Convective and Microwave Dryings of Raffia Fruit: Modeling and Effects on Color and Hardness

Abstract

Biodiversity conservation with the improvement of living conditions requires the efficiency in use of all resources. For instance, A better exploitation of the endemic oleaginous plants of the tropical forests should mitigate the extension of the palm plantations which is one of the greatest threats of the biodiversity in this area. The raffia palm fruit contains edible oil richer in nutrients than oil palm. However, oil raffia production remains weak because entirely based on empirical methods. This study compares the effect of convective and microwave dryings on the drying kinetics, color and hardness of the raffia pulp. Moreover, four drying kinetics models and the concept of characteristic drying curve have been tested for this pulp. To this end, six drying temperatures and four power levels have been used. The results show that the drying time passes from 10 h at 40°C to 3 h at 90°C and from 30 min at 140 W to 5 min at 560 W. The results could be represented by one characteristic drying curve. Among the four models used, the Modified Khazaei model is the best. The coefficient of effective diffusivity varies from 0.63×10 -10 to 3.8×10 -10 m 2 /s for convective drying and from 10.05×10 -10 to 88.5×10 -10 m 2 /s for microwave. The activation energy is 34±2 KJ/mol. It is found that convective drying degrades the color and increases the hardness of the pulp more than microwave drying.

NaOH Activation of Raw Soils: Effect of NaOH Content on the Drying Kinetic and Its Modelling

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Microwave Drying of Sewage Sludge: Process Performance and Energy Consumption

“…The "pumping effect" [24,25] of microwave heating increases the drying rate over a small temperature difference. Elenga et al [26] and Bantle et al [27] conducted a comparative analysis between microwave drying and conventional drying methods. Their finding largely favored the application of microwave drying for its ability to produce a high-quality final dried product.…”