1973; Vickery and Taylor 1986. These works aim at solving all MESH equations and determining all process variables. An alternative to using the original MESH equation is to use shortcut methods. Various simplifying assumptions have been developed and repeatedly used in the literature. These include the assumption of constant volatilities, as used in the classic work of Underwood 1948 for a convential distillation column and for dividing wall columns by the assumption of constant molar overflow used in the procedures presented in . These shortcut methods can either be used to approximate the minimum required energy, or their results can be used to calculate initial values for a rigorous optimization