Flow boiling heat transfer of propane in 1.0 mm tube

Flow patterns and local heat transfer coefficients were investigated experimentally during flow boiling of R-290 in a tube with inner diameter equal to 1.0 mm. The tests were conducted at heat fluxes ranging from 5 to 60 kW/m2, mass flux from 240 to 480 kg/(m2s) at 25 °C saturation temperature. Both mass flux and heat flux have a significant influence on the heat transfer coefficient. A new flow pattern identification method is proposed, using non-dimensional parameters based on phase velocities and heat flux. The main flow patterns identified were bubbly, plug, slug, churn, wavy- and smooth-annular flow. Convective boiling was found to be predominant for most flow patterns. Moreover, the resulting heat transfer coefficients were compared with predicting correlations available in the literature.