2 research outputs found
Predicting Temperature-Dependent Aqueous Henry’s Law Constants Using Group Contribution Methods
A first-order
temperature-dependent group contribution method was
developed to predict Henry’s law constants of hydrocarbons,
alcohols, ketones, and formates in which none of the functional groups
are attached directly to a benzene ring. Efforts to expand this method
to include ester and ether groups were unsuccessful. Second-order
groups were developed at a reference condition of 298.15 K and 100
kPa. A second-order temperature-dependent group contribution method
was then developed for hydrocarbons, ketones, esters, ethers, and
alcohols. These methods were compared to existing literature prediction
methods
New Vapor-Pressure Prediction with Improved Thermodynamic Consistency using the Riedel Equation
Vapor
pressure, heat of vaporization, liquid heat capacity, and
ideal-gas heat capacity for pure compounds between the triple point
and critical point are important properties for process design and
optimization. These thermophysical properties are related to each
other through temperature derivatives of thermodynamic relationships
stemming from a temperature-dependent vapor-pressure correlation.
The Riedel equation has been considered to be an excellent and simple
choice among vapor-pressure correlating equations [Velasco et al. J. Chem. Thermodyn. 2008, 40 (5), 789−797] but requires modification of the final coefficient to
provide thermodynamic consistency with thermal data [Hogge et al. Fluid Phase Equilib. 2016, 429, 149−165]. New predictive
correlations with final coefficients in integer steps from 1 to 6
have been created for compounds with limited or no vapor-pressure
data, based on the methodology used originally by Riedel [Chem. Ing. Tech. 1954, 26 (2), 83−89]. Liquid heat capacity was predicted using
these vapor-pressure correlations, and the best final coefficient
values were chosen based on the ability to simultaneously represent
vapor pressure and liquid heat capacity. This procedure improves the
fit to liquid heat-capacity data by 5–10% (average absolute
deviation), while maintaining the fit of vapor-pressure data similar
to those of other prediction methods. Additionally, low-temperature
vapor-pressure predictions were improved by relying on liquid heat-capacity
data