Abstract
Flow boiling heat transfer in microchannels is of significant interest and it is for industrial applications and fundamental researches. This study investigates experimentally flow boiling of degassed, de-ionized water in multi-parallel, silicon based trapezoid microchannels, including three and six parallel microchannels that having hydraulic diameter of 41.3 and 33.5μm. The tested chips are fabricated by MEMS technology. The objective of this research is to explore the boiling heat transfer and two-phase flow in microchannels including bubble growth mechanism, boiling heat transfer, two-phase flow pattern and instability. By employing a high-speed video-camera, bubbly flow, slug flow, annular flow, reversal vapor flow, dry out and other peculiar two-phase flow patterns are observed clearly in microchannels. The bubble grows rate is almost linearly by time and the bubble in slug flow grows exponentially with time. The heat transfer ability of two phase flow is prior to single phase flow. The fluctuation of inlet pressure is observed during two phase period and it depends on heat flux and mass flux.