The validity of the proposed method for total emission determination ε of furnace inner wall surface behind the flame is verified by experiments. Using the emissions established for an infrared camera (IRC) operating in a relative small infrared wavelength interval, and founded on the infrared thermograms (IRT) processing, two methods for combustion research are conceived: gas oil droplet flame testing and gas fuel testing. Developing thermographic results of the first method, the second method, for industrial gas fuels experiments, can use a small tubular furnace with the necessary measure apparatus. There are established the essential theoretic fundaments with a scientific justification and new specific notions (for characterization or synthetic comparison of combustion operation regimes at different gas fuels), referring to the stable combustion inner tubular furnace.

Keywords: Wall surface emissions, Research-testing, Gas fuel combustion, Oil-droplet flame, Infrared thermograms.