Mild Hybridization via Electrification of the Air System: Electrically Assisted and Variable Geometry Turbocharging Impact on an Off-Road Diesel Engine
Mild Hybridization via Electrification of the Air System: Electrically Assisted and Variable Geometry Turbocharging Impact on an Off-Road Diesel Engine
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DOI：
10.1115/1.4025887
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发表时间：
2013-06
影响因子：
1.5
通讯作者：
Nicola Terdich;R. Martinez-Botas;A. Romagnoli;A. Pesiridis
中科院分区：
文献类型：
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作者：
Nicola Terdich;R. Martinez-Botas;A. Romagnoli;A. Pesiridis
电动涡轮增压辅助包括在涡轮增压轴承座内安装电机/发电机，以形成轻度混合动力系统，而不改变发动机的其他机械部件。这使其成为减少二氧化碳排放的理想和经济的中短期解决方案。本文的范围是评估与空气系统混合相关的发动机能效和瞬时响应的改善。为了实现这一点，将带有可变几何涡轮的电动涡轮增压器与类似的、非混合系统进行了比较，以改变发动机负荷。变几何涡轮已被控制，以提供不同级别的初始增压，包括效率优化的涡轮，并在瞬变期间改变其流量能力。模型发动机为7升6缸柴油机，输出功率超过200千瓦，涡轮增压电动助力功率低于10千瓦。为了提高模型的精度，利用帝国理工学院提供的独特的测试设备对涡轮增压涡轮进行了实验表征，并利用涡轮平均线模型对数据进行了外推。发动机增压优化以最大限度地减少泵送损失表明，刹车比油耗降低了4.2%。通过应用电动涡轮增压辅助，效率优化系统的发动机瞬时响应损失已有可能恢复，因为它使发动机转速下降71%至86%，发动机转速恢复时间减少79%至94%。当涡轮增压器中存在电辅助时，启动涡轮叶片来辅助暂态响应并没有产生预期的结果，而只是降低了能量效率。如果在瞬变过程中打开变几何涡轮，则可在发动机暂态性能几乎不受影响的情况下提高比能效。版权所有：2013，ASME
Electric turbocharger assistance consists in incorporating an electric motor/generator within the turbocharger bearing housing to form a mild-hybrid system, without altering other mechanical parts of the engine. This makes it an ideal and economical short to medium term solution for the reduction of CO2 emissions.The scope of the paper is to assess the improvements in engine energy efficiency and transient response correlated to the hybridization of the air system. To achieve this, an electrically assisted turbocharger with a variable geometry turbine has been compared to a similar, not hybridized, system over step changes of engine load. The variable geometry turbine has been controlled to provide different levels of initial boost, including one optimized for efficiency, and to change its flow capacity during the transient. The engine modeled is a 7-litre, 6-cylindres diesel engine with a power output of over 200 kW and a sub-10 kW turbocharger electric assistance power. To improve the accuracy of the model, the turbocharger turbine has been experimentally characterized by means of a unique testing facility available at Imperial College and the data has been extrapolated by means of a turbine meanline model.Optimization of the engine boost to minimize pumping losses has shown a reduction in brake specific fuel consumption up to 4.2%. By applying electric turbocharger assistance, it has been possible to recover the loss in engine transient response of the efficiency optimized system, as it causes a reduction in engine speed drop of 71% to 86% and of 79% to 94% in engine speed recovery time. When electric assistance is present in the turbocharger, actuating the turbine vanes to assist transient response has not produced the desired result but only a decrement in energy efficiency. If the variable geometry turbine is opened during transients, an improvement in specific energy efficiency with negligible decrement in engine transient performances has been achieved.Copyright © 2013 by ASME