02238nas a2200253 4500008004100000022001400041245012400055210006900179260010600248300001200354490000700366520128200373653002701655653001701682653001701699653001901716653001901735653002201754100002101776700002301797700001901820700001901839856012601858 2013 eng d a0360-544200aHBGS (hydrate based gas separation) process for carbon dioxide capture employing an unstirred reactor with cyclopentane0 aHBGS hydrate based gas separation process for carbon dioxide cap aTHE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, ENGLANDbPERGAMON-ELSEVIER SCIENCE LTDcDEC a252-2590 v633 a

The effect of CP (cyclopentane) as a promoter/additive, in the HBGS (hydrate based gas separation) process for pre-combustion gas mixture was investigated by employing an unstirred reactor configuration. Gas uptake measurements were performed at two different temperatures (275.7 K and 285.7 K) and at an experimental pressure of 6.0 MPa to determine the kinetics of hydrate formation. Experiments were conducted with three different volumes (7.5, 15 and 22 ml) of CP and based on induction time and the rate of hydrate growth, 15 ml of CP was determined to be the optimal volume for carbon dioxide capture at 6.0 MPa and 275.7 K. In addition, the effect of a kinetic promoter, SDS (sodium dodecyl sulfate), was investigated. Surprisingly, no improvement in kinetic performance was observed at 6.0 MPa and 275.7 K in the presence of SDS and CP. From the study, it was found that at the optimal 15 ml CP (CP layer thickness of 1.8 mm), the average composition of carbon dioxide in the hydrate phase was 90.36 mol% with a separation factor of 17.82. Furthermore, the unstirred reactor also yielded better kinetic performance over the stirred tank reactor with the unstirred reactor having a 2.28 times higher average gas uptake. (C) 2013 Elsevier Ltd. All rights reserved.

10aCarbon dioxide capture10aCyclopentane10aGas hydrates10aGas separation10aPre-combustion10aUnstirred reactor1 aHo, Leong, Chuan1 aBabu, Ponnivalavan1 aKumar, Rajnish1 aLinga, Praveen uhttps://library.ncl.res.in/content/hbgs-hydrate-based-gas-separation-process-carbon-dioxide-capture-employing-unstirred-001985nas a2200169 4500008004100000022001400041245011400055210006900169260007100238300001600309490000800325520129200333100002601625700001901651700001501670856013001685 2013 eng d a1932-744700aHeat transfer calculations for decomposition of structure i methane hydrates by molecular dynamics simulation0 aHeat transfer calculations for decomposition of structure i meth a1155 16TH ST, NW, WASHINGTON, DC 20036 USAbAMER CHEMICAL SOCcJUN a12172-121820 v1173 a

Microcanonical ensemble molecular dynamics simulations of structure I methane hydrate is presented in this work to study the endothermic decomposition process. The mechanism of decomposition of methane hydrate as a function of time was explained at the molecular level. The initial temperature and pressure of the simulation were chosen so as to depict the natural gas hydrate in conditions of oceanic sediments. A more realistic strategy was developed to perform the microcanonical ensemble simulation of solid liquid interface of hydrate and amorphous water. Two water models, SPC/E and TIP4P, were used for the simulations, and the results of the simulations were compared. Heat transfer calculations were performed on the adiabatic system, and an attempt has been made to fit the MD simulation results to the heat balance equations derived from the heat transfer calculations. Estimates of the properties at the macroscopic scale, like the equilibrium temperature of methane hydrate and rate of supply of hot water for sustained release of methane from solid hydrate phase, were determined. The equilibrium temperature obtained by the above method was found to be in agreement with the experimentally observed value. Both the SPC/E and TIP4P water models gave similar results.

