| Summary: | With the ever-growing development of microelectronic equipment, a more efficient heat dissipation method is in demand. The present study seeks to enhance the heat transfer characteristic in microchannel heat sink (MCHS), while maintain low power consumption by using multi-layered microchannels, different flow configurations and tapered channel profile.
The numerical study is firstly conducted on DL-MCHS with parallel and counter flow with tapered channel profile. Parametric study is then conducted to evaluate the effect of different design parameters of channel inlet width,W_i channel outlet width, W_o and channel height, H_ch on thermal and hydraulic performance. The results show that the designs with counter flow configuration always have better thermal performance than the designs with parallel flow configuration when volumetric flow rate is large and the difference become more significant with the decrease of W_i, the maximum difference of 0.05K/W (21.67%) can be found at design with W_i=50μm W_o=200μm at H_ch=375μm. However, the DL-MCHS with parallel flow always shows better thermal-hydraulic performance as compared with counter flow with exact channel dimensions, maximum difference of 0.12(12.13%) is found between parallel and counter flow configuration for design with Wi=50μm Wo=50μm. For both parallel and counter flow, the deign Wi=150μm and Wo=200μm presents the best thermal-hydraulic performance.
The numerical study is then conducted on DL-MCHS with alternating flow. The results for DL-MCHS with alternating flow shows largely similar results of thermal resistance as compared to the DL-MCHS with counter flow configuration. The optimum DL-MCHS with alternating flow and tapered channel show about 76% better in thermo-hydraulic performance as compared with benchmark of DL-MCHS with straight channel design with inlet and outlet channel size of 50µm.
Numerical study is also conducted on three-layered MCHS with parallel flow (PF), counter flow1(CF1), counter flow 2(CF2). counter flow 3(CF3) and with tapered channel profile. The CF1 exhibits better thermal performance for converging channel design and PF presents better thermal performance for diverging channel design. For all flow configurations, PF always shows best thermal hydraulic performance among different flow configurations and the design with Wi=150μm and Wo=200μm presents the best thermal-hydraulic performance among different channel designs.
Finally, the thermal resistance network for DL-MCHS with parallel flow configuration has been obtained and the correlation of local Nusselt number in terms of axial distance and channel outlet width for different channel inlet width has been proposed. Good agreement was found between correlated results and generated numerical results, which provides a more convenient tool to predict the temperature along the flow direction for DL-MCHS with parallel flow and tapered channel profile.
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