Exchanger Reassignment Strategy ERS

The steps involved in the ERS are as follows (Sreepathi and Rangaiah, 2014b). 

Arrange elements of in descending order. This is to re-use larger existing exchangers first 

If the difference in area of the two elements is within 1% of the element of He, then assign the selected element of Hg to the element of H compared. Make these elements of Hg and Hg unavailable for subsequent assignment (by making them zero). If there is more than one element from He that can be assigned, then the element which is closer is assigned if there are two elements of H, which are equally close, then the element which comes first in H is assigned to the selected element of Hg 

Select a non-zero element of Hg and compare with non-zero elements of H  

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The rest of this chapter is structured as follows. The next section describes HENs and the structural representation used in this study for HEN retrofitting. Section 7.3 discusses the improvement techniques that can be used to retrofit HENs. Section 7.4 describes the methodology to retrofit HENs, which includes MOO, HEN model and exchanger reassignment strategy (ERS). The case study solved by the methodology is described in Section 7.5. Section 7.6 discusses the results obtained for simple, moderate and complex retrofitting. Finally, conclusions of this study are presented in Section 7.7. 

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