Thermodynamic functions of the solid-liquid transition of hydrocarbon mixtures

The dependences of the melting temperature and the enthalpy of fusion on th e composition are the essential factors for modelling precipitation and sol ubility of solid hydrocarbons in crude oils and crude oil products. Long-ch ain 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 en thalpies of fusion of different n-alkanes and fractions of crude oil were d etermined by differential scanning calorimetry. Both parameters can be corr elated with the degree of isomerization and cyclization by a quadratic fuct ion.