In this section we introduce the MESH equations that describe a mDWC. For simplicity we consider a given feed and a constant pressure p within the column. However, the following can also be extended to a variable feed and pressure. We use the equilibrium stage model widely applied to model conventional distillation columns Biegler, Grossmann, and Westerberg 1997 and adjust it to the situation where dividing walls are present. The column is modeled with a total hight of N h theoretical stages. Additionally, we model a total condenser with duty QC < 0 and a total reboiler with duty QR > 0, which are not counted within the theoretical stages. Throughout the following, stages are numbered from bottom to top. We assume that a dividing wall starts and ends with a stage.