High-resolution multi-species pollutant emission measurement by photoacoustic technique of NH3–H2 combustion in a turbulent swirl burner

• Elevated NH 3 emission was measured at low and high equivalence ratios. • High NO and NO 2 emissions were measured above 20 V/V% H 2 . • Low emissions were found at 5–20 V/V% H 2 and an equivalence ratio of 0.75–0.85. • Flame liftoff showed no correlation with pollutant emissions. • NO and NO 2 of steady operation showed normal behavior, while N 2 O and NH 3 did not. Ammonia cracking enables the compensation of the inferior ignition characteristics of ammonia flames with hydrogen enrichment to approach those of natural gas-air mixture combustion. Therefore, the present paper focuses on the simultaneous measurement of NO, NO 2 , and N 2 O besides NH 3 , which are the main pollutants of ammonia combustion. An advanced technique, photoacoustic emission analysis, was used, which allows for an effective 1–10 Hz temporal resolution compared to ∼30 s of conventional emission analyzers, enabling the detection of dynamic phenomena. The measurements were performed in an atmospheric swirl burner at 5–30 V/V% hydrogen enrichment, 10 and 13.35 kW thermal powers, and equivalence ratios in the range of 0.65–0.9. It was found that hydrogen enrichment reduces ammonia emissions at a low equivalence ratio, while the opposite may occur under a high equivalence ratio. Excessive hydrogen enrichment promotes NO and NO 2 formation, while N 2 O emission increases at low equivalence ratios up to 20 V/V% hydrogen enrichment. The temporal emission data sets showed notable fluctuations under quasi-steady operation, unique to the highly reactive hydrogen and less reactive ammonia systems. The temporal data of NO showed a normal distribution, while NO 2 was mostly normal, and N 2 O and NH 3 followed an alternative distribution.