In order to meet future emissions regulations, new combustion concepts are being developed. Among them, the development of low-temperature diesel combustion systems has received considerable attention. Low NO{sub}x emissions are achieved through minimization of peak temperatures during the combustion process. Concurrently, soot formation is inhibited due to a combination of low combustion temperatures and extensive fuel-air premixing. In this study, the effect of late-cycle mixing enhancement by post-injection strategies on combustion and engine-out emissions in the low-temperature (low soot and NO{sub}x emissions) combustion regime was experimentally investigated. The baseline operating condition considered for low-temperature combustion was 1500 rpm, 3 bar IMEP with 50 EGR rate, and extension to high loads was considered by means of post injection. Post-injection strategies gave very favorable emission results in the low-temperature combustion regime at all loads tested in this study. Since post injection leads to late-cycle mixing improvement, further reductions in soot emissions were achieved without deteriorating the NO{sub}x emissions. With smaller fuel injected amounts for the second pulse, better soot emissions were found. However, the determination of the dwell between the injections was found to be very important for the emissions.
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机译:为了满足未来的排放法规,正在开发新的燃烧概念。其中,低温柴油燃烧系统的发展受到了相当大的重视。通过最小化燃烧过程中的峰值温度,实现低NO{sub}x排放。同时,由于燃烧温度低和广泛的燃料-空气预混合,烟灰的形成受到抑制。本研究通过实验研究了低温(低烟尘和NO{sub}x排放)燃烧状态下,后喷射策略增强后循环混合对燃烧和发动机排放的影响。考虑的低温燃烧基线操作条件为 1500 rpm,3 bar IMEP,EGR 率为 50%,并且考虑通过后喷射扩展到高负载。在本研究中测试的所有负载下,后喷射策略在低温燃烧状态下都给出了非常有利的排放结果。由于后注入可改善后期混合,因此在不恶化 NO{sub}x 排放的情况下进一步减少了烟尘排放。随着第二个脉冲的燃料喷射量较小,发现更好的烟尘排放。然而,发现确定注入之间的停留对于排放非常重要。
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