Chapter 13 - Fuzzy control of heat exchangers in series using complex control structures

Abstract

Implementation of fuzzy controllers in complex control structures is presented, which can be used in industrial applications. Conventional PID control, simple fuzzy control, and two complex control structures with fuzzy controllers were studied and compared using simulation experiments. Fuzzy controllers in the role of primary and secondary controllers were used in the cascade control and in a control system with auxiliary control input. All these control structures were applied to control five counter-current heat exchangers in series, which cooled a distillation product. Simulation experiments showed that the fuzzy control system with the main fuzzy controller and auxiliary control input significantly reduced both the settling time and the overshoots. This control structure ensured also the best integral IAE and ISE quality criteria as well as the lowest coolant consumption. The disadvantage and reason for the rare use of this control structure in practice is that two manipulated variables are needed. The second best was the fuzzy cascade control. Fuzzy-based complex control structures are promising to ensure efficient operation of heat exchangers and to reduce energy consumption.