Application of a new selection algorithm to the development of a wide-range equation of state for refrigerant R134a
- Colorado School of Mines, Golden, CO (United States)
Refrigerants R134a (1,1,1,2-tetrafluoroethane) is a leading substitute for refrigerant R12. As such, there has been worldwide activity to develop accurate wide-range equations of state for this fluid. In this study, we have developed a new selection algorithm for determining high-accuracy equations of state in the Helmholtz representation. This method combines least-squares regression analysis with simulated annealing optimization. Simulated annealing, unlike stepwise regression, allows for the controlled acceptance of random increases in the objective function. Thus, this procedure produces a computationally efficient selection algorithm which is not susceptible to the function-space local-minima problems present in a purely stepwise regression approach. Two equations are presented in this work and compared against experimental data and other high-accuracy equations of state for R134a. One equation was produced strictly by using stepwise a regression algorithm, while the other was produced using the simulated-annealing selection algorithm. In both cases the temperature dependence of the equations was restricted to have no terms whose exponents were greater than five.
- Sponsoring Organization:
- USDOE
- DOE Contract Number:
- FG02-92ER14294
- OSTI ID:
- 56969
- Report Number(s):
- CONF-940633-; ISSN 0195-928X; TRN: 95:003614-0002
- Journal Information:
- International Journal of Thermophysics, Vol. 16, Issue 1; Conference: 12. symposium on thermophysical properties, Boulder, CO (United States), 19-24 Jun 1994; Other Information: PBD: Jan 1995
- Country of Publication:
- United States
- Language:
- English
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