The medium-speed diesel engine in diesel-electric propulsion systems is increasingly used as the propulsion engine for liquefied natural gas (LNG) ships and passenger ships. The main advantage of such systems is high reliability, better maneuverability, greater ability to optimize and significant decreasing of the engine room volume. Marine propulsion systems are required to be as energy efficient as possible and to meet environmental protection standards. This paper analyzes the impact of split injection on fuel consumption and NO_X emissions of marine medium-speed diesel engines. For the needs of the research, a zero-dimensional, two-zone numerical model of a diesel engine was developed. Model based on the extended Zeldovich mechanism was applied to predict NO_X emissions. The validation of the numerical model was performed by comparing operating parameters of the basic engine with data from engine manufacturers and data from sea trials of a ship with diesel-electric propulsion. The applicability of the numerical model was confirmed by comparing the obtained values for pressure, temperature and fuel consumption. The operation of the engine that drives synchronous generator was simulated under stationary conditions for three operating points and nine injection schemes. The values obtained for fuel consumption and NO_X emissions for different fuel injection schemes indicate the possibility of a significant reduction in NO_X emissions but with a reduction in efficiency. The results showed that split injection with a smaller amount of pilot fuel injected and a smaller angle between the two injection allow a moderate reduction in NO_X emissions without a significant reduction in efficiency. The application of split injection schemes that allow significant reductions in NO_X emissions lead to a reduction in engine efficiency.

中文翻译：

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分流喷射对船用中速柴油机油耗和NOx排放的影响分析

柴油-电力推进系统中的中速柴油发动机越来越多地用作液化天然气（LNG）船和客船的推进发动机。这种系统的主要优点是高可靠性，更好的可操纵性，更强的优化能力以及发动机室容积的显着减小。要求船舶推进系统尽可能节能，并符合环境保护标准。本文分析了分流喷射对船用中速柴油机燃料消耗和NO _X排放的影响。为了研究的需要，开发了柴油机的零维，两区数值模型。应用基于扩展Zeldovich机理的模型预测NO _X排放。数值模型的验证是通过将基本发动机的运行参数与发动机制造商的数据以及柴电推进船的海上试验数据进行比较来进行的。通过比较所获得的压力，温度和燃料消耗量的值，可以确认数值模型的适用性。在固定条件下，针对三个工作点和九种喷射方案，模拟了驱动同步发电机的发动机的运行情况。针对不同的燃油喷射方案获得的燃油消耗量和NO _X排放值表明，NO _X可能大量减少排放，但效率降低。结果表明，分批喷射具有较少的先导燃料喷射量和两次喷射之间的较小角度，可以适度减少NO _X排放，而不会显着降低效率。允许大幅减少NO _X排放的分流喷射方案的应用导致发动机效率的降低。