Aspen Energy Analyzer Reference Guide

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Targets
Targets are theoretical values that represent the ideal or perfect situation.
They are very important as an analysis tool as it provides a comparison for
how close the current design is to the optimal design.
Energy Targets
Energy targets are the minimum amount of utilities needed to satisfy the
process stream requirements (Papoulias & Grossmann, 1983). In Aspen
Energy Analyzer, the energy target values are calculated depending on the
Utility Load Allocation Method and pinch temperature. The hot and cold utility
energy targets are both displayed.
For more information on Utility Load Allocation Methods, refer to Utility Load
Allocation Methods on page 30.
Pinch Temperature
The pinch temperature is used in designing the optimal HEN by identifying the
following:
 Impossible heat transfer between streams when the temperature
difference between streams is equal or less than the pinch temperature.
 Unnecessary use of cold utility, when a cold utility is used to cool hot
streams in the region above the pinch.
 Unnecessary use of hot utility, when a hot utility is used to heat cold
streams in the region below the pinch.