Distribution of gas-liquid two-phase slug flow in parallel micro-channels with different branch spacing

Abstract

An experimental study was conducted in order to investigate the phase distribution of gas-liquid slug flow in six parallel micro-channels in presence of different branch spacing of 0.8 mm(2d), 4 mm(10d) and 12 mm(30d), respectively. The parallel micro-channels was composed of a header with hydraulic diameter of 0.48 mm and six branch channels with hydraulic diameter of 0.40 mm, all with rectangle cross sections. The entire test section was machined by PMMA to facilitate flow visualization. Nitrogen and 0.03 wt% sodium dodecyl sulfate (SDS) solution at ambient pressure and room temperature were used as the test fluids. A flow-regime map of bubbly, slug, slug-annular and annular was generated, covering the range of gas and liquid inlet superficial velocities of 0.28 ≤ JG ≤ 33.3 m/s and 0.008 ≤ JL ≤ 2.52 m/s, respectively. The phase distribution experiments of slug flow were conducted. The fluid dynamics of two-phase flow splitting in parallel micro-channels was captured by high speed recording technique. It was found that the phase distribution characteristics of two-phase flow in parallel channels highly depend on the inlet flow conditions and the distance between channels. Besides, the effect of branch spacing took on distinct characteristics under different inlet flow conditions. At low mass flux and quality, the increase of branch spacing can facilitate the liquid phase to flow into channels at the rear part of the header, while the first three channels are more supplied with liquid as the branch spacing increasing at high mass flux and quality. Specially, an improvement of gas distribution was also observed with the increase of the branch spacing. Finally, a correlation capable of predicting the liquid phase distribution of slug flow in parallel micro-channels was developed.