Dynamic viscosity of methane hydrate systems from non-Einsteinian, plasma-functionalized carbon nanotube nanofluids

McElligott, Adam; Guerra, André; Du, Chong; Rey, Alejandro D.; Meunier, Jean‐Luc; Servio, Phillip

doi:10.1039/d2nr02712g

Cited by 10 publications

(7 citation statements)

References 57 publications

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“…The reference water system has been tested under a 400 s –1 shear rate, a typical value for the measuring system to register accurate readings with low-viscosity, aqueous samples. A much lower shear rate of 80 s –1 was also tested in the current study to verify the hypothesis of whether 400 s –1 would inhibit the formation of critical hydrate clusters, as suggested in the previous reports . Measurements were averaged over a full revolution (AOFR) with an adjustment time of 5 s for nonhydrate runs and 1 s for hydrate-forming runs.…”

Section: Methodsmentioning

confidence: 80%

Effects of Poly(vinylpyrrolidone) on the Dynamic Viscosity of Methane Hydrate Systems at High-Pressure Driving Forces: Investigation of Concentration, Molecular Weight, and Shear Rate

Guerra

McElligott

et al. 2022

Energy Fuels

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The viscosity of methane hydrate slurries with poly(vinylpyrrolidone) (PVP) at 700 and 7000 ppm by weight, molecular weights of 40 000 (PVP40) and 360 000 (PVP360) Da, and shear rates of 400 and 80 s–1 were measured in a high-pressure rheometer with pressures up to 30 MPag and compared to pure water systems. The additives successfully reduced the formation of high-viscosity slurries but at low concentrations were incapable of delaying hydrate agglomeration at the late growth stage. The average relative time required for PVP40 solutions at 700 ppm to grow to 50 mPa·s was 1.9 times the water reference value but only 1.2 times to reach 200 mPa·s. Improved inhibition was observed for the higher concentration and higher molecular weight sets, where the relative times to reach 50 mPa·s were 8.2 and 2.6 times the water reference value, respectively. While the additives demonstrated antinucleation properties and suppressed crystal growth initially, they accelerated the hydrate clusters agglomeration rate and potentially weakened the hydrate mechanical properties.

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Section: Methodsmentioning

confidence: 80%

Effects of Poly(vinylpyrrolidone) on the Dynamic Viscosity of Methane Hydrate Systems at High-Pressure Driving Forces: Investigation of Concentration, Molecular Weight, and Shear Rate

Guerra

McElligott

et al. 2022

Energy Fuels

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“…However, the experimental limitations (kinetic, mass diffusion, and heat effects) of working with gas hydrates in shear rheometers that reduce the feasibility of such rheological work have also been identified [ 30 ]. Moreover, the addition of plasma-functionalized carbon nanotube nanofluid promoters to methane hydrate systems has been reported, suggesting molecular scale phenomena as a cause of non-Einsteinian dynamic viscosity effects [ 31 ].…”

Section: Introductionmentioning

confidence: 99%

“…A comprehensive list of best practices for the calculation of transport properties by molecular dynamics has been compiled by Maginn et al [ 42 ]. The computational estimation of the transport properties of pre-nucleation methane hydrate systems via MD is a promising alternative to overcome the limitations in the experimental rheology work of gas hydrates [ 30 , 31 ].…”

Section: Introductionmentioning

confidence: 99%

All-Atom Molecular Dynamics of Pure Water–Methane Gas Hydrate Systems under Pre-Nucleation Conditions: A Direct Comparison between Experiments and Simulations of Transport Properties for the Tip4p/Ice Water Model

et al. 2022

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(1) Background: New technologies involving gas hydrates under pre-nucleation conditions such as gas separations and storage have become more prominent. This has necessitated the characterization and modeling of the transport properties of such systems. (2) Methodology: This work explored methane hydrate systems under pre-nucleation conditions. All-atom molecular dynamics simulations were used to quantify the performance of the TIP4P/2005 and TIP4P/Ice water models to predict the viscosity, diffusivity, and thermal conductivity using various formulations. (3) Results: Molecular simulation equilibrium was robustly demonstrated using various measures. The Green–Kubo estimation of viscosity outperformed other formulations when combined with TIP4P/Ice, and the same combination outperformed all TIP4P/2005 formulations. The Green–Kubo TIP4P/Ice estimation of viscosity overestimates (by 84% on average) the viscosity of methane hydrate systems under pre-nucleation conditions across all pressures considered (0–5 MPag). The presence of methane was found to increase the average number of hydrogen bonds over time (6.7–7.8%). TIP4P/Ice methane systems were also found to have 16–19% longer hydrogen bond lifetimes over pure water systems. (4) Conclusion: An inherent limitation in the current water force field for its application in the context of transport properties estimations for methane gas hydrate systems. A re-parametrization of the current force field is suggested as a starting point. Until then, this work may serve as a characterization of the deviance in viscosity prediction.

