A Study on the Effect of Valve Timing on the Combustion and Emission Characteristics for a 4-cylinder PCCI Diesel Engine

PCCI engines can reduce NOx and PM emissions simultaneously without sacrificing thermal efficiency, but a low combustion temperature resulting from early fuel injection, and ignition occurring prior to TDC, can cause higher THC and CO emissions and fuel consumption. In conclusion, it was found that the PCCI combustion achieved by the 2-stage injection strategy with optimized calibration factors (e.g. EGR rate, injection pressure, swirl ratio, intake pressure, injection timing) can reduce NOx and PM emissions simultaneously. This research works are expected to provide valuable information conducive to a development of an innovative combustion engine that can fulfill upcoming stringent emission standards.

Authors:

• Joonsup Han
• Jaehyeon Lee
• Hyungmin Kim
• Kihyung Lee

Keywords:

• Atkinson cycle
• Diesel Engine
• LIVC (Late intakevalve closing)
• PCCI (premixed charge compression ignition)

References:

[1] Bression, G., Soleri, D., Savy, S., Dehoux, S., Azoulay, D., Hamouda, H.,
Doradoux, L., Guerrassi, N., Lawrence, N., "A study of methods to lower
HC and CO emissions in diesel HCCI", SAE 2008-01-0034, 2008.
[2] Ryu, J. D., Kim, H. M., Lee, K. H., Cho, H. M., "A study on the spray
structure and evaporation characteristic of common rail type high pressure
injector in homogeneous charge compression ignition engine", The 9th
Annual Conference ILASS-Asia, 2004.
[3] Yun, H., Sellnau, M., Milovanovic, N., and Zyekch, S., "Development of
Premixed Low-Temperature Diesel Combustion in a HSDI Diesel
Engine", SAE 2008-01-0639, 2008.
[4] Silvis, W. M., "An Algorithm for Calculating the Air/Fuel Ratio from
Exhaust Emissions", SAE 970514, 1997.
[5] Chung, J. W., Kang, J. H., Kim, N. H., Kang, W., Kim, B. S., "Effects of
the Fuel Injection Ratio on the Emission and Combustion Performances of
the partially Premixed Charge Compression Ignition Combustion Engine
Applied with the Split Injection Method", International Journal of
Automotive Technology Vol. 9, NO. 1, 1-8, 2008.
[6] Ricardo. Co., "Engine Test Manual-Mass Emissions", 2000.
[7] Christensen, M., Johansson, B., "Supercharged Homogeneous Charge
Compression Ignition (HCCI) with Exhaust Gas Recirculation and Pilot
Fuel", SAE 2000-01-1835, 2000.
[8] Jeong, D. B., Bang, J. H., Min, K. D., "A Study on the Optimization of
Operating Variables in a Diesel Engine by Design Of Experiments",
Spring Conference of KSAE Vol. 1, 2008.
[9] Kim, H. M., Kim, K. B., Lee, K. H., Ikeda, Y., "A Study on the
Optimization of Operating Conditions for Simultaneous Reduction in
NOx and PM in a 4-cylinder Premixed Diesel Engine", SAE
2009-01-0926, 2009.
[10] Murata, Y., Kusaka, J., Odaka, M., Daisho, Y., Kawano, D., Suzuki, H.,
Ishii, Y. Goto, "Achievement of Medium Engine Speed and Load
Premixed Diesel Combustion with Variable Valve Timing", SAE
2006-01-0203, 2006.
[11] Gothekar, S. A., Vora, K. C., Mutha, G. R., Walke, N. H., and Marathe, H.
V., "Design of Experiments: A Systems Approach to Engine Optimization
for Lower Emissions", SAE 2007-26-012, 2007.
[12] Park, S. W., Bang, S. H., Lee, K. H., Lee, C. S. and Lee, J. H.,
"Atomization Characteristics of Common-rail Diesel Injector with
Multi-Hole", SAE paper 2003-01-1833, 2003.