Within the area of combustion, externally heated microtubes have been introduced to study the 
combustion characteristics of fuels and fuel blends. Microreactors have advantages over other 
conventional fuel testing methods because of their potential to test small volumes (&lt;20 μl) at high 
throughput. In this work, a high-pressure microreactor is designed and implemented to test fuels up to a 
pressure of 30 bar where automated testing reduces test time substantially. The novelty of this device is 
its capability to operate at a pressure exceeding the current state of the art of 12 bar. The combustion behavior 
of fuels is tested in an externally heated quartz tube, with a diameter less than the conventional quenching 
diameter of the fuel. The objective of the experiment is to investigate the impact of fuel on flame 
characteristics. The ability to reach engine relevant pressure conditions and its inherent small volume 
requirements make this device a potential candidate for measurements of laboratory transportation fuels 
and fuel blends. 
For initial validation, tests from an earlier intermediate pressure experiment with ethane/air and nitrogen 
mixtures are repeated. Chemiluminescence images are taken to evaluate the combustion characteristics 
in terms of the three classical flame regimes: weak flames, Flames with Repetitive Extinction, and Ignition 
(FREI) and normal flames. Previous results at intermediate pressure showed that as the pressure 
increases, the weak flame and FREI regimes shift towards lower velocities. Also, increasing dilution level 
i.e. reducing oxygen concentration, the transition from the weak flame to FREI becomes less abrupt and 
is completely lost for lower oxygen concentration. The objective of this study is to document flame 
dynamics at higher pressures. 
Keywords: Micro-combustion; Flames with Repetitive Extinction and Ignition (FREI); Weak Flames; Stable 
Flames; Ethane 
&nbsp;

Towards a High-Pressure Microchannel Reactor for Fuel Characterization

Paper Proceedings: https://asmedigitalcollection.asme.org/POWER/POWER2021/volume/85109

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