An experimental study of flow boiling instability in a single microchannel

A simultaneous visualization and measurement study has been carried out to investigate stable and unstable flow boiling phenomena of deionized water in a single microchannel having a hydraulic diameter of 155 µm with a bottom Pyrex glass wall. Fifteen platinum serpentine microheaters, bonded on the Pyrex glass wall, were used to measure local instantaneous wall temperatures. At low mass flux, a syringe pump was used to drive the subcooled water passing through the microchannel. Stable and unstable flow boiling modes in the single microchannel are identified, and flow pattern maps in terms of heat flux and mass flux as well as in term of exit vapor quality are presented respectively. It was found that unstable flow boiling occurred in the single microchannel if the exit vapor quality x_e > 0.013.