Here is a description of EES (from Professor S. A. Klein's website).
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 thousands of coupled non-linear algebraic equations. EES can also be used to solve initial value differential equations. EES provides publication-quality plots, linear and non-linear regression, optimization, unit conversion and consistency checking, and uncertainty analyses. Built-in functions are provided for thermodynamic and transport properties of many substances, including steam, air, refrigerants, cryogenic fluids, JANAF table gases, hydrocarbons and psychrometrics. Additional property data can be added. EES also allows user-written functions, procedures, modules, and tabular data.
EES can be downloaded from the EES Information Website. The instructions for how to do this can also be found on Professor Klein's website.
If you are experiencing problems with EES that you believe to be a bug in the program, send a description of your problem about the EES program to Professor S.A. Klein at the email address firstname.lastname@example.org.
If you do have any concerns that need to be answered by CAE, or Professor Klein refers you back to us (CAE), please contact the CAE Help Desk by calling at (608) 262 5349, visiting us in room 116 CAE (1410 Engineering Drive), or emailing us.