A method for maximizing thermal efficiency of a power plant, the method comprising obtaining the current state of the plant from available measured data; obtaining a set of Variables representing a current state of the power plant; applying a set of constraints to the Variables; generating a revised set of Variables representing a revised state of the power plant; and testing the revised set of Variables within a mathematical model for convergence. Generating the revised set of Variable is based at least partly on: Euler's equation, the conservation of mass equation, and a mathematical description of a reversible continuum. There are also provided a related power plant thermal efficiency maximization system and computer program.