The present experimental study is performed to document the effects of carbon-to-hydrogen mass ratio (C/H) in liquid hydrocarbon fuels, on the luminosity, thermal radiation rate, and temperature of flame. Furthermore, extraction of the thermal and radiative characteristics of flame, and measurement of exhaust gases including CO, CO2, and NOx have been carried out. The CHNS elemental analyzer system was employed to ascertain fuel composition. The thermopile sensor and the lux meter were utilized to measure the flame thermal radiation and luminosity. The measured flame radiation spectrum included all possible wavelengths (i.e., flame thermal radiation) and visible wavelengths (i.e., luminosity). The flame photography technique, as a non-intrusive method, depicted the flame visible radiation, IR spectral emittance, and high temperature zone. The results revealed that the luminosity and thermal radiation of the flame increased as we increase C/H. A rise in C/H made the temperature along the flame axis more uniform. The NOx emissions were within standard levels (i.e., under 200 ppm). It was also shown that the C/H variation has a greater effect on luminosity than thermal radiation of the flame. The flame luminosity was increased by 66% when the C/H was increased from 5.47 to 5.68, whereas the flame thermal radiation increased by 26%. In addition, a new correlation is proposed to predict the linear relation of the increase in the thermal radiation and the increase in the luminosity of the flame as a function of C/H.

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