Com o intuito de analisar a dinâmica de sorção e a energia necessária para a vaporização da água na desidratação do bagaço da cana-de-açúcar, o presente trabalho teve como objetivo a determinação de seu equilíbrio higroscópico e calor isostérico, a partir de diferentes condições controladas de temperatura (20; 40; 55 e 70 ºC) e umidade relativa do ar (10; 12; 17; 18; 30; 40; 45; 50; 60 e 85%), assim como avaliar, entre diversos modelos descritos na literatura, o que melhor represente o comportamento de sorção. Como resultado, foi verificado que o modelo que melhor se ajustou aos dados empíricos do processo de sorção do bagaço de cana-de-açúcar foi o Modelo de Henderson Modificado, com coeficiente de determinação de 0,972, enquanto o calor isostérico integral de dessorção variou de 2524,09 a 2951,95 kJ kg-1, para os teores de água de equilíbrio de 0,014 a 0,170 b.s., respectivamente.

This study aimed to determine the hygroscopic equilibrium and isosteric heat of sugarcane bagasse to evaluate sorption dynamics and the required energy to vaporize water in the bagasse dehydration. The reaction was assessed at different controlled conditions of temperature (20, 40, 55 and 70 ºC) and air relative humidity (10, 12, 17, 18, 30, 40, 45, 50, 60 and 85%), as well as testing various models described in the literature to identify the condition that better represents sorption behavior. As a result, we found that the model that best fit empirical data of sugarcane bagasse sorption was the modified Henderson with determination coefficient of 0.972; while the integral isosteric heat of desorption ranged from 2,524.09 to 2,951.95 kJ kg-1, for all water contents and equilibrium of 0.014 until 0.170 bs, respectively.

The aim of this work was the preparation and the physical characterization of solid biofuel made from biomass of water hyacinth for its valorization. This work included the characteriziation of the properties of dehydrated water hyacinth, the finding of a process to transform them into briquettes and the characterization of the briquettes at room temperature. The analyzed properties depend on the charge exerted over the briquette since densification pressure strongly affects the physical properties of the briquette. Based on the results of study it is concluded that the biomass fuel could be produced at industrial level, being a good source of non convenctional energy.

El objetivo de este trabajo fue la preparación y caracterización física de biocombustible sólido usando la biomasa del lirio acuático para su valorización. Este trabajo incluye la caracterización de las propiedades del lirio acuático deshidratado, el desarrollo de un proceso de fabricación en briquetas y la caracterización de las briquetas propiedades a temperatura ambiente. Las propiedades analizadas varían dependiendo de la fuerza ejercida sobre la briqueta ya que la presión de la densificación afecta fuertemente sus propiedades físicas. Basado en los resultados del estudio, se concluye que estos biocombustibles pueden ser producidos a nivel industrial, constituyendo una buena fuente alternativa de energía.

Enhanced oil recovery methods are becoming an important source of oil production of wells that have already been explored and, by these methods, of increase of the total volume of oil extracted. An important example is the injection of polymeric solutions after the injected water has reached the breakthrough point. In the present work an experimental apparatus was built in order to test the ability of enhanced oil recovery of polymeric solutions, composed by Xanthan Gum (XG) dissolved in distilled water. This apparatus consists of an idealized porous media made with small spheres inserted in a cylindrical cell and then filled with oil with the same viscosity as the petroleum found in Campos Basin (Rio de Janeiro, Brazil). As displacing fluid, we tested polymeric solutions of different concentrations of Xanthan Gum and these non-Newtonian fluids were characterized using a rotational rheometer. The resulting characterization has shown that increasing the concentration, not only the level of viscosity, but also the elasticity of the fluid increases. The shear-thinning behavior of the solution can be well captured by a power-law model. For higher concentrations the shear-thinning feature of the Xanthan Gum solution is more pronounced. We conducted an experimental procedure to mimic enhanced oil recovery process by first injecting water until the breakthrough point. Increasing the polymer concentration, the extra amount of oil recovered also increase. Theoretical and heuristic analyses show that in the shear dominated regions, the Xanthan Gum polymeric solutions do not increase pore efficiency, but increase sweep efficiency, while the extensional character of the polymeric solution seems to indicate that in extensional dominated regions the polymeric solutions play an important role on the oil recovery efficiency from both perspectives: pore and sweep efficiencies.

Neste trabalho, estudou-se a influência do tipo de centrífuga utilizado no processamento do mel de abelha sobre os parâmetros reológicos, físico-químicos e sensoriais. Para a análise sensorial, trabalhou-se com 58 provadores que constataram mudanças no sabor das amostras. Na análise reológica, foi utilizado um reômetro RS50 conectado a um banho termostático K20-DC5, ambos da HAAKE, com um sensor de geometria cone-placa. Ocorreram diferenças significativas nos valores da viscosidade entre as duas amostras obtidas por meio dos respectivos modelos de centrífugas. O valor da viscosidade do mel obtido da centrífuga radial foi, aproximadamente, o dobro do valor do mel processado na centrífuga facial. Nenhuma alteração foi observada nos níveis de hidroximetilfurfural e umidade de ambas as amostras. No caso do mel obtido da centrífuga radial, obteve-se umidade de 20,6%, enquanto o mel processado na centrífuga facial apresentou umidade de 20,2%. Na análise sensorial, cerca de 69% dos provadores manifestaram preferência pelo mel processado na centrífuga radial, que consideraram o sabor doce menos acentuado e mais viscoso.

This work has the objective of studying the influence of the centrifuge type utilized on honey processing by the rheological, the physical-chemical and sensorial characterization. In the sensorial analysis, 58 consumers verified some alteration in the flavour of samples. In the rheological analysis, a RS50 rheometer connected with a K20-DC5 thermostatic bath, both produced by HAAKE, were used to perform the tests. The sensor used in this case was a cone plate sensor. It was observed significative differences at the viscosity value between the two samples processed at each centrifuge. The viscosity value of the honey processed at radial centrifuge was approximately the double of the viscosity value of the honey processed at facial centrifuge. None alteration in the hidroximetilfurfural level and moisture was observed. The honey processed in the radial centrifuge had 20.6% of moisture and the honey processed in the facial centrifuge had 20.2% of moisture. In the sensorial analysis, 69% of consumers preferred the honey processed in the radial centrifuge and they considered this honey less sweet and more viscous.