Keywords: exergy gradient, necessary condition, optimum, thermodynamic objective, turbine inlet, Rankine cycle power plants, thermodynamics, power plant optimisation, simulation, optimal design, economics, geothermal power plants
A necessary condition for optimum Rankine cycle power plants
Consumers pay more for electricity than necessary partly because commercial power plant operating criteria are not universally valid. Although such plants are commonly designed to provide electricity at least cost for given conditions, operating criteria lack a rigorous thermodynamic basis. The current empiricism alone costs US consumers billions of dollars per year. This dilemma exists because the required correspondence between an economically optimised plant and the identical plant operating at the most favourable thermodynamic conditions has not been previously identified. A new necessary condition for economically optimised Rankine cycle power plants is described. Formal simulations of three different power plants demonstrate exact correspondence between economically optimised designs and their thermodynamically optimised counterparts using a new objective from nearly century old thermodynamics. These are very important but controversial results, which will find broad application.