AN IMPROVED MOLECULAR DYNAMICS ALGORITHM TO STUDY THERMODIFFUSION IN BINARY HYDROCARBON MIXTURES

In multicomponent liquid mixtures, diffusion flow of chemical species can be induced by temperature gradients, which leads to a separation of the constituent components. This cross effect between temperature and concentration is known as thermodiffusion or Ludwig − Soret effect. The performance of Boundary Driven Non-Equilibrium Molecular Dynamics (BD-NEMD) along with the enhanced heat exchange (eHEX) algorithm was studied by assessing thermodiffusion process in n-pentane/n-decane (nC₅-nC₁₀) binary mixtures. The eHEX algorithm consists of an extended version of the HEX algorithm with improved energy conservation property. In addition to this, the transferable potentials for phase equilibria−united atom (TraPPE-UA) force field was employed in all molecular dynamics (MD) simulations to precisely model the molecular interactions in the fluid. The Soret coefficients of n-pentane/n-decane (nC₅-nC₁₀) mixture for three different compositions (at 300.15 K and 0.1 MPa) were calculated and compared with the experimental data and other MD results available in the literature. Results of our newly employed MD algorithm showed a great agreement with experimental data and a better accuracy compared to other MD procedures.