Preliminary Investigation Of Aluminum Combustion In Air And Steam

Author : Jorge Palomino Alva
Publisher :
ISBN 13 :
Total Pages : pages
Book Rating : 4.:/5 (971 download)

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Download or read book Ignition of Aluminum Powder with a 2.45-GHz Microwave Plasma Torch written by Jorge Palomino Alva and published by . This book was released on 2016 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Research was conducted at The Pennsylvania State University to investigate and develop a proof-of-concept aluminum igniter using a 2.45-GHz microwave plasma torch. Using Penn States Microwave Plasma Torch design, an argon and helium plasma were generated at 300-W delivered power in both air and steam environments. Injector design iterations allowed for steam, with reduced condensation effects, to become entrained within the plasma and mitigated the presence of air chemistry by employing a fused-quartz chamber. Aluminum powder, carried by argon, was able to enter the plasma volume directly at a relatively steady flow rate drawn from a beneficial pressure drop through the delivery line. It was hypothesized that a region in the microwave-generated plasma would have a temperature greater than or equal to 2300 K, the melting point of aluminum oxide, which exists as an ignition-inhibiting layer in aluminum particles. Preliminary work was performed to study the plasma temperature as a function of axial distance and delivered power via diatomic rovibrational spectra fitting of the NO, OH, and N2 2nd positive system bands from axial spectral measurements. Difference in ignition over the axial measurements was noted to depend on the diffusivity of the working gas, as the broadband continuum from the thermal emission saturated the optical spectrometer when using helium as a plasma starter near the injection tube, but it did not signal that saturation had occurred when using argon as a plasma starter. Validation of the plasma state was obtained via optical emission spectroscopy with reference to profiles of plasma radicals for helium, argon, air, water, aluminum, and aluminum monoxide. Peak lines of interest for the following elements were studied at particular wavelengths: helium at 587.56 nm; argon at 750.387 nm and 811.531 nm; hydrogen at 656.3 nm (H); and a hydroxide band from 250 nm to 340 nm (OH: A2 + X2 ). Validation of the ignition state due to the presence of aluminum powder and steam radicals from the plasma source was achieved through thermal emissions registered via optical emission spectroscopy, as well as material analysis through x-ray diffraction of condensed combustion products that showed the presence of elemental aluminum, corundum or -alumina, -alumina, and -alumina, along with other aluminum oxide forms. Initial ignition spectra showed an aluminum line present at 396 nm and an aluminum monoxide band spanning from 450 nm to 550 nm. An estimate of the flame temperature from the thermal emission peak wavelength assuming blackbody and grey-body models revealed Tf = 3583 326 K, which follows a similar pattern found in previous literature for flame temperatures.