This study investigates the emission characteristics and flame behavior of an air-staged swirl burner operating on LPG. The burner is equipped with a 45° vane swirler and an adjustable secondary-air section. Experiments were conducted at air velocities ranging from 20 to 43 m/s using a Testo 350 gas analyzer, while temperature measurements were obtained with thermocouples positioned 90 mm downstream of the burner exit. The results show that increasing the secondary-air opening leads to a monotonic decrease in the mean exit temperature and NO_x formation over the entire velocity range. In contrast, CO concentrations increase at higher air velocities and larger secondary-air fractions due to reduced residence time and partial quenching of the reaction zone. The fully staged configuration (100%) achieved the lowest NO_x levels (≤3 ppm) at 20 m/s, whereas the non-staged case resulted in the highest temperatures and NO emissions. Overall, the experimental results demonstrate that a moderate secondary-air opening provides the best compromise between low NO_x emissions and acceptable CO levels for compact LPG-fired swirl combustors.

This study presents a combined numerical and action research of burning aspects, nitrogen oxide formation in a micro-flame front device heat generator operating under high excess air conditions. The analysis covers a wide range of air excess ratios (α = 4.4–10), representative of practical heating system regimes. Numerical model was executed using ANSYS Fluent, employing a pressure-based solver, the realizable k–ε turbulence model, and a non-premixed kindling approach. The interplay among stream dynamics, blending intensity, thermal field distribution is examined in detail. The results demonstrate that increasing inlet air velocity enhances turbulent mixing, leading to a more uniform temperature field and reduced peak temperatures. This effect significantly suppresses thermal NO _x formation. The study confirms the potential of micro-flame combustion technology for stable and low-emission heat generation.