STIRRING AND MIXING EFFECTS ON CHEMICAL INSTABILITIES - BISTABILITY OF THE BRO3-/BR-/CE-3+ SYSTEM

The bistability hysteresis of the inorganic subsystem of the BZ reaction was studied in a CSTR as a function of stirring rate and mixing mode with the flow rate as the control parameter. We found that premixing (PM) of the feedstreams stabilizes the thermodynamic branch, while enhanced stirring in the nonpremixed (NPM) mode destabilizes the same branch. Furthermore, decreased stirring of the NPM system broadens the hysteresis and can, for sufficiently large changes of stirring rate, shift the loop to a domain that does not overlap that obtained at high stirring rate. These counterintuitive and surprising results demonstrate the different dynamical roles played by stirring and by the reactant premixing, and they show the importance of heterogeneous-noise-induced effects. © 1990 American Chemical Society.