A shortcut method for simultaneous energy and heat exchange area optimization with variable stream conditions

Abstract

Estimating the heat transfer area for heat integration problems with variable stream temperatures and flowrates using conventional methods can be computationally demanding. The problem becomes more challenging when the minimum approach temperature for the heat recovery (ΔTmin) is set to be a variable. This paper presents a novel area targeting shortcut method capable of estimating the total heat exchange surface using the area comprised between the two balanced composite curves, the total amount of heat transferred across the system and the ΔTmin. This innovative technique avoids the use of disjunctive formulations, greatly reduces the number of binary variables and therefore significantly shortens the solution time. Four case studies are tackled to show the numerical performance of the new approach. Results show that, in spite of its apparent simplicity, the proposed method is able to yield reliable and accurate results with a much lower CPU time when compared to existing alternative approaches.