A New Method of Calculation of Reheat Factors for Turbines and Compressors

A simple method is presented for rapid accurate calculation of reheat factors for adiabatic turbines and compressors with an infinite number of stages. The method is limited to fluids for which the following equation of state is adequate and for which the specific heat is a function of temperature only. The method is based on the concept of the step efficiency—the efficiency of an infinitesimal stage based on the reversible adiabatic work—and on the concept of the relative pressure function. The method is used to produce charts of reheat factors for turbines and compressors for several gases. A theoretical justification is given for empirical rules of thumb which have been widely used to predict reheat factors for turbines and compressors with a finite number of stages.