A New Correlation of Critical Heat Flux for Binary Mixtures in Pool Boiling

摘要

The critical heat flux (CHF) in nucleate pool boiling of seven binary mixtures of methanol/water, ethanol/water, methanol/ethanol, ethanol/ n-butanol, methanol/benzene, benzene-heptane, water/ethylene glycol, saturated at atmospheric pressure was investigated with a 0.5mm diameter horizontal platinum wire. Not all mixtures which have a large Δ T_(bp), the temperature difference between the dew and bubble point at the same mole fraction of bulk liquid, or a large |Y_1 — X_1|, the mole fraction difference of the more volatile component between vapor and liquid, reveal a higher CHF compared with the value that is linearly interpolated between CHF's of the two pure components or that is predicted from Zuber correlation using the physical properties of the mixtures. A Marangoni number was newly taken up as a dominant dimensionless parameter to control the CHF of binary mixtures, and a correlation of CHF for mixtures, which predicted CHF's of the present seven mixtures within a ± 20% accuracy was developed.