Effect of shape and arrangement of micro-structures in a microchannel heat sink on the thermo-hydraulic performance

•The cross section and arrangements of pillar and blind hole is optimized.•The blind hole increases the heat transfer coefficient and reduces the pressure drop.•The arrangement of pillar and blind hole also influences the thermo-hydraulic performances of the heat sink.•The highest thermo-hydraulic performance is obtained from MCHS with elliptical pillars. In the present article, micro-pillars and micro-blind holes has been introduced inside the microchannel heat sink (MCHS) to enhance the heat transfer coefficient and reduce the interface temperature as well as pumping power. Optimization of these micro-structures (shape and arrangements) has been performed by three computational analyses in Ansys 19.3. A microchannel of dimension 0.4 mm×0.4 mm×50 mm has been considered in this study with water as a working fluid. The three analyses are as follows- (i) selection of blind hole, (ii) selection of optimized position using selected blind hole from the first analysis, and (iii) selection of optimized pillar cross section using selected arrangement. The heat transfer coefficient, pressure drop, interface temperature, temperature gradient, and overall thermal performance of all the nineteen cases has been compared with same parameters of a plain channel for a range of Reynolds number 500 to 1000. The overall performance of the MCHS with circular blind hole has been found to be 5% higher than the plain channel the best among the selected cross sections. The optimized positions of pillars and blind holes are suggested from the second analyses. The heat transfer coefficient of the MCHS with suggested arrangement has been estimated 1.61 to 1.7 times of the same of a plain microchannel for the same range of Reynolds number. Whereas, the thermo-hydraulic performance of the same is increased by 12.4% to 16.5%. From the third analysis, the best thermo-hydraulic performance (14.8% to 19.4% higher than the plain channel) has been identified for the MCHS with elliptical pillars. A detail thermo-hydraulic analysis has been performed to support these facts.