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.