Multi-objective optimization of an offset strip fin heat exchanger applied to fuel cell electric vehicles for cooperative cooling
Gitaek Jung, Junhyuk Kim, Hongseok Choi, Hoseong Lee
Abstract
A cooperative cooling system based on an offset strip fin heat exchanger (OSFHX) was applied to cool the heat generated from the stack and power electronics (PE) of a fuel cell electric vehicle (FCEV). Furthermore, a multi-objective optimization was conducted for the fin geometries of two sections of the OSFHX to enhance the cooperative cooling performance of the system. The heat transfer rate and pumping power required to operate the heat exchanger were set as the objective functions considering nine independent geometric variables. The fin optimization on the hot fluid side of the OSFHX increased the heat transfer rate by 18.5 % and reduced the pumping power by 6.5 %. Meanwhile, the optimization on the cold fluid side resulted in a 25.6 % increase in heat transfer rate and 35.1 % reduction in pumping power. Full optimization of the OSFHX yielded a 36.7 % increase in heat transfer rate and 42.7 % decrease in pumping power. Previous studies typically focused on performance enhancement by optimizing a single fin or section. To conclude, optimizing the fins on both sides of the heat exchanger considering the operating flow rate yielded improved thermal–hydraulic performance compared with optimizing a single section. In this study, the main factors that significantly influenced the OSFHX performance were the fin geometry and operating flow rate of the fluid. This demonstrates that 1) the optimal fin geometry of the OSFHX varies according to the operating conditions and 2) performance improvements can be achieved by designing the OSFHX considering these conditions.