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The Use Of Mathcad Functions For Thermochemical Analysis Of The Chon System In An Internal Combustion Engines Course

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2004 Annual Conference


Salt Lake City, Utah

Publication Date

June 20, 2004

Start Date

June 20, 2004

End Date

June 23, 2004



Conference Session

TIME 3: Thermal Systems

Page Count


Page Numbers

9.1301.1 - 9.1301.20

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Paper Authors

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Stephen McClain

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NOTE: The first page of text has been automatically extracted and included below in lieu of an abstract

Session 2266

The Use of MathCAD Functions for Thermochemical Analysis of the CHON System in an Internal Combustion Engines Course

Stephen T. McClain Assistant Professor Department of Mechanical Engineering The University of Alabama at Birmingham 1530 3rd Ave. S., BEC 358B Birmingham, AL 35294-4461


Data from “The Chemkin Thermodynamic Data Base” were used to generate MathCAD functions for the molar specific enthalpy, internal energy, entropy, specific heat at constant volume, and the specific heat at constant pressure for twelve chemical species of the carbon-hydrogen-oxygen-nitrogen (CHON) system. The MathCAD functions were made available for students in ME 448/548 Internal Combustion Engines to use in their homework and projects. The CHON functions were generated to ease the complication of using tabulated data for ideal gas properties and were used by the students to easily determine aspects of combustion such as the heat of combustion of a fuel, adiabatic flame temperature, equilibrium constant, and equilibrium compositions of reacting ideal-gas mixtures. The details and usage of the CHON-MathCAD functions are discussed, and specific examples of their application to problems in an internal combustion engines course are presented. The CHON functions for MathCAD are available for download at, and may be referenced by any other MathCAD worksheet.


An introduction to combustion is an important component of a first course in internal combustion engines. The current manufacturers’ emphasis on lowering emissions requires that student engineers wanting a position in engine design and development understand the basics of combustion and equilibrium. Since combustion fundamentals may not be covered in their applied thermodynamics course, this material must be covered in an internal combustion (IC) engine fundamentals course.

The combustion material covered in an internal combustion engines course usually includes enthalpy of combustion, adiabatic flame temperature, and chemical equilibrium.1,2,3 Without using computer programs, working fundamental combustion problems requires the arduous use of tables. Undergraduates in an IC engines course often become frustrated using the tables, and fail to comprehend either the material or the

Proceedings of the 2004 American Society for Engineering Education Annual Conference & Exposition Copyright © 2004, American Society for Engineering

McClain, S. (2004, June), The Use Of Mathcad Functions For Thermochemical Analysis Of The Chon System In An Internal Combustion Engines Course Paper presented at 2004 Annual Conference, Salt Lake City, Utah.

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