21-02U

The work is devoted to the microscopic description of the behavior of the fluid system in the immediate vicinity of the critical point, where theoretical and experimental researches are difficult to carry out. For temperatures T<T_c, the regions of variation of the chemical potential and density are singled out and analyzed. In accordance with the chemical potential magnitude, the equation of state of a cell fluid model is written in terms of Heaviside functions. This equation is also given in temperature-density coordinates. As a result of the study of the relationship between density and the chemical potential, the equation for the binodal curve is obtained in the immediate proximity to the critical point.