Measurements of induction times for clathrate hydrate nucleation: effect of thermal history of hydrate-forming systems

摘要

The induction times for clathrate-hydrate nucleations in water/HCFC- 141 b systems, which have once experienced hydrate formation and dissociation, have been measured. The experimental data processed in the form of probability of survival of hydrate-free water/HCFC-141b samples plotted against the time through which the samples have been subjected to a hydrate-formable condition are greatly deviating from exponential decay curves predicted by the classical nucleation theories which assume a constant nucleation rate uniquely defined for each family of apparently the same hydrate-formable samples subjected to a common thermodynamic history. We suppose that even those samples may have different "memories" of prior hydrate formation/dissociation and hence have nucleation rates which are different from each other but invariable with time. The spectrum of such nucleation rates for each family of samples is deduced from the relevant probability-of-survival vs. time curve to show how the spectrum varies with the thermal history experienced by the family.