Adiabatic Gas–liquid Flow in Microchannels

Abstract

This article presents a review of adiabatic two-phase flow in minichannels and microchannels. Differences between them are identified and explained based on this review and our own research. Several channels of decreasing diameter were used in our experiments to determine the effect of the channel size on the two-phase flow of nitrogen gas and water. The effect of channel geometry was examined by characterizing the two-phase flow in a circular and square microchannel of similar size. Only slug flow was observed in the microchannels. Four new sub-classes of slug flow were subsequently defined. A new correlation was developed for the time-averaged void fraction data in the microchannels. The two-phase pressure drop in microchannels was predicted by treating the two phases as being separate with a large velocity difference. Regarding the effect of microchannel geometry, the transition boundaries on the two-phase flow regime maps were shifted for the slug flow subcategories.

Numerical study on gas–liquid nano-flows with pseudo-particle modeling and soft-particle molecular dynamics simulation

“…The flow patterns reproduced so far are similar to the macro-scale counterpart, and are in good agreement with previous experiments in micro-channel (Kawaji and Chung 2004) and in mini-channel (Triplett et al 1999). Although quantitative comparisons are still not possible owing to the strong thermal fluctuations that complicates the identification of flow patterns.…”

Ledinegg instability in microchannels

“…While there have been several successful attempts to develop two-phase frictional pressure drop models in microchannels, the well established semiempirical correlation of Lockhart-Martinelli [20] has shown to hold at the micro scale [21][22][23][24], provided the correlation's C-factor (see Eq. (7)) is properly modified to account for scale effects.…”

“…Conventional scale studies suggest that for liquid laminar and vapor laminar flows, the value of the constant C is 5 [21][22][23][24], which is used in this microchannel fluid flow study. Based on previous minichannels and microchannels results [21][22][23], Kandlikar [24] suggested to modify the C-factor of the two-phase multiplier, / 2 l , in diminishing length scales according to Eq. (7).…”

Multiphase Flow, Evaporation, and Condensation at the Microscale

“…Kawaji [15] summarized the major differences in flow patterns, void fraction, and pressure drop between adiabatic two-phase flows in channels with hydraulic diameters of O (1 mm) and of O (10 mm). However, generally the two-phase flow patterns in conventional scale channels and minichannels appear to be morphologically similar (Kawaji and Chung [16]). However, generally the two-phase flow patterns in conventional scale channels and minichannels appear to be morphologically similar (Kawaji and Chung [16]).…”

“…Kawaji and Chung [16] defined the boundaries between minichannels and microchannels for adiabatic flow to be between 100 lm and 250 lm, based on unique flow patterns and strong deviations in void fraction from that found in minichannels. Kawaji and Chung [16] defined the boundaries between minichannels and microchannels for adiabatic flow to be between 100 lm and 250 lm, based on unique flow patterns and strong deviations in void fraction from that found in minichannels.…”