It is known that the addition of small amount of alcohol such as butanol to water enhances the CHF. Such aqueous solution is actively applied to heat transfer devices such as heat pipes and microchannel cooling systems, however, the fundamental characters of boiling have not been fully understood. In the present research, the experiment of boiling heat transfer is performed on a heated wire by employing butanol aqueous solution as a typical test solution and by changing concentration 1-butanol and subcooling in a wide range. Bubbling aspects were observed using high-speed video camera. It is found from the experiment that CHF is 2 to 3 times higher than that of pure water and generating bubbles are tiny even at the saturated condition. The dependence of CHF on subcooling is found to be curious showing that CHF decreases first, takes a minimum, and then increases with increasing subcooling. These results suggest that the butanol aqueous solution is a promising liquid for the application of boiling to a small-scaled cooling device.
An electro-thermal model of the on-resistance self-heating in SiC MOSFET channel region is proposed. The model consists of the heat generation rate of the steady-state self heating due to the drain current of long channel MOSFET, lattice temperature rise due to the heat generation rate, and the electron temperature rise calculated from the lattice temperature and the electric field. This is the first attempt to consider the major factors of the mobility and to predict the electron temperature rise.