Public Thesis defense - ICTEAM

Modelling, Analysis and Control of Counterflow Heat Exchangers: An Infinite-Dimensional and Thermodynamic Approach by Jacques KADIMA KAZAKU

Pour l’obtention du grade académique de Doctorat en sciences de l’ingénieur et technologie

In industrial applications where energy is vital, heat exchangers have acquired major economic importance. Indeed, a large part of the thermal energy produced or collected in industry passes at least once through a heat exchanger. These devices mainly make it possible to transfer heat from a hot fluid to a cold fluid, and belong to the class of thermodynamic systems whose dynamics are described by partial differential equations. Heat exchangers are generally sized to operate in steady state. Unfortunately, as soon as disturbances appear due in particular to variations in temperature or supply flow rates, the efficiency of the system deteriorates. So, is it possible to maintain or improve performance by looking at neglected transients during sizing? This issue is addressed in this thesis in three parts. The first part of the work presents the infinite dimensional thermodynamic modelling of a counterflow heat exchanger, and the estimation of the model parameters in temperature (standard model in process engineering), while dealing with questions of structural and practical identifiability. The second part of the thesis addresses the issue related to the dynamic properties of the heat exchanger. In particular, the questions of existence and uniqueness of positive solutions, of controllability and observability, as well as those of passivity and stability in the thermodynamic sense are studied. The last part of the thesis first deals with the proportional-integral control by boundary action by looking for conditions on the parameters of the controller, which guarantee the stability of the closed-loop system. Next, the linear quadratic optimal control theory for the general class of linear infinite-dimensional systems is applied to the heat exchanger model considered. The simulation results show that these two control strategies make it possible to reject the disturbances due to variations in temperature and flow rates or velocities.

Jury members :

• Prof. Denis Dochain (UCLouvain), supervisor
• Prof. Raphaël Jungers (UCLouvain), supervisor et secretary
• Prof. Pierre-Antoine Absil (UCLouvain), chairperson
• Prof. Yann Le Gorrec (Univ-Bourgogne-Franche-Comté, France)
• Prof. Joseph Winkin (UNamur)
• Prof. Jimmy Kalenga Kaunde Kasongo (UNILU, RD Congo)
• Prof. Moïse Mukepe Kahilu (UNILU, RD Congo)
• Prof. Françoise Couenne (UCB – Lyon, France)

Pay attention :

The public defense of Jacques Kadima Kazaku scheduled for Tuesday 30 May at 4:30 p.m. will also take place in the form of a video conference

ID de la réunion : 336 059 875 912
Code secret : nwvAm4

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