(609d) Modeling of Surrogate Fuels with Real Components

Surrogate or substitute fuels are, based on their limited number of components and biogenic fractions, well-specified alternatives to standard – mostly fossil – fuels of complex composition. To evaluate the effect of partial admixture of feedstock of biogenic origin (e.g. biodiesel) to fossil fuel on fuel properties, reliable modeling of fuel quality is required.

Basic principle of this method is an algorithm enabling the generation of substitute fuel based on data of specified substances. Compared with characterization of fuel mixtures with pseudo components, state of the art algorithm, the molecular information offers significant advantages in fuel specification. Therefore the key properties of a complex multicomponent mixture like diesel fuel were simulated with a selected blend of real key components with rigorous thermodynamics instead of empirical correlations. The results were compared with the specification of fossil diesel fuel.

An algorithm based on minimization of differences between experimentally obtained and predicted values of the boiling point curve, density and content on paraffinic, naphthenic and aromatic components provides the basis for calculating the fraction of each real component in the simulated mixture. By means of this simulated composition safety-related parameters and further data like cloud point as an important specification for the cold flow behaviour of fuels were calculated.    

By means of this tool the matrix generation of a basic substitute fuel is the starting point for accurate estimation of the effect of adding biogenic components to fossil fuel.