Prediction of Saturation Densities and Critical Properties of n-Decane, n-Pentadecane, and n-Eicosane Using Molecular Dynamics with Different Force-Fields

IU Samad and NA Darwish and M Qasim and M Al Zarooni, ACS OMEGA, 7, 40257-40266 (2022).

DOI: 10.1021/acsomega.2c05175

Prediction of thermophysical properties of heavy hydrocarbons is important because of the recent increased interest in the extraction of heavy and shale oil to meet the global energy demand. Carrying out experimental work, such as determining the critical properties of heavy hydrocarbons, is challenging due to the possibility of thermal degradation during experimentation. This study focuses on the use of molecular simulations, specifically canonical molecular dynamics, to predict the critical properties of three hydrocarbons: n-decane (n-C10), n-pentadecane (n-C15), and n-eicosane (n-C20). The method uses volume- expansion molecular dynamics (VEMD), where a single box is enlarged in one axis and the vapor-liquid equilibrium is achieved. Three different force-fields (AMBER, COMPASS, and TraPPE) were employed to compare the accuracy of the simulated results and the required computational time. The results from the simulations were compared with available experimental data, equations-of-state, and several correlations. The results indicate that TraPPE is the most accurate and efficient force- field to predict the critical properties followed by AMBER and COMPASS.

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