Vapor Pressure

Up to now, I published 2 papers about boiling point estimation. In 2012, Jared Champion overworked and extended the boiling point and vapor pressure method in his MSc.-thesis. These results are currently prepared for publications.

The Rarey/Nannoolal and Rarey/Moller methods are availabe in ARTIST (DDBST) and online at Extended AIM Aerosol Thermodynamics Model.

 

Estimation of the vapour pressure of non-electrolyte organic compounds via group contributions and group interactions

Bruce Mollera, Jürgen Rareya, b, c,, Deresh Ramjugernatha

a School of Chemical Engineering, University of Kwa-Zulu Natal, Durban 4041, RSA, South Africa

b DDBST GmbH, Industriestr. 1, 26121 Oldenburg, FRG, Germany

c Industrial Chemistry, Carl von Ossietzky University Oldenburg, 26111 Oldenburg, FRG, Germany

Available online 16 May 2008

http://dx.doi.org/10.1016/j.molliq.2008.04.020


Abstract

A new group contribution method for the prediction of liquid vapour pressures for non-electrolyte organic compounds is presented. The model represents both a significant improvement and extension of the original method developed by Nannoolal et al. The method was developed with the aid of the Dortmund Data Bank, which contains over 180 000 data points for both solid and liquid vapour pressure (2007). Group parameters were regressed to a training set of nearly 114 000 data points for more than 2330 compounds. As in the case of the method of Nannoolal et al. the new model only requires knowledge about the molecular structure and a single vapour pressure point in order to generate the vapour pressure curve. In the absence of experimental data it is possible to predict the normal boiling point by a method developed earlier by Nannoolal et al. The relative error in pressure was found to be 5.0% (113 888 data points for 2332 compounds) which compares favourably with the previous model (6.6% for 111 757 data points and 2207 compounds).

 

 

Estimation of pure component properties: Part 3. Estimation of the vapor pressure of non-electrolyte organic compounds via group contributions and group interactions

Yash Nannoolala, b, Jürgen Rareya, c,, Deresh Ramjugernatha

a School of Chemical Engineering, University of Kwa-Zulu Natal, Durban 4041, South Africa

b SASOL Technology (Pty) Ltd., Sasolburg, South Africa

c Industrial Chemistry, Carl von Ossietzky University Oldenburg, 26111 Oldenburg, FRG

Received 3 December 2007, Revised 15 April 2008, Accepted 17 April 2008, Available online 3 May 2008

http://dx.doi.org/10.1016/j.fluid.2008.04.020

 


Abstract

A group contribution method for the estimation of the normal boiling point of non-electrolyte organic compounds, which was published earlier, has been the basis for development of subsequent physical property methods. In this work, the model was extended to enable the prediction of vapor pressure data with special attention to the low-pressure region. The molecular structure of the compound and a reference point, usually the normal boiling point, are the only required inputs and enables the estimation of vapor pressure at other temperatures by group contribution. The structural group definitions are similar to those proposed earlier for the normal boiling point, with minor modifications having been made to improve the predictions. Structural groups were defined in a standardized form and fragmentation of the molecular structures was performed by an automatic procedure to eliminate any arbitrary assumptions. The new method is based on vapor pressure data for more than 1600 components. The results of the new method are compared to the Antoine correlative equation using parameters stored in the Dortmund Data Bank, as well as, the DIPPR vapor pressure correlations. The group contribution method has proven to be a good predictor, with accuracies comparable to the correlations. Moreover, because the regression of group contributions was performed for a large number of compounds, the results can in several cases be considered more reliable than those of the correlative models that were regressed to individual components only. The range of the method is usually from about the triple or melting point to a reduced temperature of 0.75–0.8.

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