“…Such distinct nonlinearity was not observed in pure component viscosity data . Whether this is an artifact of treating a complex multicomponent mixtures such as a coal liquid as a pseudo pure component or this is because of multiple phases that exist in high molecular weight coal liquids needs to be further investigated. 1 ln(η) is plotted versus (1/ T ) for a few SRC-II cuts. Symbols represent experimental data, and model results are shown as straight lines.…”
The group contribution viscosity model for pure coal model liquids
described in a previous
paper (Energy Fuels
1995, 10, 333) has
been successfully extended to binary liquid mixtures of
coal model compounds, and a procedure has been developed to use the
model for computation of
viscosities of coal-derived liquids. It is shown that simple
mixing rules, or even a pseudopure
component model, is adequate to estimate mixture viscosity within
reasonable accuracy for these
compounds. For application of the model to coal-derived liquids, a
data set on SRC-II coal liquid
cuts available in the literature has been used. Sufficient
chemical analysis data were available
for these cuts to make the application of our model possible. The
computational procedure involved
transformation of the analytical data into functional group
characterization of the coal liquid.
Central to this procedure was the definition of types and
distributions of various ring structures
in multiring compounds. When compared to limited studies available
in the literature, this model
predicts viscosities of coal liquids with better accuracy.
Overall, this is the first viscosity model
that has been developed for the type of structures that exist in
coal-derived liquids, and provides
a reasonably accurate procedure for computation of viscosities of
narrow boiling coal liquid cuts,
a property that is necessary in designing efficient coal liquefaction
processes.
“…Such distinct nonlinearity was not observed in pure component viscosity data . Whether this is an artifact of treating a complex multicomponent mixtures such as a coal liquid as a pseudo pure component or this is because of multiple phases that exist in high molecular weight coal liquids needs to be further investigated. 1 ln(η) is plotted versus (1/ T ) for a few SRC-II cuts. Symbols represent experimental data, and model results are shown as straight lines.…”
The group contribution viscosity model for pure coal model liquids
described in a previous
paper (Energy Fuels
1995, 10, 333) has
been successfully extended to binary liquid mixtures of
coal model compounds, and a procedure has been developed to use the
model for computation of
viscosities of coal-derived liquids. It is shown that simple
mixing rules, or even a pseudopure
component model, is adequate to estimate mixture viscosity within
reasonable accuracy for these
compounds. For application of the model to coal-derived liquids, a
data set on SRC-II coal liquid
cuts available in the literature has been used. Sufficient
chemical analysis data were available
for these cuts to make the application of our model possible. The
computational procedure involved
transformation of the analytical data into functional group
characterization of the coal liquid.
Central to this procedure was the definition of types and
distributions of various ring structures
in multiring compounds. When compared to limited studies available
in the literature, this model
predicts viscosities of coal liquids with better accuracy.
Overall, this is the first viscosity model
that has been developed for the type of structures that exist in
coal-derived liquids, and provides
a reasonably accurate procedure for computation of viscosities of
narrow boiling coal liquid cuts,
a property that is necessary in designing efficient coal liquefaction
processes.
“…Although, a more detailed group description to include above classifications is possible and would have somewhat reduced the overall errors reported here it was not attempted for two reasons: (1) not enough data were available to allow for such detailed group description and (2) one of the objectives of this work is to apply this model to coal-derived liquids. Some methods are available in the literature for characterization of coal-derived liquids by molecular weight distribution and composition of heteroatom functionalities [27][28][29][30] However, it is almost impossible to characterize coal liquids in such details as to describe the group attachments by above classifications. From this perspective, such an effort would not be very meaningful.…”
Viscosity of coal-derived liquids is an important property useful in the
design of coal liquefaction
processes as well as for understanding the flow characteristics of coal
liquids. A new model for
the prediction of viscosity of coal liquid model compounds has been
developed. The model uses
Andrade equation with the constants A and B given
by a well-defined group contribution method.
The group contribution method uses the group definitions, group
parameters, and procedure for
property calculation, such that all the heteroatom functionalities and
some significant molecular
structures prevalent in coal-derived liquids are included. The
model was tested using experimental data from literature and the average error was determined to be
11.55%. Two of the
prominent liquid viscosity models available in the literature were also
evaluated using the same
experimental data set of coal model compounds. These models could
not be applied to all the
compounds, as some model parameters were not available. Both the
models resulted in errors
a few percent higher than obtained from our model, indicating that for
coal model compounds
the correlation developed here is more widely applicable and more
accurate than any other model
in the literature. Future efforts will include extension of the
correlation to mixtures of coal model
compounds and description of a procedure to compute viscosities of
appropriately characterized
coal-derived liquids.
“…Two higher temperature isotherms have been measured for the same system. For refinement of the thermodynamic model described above, The same functional groups were used as in the work of White and coworkers [5,6]. The functional groups are listed in Table 1. VLE calculations for coal fluids were carried out by the method of continuous thermodynamics [7,8].…”
The work on the thermodynamic model was performed by the graduate students Mr.°S rinivasan Lakshminarayanan and Mr. Xiaojin Xi. Experimental work on the VLE apparatus and the chromatographic characterizations of coal liquids was performed by the graduate student Mr. Shaukat Mahmood. The work is supervised and directed by the principal investigator, V.N. Kabadi. The project has also benefitted from the assistance of two undergraduate students, Ms.
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