Navegando por Assunto "Drying kinetics"

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Acesso aberto (Open Access)
Análise experimental do processo de extração do óleo essencial de Puxuri [Licaria puchury-major (Mart.), Kosterm., Lauraceae] por arraste com vapor
(Universidade Federal do Pará, 2014-04-30) MAFRA, Eduardo de Souza; FARIA, Lênio José Guerreiro de; http://lattes.cnpq.br/7428609361678173
Analyse experimentally the extraction process of the essential oil of seeds and aerial parts of puxuri for drag with steam. The puxuri, [Licaria puchury-major (Mart.)] Kosterm., Lauraceae], is a species of the Amazon forest with great potential for the Bioproducts Industry (pharmaceu-ticals, cosmetics, food and natural pesticide) due to the presence of safrole in its essential oil. This work is an anatomical study and physical and chemical characterization of plant parts used for oil extraction. Studying the kinetics of drying of seeds, thin branches and leaves of puxuri and quantifies the influence of convective drying in fixed bed in safrole content and moisture content. Through statistically designed experiments, identify levels of process variables: mois-ture content, particle size and extraction time of samples of seed of puxuri, that optimize both answers the responses: in essential oil yield and content of safrole, its major component, within the experimental domain adopted and 90% confidence (α = 0.10) in the extraction process of the essential oil by steam drag. Chemically analyzed the essential oil of puxuri by GC-MS and iden-tifies the chemical composition in terms of their senior constituents. Using the gravimetric ap-proximation method static with concentrated solutions, desorption isotherms are obtained for puxuri seeds powder, in temperatures 15, 25 and 35ºC. The experimental data hygroscopic equi-librium, fits very well the GAB model, being estimated the heats of sorption liquid and inte-grals, in addition to the equilibrium moisture content in monolayer and other constants in the equation. Noted low toxicity of essential oil of puxuri and the solid residue of extraction can be used as material for the production of saponifiable transparent soaps to cold.
Acesso aberto (Open Access)
Desenvolvimento de um túnel para secagem e emissão de minério em condições ambientais controladas
(Universidade Federal do Pará, 2021-12-15) SILVA, Artur José Cunha da; MESQUITA, André Luiz Amarante; http://lattes.cnpq.br/1331279630816662
A dust emission is present in the various stages of the mineral industry, from extraction in mines to ship loading in ports. Transport in train wagons, storage in stockpiles and handling are three major sources of particulate emissions into the atmosphere. Suspended dust does not only affect the local environment, as the wind transports the particulates and brings disturbances to urban centers close to railway networks and ports. Larger particles are deposited on surfaces, outperforming visual surfaces, and smaller, unresearched particles with a size between 10 and 2.5μm are easily inhaled and lodge in lung tissue, potentially causing irritation or necrosis. Dust emission is enhanced by local atmospheric conditions, which cause the evaporation of surface moisture from the wet ore, breaking the liquid bridges that keep the particles linked together. Aiming at studying the dynamics of drying ore, a drying tunnel was designed and built, comprising a wind tunnel, cooling, heating and humidification equipment that are interconnected by a supervision and control system. The use of the bench for drying studies using sinter feed is known to be satisfactory, as the temperature remained stabilized at the setpoint during the drying time, reflecting the good calibration of the temperature PID controller. Moisture and ore mass were automatically measured using a scale and a capacitive moisture sensor positioned in the test section of the bench. The constant rate and descending rate drying curves only in the lightest weather conditions. The biggest limitations and variations were observed only in the period with decreasing drying rate, showing the influence of environmental conditions on the drying dynamics. Therefore, this work leaves as a contribution the preparation tunnel for future research and an experimental database for the calibration of numerical models and models of mathematical models for prediction prediction.
Acesso aberto (Open Access)
Determinação de parâmetros de transferência de massa e de propriedades termodinâmicas na secagem curcuma longa L. usando a técnica de refractance window
(Universidade Federal do Pará, 2020-12-01) CUNHA, Natasha; RODRIGUES, Antonio Manoel da Cruz; http://lattes.cnpq.br/7524720020580309
The Curcuma Longa L. rhizomes (CL) presents a significant amount of starchy, lipids, vitamins, minerals and important bioactive compounds. The CL is an aromatic spice with natural dye action. However, these rhizomes are perishable, requiring dehydration treatment. The drying by Refractance Window (RW) is a very effective technique in the dehydration process. As far as we know, no information about dehydration or parameters prediction of mass transfer and thermodynamics of CL using this technique is available in literature. Thus, this study had as objective to determinate mass transfer parameters and thermodynamics properties that control the dehydration process of the Curcuma Longa L. by Refractance Window in different temperatures. (70, 80, 90° C), through applicability of the analytical model developed by Dincer e Dost (1995). It was observed that the dehydration process of the samples occurred in a small period. The unity content in natura was 80.71±1.12% (b.u) and of the dry product varied from 20.81 to 17.34% (b.u). The CL samples submitted to drying with exhaustion obtained a small influence on the drying fees when compared to the samples with no exhaustion. According to the model of Dincer & Dost, diffusivity of moisture varied from 5.21 × 107 m².s-1 to 12.89 × 107m².s-1 without exhaustion and 7.89 × 107 m².s-1 a 19.67 × 107m².s-1 with exhaustion and the mass transfer coefficient varied in the range of 9.79 × 105 to 6.73 × 105 m.s-1 without the exhaustion and 8.86 × 105 a 0.51 × 105 m.s-1 with exhaustion. All the entropy values (ΔS) obtained related to the drying of the CL by RW were negative (ΔS < 0). The study showed that the exhaustion system had a small influence on the mass transfer flee during the drying of the CL sample. The thermodynamics properties pointed to a nom spontaneous process with positive values of enthalpy and free energy of Gibbs, and negative values of entropy.