The educational value of modelling complex thermodynamic systems with system dynamics software

Abstract

The solution of problems involving complex thermodynamic systems often occupies much of a students' time and can be a distraction from them developing a clear understanding of system components, interaction of subsystems, modelling simplifications and assumptions, and design optimization. Refocusing students on the fundamental concepts of thermal systems design and analysis is possible with the introduction of system modelling software that carries some of the load of repetitive calculation required for complex systems. Models of thermodynamic systems encountered in an advanced undergraduate thermodynamics course were developed by students (some provided to students) to solve homework problems of complex steam power plants, internal combustion engines, gas turbine power plants, refrigeration, and building energy systems. Computer modelling systems used included two commercial modelling programs, an open source program, and systems developed by the authors. Use of the modelling software forced students to setup problems in the same way as if solved on paper but allowed them to identify common components and processes that could be modeled by common blocks and used in multiple thermal systems. One example presented is a simple process block that gives the state for any location in a converging/diverging supersonic nozzle with a normal shock. The initial implementation has resulted in positive feedback from students and an improved self-efficacy in understanding and modelling complex thermodynamic systems not presented in class.