Spectral Radiation Analysis of Premixed Oxy-Methane Flames

For a hydrocarbon burning with oxygen, the resulting exhaust stream is composed mainly of carbon dioxide and water vapor. This exhaust allows for easier carbon capture and sequestration since the water can be condensed out. Another advantage is the significant reduction of NO_x since much of the nitrogen found in air-fired systems is eliminated. Although beneficial, many of the exhaust gas products' radiative heat transfer characteristics are unknown. Motivated by this, this paper focuses on the spectral radiation measurement of premixed oxy-methane combustion flames. This is important for combustion system designers since radiative heat from the flame is significant for oxy-flames. This study is conducted by varying equivalence ratio, firing input, and CO₂ recirculation ratio. The spectral radiation of premixed oxy-methane flames is collected from 1.2 μm to 5 μm wavelengths. During the experimental study, it is found that the water vapor emits at 1.4 μm, 1.85 μm, and 2.5 μm wavelengths. A short band of carbon dioxide emission is detected at 1.96 μm. Three other carbon dioxide radiation maxima are observed at the proximity of 2.71 μm, 2.85 μm, and 4.38 μm. The study revealed that the spectral intensity of CO₂ and H₂O for oxy-methane combustion increases almost five times compared to the air-methane combustion at stochiometric condition. It is also found that the spectral intensity decreases as the equivalence ratio increases. The spectral radiative emission intensity increases as the firing input increases. Another observation includes the fact that spectral intensity increases up to five times when 60% CO₂ is recirculated as a diluent in the flame.