Angle Direct immersion cooling of microelectronic devices in dielectric fluids has become a leading candidate for handling the ever increasing heat flux requirements of microelectronic chips. More specifically, nucleate pool boiling is considered very attractive due to its near-isothermal characteristics. In order for this technology to be useful, many aspects of nucleate pool boiling must first be studied. Two such aspects are the heating surface size and the effect of heater orientation with respect to gravity on the boiling heat transfer rate. The scope of this study is to analyze both the effect of size and orientation on pool boiling heat transfer in saturated FC-72 with both plain surface and microporous surface conditions.
Orientations range from horizontal upward facing to horizontal downward facing.
Utilizing the data from this study, a comprehensive set of correlations are currently being developed to enable the prediction of nucleate boiling heat transfer as well as the CHF for microporous-coated surfaces at any inclination angle or size. This double enhancement technique is currently being tested. The heaters are first tested with a plain surface condition and then with the microporous surface coating. Further increase in CHF is expected when bulk fluid is subcooled conditions. Tests also showed significant increases in nucleate boiling heat transfer coefficient with the application of the microporous coating to the heater surfaces.