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Show Presented at 2012 AFRC Annual Meeting, September 5-‐7, Salt Lake City, UT © 2012 ClearSign Combustion Corp. all rights reserved 3 2. increased stability, flame speed, attachment, and turndown, 3. reduced emissions of NOx and other species such as Hg, Pb, etc. 4. directed heat transfer to a surface or rejection therefrom, 5. diffused or focused heating, 6. flame shaping, shortening, lengthening, or redirection 7. enhanced flame luminosity. Each effect is described in turn with illustrative examples. 1. Increased Mixing. Asymmetric alternating waveforms provide intimate and increased fuel-‐air mixing without the need for additional excess air. This reduces excess air requirements because the bulk momentum of the air used for mixing is enhanced by momentum transfer of high velocity ions (Figure 3). (a) System Off (b) System Engaged Figure 3. Improved mixing with ECC technology. A bird's-‐eye view of a bench scale apparatus shows a diffusion flame burning coal and tire-‐derived fuel. The flame is surrounded by a circular air opening and (at a greater radius) a metal cylinder. In Case (a) the system is off and the flame burns normally, albeit sooting. When the system is engaged (b), the flame is charged with a proprietary electrical waveform. The flame volume increases immediately with no change in firing rate as the positive ions move toward the grounded cylinder and impart momentum to the bulk fluid. Sharp-‐edged flame structures are formed as the wave is inverted and re-‐inverted many times per second causing flow reversals along the electrical field lines. The mixing and violence of the flame are greatly enhanced with no additional excess air and the soot is fully oxidized. When the system is deactivated, the flame immediately reverts the state shown in (a). Enhanced mixing generated by ECC technology suppresses CO formation especially under low excess air conditions and dramatically reduces particulate matter in otherwise sooting flames. These results are additionally depicted in Figures 4 and 5. |