High-Temperature Self-Ignition Characteristics of NH3-H2-DME Based on OH
Ammonia(NH3)is a very promising zero-carbon alternative fuel,but its low reactivity limits its devel-opment and application.Blending other low-carbon or zero-carbon fuels complementary to its low reactivity charac-teristics can significantly improve its combustion characteristics.The ignition delay time(IDT)of NH3-hydrogen(H2)-dimethyl ether(DME)ternary blended fuels with air was measured under the temperature variation from 1300-2000 K,the pressure of 0.14 MPa and 1.00 MPa,and the equivalence ratio of 0.5,1.0 and 2.0 re-spectively,by using reflected shock wave and the self-luminescence property of fuel excited hydroxyl group(OH*)on a shock tube experimental platform.The experiment focused on the effects of the blending ratio of binary activa-tor H2+DME on the shortening rate of pure ammonia under each working condition.Results show that the equiva-lence ratio affects the ignition promotion of the activator,and the H2+DME(mole fraction ratio is 1∶1)can re-duce the activation energy more than the single activator at the same mixed ratio.The ignition characteristics of the ternary fuel show obviously different depending on the activator ratio and reaction conditions,where the higher hydrogen ratio of H2+DME(mole fraction ratio is 2∶1)has a better ignition promotion effect under the lean-burn combustion conditions,and H2+DME(mole fraction ratio is 1∶2)is more active under the fuel-rich conditions.
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