ENHANCEMENT OF THE PRODUCTION-RATE IN CHEMICAL-REACTIONS WITH THRESHOLDS

In nonlinear chemical reactions with threshold properties, exceptional ly large enhancements of the production rate in a chemical flow reacto r may be achieved by external periodic forcing. A threshold may be rep resented by the turning point in a bistability curve or by a Hopf bifu rcation between a focal steady state and a limit cycle. Since the prod uction rate is equal to the (mathematical) product of the flow rate an d the reaction yield, large production rate enhancements will be achie ved at high flow rates with short pulses to lower flow rates if the pr oduct yield increases with decreasing flow rate into the reactor. Sinu soidal flow rate perturbations and perturbations using short pulses gi ve equally large production rate enhancements over the free running re action if the comparison is made at the same average flow rate. If the comparison is made for identical perturbation amplitudes, the pulse p erturbations lead to larger production rate enhancements than the sinu soidal perturbations. An easy way to achieve unusually large productio n rate enhancements (similar to 100%) is to simply turn the flow rate periodically on and off in analogy to the bang-bang method. This is de monstrated experimentally in the minimal bromate oscillator using a su bcritical Hopf bifurcation as a threshold and by corresponding NFT mod el calculations.