The Combustion of Lean Ethanol–Air Mixtures in a Swiss-Roll Combustor

A novel meso-scale 3-channel 5-turn Swiss-roll type combustor was designed and tested. The non-catalytic combustion of lean ethanol–air mixtures was experimentally investigated in relation to the oxygen excess ratio (α), which varied from 1.5 to 7. Depending on the control parameters used, two distinct regimes of combustion were experimentally observed: one with a combustion zone within the central chamber and another with a combustion zone in the inflow channel. The combustion temperature was virtually independent of stoichiometry. For richer mixtures and lower flow rates, the combustion zone is established in the inflow channel, thus limiting the combustion temperature. A qualitative model was proposed for the process and solved analytically; it described how the combustion regime self-adjusted, with the reaction zone moving into the inflow channel from the central chamber. This study confirmed the possibility of the sustainable combustion of ultra-lean fuel mixtures in a Swiss-roll combustor.