Abstract
The time-optimal control algorithm taking into consideration the bounds on control and state variables is applied to microwave freeze drying system. A general unsteady state mathematical model with time variant transport and dielectric properties is formulated as a stage wise operation problem. Microwave power, radiator temperature, water vapor pressure and air pressure are considered controllable. Constraints are set to avoid scorching, melting and gas breakdown. All control variables are kept constant during each stage.
With high non-linearity and moving boundary characteristics of this problem, an optimal sequence is computed by using direct search method.
The algorithm is illustrated in several cases. Results suggest that the hybrid microwave and radiant freeze drying can substantially reduce the drying time. It is further demonstrated that the algorithm can be used to devise an optimal policy for limited freeze drying.
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Chang, T.N., Ma, Y.H. (1985). Application of Optimal Control Strategy to Hybrid Microwave and Radiant Heat Freeze Drying System. In: Toei, R., Mujumdar, A.S. (eds) Drying ’85. Springer, Berlin, Heidelberg. https://doi.org/10.1007/978-3-662-21830-3_31
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DOI: https://doi.org/10.1007/978-3-662-21830-3_31
Publisher Name: Springer, Berlin, Heidelberg
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