Frictional Pressure Drop for Two-phase Flow of Carbon Dioxide in a Tube: Comparison between Models and Experimental Data

We compare models for two-phase frictional pressure drop with experimental data for pure CO₂ taken in a tube of 10 mm inner diameter. The flow was nearly adiabatic, and the mass fluxes ranged from 1058 to 1663 kg/(m2 s), the saturation temperatures were between 3.8 and 17 °C, and the vapor fractions varied from 0.099 to 0.742. Three models for frictional pressure drop were considered, namely a simple model assuming homogeneous flow, the model of Friedel, and the model of Cheng et al. The Friedel model is a curve fit to experimental data based on dimensionless groups, while the Cheng et al. model includes phenomenological sub-models. Our data indicate that the Friedel model is preferable for CO₂-transport purposes, at least for high mass fluxes. However, for flowing vapour fractions above 0.6, the Cheng et al. model also gives good results. A reason why the Friedel model performs better when compared to our data, may be the fact that it is based on a large experimental database. Further, our mass fluxes are higher than the ones employed by Cheng et al.