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This research work is concerned in the exergy analysis of the continuous-convection drying of onion. The influence of temperature and air velocity was studied in terms of exergy parameters. The energy and exergy balances were carried out taking into account the onion drying chamber. Its behavior was analyzed based on exergy efficiency, exergy loss rate, exergetic improvement potential rate, and sustainability index. The exergy loss rates increase with the temperature and air velocity augmentation. Exergy loss rate is influenced by the drying air temperatures and velocities because the overall heat transfer coefficient varies with these operation conditions. On the other hand, the exergy efficiency increases with the air velocity augmentation. This behavior is due to the energy utilization was improved because the most amount of supplied energy was utilized for the moisture evaporation. However, the exergy efficiency decreases with the temperature augmentation due to the free moisture being lower, then, the moisture begins diffusing from the internal structure to the surface. The exergetic improvement potential rate values show that the exergy efficiency of onion drying process can be ameliorated. The sustainability index of the drying chamber varied from 1.9 to 5.1. To reduce the process environmental impact, the parameters must be modified in order to ameliorate the exergy efficiency of the process.

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This work presents studies about the gasification of the lignocellulosic winery wastes in fluidized bed to obtain energy. Based on the exergy analysis, the exergetic improvement potential (IP) and sustainability index (SI) variations with different operational variables were analyzed. IP increases and SI decreases when moisture content, ER and SBR augment. On the other hand, both indexes present contrary behavior with the temperature increasing.Additionally, the kinetic behavior was investigated using a macro thermo-balance. The thermal decomposition of the studied biomass wastes at three heating rate, 5, 10 and 15ºC/min under steam/air mixture atmosphere show that the gasification takes place in three visible stage: water vaporization, pyrolysis and the last step associated with the reaction of the char by CO2. The distributed activation energy model method (DAEM) was used. The decomposition is not a single reaction stage, it includes the contributions of parallel reaction steps on the global reaction rate.Last, the fluidization was analyzed using air at room temperature and local atmospheric pressure.Each experiment was carried out with 100% and 75% v lignocellulosic wastes. Segregation, slugging and channelization in all studied cases. However, the addition of sand particles improves the behavior of both winery wastes.

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