Optimal Control Of A Freeze Dryer-II. Dynamic Analysis
The unsteady state model and Lagrangian equations of the freeze-drying process presented in Part I, have been solved for non-fat reconstituted milk and turkey, using the control strategies presented in ; the results were then used to evaluate the coefficients representing the necessary conditions of optimality. The results for non-fat reconstituted milk confirm the results of the quasi-steady state analysis , except for a time segment very close to t = 0. Simulations with turkey breast showed similar results at low pressures, but it was found that at higher pressures the assumed control policies which were based on a quasi-steady state analysis, were not optimal. The non-steady state results indicate that for turkey, intermediate rather than maximum, pressure control policies were optimal for cases (a) and (b) in. However, in practice these optimal pressure policies might produce only minor improvements in drying time when compared with a near optimal policy. It was also found that changes in the interface constraint affected drying times only marginally, but that large heaters operating under optimal control had a pronounced effect on the drying time. © 1982.
R. J. Litchfield and A. I. Liapis, "Optimal Control Of A Freeze Dryer-II. Dynamic Analysis," Chemical Engineering Science, vol. 37, no. 1, pp. 45 - 55, Elsevier, Jan 1982.
The definitive version is available at https://doi.org/10.1016/0009-2509(82)80066-3
Chemical and Biochemical Engineering
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01 Jan 1982