Nonlinear frequency response analysis of forced periodic operation of non-isothermal CSTR using single input modulations. Part II: Modulation of inlet temperature or temperature of the cooling/heating fluid

Abstract

Periodic operation of a non-isothermal CSTR subject to a single input modulation is analyzed considering a nth order reaction and using the nonlinear frequency response (NFR) method, introduced in our previous publications. The method is based on deriving the asymmetrical second order frequency response function (FRF) and analyzing its sign. In Part I of this paper, the periodic modulations of inlet concentration or flow-rate of the reaction stream were investigated. In this Part II, periodic operations are analyzed for modulations of the temperature of the inlet reaction stream or the temperature of the heating/cooling fluid. Conditions that need to be fulfilled in order to achieve process improvement through periodic operation are identified. The method is applied for the same numerical example taken from literature which was used in Part I. The results obtained by the NFR method are compared with the results of numerical simulations. Good agreement is obtained, except for forcing frequencies close to the resonant frequency. In these cases, even the sign of the DC component was not predicted correctly.