SENSOR CAPACITIVO PARA MONITORAMENTO DO TEOR DE ÁLCOOL ETÍLICO ANIDRO COMBUSTÍVEL (AEAC) EM AMOSTRAS DE GASOLINA COMERCIAL

Abstract

During several years, adulterated gasoline has been commercialized across all Brazil. Often such product has higher alcohol content, water traces or organic solvents insertion (e.g. paint thinner and/or turpentine). The use of nonconforming gasoline, in the short and long terms, has several problems for consumers, for the vehicle and the environment. Thus, this work aims to propose a low cost technique for analyzing gasoline blends, in relation to its oxygenated addition. Both capacitance and dielectric constant (relative permittivity) were determined by means of a high precision LCR-meter, using a metal concentric sensor. Therefore, gasoline blends were prepared by adding 16, 18, 20, 22, 24, 26, 28 and 30% of AEAF to the initial petroleum-based fuel and their dielectric constants were measured at frequencies of 0.3, 0.4, 0.5 and 0.6 kHz. The same samples were analyzed by the reference method, the Test Tube Test. According to statistical modeling, the frequency of 0.6 kHz showed the most significant results for all samples. The results show that at 95% confidence level, there is no significant difference between the two methods, indicating a good correlation between the proposed method and then standard one. However, when the density was used as evaluating parameter, instead of dielectric constant, for the same samples, a substantial discrepancy of the obtained values were observe, suggest a low sensibility of such methodology.