Thermal and Hydraulic Behavior of MEMS Heat Sinks Having Straight Microchannels Integrating Sidewall Cavities in Staggered Pattern

A MEMS heat sink having straight microchannels integrating sidewall cavities in staggered pattern is conceptualized in this work and its thermal resistance and pumping power characterized for Reynolds number ranging from 100 to 750. Over this Reynolds number range, the thermal resistance and pumping power of the proposed MEMS heat sink are lower than that of a MEMS heat sink having straight microchannels. With increase in Reynolds number, the relative reduction of thermal resistance varied from 1.8% to 23.4% while the relative reduction of pumping power varied between 18.6% and 6.5%. The proposed MEMS heat sink achieves reduction in thermal resistance with reduced pumping power and this is its novelty. The Nusselt and Poiseuille numbers of the straight microchannel integrating sidewall cavities are higher and lower than that of a straight microchannel without sidewall cavities, respectively. With increase in Reynolds number, the relative increase of Nusselt number ranged between 6.6% and 46.5% while the relative reduction of Poiseuille number ranged from 18.6% to 6.5%. The influence of the geometric features of the MEMS heat sink having straight microchannels integrating sidewall cavities is examined in this study. It is identified that there is a threshold value for the length of the sidewall cavities below which sidewall cavities do not influence thermal resistance and pumping power; above this threshold value, increase in the length of the sidewall cavities lead to reduction in thermal resistance and pumping power as well as increase and decrease in Nusselt and Poiseuille numbers, respectively. Increase in length of sidewall cavities led to the relative reduction of thermal resistance and pumping power varied from 1% and 19% at the lowest Reynolds number to 23.2% and 7.3% at the highest Reynolds number. With increase in the length of sidewall cavities, the relative increase of Nusselt number and relative reduction of Poiseuille number ranged from 2.3% and 19%, for Reynolds number of 100, to 38.9% and 7.3%, for Reynolds number of 750. It is identified that for every Reynolds number there exists an optimal value for the width of the sidewall cavities at which thermal resistance and Nusselt number are minimum and maximum, respectively; similar observation is made regarding the relationship between hydraulic diameter and thermal resistance while Nusselt and Poiseuille numbers decrease and increase with hydraulic diameter, respectively. Also, increase in the number of sidewall cavities lead to reduction in thermal resistance and pumping power; increase in the number sidewall cavities leads to increase and decrease in both Nusselt and Poiseuille numbers, respectively. With increase in the number of sidewall cavities, the relative reduction of thermal resistance at the lowest and highest Reynolds numbers are 1.4% and 1.8%, respectively; the relative reduction of pumping power at the lowest and highest Reynolds numbers are 12.6% and 7.1%, respectively. The relative increase of Nusselt number at the lowest and highest Reynolds numbers are 29.2% and 23.6%, respectively; the relative reduction of Poiseuille number at the lowest and highest Reynolds numbers are 12.6% and 7.1%, respectively. The model is validated using data from literature.INDEX TERMS Electronics cooling, microfluidics, numerical simulation, thermal resistance.