The influence of wetting films on capillary condensation in model capillary-porous bodies

Two models of porous structures were used to calculate the amount of capillary-condensed and film liquids as a function of relative vapor pressure in the surrounding medium. Pore size distribution was set by the parabolic function characterized by two parameters, namely, the mean pore size, and the distribution width. The first model was represented by the set of cylindrical capillaries where the formation of a capillary condensate occurs due to the capillary instability of the wetting films on an inner concave capillary surface. The second model was represented by the system of flat slots with various widths. In this case, films coalesce due to the dispersion forces of attraction. The influence of the parameters of the distribution and the shape of pores on the calculated isotherms of capillary and film condensation was monitored. It was shown that capillary condensation hysteresis is possible not only due to the specific pore shape or pore blocking, but can also be realized in the system of straight smooth pores.