Modelling and control of a flash evaporator through ODE system representation in PDEs form

The mass and heat balance in a multi-stage flash evaporator in once-through configuration is modelled with partial differential equations (PDEs) derived from a system of ordinary differential equations (ODEs) that represents a cascade of vacuum tanks. The derived PDE model represents the pressure head, temperature and salinity evolution in the cascade spatially and temporarily as a nonlinear diffusion-advection-reaction process. The process is controlled with relatively simple boundary controls applied on the inlet and outlet ends.