1 aBaghel, Vikesh, Singh1 aKumar, Rajnish1 aRoy, Sudip uhttps://library.ncl.res.in/content/heat-transfer-calculations-decomposition-structure-i-methane-hydrates-molecular-dynamics-001987nas a2200265 4500008004100000022001400041245010200055210006900157260009000226300001000316490000700326520103300333653002701366653001701393653001901410653002201429653001901451653001901470100002301489700001501512700002901527700001901556700001901575856012701594 2013 eng d a0021-961400aHydrate phase equilibrium of ternary gas mixtures containing carbon dioxide, hydrogen and propane0 aHydrate phase equilibrium of ternary gas mixtures containing car a24-28 OVAL RD, LONDON NW1 7DX, ENGLANDbACADEMIC PRESS LTD- ELSEVIER SCIENCE LTDcJUN a58-630 v613 a

Hydrate phase equilibrium of the ternary guest mixtures containing carbon dioxide, hydrogen and propane at two different compositions were determined. Addition of mole composition of 2.5% propane to the fuel gas (CO2 (40%)/H-2 (60%)) mixture reduces the hydrate formation conditions by 66% at the temperature of 278.4 K. A Clausius-Clapeyron plot for the experimental results was plotted and from the slope, the enthalpy of hydrate dissociation was calculated. The enthalpy of dissociation of the mixed hydrate formed from a ternary gas mixture containing mole composition 38.1% CO2, 59.4% H-2 and 2.5% C3H8 was found to be 110 kJ.mol(-1) and hence it was concluded that the mixed hydrate formed structure II (sII) hydrates. Whereas for the ternary gas mixture containing mole composition 80.0% CO2, 18.8% H-2, and 1.2% C3H8, the enthalpy of dissociation of the mixed hydrate was found to be 78 kJ.mol(-1) and hence we believe the mixed hydrate formed structure I (sI) hydrate. (C) 2013 Elsevier Ltd. All rights reserved.

10aCarbon dioxide capture10aGas hydrates10aGlobal warming10aPhase equilibrium10aPre-combustion10aThermodynamics1 aBabu, Ponnivalavan1 aYang, Ting1 aVeluswamy, Hari, Prakash1 aKumar, Rajnish1 aLinga, Praveen uhttps://library.ncl.res.in/content/hydrate-phase-equilibrium-ternary-gas-mixtures-containing-carbon-dioxide-hydrogen-and-002186nas a2200241 4500008004100000022001400041245009100055210006900146260009900215300001200314490000800326520131600334653001501650653001701665653002201682653002101704653001401725653002101739100002901760700001901789700001901808856011701827 2014 eng d a0306-261900aHydrogen storage in clathrate hydrates: Current state of the art and future directions0 aHydrogen storage in clathrate hydrates Current state of the art  aTHE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, OXON, ENGLANDbELSEVIER SCI LTDcJUN a112-1320 v1223 a

Hydrogen is looked upon as the next generation clean energy carrier, search for an efficient material and method for storing hydrogen has been pursued relentlessly. Improving hydrogen storage capacity to meet DOE targets has been challenging and research efforts are continuously put forth to achieve the set targets and to make hydrogen storage a commercially realizable process. This review comprehensively summarizes the state of the art experimental work conducted on the storage of hydrogen as hydrogen clathrates both at the molecular level and macroscopic level. It identifies future directions and challenges for this exciting area of research. Hydrogen storage capacities of different clathrate structures - sI, sII, sH, sVI and semi clathrates have been compiled and presented. In addition, promising new approaches for increasing hydrogen storage capacity have been described. Future directions for achieving increased hydrogen storage and process scale up have been outlined. Despite few limitations in storing hydrogen in the form of clathrates, this domain receives prominent attention due to more environmental-friendly method of synthesis, easy recovery of molecular hydrogen with minimum energy requirement, and improved safety of the process. (C) 2014 Elsevier Ltd. All rights reserved.

10aClathrates10aGas hydrates10aHydrogen hydrates10aHydrogen storage10aPromoters10aStorage capacity1 aVeluswamy, Hari, Prakash1 aKumar, Rajnish1 aLinga, Praveen uhttps://library.ncl.res.in/content/hydrogen-storage-clathrate-hydrates-current-state-art-and-future-directions-0