Prediction of gas and refrigerant hydrate equilibrium conditions with and without thermodynamic inhibitors using simple empirical correlations

Clathrate hydrates or gas hydrates are crystalline solid compounds which have formed from water molecules as host and gas molecules as guest. Due to the hydrogen bonds, water constructs a framework that entraps some small nonpolar molecules (typically gases) and in suitable conditions, low temperature and high pressure, gas hydrate forms. The estimation of gas and refrigerant hydrate dissociation conditions with and without alcohols and NaCl aqueous solutions by simple empirical correlations is the objective of this communication. The empirical correlations to estimate the equilibrium clathrate hydrate pressure of CH4, C2H6, C3H8, CO2, N2, H2S, R22, R23, R134a, R116, R125a, R152a, R141b, R410a, R407c, R507c, CH4+Methanol, CH4+Ethylene glycol, CH4+Triethylene glycol, CH4+Ethanol, CH4+Sodium chloride, CO2+Methanol, CO2+Glycerol, CO2+Sodium chloride, R134a+ Sodium chloride, R507c+ Sodium chloride and R410a+ Sodium chloride systems as the functions of equilibrium hydrate temperature and mass fraction and or molality have been proposed. To determine constant coefficients in correlations, genetic algorithm has been employed as an optimization method, and mean squared error has been selected as its fitness function. Due to the low values of calculated absolute average deviations (between 0.00 and 7.65), except for H2S + pure water with the highest amount of AAD% (11.51), these correlations have been enabled to predict studied hydrate dissociation conditions, well.