Thermohydraulic Characteristics of Microchannel Heat Sinks Combined With Ribs and Cavities: Effects of Geometric Parameters and Heat Flux

The effects of the geometric parameters and heat flux on the thermohydraulic characteristics of microchannel heat sinks combined with ribs and cavities are investigated numerically. The numerical study is performed under conditions of laminar flow with conjugate heat transfer between silicon and water. In order to find the optimum substrate thickness, ratios of substrate thickness to microchannel height (Hs/Hc = 0, 0.25, 0.50, 0.75, 1.00, 1.25, and 1.50) are investigated. It is found that the temperature of the substrate surface firstly decreases and then gradually increases, the minimum temperature of the substrate surface occurs with Hs/Hc = 0.25. Furthermore, the microchannel heat sinks are studied at rib width to the spacing ratios (Lr/Sr = 0.25, 0.50, 0.75, and 1.0), rib heights to parallel sidewalls width ratios (Hr/Wc = 0.10, 0.15, 0.20, and 0.25), spacing to the parallel sidewalls width ratios (Sr/Wc = 4, 8, 12, and 16) and heat fluxes (qw = 50, 100, 150, 200, 250, and 300 W cm–2). The results show that the Performance Evaluation Criterion (PEC) is continued to slowly decrease with increase of qw. For all cases of qw, the maximum value of PEC occurs in model 2 with Lr/Sr = 0.50, Hr/Wc = 0.20, and Sr/Wc = 4. For Re > 320, the wall temperature of model 1 is slightly smaller than that of model 2.