title: Determination of dew point conditions for CO2 with impurities using microfluidics.
abstract: Impurities can greatly modify the phase behavior of carbon dioxide (CO2), with significant implications on the safety and cost of transport in pipelines. In this paper we demonstrate a microfluidic approach to measure the dew point of such mixtures, specifically the point at which water in supercritical CO2 mixtures condenses to a liquid state. The method enables direct visualization of dew formation (∼ 1-2 μm diameter droplets) at industrially relevant concentrations, pressures, and temperatures. Dew point measurements for the well-studied case of pure CO2-water agreed well with previous theoretical and experimental data over the range of pressure (up to 13.17 MPa), temperature (up to 50 °C), and water content (down to 0.00229 mol fraction) studied. The microfluidic approach showed a nearly 3-fold reduction in error as compared to previous methods. When applied to a mixture with nitrogen (2.5%) and oxygen (5.8%) impurities--typical of flue gas from natural gas oxy-fuel combustion processes--the measured dew point pressure increased on average 17.55 ± 5.4%, indicating a more stringent minimum pressure for pipeline transport. In addition to increased precision, the microfluidic method offers a direct measurement of dew formation, requires very small volumes (∼ 10 μL), and is applicable to ultralow water contents (<0.005 mol fractions), circumventing the limits of previous methods.
authors: Mechanical and Industrial Engineering and Institute for Sustainable Energy, University of Toronto , 5 King's College Road, Toronto, Ontario M5S 3G8, Canada.
authors: Wen
authors: W
authors: Song
authors: Hossein
authors: H
authors: Fadaei
authors: David
authors: D
authors: Sinton
mesh_terms: D002245:Carbon Dioxide / Q000737:chemistry*; D004784:Environmental Monitoring / Q000379:methods*; D005740:Gases / Q000737:chemistry*; D044085:Microfluidics / Q000379:methods*; D011312:Pressure; D013696:Temperature; D014867:Water / Q000737:chemistry*; D014874:Water Pollutants, Chemical / Q000032:analysis*
chemical_list: D005740:Gases; D014874:Water Pollutants, Chemical; D014867:Water; D002245:Carbon Dioxide