Hydraulic Characteristics of Flow Boiling of Hydrocarbon Fluids: Effect of Subcooled Boiling

ABSTRACT

Two-phase hydraulic characteristics, in terms of pressure drop and void fraction data, are reported for boiling of hydrocarbon fluids in vertical upflow. These data were obtained simultaneously with the boiling heat transfer measurements. The systematic trends of the measured pressure gradient with respect to vapour quality, mass flux and pressure are examined. This provides useful information in terms of the relative importance of the constituent parts of the two-phase pressure gradients and confirms the internal consistency of the measured data. These two-phase pressure drop data under flow boiling conditions are then compared with various correlations from the open literature and also with the HTFS correlation. Typical results of these comparisons are presented. It is noted that in the near zero vapour quality region the measured pressure gradient data may be lower than expected because of the effect of subcooled boiling. This effect is taken into account by the HTFS method when pressure drop is calculated for flow boiling.

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