Oxygen temperature variation of a non-premixed oxy-methane flame in a lab-scale slot burner

• Temperature variation effects on oxy-fuel flame length were investigated.
• Flammable area became broadened with increasing oxygen temperature.
• The flame length decreased with an increase in oxygen temperature.
• The concept of effective diameter was used to derive an empirical formula.

The effect of temperature variation on the behavior of a non-premixed oxy-methane flame was investigated with a lab-scale slot burner at atmospheric pressure (P∞ = 1.01325 bar). The characteristics of flame behavior were simulated to analyze the flame structure and were observed by measuring the chemiluminescence from OH and CH radicals with a spectrometer and an intensified charge-coupled device (ICCD) camera. Flammable area was estimated by varying the flow velocity from mF = 0.02–0.16 g/s (i.e., uF = 7–50 m/s) for methane gas and mOx = 0.24–2.71 g/s (i.e., uOx = 18–117 m/s) for oxygen gas. The oxygen temperature at the nozzle exit (TOx) was changed from TOx = 300 to 700 K. Experimental measurements showed that the flammable area broadened as the oxygen temperature increased. The increase in oxygen temperature was associated with a decrease in the flame length. The concept of effective diameter was used to derive an empirical formula for flame length for use in a combustor design.