Solid fraction modelling for CO 2 and CO 2–THF hydrate slurries used as secondary refrigerants

Abstract

In the present paper, the suitability of hydrate slurries in secondary refrigeration was investigated by the means of a new hydrate solid-fraction model. Considering the high melting enthalpy of CO 2-containing hydrates, slurries presenting high hydrate solid fractions can carry sufficient latent heat to be useful for a two-phase secondary-refrigerant application. The model presented in this paper allowed to calculate the solid fraction of CO 2 and CO 2–THF hydrate from thermodynamic conditions of pressure and temperature. Contrary to a previous work on single CO 2 hydrates in a closed system, the present model can take into account hydrate mixture and is well adapted to additional CO 2 injections (opened system). By relying on the hydrate-conversion model results, the study of hydrates in suspension in a carrying liquid was also studied in an experimental loop and was based on a formation process by CO 2 injection in a cooled aqueous solution.