Simultaneous determination of the composition and temperature gradients in the vicinity of boiling bubbles in liquid binary mixtures using one-dimensional Raman measurements

摘要

The ability to transport large quantities of heat by nucleate boiling is reduced for mixtures compared to their pure components. To study the heat and mass transfer during the boiling process, a one-dimensional Raman spectroscopy setup was applied to measure, for the first time to the best of our knowledge, the composition and temperature gradients in the vicinity of single boiling bubbles of a mixture of acetone and isopropanol. A novel evaluation strategy allowed the simultaneous detection of the mixture composition and temperature from the C-H and the O-H Raman spectra. The composition gradients arise because of rectification effects, which cause unlike compositions in the gas and liquid phases. Heat transfer from the boiling bubble to the surrounding liquid induces temperature gradients. High temporal and spatial resolution measurements using an imaging spectrograph and an electron multiplying charge-coupled device camera revealed large composition and temperature gradients with similar shapes. The accuracy of the composition results was validated by a species conservation calculation.