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Chemical Engineering

Design, construct, and analyze process machinery including reactors, boilers, and pumps. Solve heat transfer problems and design control systems.

Controlled Mixing Unit

An important control problem is to design controllers for nonlinear systems using model inversion control. The following example uses an InverseBlockConstraints component to easily construct inverse models. It also uses the Modelica_Synchronous Library to automatically discretize the continuous-time nonlinear feedforward controller.

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The Model

This model controls the concentration of the reactant in a mixing unit. In the presence of a catalyst, the reactant splits into several base products that are continuously removed from the tank. Since it is an exothermic reaction, the mixing reactor is cooled with a cooling medium. The cooling temperature is the primary actuation signal and the concentration of the reactant is the controlled signal.

Sampled data controller for mixing unit including the inverse plant model.


The overall system presents a good control behavior, as the concentration of the reactant in the mixing unit follows the desired signal.


Use nonlinear feedforward controller to design for the whole operating region of a plant.

Simulation results.

Explore the Modelica_Synchronous Library to know more about sampled data systems.