Computational Analysis of Different EGR systems Combined with Miller Cycle Concept for a Medium Speed Marine Diesel Engine
In this work different EGR systems, combined with extreme Miller cycles, were analyzed by means of a one dimensional CFD simulation code for a W(a)rtsil(a) 6 cylinder, 4 strokes, medium speed marine diesel engine, to evaluate their potential in order to reach the IMO Tier 3 NOx emissions target. Extreme Miller cycles, with Early Intake Valve Closures (up to 100 crank angle degrees before BDC), combined with two stage turbocharging were firstly evaluated and the best solution in order to reduce NOx emissions without excessive penalties in terms of fuel consumption was found to be the adoption of a 90 CA deg EIVC, coupled with a symmetric overlap of 30 CA deg, which allowed a 35% NOx abatement with BSFC values comparable with the reference solution. Afterwards, four different external EGR architectures were evaluated for the assessment of their NOx emissions abatement potentialities. Although all the tested external EGR systems were capable to reduce NOx emissions down to approximately 20% of the reference engine when using the highest EGR rate (20%), the use of an EGR turbocharger (i.e. of an additional small turbocharger used to pump the EGR flow between the exhaust and the intake manifold), allowed maintaining components thermal loads under control, with still acceptable fuel consumption penalties (about 4%). In conclusion, the achievement of IMO Tier 3 NOx emissions levels was proved to be feasible, although further experimental investigation will be needed to confirm the numerical simulation results.
Federico Millo Marco Gianoglio Bernardi Emanuele Servetto Diego Delneri
Politecnico di Torino,Italy W(a)rtsil(a),Finland
国际会议
上海
英文
1-14
2013-05-13（万方平台首次上网日期，不代表论文的发表时间）