The enhancement of the flame radiation in gas fueled burners not only improves the thermal efficiency, but also can suppress the rate of NO emission due to reducing the flame temperature. In this experimental investigation, the effect of inlet gas temperature on the flame radiation intensity and the rate of NO formation are studied. To serve this aim, with increasing the temperature of inlet methane to the burner up to 310oC, the variations of CO and NO level in exhaust gases and also the exhaust gas temperature are recorded by gas analyzer device. In each case, the flame radiation intensity was also measured by a photovoltaic module. The results revealed that by increasing the inlet gas temperature up to 250oC, the NO concentration and the exhaust gases temperature are raising. But when the inlet gas temperature exceeds from 250oC and reaches to 310oC, the flame luminosity gradually increases which results in 70 percent growth in flame radiation and 10 percent drop in exhaust gas temperature. The results of the preheating of inlet air also show the same behavior.

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