Abstract
Evaporating and condensing heat transfer and pressure loss characteristics strongly depend on interfacial structure of gas-liquid two-phase flows. Cross-sectional average void fraction is important parameter on the one-dimensional analysis. Recently, since channel diameter becomes smaller, the effect of surface tension on the flow behaviors would become stronger. This study deals with void fraction characteristics of adiabatic two-phase flows using FC-72 as the working fluid. Crosssectional average void fraction was measured by capacitance sensor. Circular, square and triangular tubes with the hydraulic diameter of 2 mm were used. Vertically upward flow was selected to evaluate for axially symmetric phase distribution. From the results, it was confirmed that for the square and triangular tube, void fraction became lower than the circular tube because liquid was accumulated in the corner by surface tension. Although the lower void fraction leads to larger slip velocity, the gas-liquid interface of liquid film became smoother.
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Schedule a callMore From: Proceedings of the 25<sup>th</sup> IIR International Congress of Refrigeration: Montréal , Canada, August 24-30, 2019.
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