Characterizing wet and dry fluids in temperature-entropy diagrams
| Autor: | S. Velasco, J.A. White |
|---|---|
| Rok vydání: | 2018 |
| Předmět: |
Standard molar entropy
Vapor pressure 020209 energy Thermodynamics 02 engineering and technology Wet and dry fluids Industrial and Manufacturing Engineering Molar volume 020401 chemical engineering Vaporization 0202 electrical engineering electronic engineering information engineering Gas constant Saturation heat capacities 0204 chemical engineering Electrical and Electronic Engineering Civil and Structural Engineering Physics Mechanical Engineering Building and Construction Pollution General Energy Acentric factor Temperature-entropy saturation curve Saturation vapor curve Saturation properties Dimensionless quantity |
| Zdroj: | GREDOS. Repositorio Institucional de la Universidad de Salamanca instname |
| Popis: | In this work we show that the shape of the liquid-vapor saturation curve in a Tr−s∗ diagram (Tr = T/Tc and s∗ = s/R, with Tc the critical temperature, s the molar entropy and R the gas constant) for a given fluid is mainly governed by the acentric factor, ω, and the critical molar volume, vc, of the fluid. The study uses as reference the point M where the saturated vapor curve in the Tr−s∗ diagram changes its concavity, i.e. ( d 2 s *g / d T r 2 ) M = 0 . By analyzing the data provided by the National Standards and Technology (NIST) program RefProp 9.1 for 121 fluids, we find that, at this point, TMr≈0.81 and the slope ξ M * = ( d s *g / d T r ) M is well correlated with vc, existing a threshold value vc,0≈0.22 m3 kmol−1 so that ξ M * 0 (wet fluid) for vc ξ M * > 0 (dry fluid) for vc > vc,0. This direct relation between vc and the wet or dry character of a fluid is the main result of the present work. Furthermore, the dimensionless vaporization entropy at the reference point M, Δ v s M * = s M *g − s M *l , increases in a nearly linear way with ω. |
| Databáze: | OpenAIRE |
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