Variant and invariant states for chemical reaction systems

•We propose a linear transformation to decouple the states of chemical reaction systems.•The rate processes are considered as time varying signals and thus need not be known.•The approach can be seen as a generalization of the concept of reaction variants and invariants.•It is applicable to reaction systems with heat and mass transfers.•We provide an extension to distributed reaction systems with convection and diffusion.

Models of chemical reaction systems can be quite complex as they typically include information regarding the reactions, the inlet and outlet flows, the transfer of species between phases and the transfer of heat. This paper builds on the concept of reaction variants/invariants and proposes a linear transformation that allows viewing a complex nonlinear chemical reaction system via decoupled dynamic variables, each one associated with a particular phenomenon such as a single chemical reaction, a specific mass transfer or heat transfer. Three aspects are discussed, namely, (i) the decoupling of reactions and transport phenomena in open non-isothermal both homogeneous and heterogeneous reactors, (ii) the decoupling of spatially distributed reaction systems such as tubular reactors, and (iii) the potential use of the decoupling transformation for the analysis of complex reaction systems, in particular in the absence of a kinetic model.

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