Conventional and alternative fuels are composed of mixtures of various classes of hydrocarbons, including straight-chain, branched, and cyclic alkanes; aromatic compounds; and alkenes. The chemical compositions of these fuels influence their physical properties and their ability to be used in conventional engines. Understanding the molecular-level rules governing these composition-property relationships can aid in the development of fuels tailored to specific needs, as well as reduce the need for expensive experimental testing of unsuitable candidate fuels. We use all-atom molecular dynamics simulations to predict the properties of pure hydrocarbons, as well as binary and multicomponent surrogate fuel mixtures. The all-atom version of the optimized potential for liquid simulations (OPLS) and the modified Lennard-Jones adaptive intermolecular reactive empirical bond-order potential (mod-LJ AIREBO) were both used to calculate properties such as density, heat of vaporization, bulk modulus, and viscosity of the both the pure hydrocarbons and their mixtures. We obtain good agreement with experimental data, with quantitative agreement for many of the systems examined. Atomic-level details, such as radial distribution functions, and their relationship to macroscopic properties are also discussed. Additionally, we assess the performance of the potentials near the critical point, far from the temperature and pressure conditions for which they were parameterized. This work illustrates the ability of molecular dynamics to predict the properties of fuel mixtures, and shows how modeling could be used to design new fuels with desired physical properties.

Elucidating the properties of fuel mixtures using molecular dynamics

251st National Meeting (2016)

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