Assessment of Gibbs Free Energy Calculation in PI‐Controlled Heating

ABSTRACT Challenges in chemical lab experiments often differ from industrial flow process control. Small inaccuracies can become major cost factors, often ignored in lab tests. The present work connects limits of test accuracy and calculated non‐equilibrium entropy, enthalpy, and Gibbs free energy for PI‐controlled heating. While using thermodynamic models, approaches for entropy by J. W. Gibbs and L. Boltzmann as well as enthalpy show comparable trends. Another entropy by E. C. Shannon gives an impression of the instability of PI‐control. Finally, interpretation of Gibbs free energy (Gibbs–Helmholtz) for process description is possible but limited. An impact assessment reveals major limits in reliability, for example, accuracy of heat capacity, but also promising good sensitivity to external perturbation.