Synergistic effect of binary surfactant mixture for enhanced boiling heat transfer

Abstract

Surfactants are ubiquitous in our everyday life ranging from household applications to various industrial applications. One such critical application is boiling, wherein, aqueous solution of surfactant is used to enhance the heat transfer coefficient (HTC) compared to pure water. However, this accompanies with the degradation in critical heat flux (CHF). While the binary mixture of surfactants has been widely investigated for its use in numerous applications, such as, corrosion inhibition, foaming, anti-toxicity, and oil and petrochemical industry, among others, its potential to enhance the boiling heat transfer performance, HTC and CHF simultaneously, remains unexplored. In this work, we investigate pool boiling heat transfer performance of aqueous solutions of individual surfactants, namely, SDS (sodium dodecyl sulfate) and DTAB (dodecyl trimethyl ammonium bromide), and their binary mixtures at various mixing ratios. Upon boiling of aqueous solution of individual surfactant, CHF significantly deteriorates. Formation of vapor foam surrounds the heater surface, due to the strong foamability, to impede the supply of fresh liquid from the bulk, leading to the deterioration in CHF. We show that the adverse effect on CHF can be mitigated with binary surfactant mixture. The adsorption dynamics at the liquid–vapor and solid–liquid interfaces are altered favorably, which reduce the foamability and enhance the wettability. Consequently, binary mixtures exhibit not only better CHF than individual surfactant solutions but also demonstrate higher HTC (%) and CHF (%), at suitable mixing ratios and concentration, in comparison to pure water. These findings highlight the potential of binary surfactant mixtures as boiling fluids and opens new area of research for other possible combination of surfactants and ionic liquids for enhanced boiling heat transfer performance.