VISCOSITY OF COAL-DERIVED LIQUIDS .1. A GROUP-CONTRIBUTION METHOD FORPURE MODEL-COMPOUND LIQUIDS

Viscosity of coal-derived liquids is an important property useful in t he design of coal liquefaction processes as well as for understanding the flow characteristics of coal liquids. A new model for the predicti on of viscosity of coal liquid model compounds has been developed. The model uses Andrade equation with the constants A and B given by a wel l-defined group contribution method. The group contribution method use s the group definitions, group parameters, and procedure for property calculation, such that all the heteroatom functionalities and some sig nificant molecular structures prevalent in coal-derived liquids are in cluded. The model was tested using experimental data from literature a nd the average error was determined to be 11.55%. Two of the prominent liquid viscosity models available in the literature were also evaluat ed using the same experimental data set of coal model compounds. These models could not be applied to all the compounds, as some model param eters were not available. Both the models resulted in errors a few per cent higher than obtained from our model, indicating that for coal mod el compounds the correlation developed here is more widely applicable and more accurate than any other model in the literature. Future effor ts will include extension of the correlation to mixtures of coal model compounds and description of a procedure to compute viscosities of ap propriately characterized coal-derived liquids.