Optimization of 3D Branching Networks of Microchannels for Microelectronic Device Cooling

The aim of this work is to present a methodology to develop cost-effective thermal management solutions for microelectronic devices, capable of removing maximum amount of heat and delivering maximally uniform surface temperature distributions. The topological and geometrical characteristics of multiple-story three-dimensional branching networks of microchannels were developed using multi-objective optimization. The design variables which will be subject to optimization in this analysis are the geometric parameters of the microchannel network, i.e. the number of network floors in a 3D network, the amount of branching levels per floor, the connectivity of the cooling channels, their cross-sectional areas and lengths. A conjugate heat transfer analysis software package (CHETSOLP) and an automatic 3D microchannel network generator (3DBNGEN) were developed and coupled with a multi-objective particle-swarm optimization (MOPSO) algorithm with a goal of creating a design tool for 3D networks of optimized coolant flow channels. Numerical algorithms in the conjugate heat transfer solution package include a quasi-1D thermo-fluid solver (COOLNET) and a 3D steady heat diffusion solver, which were validated against results from high-fidelity Navier-Stokes equations solver and analytical solutions for basic fluid dynamics test cases. The conjugate heat transfer solution is achieved by simultaneous prediction of the quasi-1D internal flow-field in the microchannel network and 3D internal temperature field in the solid substrate [1]. Minimization of the pumping power requirement and maximization of total heat removal subject to temperature uniformity (at the heated surface) were the objectives. Pareto-optimal solutions demonstrate that thermal loads of up to 400 W/cm² can be managed with 3D multi-floor microchannel networks, with pumping power requirements that are up to 50% lower with respect to pumping power requirements in currently used high-performance cooling technologies, such as jet impingement and hybrid impingement-microchannel flow.