Cryo Power and Heat Transfer
Interim rept. 17 Jul 96-31 Jul 97
UNIVERSITY OF CENTRAL FLORIDA ORLANDO DEPT OF MECHANICAL MATERIALS AND AEROSPACE ENGINEERING
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The numerous advantages of operating electronics at the cryogenic temperature have made this research increasingly important Because the foremost problem in electronic cooling is achieving high heat removal capacity within small packages, one focus of this study is to investigate the heat transfer characteristics of various cooling techniques. Pool boiling experiment studies the effects of heater angle orientation and confined spacing on CHF Critical Heat Flux. The horizontal upward-facing heater gives the highest CHF while the downward facing position causes significant drop in CHF. The study also finds a critical value s2.5 mm for the confined spacing situation. For the heaters in an array, at the vertical orientation, the influence from the lower heater causes a lower CHF of the higher heater. Forced convective boiling in this study can achieve 4 to 5 times higher heat removal rates thin those of pool boiling. A model to describe the heat transfer mechanism near CHF is developed. It is demonstrated that the macrolayer thickness plays the most important role in determining CHF. The effect of flow channel height and heater geometry have been investigated. A practical guideline for the design of a flow boiling system is proposed. A MOSFET Metal Oxide Semiconductor Field Effect Transistor will be manufactured, simulated and tested at both room temperature and cryogenic temperature. The simulation results will be compared with the measurements of the real device.