Heat engine model exhibit super-universal feature and capture the efficiencies of different power plants

We propose a generalized model of a heat engine and calculate the minimum and maximum bounds on the efficiency at maximum power. We obtain a universal form of generalized extreme bounds on the efficiency at maximum power. Our model unifies the bounds on the efficiency and the universality features are observed for various heat engine models. Even though our model is a direct generalization of low-dissipation heat engines, the bounds on the efficiency obtained at a single target function capture those observed in the actual power plants working at different dissipation levels.