Impinging jet boiling of a fluorinert liquid on a foil heater array

An experimental study of forced convection in impinging flow, using fluoroc arbon FX3250 and a simulated electronic chip, was performed. A test section consisting of a 35 mm long, 1 mm wide slot nozzle in a 2 mm thick plate of fset 2 mm from the heat sources was used. The simulated chip array consiste d of five foil strip (4 mm wide) heaters, positioned with the center strip directly beneath the slot nozzle. The velocity of the coolant was varied fr om 0.53 to 5 m/s, and the subcooling in the range from 2 to 21 K. The exper iments were conducted focusing on two cases. First, only the center strip w as heated. Second, all the heaters were energized, and the strip-by-strip v ariations of heat transfer were measured. The critical heat flux (CHF) on t he center strip, determined by sensing the onset of oscillations and subseq uent rapid rise of foil temperatures, was found considerably lower than tho se predicted by the existing correlations. It is point out that the thermal mass of the test heater could be an important factor for the CHF. The heat transfer behavior of other strips showed channel-flow or jet-impingement m ode depending on the strip location and the coolant flow rate.