Effect of quenching region characteristics on the performance of two-region porous inert medium burners at low-power operation

[Display omitted] The Influence of the Combustion Stability Diagram by Varying the Quenching Region Material of a Two-region PIM Burner When Operating at Low Powers. •The quenching region was found to affect the two-region PIM burners performance.•This was done by varying the configuration parameters of this region.•The stability and emissions performances were examined at low-power range of 1–5 kW.•The stability diagrams were extracted from the real-time temperature measurements.•The stability limits were enhanced when a thicker alumina material was employed. Although the effects of quenching and combustion regions on the performance of two-region porous inert medium (PIM) burners are different, only the combustion regions have received the utmost consideration. This study focuses on quenching regions by exploring the effect of varying their characteristics on the performance of PIM burners operated at low powers (1–5 kW). Therefore, the axial real-time temperature distributions and the steady-state CO– and NOx-emissions due to the combustion of wide ranges of well-premixed LPG-air mixtures within a well-designed PIM burner were measured. To vary the quenching region characteristics, two different materials of alumina and cordierite and three different thicknesses of the alumina material were used. The combustion stability limits were extracted from the measured stable temperature distributions and presented as a function of the applied power. Both the lower and higher stability limits decayed toward lower excess air ratios. However, the higher limit decayed at a faster rate, thereby causing the modulation ability of the excess air ratio to shrink continuously, which limited the burner’s adaptability and capacity. Meanwhile, using the alumina material instead of the cordierite improved the entire lower stability limit by at least 0.1. Conversely, using the cordierite material improved the higher stability limit by 0.1, but only for the two lower powers of 1 and 2 kW. In addition, increasing the alumina material’s thickness from 13 to 20 mm enhanced the whole modulation ability by 0.2, where each limit was entirely improved by 0.1. Therefore, these findings emphasize the effects of quenching region characteristics on the performance of two-region PIM burners, revealing the importance of optimizing this region during their design for actual practical applications. Finally, except for the CO-emission at 1 and 2 kW, outstanding insignificant CO– and NOx-emiss