Modeling of differential-algebraic thermofluid systems using singularly perturbed dynamics

Dynamic systems described by an implicit mixed set of differential and algebraic equations (DAEs) frequently arise when modeling thermofluid control systems. This paper describes a general approach based on singular perturbation analysis for adding fast dynamics to a system of DAEs so that they can be expressed in an explicit state space form. Conditions for convergence and approximation methods are investigated. The approach is illustrated for a model of a two-phase flow heat exchanger.