Control of a Counter-Current Heat Exchanger: Modeling and Predictive Functional Control

Abstract

This paper deals with the control of a counter current heat exchanger using the predictive functional control. The outlet temperature of cold fluid is monitored under varying hot fluid flow rate while the inlet temperatures corresponding to the principal inputs are maintained constant. A simple model of first order corresponding to the system response to flow rate steps is used to implement the predictive functional control. The gain and the time constant of this model depend on initial and final steady states temperatures according to the flow rate. This dynamic model derived from the partial differential equations (PDE) is taken into account to implement the predictive functional control and tested in various configurations. The robustness of this controller has been also tested when the system is submitted to unexpected sudden change of cold fluid flow rate.