Experimental study on pyrolysis coking characteristics of n-decane in additively manufacturing channel under supercritical conditions

In this study, the experiments about supercritical hydrocarbon fuel in additively manufacturing (AM) and conventionally mechanical manufactured (CM) channel with different heating power and mass flow rates have been researched. Random roughness height has a significant impact on pyrolysis coking. The results reveal that the total coking amount increases with increasing heating power and decreases with increasing mass flow rate both in CM channel and AM channel. In addition, when the heating power increases from 0.8 kW to 1.6 kW, the coking amount in the machining channel increases by 60.70 mg, while that in the AM channel increases by 39.51 mg. When the mass flow rate increases from 0.8 g/s to 1.2 g/s, the coking amount in the machining channel decreases by 39.90 mg, whereas the AM channel experiences a decrease of 25.45 mg. Comparatively, the AM channel exhibits lower wall temperatures and reduced total coking amounts compared to the CM channel. From the Scanning Electron Microscope (SEM) results, the coke topography in the CM channel is mainly filamentous carbon, while the coke in the AM channel is mainly amorphous carbon. Raman spectra results show that the coke in AM channel exhibits a higher I_D/I_G, which is more disordering than that in CM channel. Temperature programmed oxidation (TPO) profiles reveal that the coke in AM channel has a lower oxidative activity temperature than that in CM channel. Overall, AM channel has better heat exchange performance than CM channel. Thus, AM channel has great application prospects in aircraft.