Modeling stability conditions of methane Clathrate hydrate in ionic liquid aqueous solutions

摘要

Mixing ionic liquid (IL) and water can influence the thermodynamic characteristics such as water activity. Hence, some ILs can be utilized as inhibitors for hydrate systems. This work was intended to determine the three-phase equilibria of methane hydrate in aqueous solutions of 32 lb using the least squares support vector machine (LSSVM), adaptive neuro-fuzzy inference system (ANFIS), and classification and regression tree (CART). The modeling studies on clathrate hydrates in aqueous solutions of ILs are also reviewed. The used databank contains anion groups such as sulphate, dicyanamide, tetrafluoroborate, and halides. The dissociation temperature of methane hydrate in aqueous solutions of Its is modelled considering the ILs' critical pressure and critical temperature, the pressure of hydrate system, and the concentration of IL in aqueous phase as the independent parameters. All the developed models are found to well represent/predict the methane hydrate dissociation temperatures in aqueous solutions of ILs. The calculated values of average absolute relative deviation for the presented LSSVM, ANFIS, and CART models are equal to 0.08, 0.31, and 0.10, respectively. Hence, the results reveal that the introduced CART and ANFIS models cannot compete with the developed LSSVM approach in representing the dissociation temperatures of the methane hydrate + IL + water systems studied in this research work. Using the proposed LSSVM model, all the investigated database equilibrium temperatures are within the absolute deviation percent of 0.0-1.0% except the data that show an absolute deviation percent of 1.35%. The findings of this study can help researchers and engineers to better understand the effects of ILs on methane hydrate stability conditions toward effective hydrate management. (C) 2020 Elsevier B.V. All rights reserved.