Modeling, Simulation and Control of a Thermo-hydraulic System

Several areas of practical interest, ranging from the aerospace to the pharmaceuticalindustry, have to deal with control of thermo-hydraulic systems. Moreover, the urgentneed to increase productivity and tighten product quality specifications, together withan increased awareness of environmental regulations and economic impact, led systems towork in a wide range of operating conditions. Plenty of systems are intrinsically nonlinearthus, Nonlinear Model Predictive Control represents a solution that lends itself well tothe pursuit of energy-efficient objectives by maximising productivity.In this thesis project, thanks to the national research council, it was possible to work ona thermo-hydraulic test plant. The system consists of two hydraulic circuits thermallycoupled by a heat exchanger. Both circuits have at least one tank and one pump thatallows water circulation through piping. Furthermore, the secondary circuit is subjectto a measurable disturbance, namely a fan that cools the water temperature from theheat gained by the primary circuit. Initially, the work focuses on the plant modelling, inparticular, two models were realised. The first represents a simplified version of the processbased on essential balance equations, while the second is more detailed and faithful tothe real plant. The presented control framework is based on Nonlinear Model PredictiveControl (NMPC) that allows to react to the effects of disturbances. Moreover, it manages,through the Programmable Logic Controller (PLC) that commands the actuators of theplant, to regulate the amount of heat exchanged between the two circuits thanks to controlvalves located at the heat exchanger inlets and to one submerged electrical heater insideone of the tanks. Finally, the control algorithm thought and developed for the simplemodel, has been tested on the more complex and realistic model.