Multi-parameter optimization of flow and heat transfer for a novel double-layered microchannel heat sink

• Published in: International journal of heat and mass transfer Vol. 84; pp. 359 - 369
• Main Authors: Leng, Chuan, Wang, Xiao-Dong, Wang, Tian-Hu, Yan, Wei-Mon
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 01.05.2015
• Subjects: Channels; Constants; Cooling effects; Double-layered; Heat sinks; Heat transfer; Heating; Microchannel heat sink; Microchannels; Optimization; Performance enhancement; Searching; Simplified conjugate-gradient method; Truncated top channels; Simplified conjugate-gradient method; Truncated top channels; Double-layered; Microchannel heat sink; Optimization
• ISSN: 0017-9310; 1879-2189
• DOI: 10.1016/j.ijheatmasstransfer.2015.01.040

Conventional double-layered microchannel heat sink (DL-MCHS) significantly improves temperature uniformity on the bottom wall due to temperature compensation between the two layers through conduction. However, temperature of the top coolant is always higher than that of the bottom coolant in the inlet region of bottom channels, which inevitably leads to a heating effect of the top coolant on the bottom coolant. To prevent the heating effect, a new DL-MCHS with truncated top channels was proposed in our previous study. To further enhance the cooling performance of the new design, multi-parameter optimizations are performed at various fixed pumping powers Ω and fixed coolant volumetric flow rates Qv, respectively. The optimization algorithm is composed of a three-dimensional solid–fluid conjugate heat sink model and a simplified conjugate-gradient method. Overall heat resistance R is the objective function to be minimized with channel number N, channel height Hc, channel width Wc, and the dimensionless truncation length of top channels l as search variables. With a constant heat flux of 100Wcm−2 applied to the bottom wall, and a constant Ω of 0.05W, the optimal design has N=55, Wc=0.116mm, Hc=0.525mm, l=0.28, and R=0.102KW−1. However, with a constant Qv=200mlmin−1, the optimal design has N=79, Wc=0.026mm, Hc=0.175mm, l=0.38, and R=0.093KW−1. The improvements of cooling performance for constant Ω and constant Qv are all attributed to the enhancement of cooling effect and/or the reduction of heating effect. Finally, the design directions of the four search variables are given at various Ω and Qv.