Heat transfer characteristics of simulated microelectronic chips under normal and enhanced conditions

The heat transfer characteristics of simulated microelectronic chips were investigated with direct immersion cooling in Freon-TF (R-113). The basic heater was 4.5 mm x 4.5mm electrically heated foil. The studies of plain heaters included natural convection, nucleate boiling, and critical heat flux. Water was included as a working fluid for natural convection. Ultrasonic agitation and heat sinks were studied as enhanced cooling methods. The height effect for single flush heaters agrees qualitatively with the conventional theory of natural convection; however, even the widest heaters have coefficients higher than predicted because of leading edge effects. The increase of the heat transfer coefficient with decreasing width is correlated. The protruding heaters have about 15% higher coefficients than the flush heaters. Data for natural convection were also obtained for in-line and staggered arrays of flush heaters with varying distances between heaters.