Water and Heat Exchanger Network Design for Fixed-Flowrate System

Abstract

This work presents a new model of optimization-based approaches by mathematical programming for simultaneous water and heat exchanger network (WHEN) design of fixed-flowrate system. WHEN is designed by water network (WN) followed by heat exchanger network (HEN) in sequential step. First, WN is designed by mass balance from sources to sinks. Second, HEN is designed by matching hot waste streams and cold sink streams to satisfy the outlet temperature. The main objective is to minimize total annual cost (TAC) of freshwater cost, piping cost, investment cost of heat exchanger unit, and hot/cold utility cost using developing case study data. Mixed integer nonlinear programming (MINLP) is developed for simultaneous design by cascading calculation. Initialization technique is used because of the high non-convexity of MINLP problem.