H.K. Engelien and S. Skogestad,
"Minimum energy diagrams for multieffect distillation arrangements",
AIChE J, Vol. 51, No. 6, 1714-1725 (2005).

The quality of the figures in the pdf-file is not very good.
The printed journal version is slightly better, but go to
the subdirectort old-submitted to the best quality..