Thermodynamic behavior of the polytropic gas in cosmology

In this paper, we investigate on the thermodynamic behavior of Polytropic gas as a candidate for dark energy by considering the relation P=KP^(1+1/n), where and are the Polytropic constant and Polytropic index respectively. Furthermore, indicates the pressure and is the energy density of the fluid such that where and represent the internal energy and volume, respectively. At first, we find an exact expression for the energy density of the Polytropic gas using thermodynamics and later on, discuss different physical parameters. Finally our study shows that the Polytropic gas may be used to describe the expansion history of the universe from the dust dominated era to the current accelerated era and it is thermodynamically stable.