Paper Number
SC38 

Session
Suspensions, Colloids and Granular Media

Title
Rheology of hydrate particulate suspensions

Presentation Date and Time
February 15, 2017 (Wednesday) 3:35

Track / Room
Track 1 / Audubon B

Authors (Click on name to view author profile)

1. Geri, Michela (MIT, Mechanical Engineering)
2. McKinley, Gareth H. (Massachusetts Institute of Technology, Mechanical Engineering)

Author and Affiliation Lines (in printed abstract book)
Michela Geri and Gareth H. McKinley
Mechanical Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139

Speaker / Presenter 
Geri, Michela

Text of Abstract
Hydrates are crystalline solids that form when a lattice of hydrogen-bonded water molecules is filled by guest non-polar molecules coming from an adjacent gas or liquid phase. Naturally occurring hydrates have gained a lot of attention as potential energy resources and carbon dioxide storage systems, while the formation of hydrate compounds during oil extraction from deep-water fields represents a flow assurance risk for operations if appropriate operating conditions are not established. In any of these applications, the mechanical behavior of hydrates both as bulk solids and as dispersed suspensions of solid particles is of interest and deserving of investigation. In this work we focus on the rheological behavior of hydrate particle suspensions, formed by in-situ heterogeneous nucleation of surfactant-stabilized emulsions containing cyclopentane (a hydrate former at ambient pressure). Hydrate formation is monitored through temporal changes in the linear viscoelastic behavior with a novel time-resolved technique that enables us to maintain a small mutation number during the entire transient process. Yielding and plastic flow are analyzed with creep tests and steady shear measurements at different shear rates, with care taken to eliminate the tendency of the material to slip. The rheological material response for different hydrate volume fractions is interpreted within the framework of a recently proposed model for time-dependent (or thixotropic) elasto-visco-plastic materials by connecting the model parameters to physical quantities that affect particle-particle interactions, the effective volume fraction and the maximum packing fraction of suspended hydrates. This rheological analysis helps to identify the differences observed between hydrate-particle and ice-particle suspensions, to understand the kinetics of hydrate cluster formation and eventually to design appropriate operating conditions whenever efficient transport of hydrate particles suspensions is required.