Date of Award
Master of Science in Chemical Engineering - (M.S.)
Saul I. Kreps
C. L. Mantell
George C. Keeffe
The absolute viscosity of the normal paraffins C5H12 to C20H42 was studied to determine a relationship more useful in predicting liquid viscosities than existing correlations such as the methods of Andrade, Souders, Thomas, and Doolittle.
It was found that a function of corresponding liquid states could be designed which related viscosity to the number of carbon atoms. This function, here called liquidity, is defined as the extent to which a substance exists as a liquid with respect to temperature. This function can be expressed mathematically as:
Lc = (t - tm)/(tc - tm) or Lb = (t-tm)/(tb-tm);
Lc = liquidity based on the critical temperature
Lb = liquidit based on the normal boiling temperature
t = any temperature, °C
tb = normal boiling temperature, °C
tc = critical temperature, °C
tm = normal melting temperature, °C
Once the basis for liquidity is determined, the denominator in the above expressions remain constant, and the % liquidity becomes a straight line function of the temperature.
It was further found that a plot of Lc vs. number of carbon atoms for the n - paraffins resulted in curves of iso - viscosity which, when fitted to straight lines, could be used for calculation, extrapolation, or interpolation of viscosity data. Thus, a method was developed for the viscosity prediction of the n - paraffins above C4H10 to apply at any temperature within the normal liquid range. Deviations from the experimental values of viscosity to those resulting from the designed liquidity function are within ± 10 per cent for the majority, and less than ± 20 per cent for the extreme cases. This approach to viscosity prediction is valid with or without the availability of experimental data.
Permutt, Gerald, "Absolute viscosity of the n-paraffin liquids" (1960). Theses. 1537.