Limits...
New observations and insights into the morphology and growth kinetics of hydrate films.

Li SL, Sun CY, Liu B, Li ZY, Chen GJ, Sum AK - Sci Rep (2014)

Bottom Line: The kinetics of two-dimensional film growth was inferred from the lateral growth rate and initial thickness of the hydrate film.A clear relationship between the morphology and film growth kinetics was observed.The quantitative results on the kinetics of film growth showed that for a given degree of subcooling, the initial film thicknesses of the double hydrates were larger than that of pure methane or ethane hydrate, whereas the thickest hydrate film and the lowest lateral growth rate occurred when the methane mole fraction was approximately 0.6.

View Article: PubMed Central - PubMed

Affiliation: State Key Laboratory of Heavy Oil Processing, China University of Petroleum, Beijing, 102249, China.

ABSTRACT
The kinetics of film growth of hydrates of methane, ethane, and methane-ethane mixtures were studied by exposing a single gas bubble to water. The morphologies, lateral growth rates, and thicknesses of the hydrate films were measured for various gas compositions and degrees of subcooling. A variety of hydrate film textures was revealed. The kinetics of two-dimensional film growth was inferred from the lateral growth rate and initial thickness of the hydrate film. A clear relationship between the morphology and film growth kinetics was observed. The shape of the hydrate crystals was found to favour heat or mass transfer and favour further growth of the hydrate film. The quantitative results on the kinetics of film growth showed that for a given degree of subcooling, the initial film thicknesses of the double hydrates were larger than that of pure methane or ethane hydrate, whereas the thickest hydrate film and the lowest lateral growth rate occurred when the methane mole fraction was approximately 0.6.

No MeSH data available.


Related in: MedlinePlus

Variation of formation rate constant (ψ′) with composition of the hydrate forming gas.
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f6: Variation of formation rate constant (ψ′) with composition of the hydrate forming gas.

Mentions: The product of δ and vf provides the volumetric growth rate (r) of the hydrate at the gas-water-hydrate contact line, where ψ′ is the variation of the formation rate constant. The dependence of ψ′ on the composition of the hydrate forming gas is shown in Figure 6 along with the volumetric hydrate growth rate. From the data, one can conclude that the volumetric growth rate of double hydrates is also lower than that of simple methane or ethane hydrate at a given degree of subcooling. However, the influence of gas composition on the volumetric growth rate is not as pronounced as the influence of gas composition on the lateral growth rate. As discussed previously, the gas composition also affects the morphology and consequently the porosity of the hydrate film. Therefore, r is actually the apparent growth rate of the porous hydrate film and not the true volumetric growth rate of the hydrate lattice.


New observations and insights into the morphology and growth kinetics of hydrate films.

Li SL, Sun CY, Liu B, Li ZY, Chen GJ, Sum AK - Sci Rep (2014)

Variation of formation rate constant (ψ′) with composition of the hydrate forming gas.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3928615&req=5

f6: Variation of formation rate constant (ψ′) with composition of the hydrate forming gas.
Mentions: The product of δ and vf provides the volumetric growth rate (r) of the hydrate at the gas-water-hydrate contact line, where ψ′ is the variation of the formation rate constant. The dependence of ψ′ on the composition of the hydrate forming gas is shown in Figure 6 along with the volumetric hydrate growth rate. From the data, one can conclude that the volumetric growth rate of double hydrates is also lower than that of simple methane or ethane hydrate at a given degree of subcooling. However, the influence of gas composition on the volumetric growth rate is not as pronounced as the influence of gas composition on the lateral growth rate. As discussed previously, the gas composition also affects the morphology and consequently the porosity of the hydrate film. Therefore, r is actually the apparent growth rate of the porous hydrate film and not the true volumetric growth rate of the hydrate lattice.

Bottom Line: The kinetics of two-dimensional film growth was inferred from the lateral growth rate and initial thickness of the hydrate film.A clear relationship between the morphology and film growth kinetics was observed.The quantitative results on the kinetics of film growth showed that for a given degree of subcooling, the initial film thicknesses of the double hydrates were larger than that of pure methane or ethane hydrate, whereas the thickest hydrate film and the lowest lateral growth rate occurred when the methane mole fraction was approximately 0.6.

View Article: PubMed Central - PubMed

Affiliation: State Key Laboratory of Heavy Oil Processing, China University of Petroleum, Beijing, 102249, China.

ABSTRACT
The kinetics of film growth of hydrates of methane, ethane, and methane-ethane mixtures were studied by exposing a single gas bubble to water. The morphologies, lateral growth rates, and thicknesses of the hydrate films were measured for various gas compositions and degrees of subcooling. A variety of hydrate film textures was revealed. The kinetics of two-dimensional film growth was inferred from the lateral growth rate and initial thickness of the hydrate film. A clear relationship between the morphology and film growth kinetics was observed. The shape of the hydrate crystals was found to favour heat or mass transfer and favour further growth of the hydrate film. The quantitative results on the kinetics of film growth showed that for a given degree of subcooling, the initial film thicknesses of the double hydrates were larger than that of pure methane or ethane hydrate, whereas the thickest hydrate film and the lowest lateral growth rate occurred when the methane mole fraction was approximately 0.6.

No MeSH data available.


Related in: MedlinePlus