Pareto design of conveyor-belt dryers

Most research efforts in the field of conveyor-belt dryer design focus on the evaluation of the appropriate structural and operational process variables so that total annual plant cost involved is optimized. However, the increasing need for dehydrated products of the highest quality imposes the development of new criteria that together with cost components, determine the design rules for any drying process. Quality of dehydrated products is a complex resultant of properties characterizing the final products, where the most important one is color. Color is determined as a three-parameter resultant, whose values for products, which have undergone drying should deviate from the corresponding ones of natural products, as little as possible. In this case, conveyor-belt dryer design is a complex multi-objective optimization problem, involving the color deviation and the unit cost of final product as an objective vector and as constraints the ones deriving from the process mathematical model. The mathematical model of the dryer was developed and the fundamental color deterioration laws and critical financial parameters were determined for the conveyor-belt drying process. Non-preference multi-criteria optimization methods were used and the Pareto optimal set of efficient solutions was evaluated. An example covering the drying of sliced potato was included to demonstrate the performance of the design procedure, as well as the effectiveness of the proposed approach. (C) 2000 Elsevier Science Ltd. All rights reserved.