Bubble Dynamics During Boiling in Enhanced Surface Microchannels

An experimental investigation is presented on flow boiling of deionized water in 227-<formula formulatype="inline"><tex>$\mu$</tex></formula>m hydraulic diameter microchannels with reentrant type cavities. Key features of nucleate boiling are discussed. Active nucleation site density, bubble frequency and departure diameter, and flow patterns over mass velocities ranging from 41 kg/m<formula formulatype="inline"><tex>$^{2}$</tex></formula>-s to 302 kg/m<formula formulatype="inline"><tex>$^{2}$</tex></formula>-s and heat fluxes ranging from 28 to 445 W/cm<formula formulatype="inline"><tex>$^{2}$</tex></formula> are studied. Similarities and differences with results obtained on large-scale systems and unenhanced microchannels are discussed.<papernumber>1536</papernumber>