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We determine the energy-momentum tensor of non-perfect fluids inthermodynamic equilibrium. To this end, we derive the constitutive equationsfor energy density, isotropic and anisotropic pressure as well as for heat-fluxfrom the corresponding propagation equations and by drawing on Einstein'sequations. Following Obukhov at this, we assume the corresponding space-timesto be conform-stationary and homogeneous. This procedure provides thesequantities in closed form, i.e., in terms of the structure constants of thethree-dimensional isometry group of homogeneity and, respectively, in terms ofthe kinematical quantities expansion, rotation and acceleration. In particular,we find a generalized form of the Friedmann equations. As special cases werecover Friedmann and G\"odel models as well as non-tilted Bianchi solutionswith anisotropic pressure. All of our results are derived without assuming anyequations of state or other specific thermodynamic conditions a priori. For theconsidered models, results in literature are generalized to rotating fluidswith dissipative fluxes.

Non-perfect-fluid space-times in thermodynamic equilibrium and generalized Friedmann equations