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Current analysis investigates thin layer drying experiments on passion fruit seeds. Drying characteristics of passion fruit seeds were examined using ambient air for temperature range between 40 and 65ºC and air flow velocity range between 0.6 and 1.2 m s-1. The semi-empirical models were then fitted to the drying data by Bayesian inference, based on the ratios of the difference between the initial and final moisture contents and equilibrium moisture content. The effective diffusivity varied between 1.70 x 10-10 and 4.68 x 10-10 m2 s-1 with temperature and air flow rate increase. Temperature dependence on the diffusivity coefficient was described by an Arrhenius-type relationship. The activation energy for moisture diffusion was 24.36, 35.24 and 13.86 kJ moL-1 for drying air speeds respectively equal to 0.6, 0.9 and 1.2 m s-1.

A stochastic model is used to simulate the combustion process in a turbulent inverse diffusion flame (IDF) composed of a laminar diffusive flame and a premixed turbulent flame. In addition, the influence of the turbulence intensity at the outlet of the air injection nozzle was analyzed with this model. The IDF consists of one central air injection and 12 peripheral butane injections. The interaction between the aerodynamics and the thermochemical is implemented by a transport equation for a joint probability density function (PDF). For the chemical kinetic, two different global chemical reaction schemes are used: the first consists of a one-step reaction and the second involves a two-step reaction. The numerical solution of the aerodynamic is found via the finite volume method, and a cell-based Monte–Carlo particle method is used for the transport equation of the joint PDF. The numerical results are compared with experimental data.. The comparison between both global chemical reaction schemes qualitatively represents the thermal structure of the flame. Nevertheless, the two-step reaction demonstrated good accuracy for the temperature distribution of the flame, so the two-step reaction was used to analyze the behavior of the flame. The results show the increase of turbulence intensity does not modify the thermal structure of the IDF, but the dimension and temperature distribution of the flame present significant changes with an increase in the turbulence intensity. [ABSTRACT FROM AUTHOR]

This work experimentally evaluated the pyrolysis of sugarcane bagasse in a fixed bed reactor in order to obtain products useful in energy applications. The raw material was characterized to understand its behaviour during the thermal degradation process. The effects of operating conditions on mass yields of bio-oil, biochar, and non-condensable gases were investigated. The operating variables studied were temperature (400 to 700 °C), particle size (<0.5 mm, 0.5-1.0 mm, and 1.0-1.41 mm), heating rate (5, 10, and 15 °C/min), and nitrogen flow (50, 100, and 200 mL/min). Analysis of variance showed that for almost all product mass yields, with the exception of the effect of nitrogen flow in bio-oil yield, the treatment levels result in different means. The highest bio-oil yield (0.54 g/g) occurred at 600 °C, at a heating rate of 15 °C/min, at a flow rate of 200 mL/min, and for a particle size of 0.5 to 1.0 mm. The process temperature and particle size were the most influential factors in the results. [ABSTRACT FROM AUTHOR]

This work examines some aspects of sugarcane bagasse pyrolysis. Fixed bed pyrolysis was performed varying the final process temperature. Product yields and the variation of quality properties (calorific values) of bio-oil, biochar, and non-condensable gas were investigated. A mathematical model to simulate the trend of temperature that maximizes a marginal gain was developed considering the regression equations for yields and prices of products (related to market prices and calorific value of conventional fuels) and for the amount of biomass used to supply energy to the process. Two methodologies were adopted to calculate the optimum process temperature. The results showed very close temperatures (600 and 602 °C) for the best performing simulations of endogenous and fixed prices methods, with little difference between the yields of products, but with good variation between the marginal gains ($124.9/tonne and $129.8/tonne). Finally, the results of endogenous prices method for the fixed bed reactor were compared to the vacuum and fast pyrolysis reactors. [ABSTRACT FROM AUTHOR]

This work aims to evaluate different eluents in cycles of nickel adsorption/desorption on calcined Bofe clay. The following eluents were used sequentially for nickel desorption: H2SO4 0.25 mol/L, NaCl 1.0 mol/L, CaCl2 0.10 mol/L, and EDTA 0.10 mol/L. Physical-chemical characterization analyses of Bofe clay samples were carried out under different conditions to evaluate the effect of the remaining metal on the adsorbent submitted to adsorption/desorption cycles. The adsorbent material was characterized by the following techniques: energy dispersive X-ray spectroscopy (EDX), thermogravimetry (TG), differential scanning calorimetry (DSC), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), and N2 physisorption (BET). Statistica 5.0 was used as a computational tool to adjust the rate quasi-chemical solution to the experimental data of the breakthrough curves. From the new function obtained, breakthrough curves for different bed heights could be also simulated. An increase of the clay surface area and a reduction of real density after the passage of the four eluents were observed. Among the tested eluents, NaCl (1 mol/L) presented the highest percentage of desorption (88.08 %). The nickel adsorption/desorption cycles study showed that Bofe clay retains the same nickel adsorption capacity throughout the four evaluated cycles. [ABSTRACT FROM AUTHOR]