Bernd Czech

INFLUENCE OF INTERFACIAL TENSION AND VISCOSITY ON THE BEHAVIOR OF A PACKED COLUMN IN NEAR-CRITICAL FLUID EXTRACTION

Abstract Density and viscosity of the coexisting phases and interfacial tension of the following binary systems were measured: pelargonic acid, linoleic acid, oleic acid or stearic acid as subcritical and carbon dioxide as superecritical components. Also the corresponding phase equilibria were investigated at pressures ranging from 2 to 20 MPa and temperatures from 313 K to 393 K. With increasing pressure the concentration of the supercritical component in the liquid phase increases and viscosity and liquid interfacial tension decreases. At greater activities of the dense gases the interfacial tension decreases dramatically to values less than 2 mN/m. If the pressure exceeds a certain limit, a falling film disintegrates into small droplets. The surface excess passes through a maximum at these conditions. At first appearance of instabilities on a falling film, the logarithm of the Reynolds number is a linear function of the logarithm of the film number. Independent of the type of the investigated packings,...