Numerical optimisation of conjugate Hexagonal cooling channels with internal heat generation using Al2O3-water nanofluid

Abstract

Papers presented to the 11th International Conference on Heat Transfer, Fluid Mechanics and Thermodynamics, South Africa, 20-23 July 2015.This paper presents a three-dimensional geometric optimisation of conjugate cooling channels in forced convection with internal heat generation within the solid. Hexagonal cooling channels configuration are considered and Al2O3-water nanofluid is used as cooloing fluid because of its promising superior thermal properties over traditional cooling fluids The main objective is to optimise the configuration in such a way that the peak temperature is minimised subject to the constraint of fixed global volume of solid material. The cooling fluid is driven through the channels by the pressure difference across the channel.The elemental volume of the structure and hydraulic diameter of the cooling channel were considered as design variables. Also, different values of volume fraction of Al2O3 nanoparticles added into water that enhanced the cooling effect are considered. The shape of the channel is allowed to morph to determine the best configuration that gives the lowest peak temperature. A gradient-based mathematic optimisation algorithm (Dynamic-Q) is applied in order to search for the best optimal geometric configuration that improves thermal performance by minimising peak temperature for a wide range of pressure difference. Results obtained show that there are unique optimal geometry for a given pressure difference. Also, the results show that the effects of pressure difference, volume fraction of Al2O3 nanoparticles on minimum peak temperature and hydraulic diameter of the channel are consistent with those obtained in the open literature.