Liquid-cooled systems have high heat transfer coefficients associated with them, but they have the inherent disadvantage that they present potential leakage problems. Therefore, air is proposed to be used as the micro channel coolant. Repeat Problem 8€“71 using air as the cooling fluid instead of water, entering at a rate of 0.5 L/s.
D. B. Tuckerman and R. F. Pease of Stanford University demonstrated in the early 1980s that integrated circuits can be cooled very effectively by fabricating a series of microscopic channels 0.3 mm high and 0.05 mm wide in the back of the substrate and covering them with a plate to confine the fluid flow within the channels. They were able to dissipate 790 W of power generated in a 1-cm2 silicon chip at a junction-to-ambient temperature difference of 71(C using water as the coolant flowing at a rate of 0.01 L/s through 100 such channels under a 1-cm ( 1-cm silicon chip. Heat is transferred primarily through the base area of the channel, and it was found that the increased surface area and thus the fin effect are of lesser importance. Disregarding the entrance effects and ignoring any heat transfer from the side and cover surfaces, determine (a) the temperature rise of water as it flows through the micro channels and (b) the average surface temperature of the base of the micro channels for a power dissipation of 50 W. Assume the water enters the channels at 20(C.

Cover plate 1 cm 0.3 Silicon mm substrate Microscopic channels 0.05 mm Electronic circuits on this side