Abstract:
This article is the second part of a two-part paper, dealing with an experimental study of convective condensation
of R134a at a saturation temperature of 40 C in an 8.38 mm inner diameter smooth tube in
inclined orientations. The first part concentrates on the flow pattern and the heat transfer coefficients.
This second part presents the pressures drops in the test condenser for different mass fluxes and different
vapour qualities for the whole range of inclination angles (downwards and upwards). Pressures drops in a
horizontal orientation were compared with correlations available in literature. In a vertical orientation,
the experimental results were compared with pressure drop correlations associated with void fraction
correlations available in literature. A good agreement was found for vertical upward flows but no correlation
predicted correctly the measurements for downward flows. An apparent gravitational pressure
drop and an apparent void fraction were defined in order to study the inclination effect on the flow.
For upward flows, it seems as if the void fraction and the frictional pressure drop are independent of
the inclination angle. Apparent void fractions were successfully compared with correlations in literature.
This was not the case for downward flows. The experimental results for stratified downward flows were
also successfully compared with the model of Taitel and Dukler
