Investigation of partially-premixed combustion in a household cooker-top burner

The present paper provides an examination of the CH₄/air flame in a self-aerated cooker-top burner currently in production. The operating conditions, the design characteristics and their effects on the combustion were investigated by calculating velocity, turbulence, temperature and reactive scalars using a modified temperature-composition pdf method. The two-stream nature of the problem allowed the use of the non-premixed formulation in that the calculations were started from the premixing chamber wherein fuel and air inflows were separated. The ingredients of the present study also included in-situ measurements of velocity with a PIV and the visualization of temperature by a line-of-sight infrared light detection system. The study shows that the current modelling of turbulent combustion is successful in predicting the location of the reaction zone as well as the shape and the properties of the flame. The results reveal that the present burner seems to produce flames which impinge only on the edges of the standard cooking vessel and lose the most of the available energy to the surrounding ambient air. Hence, the current flame position does not only reduce the thermal efficiency, but also re-cycles a large amount of burned gases into the premixing chamber. This situation decreases the aeration efficiency and eventually leads to an incomplete combustion and increased emissions of carbon monoxide. However, the flue gas recirculation also reduces the combustion intensity and the peak flame temperatures so that the thermal NO formation is expected to be inhibited.