Correlation and prediction of hydrocarbon thermal conductivity using the SPEAD model

In the petrochemical industry, the ability to predict and control transport properties of chemical compounds and their mixtures is critical for rational product design and process optimization. Our purpose is to implement methods of calculating transport properties like viscosity, thermal conductivity, and diffusivity in addition to the equilibrium and coexistence properties that we have already computed by the SPEAD model. The Step Potential Equilibria And Dynamics (SPEAD) model is a combination of chemical process simulation with molecular simulation based on Discontinuous Molecular Dynamics (DMD) with second order Thermodynamic Perturbation Theory (TPT). The proposed presentation focuses on the thermal conductivity of straight chain and branched hydrocarbons. The method of calculating the hard chain thermal conductivity by the Einstein relationship given by Smith (Smith et al., J.Chem.Phys., 102, 1057, 1995) has shown the advantage of using overlapping united atom segments as opposed to tangent sphere segments. This gives the possibility of developing a correlation for predicting thermal conductivity from the hard chains. The thermal conductivities of n-alkanes modeled using the purely repulsive reference fluid are compared to those from experimental data at 300K. The thermal conductivity results presented in this work are preliminary in the sense that attractive forces have not been taken into account. For further study, preliminary evaluations of the SPEAD model for branched alkanes are performed in order to investigate the effect of branching and side chain position on thermal conductivities.