Heat Transfer Characteristics and Flow Visualization during Flow Boiling of Acetone in Semi-Open Multi-Microchannels

摘要

Experimental results of flow boiling characteristics and flow patterns with acetone in two different microchannel heat sinks are presented in this paper. A semi-open microchannel heat sink and a straight microchannel heat sink with 19 parallel microchannels each were designed and tested. The semi-open microchannels have a channel width of 0.8mm, fin width of 0.4mm, and pedestal height of 0.2mm and the straight microchannels have a rectangular cross section of 0.8mm x 1mm. The experimental heat fluxes ranged from 0 to 90kW/m(2), vapor quality ranged from 0.05 to 0.5, mass fluxes ranged from 4.34 to 15.62kg/m(2)bolds and the inlet temperatures were /bold20 and 30 degrees C, respectively. Compared to those in the straight microchannels, flow boiling heat transfer coefficients can be improved by up to 36.2%. Furthermore, flow patterns were observed with a speed video camera. The flow boiling heat transfer mechanisms are analyzed according to the observed flow patterns.