Lewis Honors College Capstone Collection

Year of Publication

2013

College

Engineering

Department/School/Program

Mechanical Engineering

Degree Name

Bachelor of Science in Mechanical Engineering

First Capstone/Thesis Advisor

Dr. Alexandre Martin

Abstract

In the field of Fluid Mechanics, the determination of various thermodynamic properties of substances is of utmost importance. Many calculations require values for internal energy or specific heats. If experimental data does not exist to facilitate these calculations, an approximation must be made. This report analyzes three different approximation approaches to examine their relative strengths and weaknesses. The first approach, the Exact Method, uses NASA thermodynamic data to give a numerical interpolation. The second, the Summation Method, breaks up the total energy of the species into different contributions and performs an approximation based on thermodynamic theory. Finally, the Spectroscopic Method utilizes spectroscopic data for the species to give another theoretical model of energy contributions.

These three methods were analyzed by creating a computer program and conducting analyses on various gaseous species. The Exact Method, while giving the most accurate results, is limited in scope and not based on theory. The Summation Method is the simplest theory- based approach, but it is also the least accurate of the three. Although the Spectroscopic Method was the most accurate of the theory-based methods, the level of difficulty of the equations used and the large amount of data required created issues. All three methods matched well at low temperatures, but the theory-based procedures showed problems at higher temperatures, often varying by significant margins.

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