H∞ output feedback control for heat exchangers with a bilinear input flow rate term and a bilinear disturbance flow rate term

If we approximate distributed parameter heat exchanger systems as bilinear systems, the systems often contain not only product terms of the state variables and the input flow rates but also product terms of the state variables and the disturbance flow rates. In almost bilinear systems investigated so far, disturbances were applied to the systems linearly. Therefore we cannot apply such controllers to heat exchanger systems directly. In this paper, we consider two kinds of H
_infin
controllers for heat exchanger systems: a bilinear H
_infin
output controller and a bilinear H
_infin
state feedback controller combined with a bilinear observer. For the latter controller, three types of observers, a full order bilinear observer, a disturbance decoupling bilinear observer, and a disturbance bilinear observer with disturbance estimator, are used. The performance of each controller is evaluated with several simulation results.