Start temperatures of the cracking process at different pressures

3 Start temperatures of the cracking process at different pressures 

The start temperature of evaporation and of pyrolysis reaction may be defined by means of the onset temperature, which is itself defined as the temperature of the intersection of the tangents to the two branches of the curve, which have different slopes. The small drift of the curve of energy versus temperature introduces errors in the determination of the onset temperatures of evaporation events. For the experiment in methane at 10 bar pressure the onset temperatures and the peak maximum (minimum) temperatures of the evaporation are sometimes, quite close, due to the mode of determination (table 4-40)  

The start temperature of the pyrolysis reaction may in all cases be clearly ascertained. The onset temperatures of the experiments in 1 bar argon fall between 390-422 °C and for the experiments in 10 bar methane, from 392-420 °C. Statistical evaluation gives small coefficients of variation (Table 4-41). 

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