Direct contact heat transfer between two immiscible liquids during vaporisation

A cine‐photographic technique was used to study the evaporation of single droplets of furan, cyclopentane and isopentane rising in water. Measurements were possible over a range from zero to 10% evaporation. The best correlation of the data for the three systems over the measurable range of parameters was:\documentclass{article}\pagestyle{empty}\begin{document}$$ Nu = 0.0505\left({Pe'} \right)^{0.417} \left({\frac{{\rho c}}{\rho }} \right)^{1.25} $$\end{document}All the data was fitted by this equation to within ± 20%. A second correlation with a slightly larger variance\documentclass{article}\pagestyle{empty}\begin{document}$$ Nu = 0.5\left({Pe'} \right)^{0.445} \left({\frac{{\rho c - \rho }}{{\rho c}}} \right)^{1.81} $$\end{document}because of the manner in which the density ratio term varies with % evaporation, was recommended for extrapolation to higher percentage evaporations.