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| Predictive Mixture Crossover Volume-Translation SRK Equation of State and Computational Evaluation |
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Abstract Supercritical fluids are applied widely in advanced energy systems and low-temperature heat utilization. The accurate description of their thermodynamic properties is the foundation of thermal system design and analysis. Due to the severe density fluctuations and singularity of properties in near-critical region, classical equations of state fail in critical description. The crossover method based on renormalization group theory can make the equations of state effectively describe near-critical thermodynamic properties. However, existing researches often rely on experimental data fitting, and the data of mixtures is much rarer than that of pure fluids. The applicability and predictive performance of these equations need to be evaluated. This work adopts Kiselev crossover method to establish a crossover volume-translation (VT) Soave-Redlich-Kwong (SRK) equation of state for pure fluid to improve the performance of classical equations in near-critical regions. The new equation does not rely on the correlation of experimental data and can achieve reliable prediction of natural fluid CO2 and refrigerant HFOs from the normal region to the near-critical region. On the basis of the equation of state for pure fluid, a crossover VTSRK equation of state with predictive performance was constructed for mixture systems. The computational performance of the crossover equation of state in critical parameters and pvTx properties was evaluated for CO2 and HFO mixtures. The average relative deviation of the predicted critical temperature was only 0.53%, and the predicted pvTx properties were within 1% deviation for most experimental points. The crossover VTSRK equation of state for mixtures shows good consistency with existing data and has predictive performance for non-associative fluid mixtures.
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Received: 28 October 2024
Published: 03 April 2025
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2025, Vol. 46 
