In this study, a biodiesel was produced from blending vegetable and animal sources with diesel and diesel-ethanol using a motor-generator set to evaluate its performance and emission characteristics. Fifteen and twenty percent of animal-vegetable biodiesel were added to each diesel-ethanol blend. A motor-generator test was conducted for each mixture; each sample was subjected to resistive loads from 2 to 5 kW with six repetitions. The physicochemical properties met the national standard guidelines, while the best specific fuel consumption (SFC) was observed for the 15% biodiesel-1% ethanol (B15E1) blend at the load of 5 kW with 327.069 g kW h, followed by diesel (334.875 g kW h). The exhaust gas temperature behaved differently depending on the ethanol concentration; it was lower when the concentration of added ethanol was higher. The NO emissions decreased while the SO emissions increased as the ethanol concentration increased.
Automatized irrigation systems under nursery conditions have become an essential tool to satisfy rationally the water needs for plants without forgetting the sustainability aspects. The present study aimed to evaluate two sprinkler irrigation systems under nursery conditions: one with fixed laterals (fixed system) and another with self-propelled laterals (mobile system) and study the effect of their use on the behavior of tree lettuce seedlings production. The experiment was conducted on a greenhouse with a polystyrene (PVC) plastic film coverture and laterals closed with 60% plastic screen. The statistical design used was a 2x3 completely randomized factorial with four replicates, and the results analyzed using the Tukey test. To compare the lettuce seedlings behavior under both irrigation systems it was evaluated the leaves number, seedling's height, root length and fresh and dry mass of the aerial and root part of the plant. The Christiansen uniformity coefficient (CUC) and the water distribution coefficient (WDC) for the fixed irrigation system were considered adequate and for the self-propelled laterals system (mobile system) they were considered excellent. The volume of water used with the fixed system was 109.12% higher than with the selfpropelled system. The lettuce seedlings irrigated with the self-propelled system had a growth, production and a seedling quality statistically superior than when irrigated with the fixed system. Independent of the irrigation system used, the Elizabeth lettuce cultivar had a greater seedling behavior. According with the results obtained, it is recommended the use of the self-propelled irrigation system (mobile system) on the production of lettuce seedlings.
O estudo da refletância solar e, por conseguinte do albedo são essenciais para sistemas fotovoltaicos bifaciais para estimar seu desempenho. Para atender a essa necessidade, instalou-se dois piranômetros, um observando a radiação solar direta e outro a refletida, visando desta forma obter dados do albedo do solo, durante a atividade experimental. O albedo da superfície do solo é um fator importante na relação custo-benefício de um sistema fotovoltaico bifacial. Os conjuntos de dados medidos incluem séries temporais de albedo no período mensal e horários, para o período de 2022. Os resultados preliminares indicaram para um solo típico, o Latossolo Vermelho Eutrófico, que apresenta uma textura argilosa a moderada, um valor de albedo de 0,15 com uma incerteza de medição de ±0,02; Os dados visam facilitar a compreensão dos valores de albedo e as características necessárias, tanto para a uso em um projeto fotovoltaico bifacial instalado no local, quanto para a sua análise financeira futura, como para melhor estimar o desempenho e reduzir o risco de implantação dos sistemas.
The increase in distributed generation (DG) interferes with the energy distribution system, which may present low voltages due to voltage drops and high voltages due to the insertion of distributed generation, resulting from renewable energy sources in rural areas. These voltage levels must be controlled to comply with the limits imposed by the distribution rules and procedures (PRODIST). This study aims to evaluate the voltage rise caused by DG, simulating three DG insertion scenarios, as well as simulate strategies to correct these voltage levels, such as the limitation of the active power supply, the reactive supply by the consumer and the utility, and the installation of on-load tap changers. The simulations were performed using the MATLAB ® program, more specifically the PSAT toolbox. Correction techniques were simulated using the active power supply limitation method, the reactive power supply method by consumers, and the voltage regulator process once the voltage rise effect was identified. The first two proved to be ineffective in this case, while the last one meets the voltage levels required by the National Electric Energy Agency.
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