Vertical in-tube flow boiling of mixtures.

摘要

There are many practical applications of convective boiling of fluid mixtures in the refrigeration and chemical process industries. It is well-known that most binary mixtures exhibit significantly lower pool boiling heat transfer coefficients than either of the pure components. Though many previous experimental and theoretical studies have examined in-tube flow boiling of pure fluids, aqueous mixtures have received relatively little consideration.In the current study, experiments have been conducted to measure two-phase heat transfer coefficients in vertical (upward) in-tube flow boiling of binary mixtures of methanol and water. Pressure drop and single-phase and subcooled boiling heat transfer data have also been collected and analyzed.This study presents comparisons of the measured two-phase heat transfer coefficients with predictions from two previously-published models of flow boiling in saturated mixtures. A new predictive method, based on contemporary models of mass transfer resistance effects, is proposed. The new correlation exhibits better agreement with the current data set than the two previous methods.