Riedel equation

For purposes of the API Technical Data Book (Daubert and Danner S), another modified Riedel equation (2-29) was chosen and found to fit hydrocarbon data well over the entire pressure range. Coefficients are given for several hundred hydrocarbons. 

Liquid viscosity is accurately correlated as a function of temperature by the modified Riedel equation previously discussed for correlation of vapor pressure and shown by Eq. (2-96). 

Equation 11.8 may be used for the evaluation of vapour pressure over a small range of temperature, although large errors may be introduced over large temperature intervals. If the critical values of temperature and pressure are available along with one other vapour pressure point such as, for example, the normal boiling point, then a reduced form of the Riedel equation may be used this takes the form ... 

In preparing the tabulation, a literature search was conducted to identify data source publications (1-35). The publications were screened for appropriate data. The compilation resulting from the screening is based on both experimental data and estimated values. In the absence of experimental data, estimates were primarily based on Riedel equation and on adjusting the A value in the equation to match the boiling point temperature of the compound. The estimates of the other coefficients for the compound were based on the same values of the compound s brother (closest member of same chemical family). Experimental data and estimates were then regressed to provide the same equation for all compounds. 

Constants of organic compounds for the modified Riedel equation... 

Estimate AHv using Riedel equation (4.12) and Watson correction (4.13)... 

The accurate representation of vapor-pressure data over a wide temperature range requires an equation of greater complexity an example is the Riedel equation ... 

Latent heat, 114-116, 181 Riedel equation for, 115-116 Watson correlation for, 116... 

Correlation of experimental data within a few tenths of a percent over the entire fluid range can usually be obtained with either the Wagner or Riedel equations. 

Two prediction methods are recommended for liquid vapor pressure. The first method is based on the Riedel equation the second is a CS method. Both methods require T and P as input, but these can... 

The Riedel equation for vapour pressure gives greater accuracy by relying on four constants rather than three ... 

The vapour pressure curves, Kj(Ti), may be represented by either Antoine or Riedel equations, as explained for the single-component case in Section 12.3. Similarly table lookups or low-order polynomial expressions may be used to describe the dependence on temperature (only) of the specific volume of each liquid component and the specific internal eneigy of each component in both the liquid and the vapour phase. 

Several methods for the estimation of liquid thermal conductivities are presented by Reid etal. (1987), namely, the method of Latini and co-workers (Latini Pacetti 1978 Bar-roncini etal. 1980,1981,1983a,b, 1984), the Sato-Riedel method and the Missenard-Riedel method (Riedel 1949,1951a,b,c Missenard 1973). The Latini method employs different parameters for compounds from different families, such as acids, esters, etc., while the other two methods are simply equations that give the thermal conductivity as a function of the molar mass and the reduced temperature. For example, the Sato-Riedel equation reads... 

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