Validation of a new apparatus using the dynamic and static methods for determining the critical properties of pure components and mixtures

In this paper the experimental setup of a new apparatus able to provide the critical properties of pure components and mixtures using either a dynamic or a static method is described. Critical temperatures (Tc) and critical pressures (Pc) of pure components (n-pentane, n-heptane and n-decane) and critical loci of three binary mixtures (n-pentane + n-heptane, n-pentane + n-decane and n-heptane + n-decane) are investigated using the dynamic method. For the system n-pentane + n-heptane, the results obtained with the dynamic method are compared with those obtained with the static method. The critical points are visually determined by observing the critical opalescence and the simultaneous disappearance and reappearance of the meniscus in the middle of the view cell which withstands operations up to 673 K and 20 MPa. The experimental critical data are compared with success to literature database and with their prediction from the PPR78 thermodynamic model.

Figure optionsDownload as PowerPoint slideHighlights
► A new apparatus to measure critical points was built.
► Critical points were measured using either a dynamic or a static method.
► Critical loci of never measured systems are determined.