High Pressure Homogeneous Nucleation of Bubbles within Superheated Binary Liquid Mixtures

The limits of superheat of some binary normal paraffin mixtures were measured at pressures up to 2128 kPa using the floating droplet method. The variation of nucleation temperature with liquid phase mole fraction was found to be nearly linear for these n-paraffin solutions over the whole pressure range in which the experiments were performed. Homogeneous nucleation theory was used to predict the limits of superheat of the solutions tested. The vapor pressures of the mixtures were estimated by using the Peng-Robinson equation of state to evaluate the liquid and vapor phase fugacities, and the mixture surface tensions were calculated using an empirical adaptation of the van der Waals expression for the surface tension of a pure liquid near the critical point. The predicted and measured limits of superheat were found to be in good agreement over the entire pressure range for all liquid phase compositions. The results of the present work could be useful for predicting liquid phase temperatures and compositions at which the microexplosive or disruptive burning of droplets of fuel blends which are mixtures of volatile and nonvolatile liquids will be initiated during droplet combustion at high ambient pressures.