Pool Boiling Heat Transfer With an Array of Flush-Mounted, Square Heaters on a Vertical Surface

Abstract

Results from pool boiling heat transfer experiments with flush-mounted, square heat sources on a vertical surface cooled with electronic cooling fluid, FC-72, are presented. The fluid contains moderate levels of a dissolved, noncondensable gas. Each heat source, 25mm2 in area, has an aluminum oxide surface covering a sputtered thin film of platinum. It is intended that these heaters and their juxtaposition simulate the distribution of heating on semiconductor chip arrays. The results show that, in pool boiling, the incipience event is highly variable, while the remainder of the boiling curve is repeatable. The effect of heating an element on the initiation of boiling of nearby elements is documented. Boiling from a heater below the test heater is shown to eliminate the excursion in temperature at incipience. This is attributed to the transport of noncondensable gas component which is contained in the rising bubbles to the embryonic bubbles which reside within the test heater surface. Such transport allows a concomitant rise of the gas partial pressure within the embryonic bubbles.