vdWP-FL: An Improved Thermodynamic Theory for Gas Hydrates with Free-Energy Contributions due to Hydrate Lattice Flexibility

Veesam, Shivanand Kumar and Punnathanam, Sudeep N (2019) vdWP-FL: An Improved Thermodynamic Theory for Gas Hydrates with Free-Energy Contributions due to Hydrate Lattice Flexibility. In: JOURNAL OF PHYSICAL CHEMISTRY C, 123 (43). pp. 26406-26414.

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Abstract

A modification of the original van der Waals and Platteuw (vdWP) theory that accounts for free-energy contributions due to the vibrational and librational movement of water molecules in the hydrate lattice is presented. The modified theory is labeled vdWP-FL. In our previous work, we had presented a method to compute these contributions to the partition function. This was successfully applied to simulated phase equilibria of various gas hydrates. In this work, we apply the vdWP-FL theory to experimental data of gas hydrate phase equilibria and recompute the guest-water potentials. The empty hydrate reference properties are directly computed from molecular simulations. In this implementation of the vdWP-FL theory, only one parameter per guest molecule per cavity type is regressed from the experimental data on gas hydrates. The gas hydrates chosen for this study are methane, ethane, carbon dioxide, propane, iso-butane, and the hydrates formed by their binary mixtures. The vdWP-FL theory gives accurate predictions of the dissociation temperatures and pressures of the above gas hydrates and their mixtures. In addition, it also predicts the hydrate cage occupancy accurately.

Item Type:	Journal Article
Publication:	JOURNAL OF PHYSICAL CHEMISTRY C
Publisher:	AMER CHEMICAL SOC
Additional Information:	Copyright of this article belongs to AMER CHEMICAL SOC
Keywords:	MONTE-CARLO; POTENTIAL-ENERGY; CHEMICAL-POTENTIALS; PHASE-EQUILIBRIA; FUGACITY MODEL; WATER; METHANE; PREDICTION; OCCUPANCY; MOLECULES
Department/Centre:	Division of Mechanical Sciences > Chemical Engineering
Date Deposited:	11 Dec 2019 07:26
Last Modified:	11 Dec 2019 07:26
URI:	http://eprints.iisc.ac.in/id/eprint/63954

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