A mathematical study of bubble dynamics in superheated sodium chloride solution

Abstract

A mathematical study of bubble growth in the superheated binary solution with a non-volatile solute is conducted by solving the momentum, energy and species equations around the bubble. Additionally, the two-characteristic-parameter correlation (TCPC) model is used to identify the thermodynamic conditions at the bubble-solution interface. By considering a single bubble and ignoring the interactions between the bubbles, the bubble growth characteristics in the NaCl solution are analyzed in detail, and the effects of NaCl concentration and operating conditions on bubble growth are discussed. It is observed that the non-volatile solute of NaCl slows down the bubble growth process in the entire duration of the growth period due to the extension of delay time and reduction of the driving forces with increase of solute concentration. The effects of solute concentration on bubble growth cannot be entirely eliminated by modifying the operating conditions to give the same degree of superheat by compensating the boiling point elevation (BPE). The increase of solute concentration near the bubble at moderate or high superheated conditions has non-negligible influence on bubble growth. A revised Mikic-Rohsenow-Griffith (MRG) formula by considering the solute effect and the increase in solute concentration near the bubble surface is proposed to predict the bubble growth in salt solutions. The predictions from the revised formula agree well with the complete simulations of bubble growth at various salt concentrations.