Heat recovery and metal oxide particles trapping in a power generation system using a swirl-stabilized metal-air burner. (15th April 2020) - Laraqui, Driss
Graphical abstract: Highlights: A metal-air flame was swirl-stabilized for two geometrical swirl numbers. 80% of the produced heat was clearly localized in the system. About 45% of the total energy was the localized thermal radiation energy of the particles. The mass trapping efficiency exhibited an average of about 98%. SEM and TEM pictures showed nanometric MgO cubes which form micron-sized particles. Abstract: In order to tackle future challenges concerning zero greenhouse gases emissions, an innovative power generation system was designed and analyzed. It included a swirled-stabilized metal-air burner confined in a water-cooled combustion chamber, a secondary heat exchanger and a particle filtration system leading to a unique system of this kind. Magnesium particles in the range 50–70 µm were used as metal fuel. The effect of the swirl intensity was evaluated first on the flame position within the combustion chamber. As expected, the flame was stabilized closer to the burner head with the high swirl number than with the low one. To reach optimal heat to-mechanical conversion efficiency, an analysis of the heat recovery in the power generation system was performed. Experiments were conducted with a total chemical power ranging from 6 kW to 11 kW. Eighty percent of the power released by combustion were recovered in the power generation system and 50% in the combustion chamber. Ninety-eight percent of the magnesium oxide produced by combustion were trapped inside the system. Laser granulometry showed a number distribution for the metal oxide particles around 500 nm. Untrapped particles were measured by a Pegasor Particle Sensor (PPS), which was previously calibrated by comparison with measurements of the total suspended particles (TSP). Complementary TEM analysis confirmed that the metal oxide particles were aggregates of elementary submicron MgO cubic particles (10–1000 nm).