Drying properties of high moisture potato slices with initial moisture content of about 4.06 (db) under thin layer fixed, semi FLUIDIZED and FLUIDIZED bed conditions were studied. Drying air temperatures of 40, 50, 60 and 70oC were applied in experiments using a laboratory FLUIDIZED bed convective dryer. In order to predict the drying behavior of potato slices, seven thin layer drying models were applied from where finally Midilliet al. model was selected as the suitable one, based on comparative indices. Effective moisture diffusivity of the potato slices varied between 4.29×10-9 and 15.70×10-9 m2 s-1 for fixed and FLUIDIZED bed conditions, respectively. Moisture diffusivity values of the slices were increased as the drying air temperature levels increased. Activation energy values varied between 15.88 and 24.95 kJ mol-1. Minimum and maximum values of activation energy were obtained at minimum FLUIDIZED and fixed bed conditions, respectively. Consumption of specific energy for thin layer drying of high moisture potato slices was obtained between 0.45×105 and 1.64×105 (kJ kg-1). Increase in the drying air temperature in each bed condition caused increase in energy consumption. The maximum value of energy consumption was obtained at FLUIDIZED bed conditions.

A dynamic model representing the continuous FLUIDIZED bed dryer is presented. The model takes into account the presence of the three phases: bubble phase, cloud phase and emulsion phase. The transient analysis for step disturbances in the input variables is obtained. The influence of operating conditions on the dynamics of the dryer is discussed and the results are compared with the experiment. The model can be used for developing a model based on other suitable control strategies.

In present paper, dynamic behavior and control of a FLUIDIZED bed reactor for polyethylene production has been considered. A double active sites model for Ziegler-Natta catalysts is used for simulation of polymerization reaction. Hydrodynamic behavior of the bed is modeled using a two phase model including bubble and emulsion phases in which bubble phase has plug flow pattern with differentially variable velocity and size through the bed and emulsion phase has the CSTR flow pattern. The reactor model is validated using industrial data. Conventional PID controllers with anti-windup are considered for control purposes. It has been shown that the control system has satisfactory performances either for set point tracking or load rejection. To improve the performance of the control system for load rejection the cascade control strategy has been considered.

The objective of this study was to examine the effects of the FLUIDIZED-bed drying method on the final quality of two varieties of Iranian rice, medium- and long grain. The results were compared to that of paddy drying using a traditional method. Rough rice was treated in the FLUIDIZED bed drier at 140°C for 2 minutes. Similar samples were dried for 8-10 hrs by the traditional method. Dried samples were dehusked and polished. Quality factors, including trade quality (head rice yield percent and whiteness), cooking quality (amylose content, gelatinization temperature, gel consistency, aroma and flavor) and nutritional quality (thiamine and lysine contents), were then measured for each sample. Finally, the data was analyzed. Results show that paddy drying in a FLUIDIZED bed dryer would reduce the quality factors except for rice whiteness for which conventional drying is more acceptable. Therefore modification of FLUIDIZED-bed drying technique is recommended.