Comparison between bubbling and turbulent regime for the simulation of batch pharmaceutical powders fluidized bed drying

[EN] The two-phase theory has been frequently used to model fluidised bed drying. At high air velocities, a transition from the bubbling regime to the turbulent regime may occur. In this work, we compare a bubbling model and a turbulent model for the simulation of a two pharmaceutical powders drying in a pilot plant and an industrial plant fluidised bed. The bubbling model was based on a discrete variable bubble size. Heat and mass transfer coefficients were based on the Kunii and Levenspiel correlation [1]. Flow regime was supposed to be completely mixed for the emulsion phase. For the turbulent model, the bubble size is not anymore discrete but continuous and bubble phase is less distinguishable than in the bubbling regime. Heat and mass transfer were those proposed by Foka[2]. In addition, the freeboard section was considered since high entrainment is specific of this regime. Gas backmixing was taken into account by considering a plug flow with axial dispersion for the interstitial gas flow. The bubble phase being dilute, was modeled by a plug flow. A plug flow was also considered for the freeboard gas. The solid phase was supposed to be completely mixed. The bubbling regime simulation gave good agreement with experiment in the case of the pilot plant experiment, while the turbulent model better simulated the industrial scale experiment.Zammouri, A.; Boudhrioua Mihoubi, N.; Kechaou, N. (2018). Comparison between bubbling and turbulent regime for the simulation of batch pharmaceutical powders fluidized bed drying. En IDS 2018. 21st International Drying Symposium Proceedings. Editorial Universitat Politècnica de València. 457-464. https://doi.org/10.4995/IDS2018.2018.7703OCS45746

Thermodynamic properties and moisture sorption isotherms of two pharmaceutical compounds

[EN] This investigation examines and compares the water sorption isotherms and the thermodynamic properties of two pharmaceutical preparations (Hypril and Azix) intended to be manufactured with the same process plant and equipment. The moisture equilibrium isotherms were determined at 50, 60 and 70 °C using a gravimetric technique. Five isotherm models were explored for their fitting to the experimental data. Azix showed sigmoid type II isotherms while Hypril showed type III isotherms according to the BET classification. All investigated models fitted well the water sorption isotherms of Hypril. By contrast, only GAB and Adam and Shove equations gave appropriate fit to the experimental data of Azix. For both formulations, the isosteric heat and the differential entropy decreased sharply with the increase of equilibrium moisture content to minimum values and thereafter remain constant. In the case of Azix, the integral enthalpy decreased with equilibrium moisture content while the integral entropy increased until reaching a constant value. Contrariwise, Hypril showed decreasing of the integral enthalpy and entropy with the equilibrium moisture content.Zammouri, A.; Ben Zid, M.; Kechaou, N.; Boudhrioua Mihoubi, N. (2018). Thermodynamic properties and moisture sorption isotherms of two pharmaceutical compounds. En IDS 2018. 21st International Drying Symposium Proceedings. Editorial Universitat Politècnica de València. 449-456. https://doi.org/10.4995/IDS2018.2018.7702OCS44945

Etude de l’effet des conditions du séchage sur la texture et la couleur des filets de Sardina pilchardus

Le but de ce travail est d’étudier l’effet des conditions opératoires de séchage convectif par air chaud sur la couleur et la texture des filets de la sardine (Sardina pilchardus). Les filets de sardine ont été déshydratés par séchage convectif à vitesse d’air constante (Va = 1,5 m/s), différentes températures (40, 50 et 70°C) et à humidité relative d’air ambiante. Le critère final des expériences de séchage a été fixé de manière à avoir une teneur en eau finale des filets de l’ordre de 25% en base humide. La texture (mesure de la dureté par un texturomètre) et la couleur (paramètres L*a*b*) des filets ont été analysées à différents temps du séchage. L’évaluation des paramètres de qualité au cours du séchage (texture et couleur) montre que ces derniers dépendent de la teneur en eau du produit et des conditions de séchage. L’évaluation de latexture par le test de flexion trois points montre que l’augmentation de la température engendre une augmentation de la dureté des filets. Les paramètres L* et a* ont tendance à diminuer au fur et à mesure que la température de l’air augmente et la teneur en eau du produit chute. The aims of this work is the study of the effects of air drying process on the dehydration kinetics of sardine muscles (Sardina pilchardus).The effects of the air temperature (from 40 to 80°C) and the relative humidity (ambient and 40%) on the drying kinetics and on the color (L*a*b* parameters) and the textural (TAXT2i texturometer measurements)properties of the muscles were examined. Air drying kinetics were accelerated by increasing the air temperature and were attenuated by the humidification of drying air. The L* and a* parameters decreased with the increasing of air temperature. The injection of the moisture vapor on the air decreases this effect. The increasing of air temperature induced the hardness of the muscle and this effect was attenuated by moisture vapor’s injection. The moisture loss of the product induces a considerable decreasing of the muscle length

Water desorption of osmotic dehydrated apple and pear at different water activities: desorption isotherms and glass transition temperature

Water desorption of osmotic dehydrated apple and pear at different water activities: desorption isotherms and glass transition temperature. Journée AFSI