Shifted-ectropy based self-stability analysis method for general thermodynamic systems and its application

Self-stability, which is the ability that system state can converge to an equilibrium point without any control input, is one of the most crucial features of every dynamic system. Self-stability analysis is the basis of designing a regulation strategy, and is also one of the key parts of the recently developed physical control theory. For electrical or mechanical systems, generalized Hamiltonian system theory provides a strong tool for not only self-stability analysis but also control law design. However, there is still no mature strategy for analyzing the self-stability of any thermodynamic systems. In this paper, after introducing the concepts of irreversibility function and shifted-ectropy for general thermodynamic systems, a new self-stability analysis approach based on regarding the shifted-ectropy as a Lyapunov function is established for general thermodynamic systems. Moreover, this newly built method is applied to analyzing the self-stability of the thermo-hydraulic loop of a modular high temperature gas-cooled reactor (MHTGR).