16 - Minimum number of units (MNU) and minimum total surface area (MTA) targets

Abstract

Targeting approaches developed for a minimum number of units and a minimum total surface area account for the types of heat exchangers applied. Most often, they are limited to shell-and-tube apparatuses with pure countercurrent flows. Related calculation methods are used to determine the minimum number of matches (target) and the minimum total surface for matches. General targeting approaches for multishell apparatuses can be developed, where further division into utilities and process streams is not necessary. The necessary data for process streams are the same as those required for calculating the MUC target; we need the data for all utilities. To calculate minimum area target, heat transfer coefficients should be known for all streams, or alternatively, overall heat transfer coefficients should be available for all pairs of hot and cold streams. Efficient method of Shethna and Jeżowski is exemplified and expected to work for large-scale tasks and large number of streams.