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“…There have also been many recent studies on the viscosity of graphene and graphene oxide nanofluids. − This is the first time the viscosity of plasma-functionalized graphene has been measured in any system, including liquid and hydrate systems. Though other nanofluids have been analyzed at similar pressures, evaluating the viscosity of graphene nanofluids at high pressure is also entirely novel. − Additionally, this study is paired with another publication that used oxygen-functionalized multiwalled carbon nanotubes in similar systems . A comparison between these two studies is found in that study and will not be further referenced here.…”

Section: Introductionmentioning

confidence: 99%

“…[36][37][38][39] Additionally, this study is paired with another publication which used oxygen-functionalized multi-walled carbon nanotubes in similar systems. 40 A comparison between these two studies is found in that study and will not be further referenced here.…”

Section: Introductionmentioning

confidence: 99%

Non-Einsteinian Viscosity Behavior in Plasma-Functionalized Graphene Nanoflake Nanofluids and Their Effect on the Dynamic Viscosity of Methane Hydrate Systems

McElligott

Guerra

et al. 2022

ACS Appl. Energy Mater.

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The dynamic viscosities of nanofluids containing oxygen-functionalized graphene nanoflakes (O-GNFs) were measured for concentrations ranging from 0.1 to 10 ppm under pressures from 0 to 30 MPag and temperatures from 0 to 10 °C. Water’s viscosity dependence on temperature was not affected by the presence of O-GNFs, though the effective viscosity of the solution was reduced (termed non-Einsteinian viscosity) against common expectations. Hydrogen bond strength may have been reduced at the hydrophobic part of the O-GNF surface, whereas density fluctuations were enhanced. Therefore, larger sites of free volume may have formed, and weaker intermolecular interactions could allow for less-restricted diffusion into those sites, reducing the effective viscosity. The internal friction that would otherwise raise the solution viscosity could be overcome by these surface effects. Water’s viscosity dependence on pressure was also not affected by O-GNFs, except at 10 ppm, where the shuttle effect may have increased the presence of hydrophobic methane bubbles in the solution. Under high pressures, the relative viscosity of the system remained non-Einsteinian at all temperatures except 2 °C. This may have been because the density anomaly of water was shifted to a colder temperature as the hydrogen bonding network was weaker. The phase transition from liquid to hydrate was identical to that of pure water, indicating that the presence of different stages of growth was not affected by the presence of O-GNFs. However, the times to reach a maximum viscosity were faster in O-GNF systems compared to pure water. This said, the hydrate formation limitations inherent to the measurement system were not overcome by the addition of O-GNFs. The times to application-relevant viscosity values were maximized in the 1 ppm system at 49.75% (200 mPa·s) and 31.93% (500 mPa·s) faster than the baseline. Therefore, the presence of O-GNFs allowed for shorter times to desired viscosities at lower driving forces than the baseline, improving the viability of the hydrate technologies to which they can be added.

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Dynamic viscosity of methane hydrate systems from non-Einsteinian, plasma-functionalized carbon nanotube nanofluids

Abstract: The viscosity of oxygen-functionalized multi-walled carbon nanotube (O-MWCNT) nanofluids was measured for concentrations from 0.1 to 10 ppm under conditions of 0 to 30 MPag pressures and 0 to 10...

Cited by 10 publications

References 57 publications

Effects of Poly(vinylpyrrolidone) on the Dynamic Viscosity of Methane Hydrate Systems at High-Pressure Driving Forces: Investigation of Concentration, Molecular Weight, and Shear Rate

Effects of Poly(vinylpyrrolidone) on the Dynamic Viscosity of Methane Hydrate Systems at High-Pressure Driving Forces: Investigation of Concentration, Molecular Weight, and Shear Rate

All-Atom Molecular Dynamics of Pure Water–Methane Gas Hydrate Systems under Pre-Nucleation Conditions: A Direct Comparison between Experiments and Simulations of Transport Properties for the Tip4p/Ice Water Model

Non-Einsteinian Viscosity Behavior in Plasma-Functionalized Graphene Nanoflake Nanofluids and Their Effect on the Dynamic Viscosity of Methane Hydrate Systems

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