Stabilization of flow boiling in microchannels using pressure drop elements and fabricated nucleation sites

The flow boiling process suffers from severe instabilities induced due to nucleation of vapor bubbles in a superheated liquid environment in a minichannel or a microchannel. In an effort to improve the flow boiling stability, several modifications are introduced and experiments are performed on 1054 X 197 mu m parallel rectangular microchannels (hydraulic diameter of 332 mu m) with water as the working fluid. The cavity sizes and local liquid and wall conditions required at the onset of nucleation are analyzed. The effects of an inlet pressure restrictor and fabricated nucleation sites are evaluated as a means of stabilizing the flow boiling process and avoiding the backflow phenomenon. The results are compared with the unrestricted flow configurations in smooth channels.