Design-Oriented Structural Controllability and Observability Analysis of Heat Exchanger Networks

Abstract

The control-relevant design and analysis of Heat Exchanger Networks (HENs) is an essential issue in terms of the design and intensification of sustainable production systems. The structural controllability and observability of HENs should be studied based on their dynamical model. Recently, a maximum matching based algorithm was developed to determine the locations of the minimum number of actuators and sensors needed to ensure the controllability and observability of linear dynamical systems. In this paper, the ability of concentrated parameter state-space models of the heat exchanger units to serve as building blocks of the network of state variables in HENs, and the use of the resultant network of state variables to study the control of relevant topologies and properties of HENs is highlighted. Based on the results of the systematic analysis, the structural patterns that facilitate the control and observation of HENs with a relatively small number of actuators and sensors were determined. Two methods were proposed to define the sets of additional actuators and sensors which are required to improve the operability of the network by decreasing the order of the controlled system. The first method is based on the interpretation of the placement of the sensors and actuators as a set cover problem, while the second one uses two network science-based measures: closeness centrality and betweenness centrality. The proposed methodologies are demonstrated on a benchmark example that is well covered in the literature.