Incremental Identification of Reaction Systems - A Comparison between Rate-based and Extent-based Approaches

An incremental identification approach for determining the kinetics of homogeneous reaction systems from transient concentration measurements has been developed in previous work (Marquardt, W. Chemical Engineering Research and Design 83(A6), 561–573, 2005). This approach decomposes the identification task into a sequence of sub-tasks that include the identification of the rate expressions for every reaction and of the corresponding rate parameters. The approach is of the “differential” type, because reaction rates are estimated through numerical differentiation of concentration measurements. An alternative incremental identification approach based on the “integral method” using the concept of extents has been proposed recently (Bhatt et al., submitted to Industrial & Engineering Chemistry Research, 2011). The present paper compares the performance of these two incremental approaches with respect to their ability to discriminate between two or more competing rate expressions, to estimate the rate parameters with high accuracy, and the associated computational effort. The two incremental approaches are described and their main features investigated via the simulated start-up of a continuous stirred-tank reactor.