Abstract

The available experimental data in literature for enthalpies of hydrate formation and dissociation are limited and often lacks relevant information required for interpretation. Commonly missing information include hydrate composition, hydration number, temperature and/or pressure data, and degree of super heating during dissociation of hydrate.   
Clausius-Clapeyron equations used with measured or calculated hydrate formation pressure-temperature equilibrium data is the simplest indirect methods used for evaluating enthalpy change involved in phase transition during hydrate formation or dissociation. This approach involves over-simplifications. These oversimplifications make all the data based on Clausius-Clapeyron to be unreliable. And old data using Clapeyron do not have appropriate volume corrections. We therefore propose a thermodynamic scheme (residual thermodynamics approach) which does not have these limitations. This method is based on residual thermodynamics for all properties like equilibrium (pressure-temperature) curves, free energy change as thermodynamic driving force in kinetic theories and enthalpies of hydrate formation and dissociation. The pressure-temperature equilibrium curve obtained in this work agrees well with literature.