Heat transfer and flow characteristics of Taylor flow in micro capillary tubes have been investigated numerically with the Volume of Fluid (VOF) method. A constant heat flux (32kwm−2) is adopted at the tube wall. All seven computational cases have the same Reynolds number (Re=280), Capillary number (Ca=0.006) and homogenous void fraction (β=0.51), while the inlet gas volume fraction varies from 0.2 to 0.8. The results indicate that liquid slug length (Ll), gas slug length (Lg) and cell length (Lc) vary with α, while liquid film thickness δ remains constant. The friction factor f of Taylor flow is higher than single phase flow. The simulation results agree well with the correlation proposed by Kreutzer et al.. The Local Nusselt number (Nux) gets its peak value at the liquid film region, where the temperature difference between wall temperature (Tw) and fluid bulk temperature (Tbx) is smallest. The average Nu (Nuav) is about 2.8 times of single phase. This means that Taylor bubble can enhance the heat transfer coefficient in micro capillary tubes.

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