Experimental analysis and modeling of internal combustion engine operating with wet ethanol

Abstract

a b s t r a c tThe use of ethanol as fuel has encouraged many countries to improve their production processes. However, costs related to its current production model have been occasionally mentioned as a disadvantage to the use of this biofuel. One of the main costs is the energy expenditure for an effective distillation of the fermented ethanol wort, to result a final product called hydrous ethanol (about 95% by volume of ethanol in water). A promising alternative is the use of ethanol fuel with high fractions of water (above 5% by volume), the so-called wet ethanol, which would reduce the energy cost of production during the distillation. Thus, this study proposes the development of a mathematical model that, along with experimental data, is able to predict the effect that the use of wet ethanol has on the performance of internal combustion engines. In order to do so, along with commercial hydrous ethanol, blends were prepared with the following volume fractions of water: 10% (E90W10), 20% (E80W20), 30% (E70W30) and 40% (E60W40). Tests were performed considering two engine operating conditions: (a) fixed ignition timing and (b) adjusted ignition timing for maximum engine torque. The model was able to successfully simulate the gradients of pressure and temperature in the cylinder and it showed good ability to predict engine performance based on the variations of power, torque, conversion efficiency, and specific fuel consumption. Except for the specific fuel consumption, where the estimated error for variations was greater than 20%, the estimates for the other performance parameter presented relative errors lower than 7%. For all tests, the relative error was lower than 13%. The gradual increase of specific fuel consumption was associated with the increasing water content. Among the fuels tested, E70W30 showed the best performance, followed by the E80W20 blend; both were more efficient than the commercial ethanol.

Spark Ignition Engine Combustion, Performance and Emission Products from Hydrous Ethanol and Its Blends with Gasoline

“…In addition, the engine thermal efficiency under MBT condition was also obtained using a water content of 30% [76,78]. Finally, Lanzanova et al [78] and Ambros et al [77] found that for SI engine, running at MBT timing decreases SFC for hydrous ethanol. Munsin et al [80] also noticed that by enlarging the generator load the BSFC reduced by about 76% for hydrous ethanol.…”

“…The authors illustrated that to the ethanol molecules being trapped in the large cavities within the water structure, which can lead to volume contraction of the ethanol-water blend [9]. In a related study, Ambros et al [77] tested commercial hydrous ethanol blends ranging from 10% to 40% by volume prepared by the addition of water. The results showed that for an SI engine running under fixed ignition timing advance, high-water content in ethanol mixtures caused high pressures at the end of compression phase, with the in-cylinder pressures decreasing with an increased water content in the fuel.…”

“…The increase in water percentage (5%-30% by volume) in ethanol allow one to work with advanced ignition points, aiming maximum brake torque condition lead to increases the cylinder pressure [77][78][79]. Moreover, any water addition beyond this 30% content had an adverse effect on engine combustion [9,77,78], attributed to the ethanol molecules being trapped in the large cavities within the water structure and decreases in the laminar burning velocities with increased water content in ethanol. Finally, at fixed ignition timing setting conditions, the increased water content in ethanol fuel blends decreases the cylinder pressure [68,77], and combustion duration [68,79].…”

“…Moreover, any water addition beyond this 30% content had an adverse effect on engine combustion [9,77,78], attributed to the ethanol molecules being trapped in the large cavities within the water structure and decreases in the laminar burning velocities with increased water content in ethanol. Finally, at fixed ignition timing setting conditions, the increased water content in ethanol fuel blends decreases the cylinder pressure [68,77], and combustion duration [68,79]. Moreover, an increased water content in ethanol fuel increases the cycle-to-cycle variations [68,75].…”

Investigação Do Uso De Elevadas Razões De Compressão Com Etanol Hidratado Através Da Análise De Liberação De Calor

“…Além disso, constatou-se um aumento na resistência à detonação conforme aumentado o percentual de água, visto que tal fenômeno foi suprimido para percentuais de água superiores à 20%. Ambrós et al [20] e Fagundez et al [21] reportaram desvantagens como maior duração de combustão e acréscimo no consumo de combustível, com o aumento da concentração de água em motores a ignição por centelha operando em condição de MBT.…”