3.1.0 Introduction: Heat exchanger network synthesis (HENS) is an important field in thermal engineering and has been the subject of a considerable amount of research over the past 50 years. Its significance can be attributed to its role in controlling the costs of energy for a process. The heat-exchanger network (HEN) design problem was introduced into the literature by Ten Broeck in 1944. The...

Heat exchanger networks (HENs) play a significant role in the energy conservation of any process industry. The HENs are used to maximize heat recovery by exchanging between hot and cold streams. Therefore, optimum design is extremely important reach maximum efficiency systems. Many graphical methods have been developed during last four decades for synthesizing (HENs). However, most these only e...

The objective of this work is to propose a systematic procedure to find a control structure for optimal operation of heat exchanger networks. Optimal operation in this context requires that 1) all controlled temperatures are kept at their targets and 2) utility cost is minimized. The degrees of freedom of heat exchanger networks are analyzed and used to identify if the operation is structurally...

Heat Exchanger Networks (HENs) are commonly represented on grid diagrams (GD). However, the traditional GD has some drawbacks with regard to calculation and evaluation. In this paper a representation of HENs in the form of a matrix called HEN Steam Matrix (HENSM) is presented. This numerical way has some advantages over graphical representation. In HENSM the heat exchangers are arranged in orde...

The paper discusses optimal operation of a general heat exchanger network with given structure, heat exchanger areas and stream data including predefined disturbances. A method that combines the use of steady state optimization and decentralized feedback control is proposed. A general steady state model is developed, which is easily adapted to any heat exchanger network. Using this model period...

The last few decades have seen considerable research into the synthesis of optimal heat exchanger networks (HENs). Process integration has paved the way for designs that are optimal from the point of view of energy recovery. Subsequent optimization of net exchanger area in such designs results in a network that is optimal from the point of view of utility consumption and exchanger area. Of late...

Improving energy efficiency is probably the most generic issue for the process industry today, and process integration is a common tool to successfully achieve this. However, an increased level of process integration, usually implemented by re-circulation and other physical feedback structures, can increase the complexity of the dynamics drastically. This, in turn, implies increased control dif...

Abstract This paper presents a novel optimization method for retrofitting heat exchanger networks (HENs). The developed optimization framework is based on the iterative optimisation of a relatively simple mixed integer linear programming (MILP) which can effectively deal with computational difficulties associated with nonlinearity. The new approach is proposed to facilitate the automated design...

A low-level flexible-structure control is proposed for designing control systems capable of efficiently handling constraints on the manipulated variables of heat exchanger networks (HENs). Flexible-structure refers to the capability of the resulting control system to switch from one closed-loop structure to another in order to keep regulation, and low-level means that it can be configured in mo...

When only single bypasses and utility duties are used as manipulations, optimal operation of heat exchanger networks (HENs) can be categorized as an active constraint control problem. This work suggests a simple split-range control scheme to implement the optimal operation. The control structure can be found by solving an integer-linear programming (ILP) problem with two objective functions pro...