Corresponding states vapour–liquid phase equilibria of confined square–well fluid

Abstract

Corresponding states vapour–liquid phase equilibria of confined square-well fluid are studied by means of grand-canonical transition-matrix Monte Carlo simulation and histogram reweighting method. In this study, square-well fluid is considered under hard and attractive slit pore confinements ranging from 1.5 to 40 molecular diameters. Corresponding states vapour–liquid phase coexistence envelopes display insignificant effect of wall−fluid interaction for slit pore confinements ranging from 1.5 to 3 molecular diameters. On the other hand, significant effect of wall−fluid interaction on the corresponding state coexistence envelope is observed for slit pore confinements ranging from 4 to 40 molecular diameters. Moreover, at a given slit width, shrinking in corresponding state coexistence envelope is observed with increase in the wall−fluid interaction. However, in the larger slit pore width of 30 to 40 molecular diameters, shrinking in the corresponding state vapour–liquid coexistence envelopes become indifferent with the stronger wall−fluid interactions studied in this work. Structural behaviour of coexisting phases in slit pores are also investigated through local density profiles, to understand the overall behaviour of corresponding states coexistence envelopes. Fluctuating positive and negative deviations in the corresponding state spreading pressure with respect to corresponding bulk value is observed for studied wall−fluid interactions and slit pore confinements.