Enhancement of pool boiling critical heat flux in dielectric liquids by microporous coatings

An experimental investigation into the effects of pressure and subcooling on the pool boiling critical heat flux from a bare silicon chip-like heater and from a silicon heater coated with microporous layers, is reported. The dual inline heater package was immersed in FC-72, a dielectric fluid, and the experiments were performed in the horizontal orientation, with subcooling varying between 0 K and 72 K, and the pressure between 101.3 kPa and 303.9 kPa. The maximum CHF values on the diamond-base microporous-coated silicon heater were found to reach 47 W/cm2, at 3 atm and nearly 50 K of subcooling, and to provide an average enhancement of approximately 60% over the values attained with un-treated silicon surfaces. An available CHF correlation, with a reported standard deviation of 12.5% for un-treated surfaces over a large range of pressures, subcoolings, and surface conditions, was shown to predict the pressure and subcooling effects on CHF from the surface-enhanced chip with a standard deviation of 12%.