Frictional pressure drop and two-phase flow pattern of gas-liquid two-phase flow in circular and rectangular minichannels

The frictional pressure drops of gas-liquid two-phase flow in mini-pipes and mini-rectangular channels were investigated experimentally. The following test channels were used in the present experiments: commercial stainless-steel circular tubes with 0.6, 0.5 and 0.25 mm in inner diameter, FEP circular tube of 0.4 mm in inner diameter and rectangular channels, made of Acrylic resin, with 0.39 X 20.4 mm, 0.21 X 9.75 mm, 0.26 X 4.28 mm and 0. 18 X 1.87 mm in height and width, respectively. The pressure drops of straight pipe, sudden enlargement and sudden contraction of gas-liquid two-phase flow in mini-pipes were measured for the test mini-channels. The pressure drops of rectangular minichannel were also measured. Experimental result showed that measured two-phase friction multipliers agreed well with a conventional Lockhart-Martinelli correlation for circular tubes and Mishima-Hibiki's correlation for rectangular channels. Observed flow patterns by visualization were bubbly, slug, chum, ring and annular flow; the flow patterns in the present experiments were reproduced well by Baker's flow pattern map.