Robust controller design for a heat exchanger using ℋ₂, ℋ_∞, ℋ₂/ℋ_∞, and μ-synthesis approaches

Abstract

Possibilities of using robust controllers for a shell-and-tube heat exchanger control were studied, tested and compared by simulations and obtained results are presented in this paper. The heat exchanger was used to pre-heat petroleum by hot water; the controlled output was the measured output temperature of the heated fluid — petroleum, and the control input was the volumetric flow rate of the heating fluid — water. Robust controllers were designed using ℋ2, ℋ∞, ℋ2/ℋ∞ strategies and μ-synthesis. A comparison with the classical PID control demonstrated the superiority of the proposed robust control especially in case when the controlled process is affected by disturbances.

Robust stability of thermal control systems with uncertain parameters: The graphical analysis examples

“… A shell-and-tube heat exchanger [50],  A heat transfer process [56], and  A heating-cooling system with a heat exchanger [58].…”

“…They include e.g. robust control [49], [50], (robust) model predictive control [51], adaptive control [52], artificial neural networks, fuzzy control [53] and many others. Obviously, these methods are often interconnected as well.…”

“…In order to show the usability of the method, three robust stability examples inspired by control of the real-world thermal processes are elaborated. Specifically, the paper contains the robust stability analysis of the feedback control loops with:  A shell-and-tube heat exchanger which was identified as the (integer order) time-delay model with parametric uncertainty [50],  A heat transfer process modeled as the fractional order time-delay plant with parametric uncertainty [56], and  A heating-cooling system with a heat exchanger described by the anisochronic model with internal delays and parametric uncertainty [58].…”

“…In Section 2, the theoretical foundations of a graphical approach to robust stability analysis for integer order or fractional order systems with parametric uncertainty are presented. The key Section 3 then shows three graphical analysis examples for the thermal control systems with, successively, a shell-and-tube heat exchanger [50], a heat transfer process [56], and a heating-cooling system with a heat exchanger [58]. Finally, Section 4 offers some conclusion remarks.…”

Value-Set-Based Approach to Robust Stability Analysis for Ellipsoidal Families of Fractional-Order Polynomials with Complicated Uncertainty Structure

“…Robustness plays a fundamental role in automatic control theory and practice [1][2][3][4]. Parametric uncertainty represents a natural, effective, but also a relatively simple tool for the mathematical description of real-life systems with potentially complex behavior (including nonlinearities, fast dynamics or changes in physical parameters) by means of linear time-invariant (LTI) models.…”