A combined density gradient theory with equation of state model for the study of surface tension of refrigerant fluids

Toward the modelling of surface tension of refrigerant mixture based on linear gradient theory

“…The Gradient Theory (GT) has been thoroughly investigated in the previous studies [14][15][16][17][18][19][20][21][22][23]28], so here, only the framework and essential equations of the Linear Gradient theory (LGT) are presented. According to GT, before the calculation of the surface tension, a series of equations should be solved so as to acquire the density profile in the mixture.…”

“…On the contrary, using predictive models can reduce greatly the cost and time. In the previous studies, several methods for predicting the surface tension have been proposed, including the parachor method [3][4][5][6] and its derivatives, the corresponding-states principle [7][8][9], the Monte Carlo simulation [10,11], the perturbation theory [12,13], and gradient theory [14][15][16][17][18][19][20][21][22][23] to mention only a few. Besides, Zuo and Stenby developed the Linear Gradient Theory (LGT) [24] based on the gradient theory, simplifying the density gradient in a mixture as linear, thus reduced the calculation time without losing accuracy.…”