We investigate the relation between the Friedmann and thermodynamic pressure equations,
through solving the Friedmann and thermodynamic pressure equations simultaneously.
Our investigation shows that a perfect fluid, as a suitable solution for the
Friedmann equations leading to the standard modeling of the universe expansion history,
cannot simultaneously satisfy the thermodynamic pressure equation and those of
Friedmann. Moreover, we consider various energy definitions, such as the Komar mass,
and solve the Friedmann and thermodynamic pressure equations simultaneously to get
some models for dark energy fluids. The cosmological consequences of obtained solutions
are also addressed. Our results indicate that some of obtained solutions may unify the
dominated fluid in both the primary inflationary and current accelerating eras into one
model. In addition, by taking into account a cosmic fluid of a known equation of state
(EoS), and combining it with the Friedmann and thermodynamic pressure equations,
we obtain the corresponding energy of these cosmic fluids and face their limitations.
Finally, we point out the cosmological features of this cosmic fluid and also study its
observational constraints.