  We Consider a cosmological model based on a generalization of the equation of
state proposed by Nojiri and Odintsov [46] and \v{S}tefan\v{c}i'c [47], [48].
We argue that this model works as a dark fluid model which can interpolate
between dust equation of state and the dark energy equation of state. We show
how the asymptotic behavior of the equation of state constrained the parameters
of the model. The causality condition for the model is also studied to
constrain the parameters and the fixed points are tested to determine different
solution classes. Observations of Hubble diagram of SNe Ia supernovae are used
to further constrain the model. We present an exact solution of the model and
calculate the luminosity distance and the energy density evolution. We also
calculate the deceleration parameter to test the state of the universe
expansion.
