A Generalized Saturated Liquid-Vapor Pressure Equation Based on Critical and Triple Point Temperature and Pressure Data

Pooria Samandi; Amir Karimi; Jasmine Pae

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Conference: 2025 ASEE -GSW Annual Conference
Location: Arlington, TX, Texas
Publication Date: March 9, 2025
Start Date: March 9, 2025
End Date: March 11, 2025
Page Count: 10
DOI: 10.18260/1-2--55024
Permanent URL: https://peer.asee.org/55024
Download Count: 10

Paper Authors

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Pooria Samandi The University of Texas at San Antonio

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I received my Bachelor's Degree in mechanical engineering from the Imam Khomeini Internation University in Iran and immigrated to the United States to study mechanical engineering at the University of Texas at San Antonio as a Master's student. I am also currently employed as a mechanical engineer focusing on HVAC system design for residential, commercial, and industrial buildings.

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Jasmine Pae The University of Texas at Arlington

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Jasmine Pae is a PhD student in Mechanical Engineering at the University of Texas at Arlington. She earned her Bachelor of Science in Mechanical Engineering from the University of Texas at San Antonio and an MBA from the University of Arkansas.

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Amir Karimi P.E. The University of Texas at San Antonio

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Amir Karimi, University of Texas, San Antonio Amir Karimi is a Professor of Mechanical Engineering at The University of Texas at San Antonio (UTSA). He received his Ph.D. degree in Mechanical Engineering from the University of Kentucky in 1982. His teaching and research interests are in thermal sciences. He has served as the Chair of Mechanical Engineering (1987 to 1992 and September 1998 to January of 2003), College of Engineering Associate Dean of Academic Affairs (Jan. 2003-April 2006), and the Associate Dean of Undergraduate Studies (April 2006-September 2013). Dr. Karimi is a Fellow of ASEE, a Fellow of ASME, senior member of AIAA, and holds membership in ASHRAE, and Sigma Xi. He has served as the ASEE Campus Representative at UTSA, ASEE-GSW Section Campus Representative, and served as the Chair of ASEE Zone III (2005-07). He chaired the ASEE-GSW section during the 1996-97 academic year.

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Abstract

Saturated liquid-vapor pressure (SLVP) is an essential thermodynamic property whose prediction is of great essence across many industrial and academic applications. Most Current models rely on substance-specific constants or empirical data that introduce logistical challenges and limit their applicability across a wide range of substances. Classic models such as the Antoine equation, the Clausius Clapeyron relation, and the more modern Dong-Lienhard equation have served as the main approaches for the prediction of SLVP, however, they fail to remain accurate across a wide enough temperature range while also relying on substance specific constants. More advanced and complex methods, including the Lee-Kesler equation,the Redlich-Kwong method, and the Ambrose Walton Corresponding States Method provide a significant accuracy advantage by incorporating Pitzer Factor Constants in order to account for the non-ideal and substance-specific behavior of varying substances. Although such models provide far greater accuracy compared to classic approaches, they require extensive substance-specific data and correlations that not only add complexity to the equations, but also can be a major roadblock for new or peripheral substances that might not have such constants available.

Our approach proposes a generalized SLVP equation that foregoes the need for Pitzer Factor or other substance-specific constants by solely relying on temperature and pressure data at the critical and triple points. Such an approach offers a far simpler and more universal model that can be applied across a very wide field of substances with minimal substance-specific information. Because the primary basis of our approach involves critical and triple point data, SLVP for novel substances can be readily predicted, which will often lack substance-specific data such as Pitzer Factor Constants. In contrast, Pitzer Factor-based models, while more accurate for certain substances, introduce additional complexity and will require detailed experimental data for each compound.

Although the full derivation of our generalized equation is still in progress, we have developed an interim equation based on reduced pressure and temperature data, derived using critical and triple point temperature and pressure values. This equation has enabled the collapse of experimental temperature and pressure data across several pure substances, including water, carbon dioxide, and other common refrigerants. The data correlation for these substances is illustrated in Figure 1 (provided in full paper), highlighting the potential of our approach to provide consistent results across different fluids. In the future, we will be employing our MATLAB-based optimization tool to further enhance our equation through the correlation of NIST experimental data, enabling us to refine our model and achieve a more universal and accurate fit.

