Evaluating the thermal and hydraulic performances of heat sinks having microgap integrating ridges

This document presents a heat sink having microgap integrating ridges as the flow passage for purposes of thermal management of microelectronics. Studies are carried out for Reynolds number ranging from 250 to 1600. Increase in Reynolds number, irrespective of the dimensions of the heat sink, is observed to decrease and increase the thermal resistance and pressure drop, respectively. Regarding the influence of the height of the ridges, there exists a threshold for the same for influencing the thermal resistance of the heat sink. When the height of the ridges is increased by 3 times, the thermal resistance at the largest height is reduced by as much as 70 % relative to the thermal resistance at the smallest height; the pressure drop increased by as much as 3 times with increase in the height of ridges. When the number of ridges is increased by 16 times, the thermal resistance for the largest number of ridges is 75 % lower than that for the smallest number of ridges; the pressure drop increased by as much as 2 times for the same increase in the number of ridges. Regarding the length of the ridges, it must be below a threshold for positively influencing the thermal resistance of the heat sink. With increase in the length of the ridges by 4 times, the thermal resistance at the largest length is observed to be as much as 85 % lower than that at the smallest length and over the same increase in the length of the ridges, the pressure drop increased by 1.14 times. Increase in the height of the microgap from 150 μm to 250 μm reduced the thermal resistance of the heat sink by as much as 45 %; the pressure drop increased by as much as 7 times for this change in height of the microgap. The Nusselt number and friction factor associated with different designs of the microgap integrating ridges that are considered as part of this study are provided in this document.