On Order Reduction of Nonlinear Differential-Algebraic Process Models

A method for order reduction of nonlinear differential-algebraic models of arbitrary index is presented. The approach is a direct generalization of a method suggested by Pallaske (1987) for the reduction of explicit differential equation models. A rigorous development as well as a theoretical and numerical evaluation of the reduction technique is provided. Strong emphasis is on implementational issues such as the choice of tuning parameters for a particular problem. The case studies discussed include the reduction of a strongly nonlinear catalytic fixed bed reactor model.