Application of H₂ and H₈ Approaches to the Robust Controller Design for a Heat Exchanger

Abstract

A shell-and-tube heat exchanger and possibilities to use the robust controllers for its control are studied, tested and compared by simulations in this paper. Simulation results obtained using designed controllers were measured calculating integral performance index IAE. The control objective is to keep the output temperature of the heated stream at a reference value. The controlled output is the measured output temperature of the heated stream - kerosene and the control input is the volumetric flow rate of the heating stream - water. The use of the robust controllers can lead to smaller consumption of the heating medium. For controller design the heat exchanger was identified in the form of the 3rd order plus time delay system. As several step responses were measured, interval values of the gain, the time constant and the time delay were obtained. Simulations of control were done in the Matlab/Simulink environment. The simulation results confirmed that designed robust controllers represent the possibilities for successful control of heat exchangers. Comparison with classical PID control demonstrates the superiority of the proposed control especially in the case, when the controlled process is affected by disturbances.