This content is not included in
your SAE MOBILUS subscription, or you are not logged in.
Impact of Miller Cycle Strategies on Combustion Characteristics, Emissions and Efficiency in Heavy-Duty Diesel Engines
Technical Paper
2020-01-1127
ISSN: 0148-7191, e-ISSN: 2688-3627
This content contains downloadable datasets
Annotation ability available
Sector:
Language:
English
Abstract
This study experimentally investigates the impact of Miller cycle strategies on the combustion process, emissions, and thermal efficiency in heavy-duty diesel engines. The experiments were conducted at constant engine speed, load, and engine-out NOx (1160 rev/min, 1.76 MPa net IMEP, 4.5 g/kWh) on a single cylinder research engine equipped with a fully-flexible hydraulic valve train system. Early Intake Valve Closing (EIVC) and Late Intake Valve Closing (LIVC) timing strategies were compared to a conventional intake valve profile. While the decrease in effective compression ratio associated with the use of Miller valve profiles was symmetric around bottom dead center, the decrease in volumetric efficiency (VE) was not. EIVC profiles were more effective at reducing VE than LIVC profiles. Despite this difference, EIVC and LIVC profiles with comparable VE decrease resulted in similar changes in combustion and emissions characteristics. Miller cycle operation at constant intake pressure resulted in lower peak cylinder pressures, higher exhaust temperatures and lower EGR requirements compared to the baseline case, albeit with a significant fuel consumption penalty. Increasing intake manifold pressure to match the baseline lambda overcame the fuel consumption penalty, without compromising NOx emissions. As Miller cycle implementation was shown to affect overall turbocharger efficiency (nTC), select EIVC/LIVC profiles were compared to the baseline condition at three different overall turbocharger efficiencies. At the baseline ηTC, Miller cycle profiles reduced peak cylinder pressures and increased exhaust temperatures with minimal BSFC and particulate matter (PM) emission penalties. At high overall turbocharger efficiencies, using Miller cycle offered reduced peak cylinder pressures and elevated exhaust temperatures over conventional intake valve profiles, without compromising BSFC, NOx or PM emissions.
Recommended Content
Authors
Topic
Citation
Garcia, E., Triantopoulos, V., Boehman, A., Taylor, M. et al., "Impact of Miller Cycle Strategies on Combustion Characteristics, Emissions and Efficiency in Heavy-Duty Diesel Engines," SAE Technical Paper 2020-01-1127, 2020, https://doi.org/10.4271/2020-01-1127.Data Sets - Support Documents
Title | Description | Download |
---|---|---|
Unnamed Dataset 1 | ||
Unnamed Dataset 2 |
Also In
References
- NHTSA August 2016
- Uchihara , K. , Ishii , M. , Nakajima , H. , and Wakisaka , Y. A Study on Reducing Cooling Loss in a Partially Insulated Piston for Diesel Engine SAE Technical Paper 2018-01-1276 2018 https://doi.org/10.4271/2018-01-1276
- Borgnakke , C. and Sonntag , R.E. Fundamentals of Thermodynamics Vol. 8 New York Wiley 2012
- Wang , Y. , Zeng , S. , Huang , J. , He , Y. et al. Experimental Investigation of Applying Miller Cycle to Reduce NO x Emission from Diesel Engine Proceedings of the Institution of Mechanical Engineers, Part A: Journal of Power and Energy 219 8 631 638 2005 https://doi.org/10.1243/095765005X31289
- Benajes , J. , Molina , S. , Martín , J. , and Novella , R. Effect of Advancing the Closing Angle of the Intake Valves on Diffusion- Controlled Combustion in a HD Diesel Engine Applied Thermal Engineering 29 p1947 p1954 2009 https://doi.org/10.1016/j.applthermaleng.2008.09.014
- De Ojeda , W. Effect of Variable Valve Timing on Diesel Combustion Characteristics SAE Technical Paper 2010-01-1124 2010 https://doi.org/10.4271/2010-01-1124
- Ehleskog , M. , Gjirja , S. , and Denbratt , I. Effects of Variable Inlet Valve Timing and Swirl Ratio on Combustion and Emissions in a Heavy Duty Diesel Engine SAE Technical Paper 2012-01-1719 2012 https://doi.org/10.4271/2012-01-1719
- Brückner , C. , Kyrtatos , P. , and Boulouchos , K. Extending the NO x Reduction Potential with Miller Valve Timing Using Pilot Fuel Injection on a Heavy-Duty Diesel Engine SAE Int. J. Engines 7 4 1838 1850 2014 https://doi.org/10.4271/2014-01-2632
- Zhao , C. , Yu , G. , Yang , J. , Bai , M. et al. Achievement of Diesel Low Temperature Combustion through Higher Boost and EGR Control Coupled with Miller Cycle SAE Technical Paper 2015-01-0383 2015 https://doi.org/10.4271/2015-01-0383
- Kovács , D. and Eilts , P. Potentials of the Miller Cycle on HD Diesel Engines Regarding Performance Increase and Reduction of Emissions SAE Technical Paper 2015-24-2440 2015 https://doi.org/10.4271/2015-24-2440
- Hoag , K. An Exploratory Look at an Aggressive Miller Cycle for High BMEP Heavy-Duty Diesel Engines SAE Technical Paper 2019-01-0231 2019 https://doi.org/10.4271/2019-01-0231
- Vos , K.R. , Shaver , G.M. , Lu , X. , Allen , C.M. et al. Improving Diesel Engine Efficiency at High Speeds and Loads through Improved Breathing Via Delayed Intake Valve Closure Timing International Journal of Engine Research 20 2 194 202 2019 https://doi.org/10.1177/1468087417743157
- Guan , W. , Pedrozo , V. , Zhao , H. , Ban , Z. et al. Exploring the NO x Reduction Potential of Miller Cycle and EGR on a HD Diesel Engine Operating at Full Load SAE Technical Paper 2018-01-0243 2018 https://doi.org/10.4271/2018-01-0243
- Heywood , J. Internal Combustion Engine Fundamentals New York McGraw-Hill 1988