Dynamic simulationon a thermodynamic canonical basis

Abstract

In this thesis a general approach is outlined for the modeling and simulation of dynamic processes involving phase and reaction equilibria. A new methodology is presented that exploits the intrinsic structure of thermodynamic functions in their canonical form.

The equations for the equilibrium sub-problems of the dynamic process are stated such as to get a mathematical problem with linear constraints. This implies iterating in the variables most suited for the problem. A methodology is given by an equation structure called the dynamic Newton-Lagrange-Euler formulation. The equation structure is a set of linear equations that when solved yield a simultaneous integration in time and iteration towards the equilibrium of each sub-problem.

A software tool has been designed and implemented in order to automate the construction and updating of the dynamic Newton-Lagrange-Euler equations. Two case studies are shown that explore the described methodology. The simulation results are on par with the results found in the literature.

This systematic approach to the process modeling of flow sheets on a canonical thermodynamic basis has some promising benefits compared to traditional approaches based on a single choice of iteration variables. The presented methodology and software design is very general and has the potential for wide application in dynamic simulation and the development of simulation software.