POOL BOILING HEAT-TRANSFER WITH AN ARRAY OF FLUSH-MOUNTED, SQUARE HEATERS ON A VERTICAL SURFACE

Results from pool boiling heat transfer experiments with flush-mounted , square heat sources on a vertical surface cooled with electronic coo ling fluid FC-72, are presented. The fluid contains moderate levels of a dissolved, noncondensable gas. Each heat source, 25 mm(2) in area h as an aluminum oxide surface covering a sputtered thin film of platinu m. 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, w hile the remainder of the boiling curve is repeatable. The effect of h eating an element on the initiation of boiling of nearby elements is d ocumented. Boiling from a heater below the test heater is shown to eli minate 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 t est heater surface. Such transport allows a concomitant rise of the ga s partial pressure within the embryonic bubbles.