Master of Science in Mechanical Engineering (MSME)
Ethanol is currently being considered as a potential alternative to traditional fuels. However, the fuel offers a low return in terms of energy output per dollar invested when compared to fossil fuels. More than 1/3 of the cost associated with bio-ethanol production is devoted to distillation and water removal. This study seeks to validate the use of hydrous ethanol as a practical fuel to be used in lieu of fossil fuels or anhydrous ethanol. Success would reduce the production cost associated with ethanol fuel. Hydrous ethanol was burned in a swirl-stabilized combustor, air is introduced at a constant flow rate through a dump diffuser, and fuels ranging from 0%-40% water by volume was tested for practicality. A stable flame was achieved with up to 35% water and the Lean Blow Out limit was determined for these fuels. Fuels ranging from 0% to 20% water were tested in greater detail. This included thermal mapping of the flame, exhaust temperature measurements, exhaust NOx, CO2, and O2 measurement, as well as CH* and OH* imaging of the low-flame region. Equivalence ratio was varied to include test points at 0.6, 0.8, 1.0 and 1.1. This range provides insight into flame behavior at extremely lean, lean, stoichiometric, and rich test conditions. Results revealed that exhaust heat rate, combustion efficiency, and combustor thermal efficiency were not affected negatively by elevated water content. However, flame temperature decreased as a result of water addition, particularly in the low flame region. CH*/OH* emissions in the low-flame region were also reduced due to the parasitic heat load of water vaporization and local quenching. The practical consequence of burning hydrous fuel was reduced exhaust temperature. This negative consequence, coupled with the desirable consequence of increased mass flow rate, did not appreciably affect the net exhaust heat rate. Reduced peak temperatures lead to exhaust NOx reductions. In conclusion, this study reveals that ethanol with proof as low as 140 behaves as a practical fuel and is recommended as a means of increasing the economic return when using ethanol as fuel in situations where increased volumetric consumption of the fuel is acceptable.
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Breaux, Baine Bernard, "The effect of elevated water content on ethanol combustion" (2012). LSU Master's Theses. 1548.