Multi-objective NSGA-II based shape optimisation of the cross-sectional shape of passively cooled heat sinks

Purpose: The purpose of the study is to optimise the cross-sectional shape of passively cooled horizontally mounted pin fin heat sink for higher cooling performance and lower material usage. Design/Methodology/Approach: Multi-objective shape optimisation technique is used to design the heat sink fins. Non-dominated sorting genetic-algorithm (NSGA-II) is combined with a geometric module to develop the shape optimiser. High fidelity Computational Fluid Dynamics (CFD) is used to evaluate the design objectives. Separate optimisations are carried out to design the shape of bottom row fins and middle row fins of a pin-fin heat sink. Finally, a computational validation was conducted by generating a 3D pin-fin heat sink using optimised fin cross-sections and comparing its performance against the circular pin-fin heat sink with the same inter-fin spacing value Findings: Heat sink with optimised fin cross sections, has 1.6% higher cooling effectiveness than circular pin-fin heat sink of same material volume, and has 10.3% higher cooling effectiveness than the pin-fin heat sink of same characteristics fin dimension. The special geometric features of optimised fins which resulted in superior performance are highlighted. Further, Pareto optimal fronts for this multi-objective optimisation problem are obtained for different fin design scenarios Originality/Value: For the first time, passively cooled heat sink’s cross sectional shapes are optimised for different spatial arrangements, using NSGA-II based shape optimiser, which makes use of CFD solver to evaluate the design objectives. The optimised, high performance shapes will find direct application to cool power electronic equipment.