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Purpose The purpose of this paper is to investigate the optimal geometry parameters in a dimple/protrusion-pin finned channel with high thermal performance.Design/methodology/approach The BSL turbulence model is used to calculate the flow structure and heat transfer in a dimple/protrusion-pin finned channel. The optimization algorithm is set as Non-dominated Sorting Genetic Algorithm II (NSGA-II). The high Nusselt number and low friction factor are chosen as the optimization objectives. The pin fin diameter, dimple/protrusion diameter, dimple/protrusion location and dimple/protrusion depth are applied as the optimization variables. An in-house code is used to generate the geometry model and mesh. The commercial software Isight is used to perform the optimization process.Findings The results show that the Nusselt number and friction factor are sensitive to the geometry parameters. In a pin finned channel with a dimple, the Nusselt number is high at the rear part of the dimple, while it is low at the upstream of the dimple. A high dissipative function is found near the pin fin. In the protrusion channel, the Nusselt number is high at the leading edge of the protrusion. In addition, the protrusion induces a high pressure drop compared to the dimpled channel.Originality/value The originality of this paper is to optimize the geometry parameters in a pin finned channel with dimple/protrusion. This is good application for the heat transfer enhancement at the trailing side for the gas turbine. [ABSTRACT FROM AUTHOR]

Purpose - The purpose of this paper is to show how, with a view to the shortcomings of traditional optimization methods, a multi-objective optimization concerning the structure sizes of micro-channel heat sink is performed by adaptive genetic algorithm. The optimized micro-channel heat sink is simulated by computational fluid dynamics (CFD) method, and the total thermal resistance is calculated to compare with that of thermal resistance network model. Design/methodology/approach - Taking the thermal resistance and the pressure drop as goal functions, a multi-objective optimization model was proposed for the micro-channel cooling heat sink based on the thermal resistance network model. The coupled solution of the flow and heat transfer is considered in the optimization process, and the aim of the procedure is to find the geometry most favorable to simultaneously maximize heat transfer while obtaining a minimum pressure drop. The optimized micro-channel heat sink was numerically simulated by CFD software. Findings - The results of optimization show that the base convection thermal resistance contributes to maximum the total thermal resistance, and base conduction thermal resistance contributes to least. The width of optimized micro-channel and fin are 197 and 50?µm, respectively, and the corresponding total thermal resistance of the whole micro-channel heat sink is 0.838?K/W, which agrees well with the analysis result of thermal resistance network model. Research limitations/implications - The convection heat transfer coefficient is calculated approximately here for convenience, and that may induce some errors. Originality/value - The maximum difference in temperature of the optimized micro-channel cooling heat sink is 84.706?K, which may satisfy the requirement for removal of high heat flux in new-generation chips. The numerical simulation results are also presented, and the results of numerical simulation show that the optimized micro-channel heat sink can enhance thermal transfer performance. [ABSTRACT FROM AUTHOR]