Optimal boundary control for the heat equation with application to freezing with phase change

In this paper an approach for optimal boundary control of a parabolic partial differential equation (PDE) is presented. The parabolic PDE is the heat equation for thermal conduction. A technical application for this is the freezing of fish in a vertical plate freezer. As it is a dominant phenomenon in the process of freezing, the latent heat of fusion is included in the model. The aim of the optimization is to freeze the interior of a fish block below -18 °C in a predefined time horizon with an energy consumption that is as low as possible assuming that this corresponds to high freezing temperatures.