Introducing thermal system optimization in an introductory engineering thermodynamics course

摘要

This paper describes a thermal system analysis, design, and optimization project that has been successfully used for two years in an introductory engineering thermodynamics course. The project has provided the students with an opportunity to gain a first-order understanding of the optimization process through the use of spreadsheets and math applications packages. The assignment has been based on the modeling and optimization of a non-ideal gas turbine cycle for use in an Unlimited Class Hydroplane. Student teams are guided through the five steps of the engineering design process including 1.) "information gathering" using mostly web-based material; 2.) "problem definition and alternative generation" using the rules published by the Unlimited Class Hydroplane Racing Association; 3.) "evaluation" of the alternatives using a predictive model based upon thermodynamic principles; 4.) "decision making" using graphical and numerical results generated by spreadsheets and math applications packages; and 5.) "presentation" of the design recommendations in both oral and written reports. Compressor pressure ratio and isentropic efficiencies for the compressor and turbine were the three design variables. Penalty functions were assigned to each to account for component cost, weight, volume, and complexity. The objective function was defined as the ratio of "shaft power to total penalty units" and was maximized using surface plots generated in Excel 97. The optimal solution was also obtained using Mathcad 8.0, Mathematica 3.0, Solver (an add-in tool for Excel 97), and Ada 95, a general programming language. Animated surface plots clearly illustrated the underlying mathematical operations of optimizing a system of non-linear equations.