfer and stress of plate fin heat exchanger (PFHE) on cryogenic condition are analyzed quantitatively, based on computational fluid dynamics (CFD), fluid structure interaction (FSI), response surface methodology (RSM) and sobol sensitivity analysis. The stress distribution in serrated fin structure shows that the large stress is mainly distributed in the regions of keen-edged geometric structure such as weld joint region and the region connecting two rows of fin. The sensitivity analysis results reveal that j factor is the most sensitive to fin interrupted length, and f factor and maximum stress are most sensitive to fin thickness. The sobol sensitivity analysis results show that, for j factor and maximum stress, it is sufficient to investigate the first-order sensitivity indices and high-order sensitivity is weak. For f factor, it is necessary to consider the second-order sensitivity, especially for fin space and fin thickness. Based on above analyses, by combining with Multi-Objective Genetic Algorithm (MOGA), the serrated fin structure is optimized from perspective of two objectives (maximizing JF factor and minimizing maximum stress) and three objectives (maximizing j factor, minimizing f factor and minimizing maximum stress). In general, the optimization results based on two objectives are more intuitive, and they offer a smaller solution space. An original point is optimized, the results reveal that, compared with original point, JF factor of optimized point 1 increases by 17.8% without changing maximum stress, while maximum stress of optimized point 2 decreases by 50.0% without changing JF factor.