Heat transfer from oxygen-enhanced/natural gas flames impinging normal to a plane surface

Abstract This study investigated the heat transfer from oxygen-enhanced/natural gas flames impinging normal to a plane surface. The objective was to determine the effects of the burner firing rate ( q f =5–25 kW), the oxidizer composition ( Ω =0.21–1.00), and the axial ( L =0.5–6.0) and radial ( R eff =0.16–1.04) positions of the surface. A round flame, from a flame-working torch burner, impinged onto a water-cooled metal disk ( d b =135 mm) that was segmented into six concentric calorimetric rings. The heat flux from the flame to the plane surface increased by 78–280% by increasing the firing rate from 5 to 25 kW. The thermal efficiency decreased with the firing rate. The heat flux increased 54% to 230% by increasing Ω from 0.30 to 1.00. For higher purity oxidizers (large Ω ), the peak flux always occurred at the stagnation point ( R eff =0.16) and the closest axial spacing ( L =0.5). For lower purity oxidizers (small Ω ), the peak flux occurred at about L =1–2 and a radial spacing of about R eff =0.6. The thermal efficiency increased with the oxidizer purity. This is the first study to investigate the range of oxidizer compositions between air ( Ω =0.21) and pure O 2 ( Ω =1.00).