MODELLING A NON-LINEAR PROCESS WITH ASYMMETRICAL DYNAMICS

Strictly speaking, any chemical process is nonlinear, but a continuous process under the steady state operation can usually be regarded as linear since each process variable changes within a limited narrow range. However, it has been pointed out by several workers that there exists some processes whose step responses are considerably different by nature according as the sign of input is plus or minus. It is probably impossible to linearize such a process by use of the conventional perturbation technnique even if the change of each process variable is limited in a narrow range. In this paper, a continuous flow unstirred tank is taken into consideration as an example of processes with asymmetrical dynamics. Based on the experimental studies of its thermal dynamics, its nonlinear mathematical model is constructed and the validity of the model is verified by use of the analog simulation technique. © 1969.