THODOS

When the reduced temperature is greater than 0.8, the conductivity of pure hydrocarbons can be calculated by the method of Stiel and Thodos (1963) ... 

The conductivity of a pure hydrocarbon in the ideal gas state is expressed as a function of reduced temperature according to the equation of Misic and Thodos (1961) ... 

The conductivity of a real gas can be calculated by the Stiel and Thodos method, already used for liquids and given in article 4.3.2.2.a ... 

L. I. Stiel and G. Thodos, Progress in International Research on Thermodynamics and Transport Properties, American Society of Mechanical Engineers, Academic Press, Inc., New York, 1962. 

Other data and estimation techniques for the elements are contained in Gates and Thodos, Am. Jn.st. Chem. Eng. J., 6 (1960) 50-54 and Ohse and von Tippelsldrch, High Temperature.s—High Pre.s.sure.s, 9... 

Various methods are available for estimation of the normal boiling point of organic compounds. Lyman et al. review and give calcula-tional procedures for the methods of Meissner, Miller, and Lydersen/ Forman-Thodos. A more recent method that has been determined to be more accurate is the method of Pailhes, which reqmres one experimental vapor pressure point and Lydersen group contributions for critical temperature and critical pressure (Table 2-385). 

For prediction of the vapor viscosity of pure hydrocarbons at low pressure (below Tr of 0., the method of Stiel and Thodos is the most accurate. Only the molecular weight, the critical temperature, and the critical pressure are required. Equation (2-97) with values of N from Eqs. (2-98) and (2-99) is used. 

Gases For pure eomponent, low pressure (<350 kPa) hydro-earbon gases, Misic and Thodos recommend the following equations. For methane and eyelie eompounds below reduced temperatures of 1.0 ... 

For pure component hydrocarbon hquids above the noiTnal boiling point and all presSLU es, the method of Kanitkar and Thodos is recommended ... 

Mathur-Thodo.s showed that for reduced densities less than unity, the product is approximately constant at a given temperature. 

Lee-Thodos presented a generahzed treatment of self-diffusivity for gases (and liquids). These correlations have been tested for more than 500 data points each. The average deviation of the first is 0.51 percent, and that of the second is 17.2 percent. 8 = PyVr, s/cm and where G = (X - X)/(X - 1), X = p,/T h and X = p /T evaluated at the solid melting point. 

Lee and Thodos expanded their earlier treatment of self-diffusivity to cover 58 substances and 975 data points, with an average absolute deviation of 5.26 percent. Their correlation is too involved to repeat here, but those interested should refer to the original paper. 

Riazi-Whitson They presented a generahzed correlation in terms of viscosity and molar density that was apphcable to both gases and liqmds. The average absolute deviation for gases was only about 8 percent, while for liquids it was 15 percent. Their expression relies on the Chapman-Enskog correlation [Eq. (5-194)] for the low-pressure diffusivity and the Stiel-Thodos correlation for low-pressure viscosity ... 

B. For gases, fixed and fluidized beds, Gupta and Thodos correlation... 

---