A consistent and verifiable macroscopic model for the dissolution of liquid CO2 in water under hydrate forming conditions

Direct injection of liquid CO2 into the ocean has been proposed as one method to reduce the emission levels Of CO2 into the atmosphere. When liquid CO2 is injected (normally as droplets) at ocean depths > 500 in, a solid interfacial region between the CO2 and the water is observed to form. This region consists of hydrate clathrates and hinders the rate of dissolution Of CO2 . It is, therefore, expected to have a significant impact on the injection of liquid CO2 into the ocean. Up until now, no consistent and predictive model for the shrinking of droplets Of CO2 under hydrate forming conditions has been proposed. This is because all models proposed to date have had too many unknowns. By computing rates of the physical and chemical processes in hydrates. via molecular dynamics simulations, we have been able to determine independently some of these unknowns. We then propose the,most reasonable model and use it to make independent predictions of the rates of mass transfer and thickness of the hydrate region. These predictions are compared to measurements, and implications to the rates of shrinkage Of CO2 droplets under varying flow conditions are discussed. (C) 2002 Elsevier Science Ltd. All rights reserved.