Flow Properties of CO2 Hydrate Slurry Used as a Secondary Refrigerant

An experimental loop was used to produce CO2 hydrate slurries by cooling after CO2 injection in precooled water. The flow characteristics of CO2 hydrate slurry for 8.2~23.1% volume fraction in 8mm straight stainless steel tubes were studied in a dynamic loop. The pressure drops of CO2 hydrate slurry were measured which shows increase with the increase of flow rate. The flow of CO2 hydrate slurry presents a non-Newtonian behavior. The flow transition of CO2 hydrate slurry was determined at 0.60 < v < 0.65m/s. At flow rate v < 0.60m/s, CO2 hydrate slurry behaves as a Herschel-Bulkley fluid. The apparent viscosity decreases with the increase of shear rate, which accords with its shear-thinning feature. At flow rate v > 0.65m/s, the apparent viscosity increases as the increase of shear rate which shows a shear-thickening feature. CO2 hydrate slurry behaves as a Dilatant fluid. The apparent viscosity of CO2 hydrate slurry changes from 8.5 to 10.6mPa·s at shearing rate γ̇=600s⁻¹. The rheological parameters and equations are determined which can provide the guideline for the research of CO2 hydrate slurry flow property and its application.