Optimality of Process Networks.* *This work was supported by the Center for Integrated Operations in the Petroleum Industry, Trondheim, Norway.

Abstract Abstract In this paper we show that conservation laws for extensive quantities and the second law of thermodynamics lead to conditions for stability and optimality of a process network. Interconnections among nodes are represented through connectivity matrices and network graphs. A generalized version of Tellegen's theorem from electrical circuit theory plays a central role in deriving the objective function of the regarded dynamic process networks. The application of irreversible thermodynamics lead to stability and optimality results based on the co-content and content of the regarded process networks. The principle is illustrated in a pipeflow example.