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Ignition delay times of Diethyl Ether (DEE) were measured behind reflected shock waves for the temperatures from 1050 to 1600 K, pressures of 1.2, 4 and 16 atm and equivalence ratios of 0.5 and 1.0. Result shows that the ignition delay times increase with the increase of the equivalence ratio and the decrease of the pressure. The only literature DEE mechanism (Yasunaga et al. model) was employed to simulate the experimental data and result shows that the model gives reasonable prediction on lean mixtures, while the prediction on stoichiometric mixtures is slightly higher. Sensitivity analysis was conducted to pick out the key reactions in the process of DEE ignition at high and low pressures, respectively. Reaction pathway analysis shows that the consumption of DEE is dominated by the H-abstraction reactions. Through linear analysis, a correlation for the DEE ignition data was obtained.

In this paper, 20%H₂ (20% hydrogen in natural gas-hydrogen blends, by volume) is selected as the test fuel, and the ignition timing and EGR ratio are adjusted to optimize the performance, combustion, and emissions of a natural gas-hydrogen engine. An experimental investigation on the effect of ignition timings, EGR ratios on combustion behaviors and emissions of a spark-ignition engine fuelled with natural-gas and hydrogen blends was conducted. When increasing the ignition timing at specified EGR ratio, engine power output will give its peak value at MBT timing. Large EGR introduction decreases engine power output and increases combustion duration. Effective thermal efficiency shows an increasing trend at the small EGR ratio and a decreasing trend with further increasing EGR ratio. With advancing the ignition timing, the flame development duration is increased, and the rapid combustion duration and total combustion duration are decreased.

Ignition delay times of stoichiometric dimethyl ether (DME) and n-butane blends were measured in a shock tube at varied DME blending ratios, temperatures and pressures. Simulation work extended the pressure to 20 atm by using Chemkin and NUI C4_47 mechanism. The experimental ignition delay times of DME/n-butane were obtained at different DME blending ratios. Measured ignition delay times were compared to simulations based on NUI C4_47 mechanisms by Curran et al. The mechanism predicts the magnitude of ignition delay times well and a slightly higher activation energy. The ignition delay times increase linearly with the increase of 1000/T and the overall activation energy keeps almost the same value at the conditions in this study. Increasing pressure decreases exponentially the ignition delay time. Ignition delay time decreases linearly with the increase of DME blending ratio.