3417 -- Techniques for Obtaining Improved Initial Estimates of Explicit State Variables for Computer-Based Thermodynamic Property Routines PDF

In thermal system simulations, evaluation of thermodynamic properties consumes much of the required computational effort, even dominating computer time in some cases. Numerical convergence routines are required to evaluate the thermodynamic properties for implicit independent variables, such as enthalpy and pressure, rather than explicit variables, such as temperature and specific volume. Convergence is accelerated by good initial approximations of the explicit variables. Presents innovative techniques for obtaining improved initial estimates from approximate equations of state. Improvements over estimates based on ideal gas assumptions, reductions in computation time, and increased numerical stability are documented.

KEYWORDS: calculating, thermodynamics, properties, computers, algorithms.