Problem statement: Drying a packed bed of porous particle at high temperature with varying humidity of hot air is an attractive process. Many researches on experimental and simulation on a fixed bed drying at low and average temperature are proposed. Few studies showed drying at high temperature with humid air or using superheated steam. The latest is compared to dry air. Approach: In this study, we present an experimental and numerical study of humid air drying of a fixed bed of moist porous alumina particles. The air velocity, the air temperature and the vapor pressure were varied from 1.7-2.3 m sec, 120-160°C and 0.1-0.6 bar, respectively and the experiments were performed at atmospheric pressure. Then a mathematical model describing heat and mass transfer during drying is developed. This model is based on the averaging volume approach using two scale changes. Results: From the experimental works, the solid temperature and the bed moisture content have been presented at different drying conditions. The previous results show that an increase in humidity leads to an increase of the wet bulb temperature and a decrease in the drying time. At the same drying temperature, the variation in the gas velocity affects also the drying time. In addition, we note that the drying time increases if the bed depth increases. The predicted results deduced from the developed model were compared with the experiment. Conclusion: The experimental and predicted results obtained from this study describing drying of a packed bed illustrate clearly the effect of the air humidity on the drying kinetics.
The assemblages of peracarid crustaceans associated with the red alga Corallina elongata were studied from November 2006 to November 2007 in Rafraf, Tunisia (Mediterranean Sea). Monthly sampling yielded a total of 3593 individuals comprising 22 different species. The peracarids showed significant differences in mean density. Amphipoda were dominant in both numbers of individuals and species diversity. The amphipods Elasmopus pocillimanus, Caprella grandimana, and Stenothoe monoculoides were the dominant species and exhibited seasonal differences in density. The complex structure of C. elongata can provide a permanent refuge for peracarid Crustacea, and species such as the caprellid Caprella grandimana, in particular, seem to be are well adapted to this habitat. RÉSUMÉLes assemblages de Crustacés péracarides associés à l'algue rouge Corallina elongata ont été étudiés de Novembre 2006 à Novembre 2007 à Rafraf, Tunisie (Mer Méditerranée). Les échantillons mensuels contenaient un total de 3593 individus comprenant 22 différentes espèces. Les péracarides montrent des différences significatives dans leur densité moyenne. Les Amphipodes sont dominants à la fois en nombre et en diversité d'espèces. Les amphipodes Elasmopus pocillimanus, Caprella grandimana et Stenothoe monoculoides ont été les espèces dominantes et ont montré des différences saisonnières en densité. La structure complexe de C. elongata peut fournir un refuge permanent pour les Crustacés péracarides, et en particulier, les espèces telles que le caprellidé Caprella grandimana semblent bien adaptées à cet habitat. 1 )
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