Estimation of inner-domain temperatures for a freezing process

In this paper a state observer for a distributed parameter system (DPS) with nonconstant parameter functions is presented. The DPS describes the freezing of foodstuff in vertical plate freezers and is a nonlinear heat equation. The observer is based upon the Extended Kalman Filter, meaning that the nonlinear heat equation has been discretized in the spatial domain before designing the observer. We show that the observer is robust with respect to perturbations of parameter functions and noisy measurement signals and that the innerdomain temperatures can be correctly estimated.