Kinetics of Crystallization of Aqueous Droplets in Water-in-Crude Oil Emulsions at Low Temperatures

This study focused on the examination of the isothermal crystallization of aqueous droplets in water-in-crude oil emulsions with water concentrations in the range of 5 to 20 wt %. Experiments were carried out using differential scanning calorimetry (DSC) with temperatures ranging from −36 °C to −41 °C. The experimental results were approximated using a mathematical kinetic model including the effect of self-acceleration. The rate of crystallization increases with decreasing temperature, and the final accepted degree of crystallinity also increases along with a decrease in temperature. Correlation was observed between the kinetics of isothermal and nonisothermal crystallization. Furthermore, the complete crystallization in the isothermal process is reached at −40 °C; however, at high rates of cooling (10 to 20 °C/min), complete crystallinity is not achieved even at −50 °C. Complete crystallinity in the nonisothermal process can only be reached at cooling rates lower than 5 °C/min.