Dew‐point measurements for water in compressed carbon dioxide

When transporting CO₂ for sequestration, it is important to know the water dew point in order to avoid condensation that can lead to corrosion. A flow apparatus to measure the water content at saturation in a compressed gas has been constructed. A saturator humidifies the flowing gas by equilibrating it with liquid water. Then, a gravimetric hygrometer measures the water mole fraction of the humid gas. Dew‐point data for H₂O in CO₂ on six isotherms between 10 and 80 °C at pressures from 0.5 to 5 MPa are reported. The uncertainties in water content at the dew point (expanded uncertainty with coverage factor k = 2) are on average 0.3%, significantly smaller than in any previous work. The data have been analyzed to extract the interaction second virial coefficient; the values are consistent with the theoretical estimates of Wheatley and Harvey but have a much smaller uncertainty. Published 2015 American Institute of Chemical Engineers AIChE J, 2015 © 2015 American Institute of Chemical Engineers AIChE J, 61: 2913–2925, 2015