City Research Online

Abstract

Highly branched alkanes exhibit enhanced free volume relative to their straight chain analogs leading to increased solubility of sparingly soluble gases, such as N2, as well as lower hydrocarbon-gas interfacial tension (IFT) values. In this study high-pressure, high-temperature (HPHT) IFT data are reported for two C16 isomers, hexadecane (HXD) and heptamethylnonane (HMN), with N2 from ~298 to 573 K and pressures to 100 MPa. The IFT data are modeled with Density Gradient Theory (DGT) in conjunction with the Perturbed-Chain, Statistical Associating Fluid Theory equation of state (EoS) with pure component parameters calculated with three different group contribution (GC) methods. One GC method (B-GC) is developed from a database of high-pressure density data and the other two GC methods (S-GC and T-GC) are developed from a large database of pure component vapor pressure and saturated liquid density data. DGT calculations incorporating the B-GC method reasonably represent the IFT for both HXD + N2 and HMN + N2 at low temperatures, but result in significant deviations from experimental IFT values at high temperatures. The S-GC method provides improved IFT predictions relative to the B-GC method at high temperatures, but S-GC predictions are inferior to those obtained using the T-GC method. The superior performance of the T-GC method is attributed to the use of second order GC parameters and to the ability of this method to more correctly predict EoS parameters for both normal and branched alkanes.

Publication Type:	Article
Additional Information:	This document is the Accepted Manuscript version of a Published Work that will appear in final form in Industrial and Engineering Chemistry Product Research and Development, copyright © American Chemical Society after peer review and technical editing by the publisher. To access the final edited and published work see http://pubs.acs.org/journal/iepra6/about.html.
Publisher Keywords:	PC-SAFT, Density Gradient Theory, Diesel Surrogates, n-hexadecane, 2,2,4,4,6,8,8-heptamethylnonane
Subjects:	T Technology > TJ Mechanical engineering and machinery T Technology > TL Motor vehicles. Aeronautics. Astronautics
Departments:	School of Science & Technology > Engineering
SWORD Depositor:	Symplectic Administrator

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