Study on pressure loss of liquid single-phase flow and two phase flow in micro- and mini-channels

The pressure drop of water single-phase and argon-water two-phase flows in mini pipes at sudden expansion and contraction (form losses) and in rectangular microchannels were investigated experimentally. Diameter of the present mini pipes was 0.57, 0.4, 0.25 and 0.12 mm, respectively. The superficial gas velocity was 2.1 < Ug < 92.5 m/s, the superficial liquid velocity was 0.03 < Ul < 10 m/s. Width and height of the present rectangular microchannel were 0.14 mm and 0.04 mm. Length of the micro channels was 5 mm and 20 mm respectively. A range of pressure at inlet of the test section was 0.1 < P < 0.4 MPa. The liquid velocity was 6.67 < u < 45.32 m/s:a range of Reynolds number was 695 < Re < 4875. The two-phase friction multiplier data for D > 0.5 mm showed to be in good agreement with the conventional correlations. On the other hand, the two-phase friction multiplier data for D < 0.25 mm differed from the calculated values by the conventional correlations. New correlation of mini pipes was obtained for frictional pressure drop of gas-liquid two-phase flow. The coefficients of sudden expansion and sudden contraction in mini-pipes for the gas-water two-phase flow were proposed from the present experimental results. The experimental results were also examined through numerical simulation by a commercial code. New correlation of coefficients of form losses based on Martinelli parameter was obtained for gas-liquid two-phase flow. For the present rectangular microchannel, frictional pressure drop of water single-phase was in good agreement with theoretical value(=64/Re) in the present experimental range. (author)