Factors influencing the surface tension of binary hydrocarbon mixtures

The surface tension plays a major role in interfacial transport and reaction processes in many combustion processes. Since the surface tension is related to differences between the vapor and liquid phases, the saturated vapor pressure, vapor composition and liquid density are three of the key factors influencing the surface tension. However, there are few quantitative analyses of the effects of these factors on the surface tension. This study uses gradient theory combined with cubic equation of state (EOS) and van der Waals mixing rule to make a quantitative study of the influence of the saturated vapor pressure, vapor composition and liquid density on surface tension calculation. The effects of the saturated vapor pressure and vapor composition are analyzed by comparing the results of setting the binary interaction parameter kij in the van der Waals mixing rule to zero and the correlated value. The effect of the liquid density is investigated by comparing the results of using Peng-Robinson (PR) EOS and Volume Translation Peng-Robinson (VTPR) EOS. The results show that, for the binary hydrocarbon mixtures investigated, the liquid density has much more influence on surface tension compared with the saturated vapor pressure and vapor composition. And the gradient theory combined with VTPR EOS and the van der Waals mixing rule can accurately predict the surface tension with an average error of ±1% for the binary hydrocarbon mixtures.