Experimental investigation of surface phenomena on quasi non-porous and porous materials near dew points of pure fluids and their mixtures

Density and sorption measurements were carried out with ethane, carbon dioxide, and their binary mixture with an ethane mole fraction of 0.2003 using a modified gravimetric sorption analyzer. Three solid sinkers with a large surface-to-volume ratio and different (quasi non-porous) surface materials and the zeolite 13X (porous material) were investigated. In the vicinity of the dew point, the density measurements were distorted, thus, implying an impact of surface phenomena. Three hypothetical regions were identified for the distortion: (1) gas adsorption of a single layer or a few layers at pressures lower than 0.85∙ps, where ps is the dew-point pressure; (2) multi-layer gas adsorption followed by the beginning of capillary condensation up to about 0.995∙ps; (3) domination of capillary condensation up to ps. With the goal to deliver a sound data basis for the development of an advanced description of fluid-mixture vapor-liquid-equilibrium through equations of state, we established an empirical method to c...