ABSTRACT

The usage of Tamanu methyl ester (TME) in a conventional CI engine produces more NO _x emission because of in-built oxygen content in biodiesel. Simultaneous reduction of NO _x and smoke is a really difficult way in a conventional CI engine. The usage of biodiesel in the HCCI engine would be a better way to reduce smoke and NO _x emission due to the homogenous mixture rather than heterogeneous combustion and lower in-cylinder temperature. In this study, the experimental analysis was carried out on a single-cylinder engine operated in HCCI mode. The test fuels used for this experiment are TME 90% + n-heptane 10% (TME90nH10), TME 80% + n-heptane 20% (TME80nH20), TME 70% + n-heptane 30% (TME70nH30), and TME 60% + n-heptane 40% (TME60nH40). The test results noticed that brake thermal efficiency (BTE) of TME70nH30 showed higher when compared to neat TME, diesel, and other blends. The CO, HC, and smoke emission were decreased by 3.1%, 6.5%, and 9.2%, respectively, for a blend TME60nH40 when compared to TME70nH30. The smoke and UBHC emission of TME60nH40 was 23.5% and 26.4% lower than the HCCI mode of operation in diesel fuel. When n-heptane concentration increases beyond 40% in the blend, the performance characteristics of the engine started to decrease due to the high cetane rate of n-heptane which leads to shortening the span of the autoignition period that results in too advanced combustion. Based on emission characteristics of the engine, TME60nH40 was chosen to be the best blend and further study was carried out using TME60nH40 at different exhaust gas recirculation (EGR) percentages. The engine was operated with TME60nH40 with different EGR percentages of 5, 10, and 15. With the increase in the percentage of EGR increases the CO and UBHC emissions but on the other side, NO _x emission was drastically decreased.

摘要

琼崖海棠甲酯在常规CI发动机的使用（TME）产生更多的NO _X，因为在生物柴油内置氧含量排放。NO的同时减少_X和烟雾是在传统的CI发动机真的很难方式。在HCCI发动机生物柴油的使用将是一个更好的办法，以减少烟雾和NO _X 由于均质混合物而不是非均质燃烧和较低的缸内温度而产生的气体排放。在这项研究中，实验分析是在HCCI模式下运行的单缸发动机上进行的。用于此实验的测试燃料为TME 90％+正庚烷10％（TME90nH10），TME 80％+正庚烷20％（TME80nH20），TME 70％+正庚烷30％（TME70nH30）和TME 60 ％+正庚烷40％（TME60nH40）。测试结果表明，与纯净的TME，柴油和其他混合物相比，TME70nH30的制动热效率（BTE）更高。与TME70nH30相比，混合TME60nH40的CO，HC和烟气排放分别减少了3.1％，6.5％和9.2％。TME60nH40的烟雾和UBHC排放量比HCCI柴油机运行模式低23.5％和26.4％。当正庚烷浓度增加到混合物中的40％以上时，由于正庚烷的十六烷值高，发动机的性能特征开始下降，这导致自燃时间段缩短，从而导致燃烧提前。根据发动机的排放特性，选择TME60nH40为最佳混合物，并使用TME60nH40在不同的废气再循环（EGR）百分比下进行进一步研究。发动机使用带有5、10和15的不同EGR百分比的TME60nH40进行操作。随着EGR百分比的增加，CO和UBHC排放量增加，但另一方面，NO 由于十六烷的十六烷值高，发动机的性能特征开始下降，这导致自燃期缩短，从而导致燃烧提前。根据发动机的排放特性，选择TME60nH40为最佳混合物，并使用TME60nH40在不同的废气再循环（EGR）百分比下进行进一步研究。发动机使用带有5、10和15的不同EGR百分比的TME60nH40进行操作。随着EGR百分比的增加，CO和UBHC排放量增加，但另一方面，NO 由于十六烷的十六烷值高，发动机的性能特征开始下降，这导致自燃期缩短，从而导致燃烧提前。根据发动机的排放特性，选择TME60nH40为最佳混合物，并使用TME60nH40在不同的废气再循环（EGR）百分比下进行进一步研究。发动机使用带有5、10和15的不同EGR百分比的TME60nH40进行操作。随着EGR百分比的增加，CO和UBHC排放量增加，但另一方面，NO _x 排放量大大减少。