Thermodynamic functions of the solid-liquid transition of hydrocarbon mixtures

The dependences of the melting temperature and the enthalpy of fusion on the composition are the essential factors for modelling precipitation and solubility of solid hydrocarbons in crude oils and crude oil products. Long-chain iso-alkanes and cyclic alkanes must be considered besides of n-alkanes. Therefore a degree of isomerization and cyclization was defined using the refractive index and the carbon number. The melting temperatures and the enthalpies of fusion of different n-alkanes and fractions of crude oil were determined by differential scanning calorimetry. Both parameters can be correlated with the degree of isomerization and cyclization by a quadratic fuction.