Modeling of the Seedless Grape Drying Process using the Generalized Differential Quadrature Method

• Published in: Chemical engineering & technology 2007-02, Vol.30 (2), p.168-175
• Main Authors: Esmaiili, M., Rezazadeh, G., Sotudeh-Gharebagh, R., Tahmasebi, A.
• Format: Article
• Language: English
• Subjects: Applied sciences; Chemical engineering; Drying; Exact sciences and technology; Foodstuff; Modeling
• ISSN: 0930-7516; 1521-4125
• DOI: 10.1002/ceat.200600151

Mathematical modeling of the grape drying process is important in understanding the transport phenomena involved in the production and processing of dried grapes. Drying models proposed in the literature have simplifying assumptions, and thus ignore important phenomena such as shrinkage and changes in transport properties which occur during the drying process. Consequently, a mathematical model is developed for the seedless grape drying process, which considers the effects neglected in previous models. Since an analytic solution to this nonlinear model is impossible, the generalized differential quadrature method is used to solve the models' equations. The model is validated with experimental data obtained from a laboratory scale convective tray dryer operating at 50–70 °C and an air velocity of 1.5 m/s. Model predictions are in close agreement with experimental data due to the inclusion in the model of shrinkage and variation in moisture diffusivity. Model results can serve as a framework to improve the performance of existing and novel dryers, and also in the design of process simulators for dryers. A detailed drying model is developed which simul‐taneously takes into account variable diffusivity and the shrinkage pheno‐menon. Model predictions are in close agreement with experimental data and can serve as a framework to improve the performance of existing and novel dryers.