Julian Hofmann

• Dr.-Ing.
• Automation Engineer at GEA Group

Due to their energy efficient operation and flexible designs, falling film evaporators (FFEs) have a wide field of application in the industry. Besides questions about construction, dominant time delays pose a large challenge to modeling and control of this process. Especially, the automation of production system requires digital twins, i.e., plant...

The paper presents a new multivariable control concept for falling film evaporators (FFEs). Our concept solves the major challenges encountered in modern FFE control: large transport delays, additional control of the output mass flow, coupling of controlled variables, and disturbances due to time-varying input dry matter content. The challenges are...

The paper solves the control loop pairing problem of the falling evaporator process. To this end, we derive a dynamic input-output model by taking dominant time-delays into account. Besides classical methods to solve the loop pairing problem, such as Bristol’s relative gain array or the Niederlinski index, we apply modern approaches, namely, the pa...

The paper presents an identification strategy to obtain relations between time delays of a transport model for an evaporating liquid film and corresponding flow/liquid properties. To this end, step-response based pilot plant experiments referring to the falling film evaporator process are conducted. In this context, the time-delay relations are ide...

The paper presents novel control-oriented transport models for evaporating liquid films in the tubes of a falling film evaporator. In this context, our goal consists in qualitatively mapping the experimentally observed input-output behavior. Two transport models are proposed, where the difference between them is that one allows overtaking of liquid...

Der Beitrag behandelt Modelle für Flüssigkeitsfilme in Rohrleitungen. Da sich das Ein-/Ausgangsverhalten von Flüssigkeitsfilmen nur in grober Näherung mit klassischen Transportmodellen beschreiben lässt, werden zwei neue Modelle entwickelt. Letztere basieren auf Liquidelementen und sind auf andere Transportprozesse, bspw. im Verkehrsfluss, übertrag...

A modular simulation model of the evaporator is developed by dividing it into design-independent subsystems. By introducing this modularity, numerous different evaporator designs, system parameters, operating points or control concepts can be configured and simulated. The plant operation or design can therefore be easily tested and costs for staff...

The paper deals with computer simulation of first-order quasilinear partial differential equations in an online computer simulation environment, such as Simulink. The well-known and well-recommended method of characteristics is employed as it provides better numerical stability than the space discretization methods most commonly used in this contex...