So far in this work, our efforts have been focused on a subset of pure substances, but as we continue to refine and sharpen our model, we plan to incorporate more substances and even venture out of the pure substance category. Once the full equation is realized, we will compare accuracy with experimental data and also other popular models, including those that rely on Pitzer Factors, in order to prove that the simplicity of our approach doesn’t compromise its accuracy. Ultimately, our objective is to develop a generalized SLVP prediction model that balances simplicity with predictive accuracy across a wide range of substances. The full paper will include a more completed result of this study.

Citation
Format

Samandi, P., & Pae, J., & Karimi, A. (2025, March), A Generalized Saturated Liquid-Vapor Pressure Equation Based on Critical and Triple Point Temperature and Pressure Data Paper presented at 2025 ASEE -GSW Annual Conference, Arlington, TX, Texas. 10.18260/1-2--55024

TY  - CPAPER
AB  - Saturated liquid-vapor pressure (SLVP) is an essential thermodynamic property whose prediction is of great essence across many industrial and academic applications. Most Current models rely on substance-specific constants or empirical data that introduce logistical challenges and limit their applicability across a wide range of substances. Classic models such as the Antoine equation, the Clausius Clapeyron relation, and the more modern Dong-Lienhard equation have served as the main approaches for the prediction of SLVP, however, they fail to remain accurate across a wide enough temperature range while also relying on substance specific constants. More advanced and complex methods, including the Lee-Kesler equation,the Redlich-Kwong method, and the Ambrose Walton Corresponding States Method provide a significant accuracy advantage by incorporating Pitzer Factor Constants in order to account for the non-ideal and substance-specific behavior of varying substances. Although such models provide far greater accuracy compared to classic approaches, they require extensive substance-specific data and correlations that not only add complexity to the equations, but also can be a major roadblock for new or peripheral substances that might not have such constants available.

Our approach proposes a generalized SLVP equation that foregoes the need for Pitzer Factor or other substance-specific constants by solely relying on temperature and pressure data at the critical and triple points. Such an approach offers a far simpler and more universal model that can be applied across a very wide field of substances with minimal substance-specific information. Because the primary basis of our approach involves critical and triple point data, SLVP for novel substances can be readily predicted, which will often lack substance-specific data such as Pitzer Factor Constants. In contrast, Pitzer Factor-based models, while more accurate for certain substances, introduce additional complexity and will require detailed experimental data for each compound.

Although the full derivation of our generalized equation is still in progress, we have developed an interim equation based on reduced pressure and temperature data, derived using critical and triple point temperature and pressure values. This equation has enabled the collapse of experimental temperature and pressure data across several pure substances, including water, carbon dioxide, and other common refrigerants. The data correlation for these substances is illustrated in Figure 1 (provided in full paper), highlighting the potential of our approach to provide consistent results across different fluids. In the future, we will be employing our MATLAB-based optimization tool to further enhance our equation through the correlation of NIST experimental data, enabling us to refine our model and achieve a more universal and accurate fit. 

So far in this work, our efforts have been focused on a subset of pure substances, but as we continue to refine and sharpen our model, we plan to incorporate more substances and even venture out of the pure substance category. Once the full equation is realized, we will compare accuracy with experimental data and also other popular models, including those that rely on Pitzer Factors, in order to prove that the simplicity of our approach doesn’t compromise its accuracy. Ultimately, our objective is to develop a generalized SLVP prediction model that balances simplicity with predictive accuracy across a wide range of substances. The full paper will include a more completed result of this study.


AU  - Pooria Samandi
AU  - Jasmine Pae
AU  - Amir Karimi P.E.
CY  - Arlington, TX, Texas
DA  - 2025/03/09
PB  - ASEE Conferences
TI  - A Generalized Saturated Liquid-Vapor Pressure Equation Based on Critical and Triple Point Temperature and Pressure Data
UR  - https://peer.asee.org/55024
DO  - 10.18260/1-2--55024
ER  -