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Engineering Equation Solver


EES (pronounced 'ease') is an acronym for Engineering Equation Solver. The basic function provided by EES is the solution of a set of algebraic equations. EES can efficiently solve hundreds of coupled non-linear algebraic equations. EES can also be used to solve initial value differential equations.

A major difference between EES and existing equation solving programs is the many built-in mathematical and thermophysical property functions which EES provides. For example, the steam tables are implemented such that any thermodynamic property can be obtained from a built-in function call in terms of any two other properties. Similar capability is provided many other fluids, e.g., ammonia, nitrogen, methane, propane, all common CFC refrigerants, R-134a and others. Air tables are built-in, as are psychrometric functions and JANAF table data for many common gases. Transport property functions are also provided. Thermophysical property functions operate in either SI and English units. Additional property data may be added by the user.

EES provides the capability to do parametric studies. Selected variables can be included in a spreadsheet-like table. The user determines which variables are independent by entering their values in the table cells. EES will solve the table to determine the values of all dependent variables. A plotting option is provided to display the relationship between any two variables in the table. Multiple plots can be overlayed. Publication quality plots can be output on Postscript - compatible printers.

EES offers the advantages of a simple set of intuitive commands with which a novice can quickly learn to use for solving numerical problems. The large data bank of thermodynamic and transport properties built into EES are helpful in solving problems in thermodynamics, fluid mechanics, and heat transfer. Additional data can be added by the user as functions (written in Pascal, C, or EES) or in a tabular form, which EES will automatically interpolate. As a result, EES is can be used to solve problems in any engineering application.

Click to see an example using EES.

Click to get more information, ordering information, and downloadable demonstrations for EES.

Professor S.A. Klein
Department of Mechanical Engineering
University of Wisconsin-Madison


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