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摘要
To investigate the effect of the above phase separation structure on the boiling pressure drop of the flow within the microchannels, an experimental section of the microchannels with the phase separation structure was machined using CNC technology. The pressure drop of two (porous/low-porous) phase separation structures and a normal microchannels without venting holes were analyzed at an inlet temperature of 70℃, a mass flow rate of 121.25kg/(m2·s) and a heat flow density of 76.61—150.70kW/m2 using an aqueous glycerol solution with a mass fraction of 30% as the experimental working medium. To examine how different phase separation structures of microchannels affect the length-to-diameter ratio (l/w) of confined bubbles, the bubble dynamics in the channels were visualized and a gas phase separation coefficient was employed to quantify the growth behavior of confined bubbles in the channels. The experimental results showed that the phase separation structure could improve the total pressure drop of the two phases in the channels. In the porous, less porous, and ordinary microchannels, the larger the gas phase transfer area of the microchannels, the larger the gas phase separation coefficient, the smaller the length-diameter ratio of the confined bubbles in the channels, the smaller the total pressure drop loss of the two phases, and could improve the system reliability. In addition, by increasing the pressure difference between adjacent channels and adjusting the appropriate pressure switching period, the gas phase transfer rate of the phase separation membrane could be further improved and the total pressure drop of the two phases in the channels could be slowed down. This study could provide a new design idea for the improvement of flow boiling pressure drop in microchannels. ? 2023 Chemical Industry Press.
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