The impacts of gas-liquid two-phase flow regimes on heat transfer performance and pressure drop in microchannels-an experimental study

The two-phase flow regimes have significant effects on pressure drop and performances of heat transfer. There are few studies on the heat transfer of non-boiling two-phase flow in silicon microchannels. The gas-water two-phase flows is highly influenced by surface configurations. Here, a novel nanoengineered microchannel design, names as nanofenced microchannel, was proposed to rectify the disordered two-phase flows into annular flow. This supercapillary nanofence can dramatically boost the liquid spreading along the side walls that can favor the thin film evaporation. Also, two-phase flow instabilities might be significantly reduced upon establishment of annular flow. In this work, Nitrogen gas (N 2 ) and water two-phase flows are experimental studied in parallel five microchannels. The dimensions of each channel are W = 220 μm, H = 250 μm, L = 10 mm, respectively. The gap between the nanofence and sidewall is 5 μm. The height of nanofence is 100 μm. The performances of heat transfer and pressure drop are investigated with water superficial velocity varying from 0.06 m/s to 0.6 m/s under a constant heat flux of 30 W/cm 2 . The N 2 quality ranges from 0.0025 to 0.3. Bubbly, slug, slug/annular and annular flow patterns were observed by changing the N 2 quality. The results demonstrate that the heat transfer performance in nanofenced microchannels is significantly enhanced, accompanying with the decrease of two-phase pressure drop, reduced by 15 % at moderate water flow rates. However, it increases at high water superficial velocity by 20 %. Transient results show that performances of heat transfer and pressure drop are close related to two-phase flow patterns. • A nanoengineered microchannel was proposed to rectify the disordered two-phase flows. • The impacts of gas-liquid two-phase flow regimes on heat transfer performance were experimentally studied. • Bubbly, slug, slug/annular and annular flow patterns were observed by changing the N 2 quality. • Convective heat transfer performance in nanofenced microchannels is significantly enhanced.