Experimental study of combustion characteristics of nanoscale metal and metal oxide additives in biofuel (ethanol)
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NANO EXPRESS
Open Access
Experimental study of combustion characteristics of nanoscale metal and metal oxide additives in biofuel (ethanol) Matthew Jones1, Calvin H Li1,2*, Abdollah Afjeh1, GP Peterson3
Abstract An experimental investigation of the combustion behavior of nano-aluminum (n-Al) and nano-aluminum oxide (nAl2O3) particles stably suspended in biofuel (ethanol) as a secondary energy carrier was conducted. The heat of combustion (HoC) was studied using a modified static bomb calorimeter system. Combustion element composition and surface morphology were evaluated using a SEM/EDS system. N-Al and n-Al2O3 particles of 50and 36-nm diameters, respectively, were utilized in this investigation. Combustion experiments were performed with volume fractions of 1, 3, 5, 7, and 10% for n-Al, and 0.5, 1, 3, and 5% for n-Al2O3. The results indicate that the amount of heat released from ethanol combustion increases almost linearly with n-Al concentration. N-Al volume fractions of 1 and 3% did not show enhancement in the average volumetric HoC, but higher volume fractions of 5, 7, and 10% increased the volumetric HoC by 5.82, 8.65, and 15.31%, respectively. N-Al2O3 and heavily passivated nAl additives did not participate in combustion reactively, and there was no contribution from Al2O3 to the HoC in the tests. A combustion model that utilized Chemical Equilibrium with Applications was conducted as well and was shown to be in good agreement with the experimental results. Introduction Metal additives have been utilized in solid propellants and fuels for some time and have been shown to dramatically increase combustion enthalpies and quality. In addition, these metalized propellants offer increases in the overall energy density of the fuel and increase specific impulse, and they effectively reduce the tank storage volume. In the current state-of-the-art implementation, energetic additives offer a high volumetric enthalpy of combustion, facilitating transportation of more payload per given fuel volume. However, given that the energetic additive sizes are in the micron range and sometimes even in the millimeter range, there are numerous side effects to the combustion process, including ignition delays, slow burn rates, and incomplete combustion of large (micron-sized) metal particles. Furthermore, the stability of liquid-based fuels is also a major concern; conventional liquid fuels may need to be remixed or processed before use, because of rapid settling of the * Correspondence: [email protected] 1 Department of Mechanical, Industrial, and Manufacturing Engineering University of Toledo, Toledo, OH 43606, USA. Full list of author information is available at the end of the article
energetic additive particles. New approaches and advances in nanotechnology are being developed to mitigate several of the disadvantages of metal particle additions, which will enable their large-scale implementation as viable secondary energy carriers [1]. Nanoparticle-laden fuels are known to exhibit significantly different thermophysical
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