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Jitendra Sangwai
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Jitendra Sangwai
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Jitendra Sangwai
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Sangwai, Jitendra S.
Sangwai, Jitendra
Sangwai, J. S.
Sangwai, Jitendra Shital
Sangwai, J.
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2 results
Now showing 1 - 2 of 2
- PublicationA robust model for the phase stability of clathrate hydrate of methane in an aqueous systems of TBAB, TBAB + NaCl and THF suitable for storage and transportation of natural gas(01-07-2016)
;Avula, Venkata Ramana; Semiclathrate hydrates of natural gas have shown potential applications in natural gas storage and transportation. Promoters, viz., tetra-n-alkyl ammonium bromide (TBAB) and tetrahydrofuran (THF) have positive impacts on the phase stability condition in lowering the required pressure for hydrate formation. As part of this work, a predictive model for the phase stability of gas hydrate, which are necessary to understand the phase behavior of methane (CH4) hydrate in promoters, has been proposed. The fugacity of hydrate former in the gaseous phase is calculated from Peng-Peng-Robinson equation of state (PR-EoS), while the fugacity of water in the liquid phase is computed from recently proposed Pitzer-Mayorga-Zavitsas-Hydration (PMZH) model for TBAB system and non-random two liquid (NRTL) model for THF system. The van der Waals Plattew model is employed for the hydrate phase. The vapor pressure of water in the empty hydrate lattice as well as Langmuir adsorption constants have been expressed in terms of concentration of the promoters. The predictions of the proposed model are found to be match well with experimental data on phase stability of CH4 hydrate formed using TBAB and THF aqueous systems. Furthermore, the developed model is employed for the prediction of phase stability conditions of the semiclathrate hydrates of CH4 in TBAB + NaCl system. The developed model is found to interpret the promotion effects of both TBAB (with or without NaCl) and THF on phase stability conditions of CH4 hydrate. AARD-P% with PMZH model are observed to be 3.21% and 8.73% for semiclathrate hydrates of CH4 in TBAB and TBAB + NaCl, respectively, and 8.56% for clathrate hydrate of CH4 in THF. The model may be extended to evaluate the phase stability conditions of hydrates of multicomponent gas systems in TBAB/THF which are necessary for real field applications. - PublicationAn efficient model for the prediction of CO2 hydrate phase stability conditions in the presence of inhibitors and their mixtures(01-01-2015)
;Avula, Venkata Ramana; A thermodynamic model for the prediction of CO2 hydrate phase stability conditions in the presence of pure and mixed salts solutions and various ionic liquids (ILs) is developed. In the proposed model van der Waals and Platteeuw model is used to compute the hydrate phase, Peng-Robinson equation of state (PR-EoS) for the gas phase and the Pitzer-Mayorga-Zavitsas-Hydration model is employed to calculate the water activity in the liquid water phase. This model is an extension of the model developed by Tumba et al. (2011) for the prediction of methane and CO2 hydrate phase stability conditions in the presence of tributylmethylphosphonium methylsulfate IL solution. Shabani et al. (2011) mixing rule is modified by incorporating the water-inhibitor (salt/IL) interaction parameter to calculate the water activity in mixed salt solutions. The model predictions are also calculated using the Pitzer-Mayorga model separately and compared with predictions of the developed model. The model predictions are compared with experimental results on the phase stability of CO2 hydrate in the presence of ILs, pure and mixed salts as reported in literatures. The ILs are chosen from imidazolium cationic family with various anion groups such as bromide (Br), tetrafluoroborate (BF4), trifluoromethanesulfonate (TfO), and nitrate (NO3) and the common salts such as NaCl, KCl and CaCl2. Good agreement between the developed model predictions and the literature data is observed. The overall average absolute deviation (AARD%) with Pitzer-Mayorga-Zavitsas-Hydration model is observed to be within ±1.36% while Pitzer-Mayorga model accuracy were about ±1.44 %. Further, the model is extended to calculate the inhibition effect of selected inhibitors (ILs and salts) on CO2 hydrate formation.