Steady and transient thermo-hydraulic performance of disc with tree-shaped micro-channel networks with and without radial inclination

Steady and transient conjugate heat transfer and fluid flow through tree-shaped radially branching micro-channel networks, embedded in a disk-shaped heat sink, are investigated using numerical simulations. The typical dimensions of the disk are taken as 20 mm radius and 2 mm thickness while the hydraulic diameters of the micro-channel network are in the range of 0.67-0.44 mm, with a constant 0.5 mm height. In steady state, increased levels of complexity of the tree network result in more uniform temperature distribution in the disc (T¯max→T¯avg). However the degree of reduction in temperature reduces for higher complexity. Using the steady state result for minimal flow resistance that yields minimal thermal resistance for heat transfer, the transient response of the disk with differing levels of tree complexities is shown to behave more uniformly under similar imposed heat transfer load. The effect of radial inclination of the flow tree channels on the overall pressure drop of the coolant flow and the disk temperature distribution is also investigated. By allowing 0.1 mm radial inclination to the channel network shows 45 percent reduction in pressure drop for the first level of branching complexity (k=1, n=3) and 25 percent for the highest level (k=4, n=3) as compared to the corresponding planar channel.