Development of an interactive computational tool to enhance student learning of Multiple Steady States and Stability in Continuous Stirred Tank Reactors

SEOANE, I.T.; MELLONI, T.; DOUMIC, L.; FASCE, L. A.; AYUDE, M. A.

Congreso; 11th World Congress of Chemical Engineering, WCCE 11; 2023

Computational tools promote the development of novel strategies to teach chemical engineering principles to undergraduates in both traditional face-to-face and virtual classes. In undergraduate courses regarding homogeneous reactors, the comprehensive learning of the dynamic behavior of non-isothermal continuous stirred tank reactors (CSTRs) is challenging. For exothermic reactions, multiple steady states may arise when solving steady state coupled material and energy balances in the CSTR due to the non-linear dependence of reaction kinetics with temperature. The steady-state operating point as well as the reactor operation safety will depend on the start-up process described by non-steady state material and energy balances. All possible reactant concentration vs. temperature trajectories during the transient operation of the CSTR are represented in a Phase-Plane plot. In this work, we present an interactive and versatile computational tool to generate Phase-Plane plots for no-isothermal CSTRs systems. The analysis tool was developed by using Python programming language and NumPy, SciPy and Bokeh libraries. It was improved through years of experience with students of the “Homogeneous Chemical Reactions Engineering” course at the Universidad Nacional de Mar del Plata. Figure 1 illustrates the friendly software interface. After introducing the system parameter values (moving the bars in the “Inlet parameters” section), the transient trajectories are built online by clicking on different initial temperature and reactant concentration values in the Phase-plane plot. Students can observe the existence of multiple steady-state points, infer their stability, and also select proper and safe initial conditions for the start-up process, understanding that depending on them, the system converges to different steady-state operating points and/or thermal run-aways may be induced. Therefore, they can explore the influence of main operating variables, as well as thermodynamics and kinetic parameters, on the system response. When applied as a complement to traditional teaching, the tool provides a valuable insight into the conceptual understanding, and greatly enhances the learning experience. Our practice demonstrates that it helps students to construct knowledge and make meaningful learning.