Characteristics of Void Fraction and Velocity of Gas-Liquid Two-Phase Flow in a Microchannel (Effects of Gas-Liquid Mixing at the Inlet and Channel Length)

Abstract

An optical measurement system was developed to investigate gas-liquid two-phase flow characteristics in a circular microchannel of 100 μm diameter. By using multiple optical fibers and infrared photodiodes, void fraction and gas slug and liquid slug lengths, and their velocities were measured successfully. Experiments were conducted with 146 mm and 1571 mm long microchannels. The effects of inlet configurations and gas-liquid mixing, i.e., (a) reducer and (b) T-junction, on the two-phase flow phenomena were also investigated. The mean void fraction data obtained in a 146 mm microchannel with the reducer inlet agreed well with the equation by Kawahara and Kawaji which was previously proposed. On the other hand, the mean void fraction obtained in a 1571 mm microchannel corresponded well with the homogeneous flow model and Armand's equation for both reducer and T-junction inlet configurations. Thus, both the microchannel length and inlet geometry were found to affect the two-phase flow characteristics such as mean void fraction and gas slug and liquid slug lengths in a microchannel.