Modular design of heat exchanger networks

Abstract

Heat exchanger networks (HENs) are essential for energy recovery in process plants. Current HEN design methods use approximate models to improve convergence. This work presents a novel linear rigorous algorithm for computation of mass and energy balances which enables rapid synthesis of optimal HEN structure by using modular size heat exchangers. HEN non-iterative simulation algorithm: 1) solves mass balance equations for the network; 2) computes heat exchanger energy transfer factor which depends only on the current flows through the exchanger and conditions for a typical counter-current heat exchanger; 3) solves linear energy balance given results from 1 and 2. This once-through rapid computation enables network design via differential evolution algorithm by using heat exchangers in modular sizes. Several examples illustrate the algorithm capability to determine the best structures. Proposed method enables design of lower capital cost networks that are as efficient as the networks with custom exchanger sizes.