whats the temperature of nonluminous flame?

Answer 1

There is not a direct causal effect between luminosity of a flame and temperature. Given the same energy output, though, a nonluminous flame will be hotter than a luminous flame since no energy is being emitted as light.

Luminous flames may be caused for a number of reasons. If oxidation is occurring with incomplete combustion, the resultant soot will give a yellowish tinge to a flame. Such flames are cooler than the same combustion with excess oxygen.