Diesel Cold Start Emission Control Research for 2015-2025 LEV III Emissions, 03-R8299
Principal Investigators
Gary D. Neely
Jayant Sarlashkar
Darius Mehta
Inclusive Dates: 04/01/12 – Current
Background — The diesel engine can be an effective solution to help vehicle manufacturers meet the impending 2017-2025 U.S. EPA and National Highway Traffic Safety Administration greenhouse gas and fuel economy standards, especially for larger segment vehicles. However, meeting the very stringent 2025 LEV III emissions standards poses a significant challenge for the diesel due to the difficulty in obtaining rapid emissions control with aftertreatment following a cold-start.
Approach — The goal of this project is to develop and evaluate a novel diesel cold-start emissions control strategy. The strategy combines several engine tuning and aftertreatment technologies to simultaneously reduce NOx and hydrocarbons (HC) during the first hill of the FTP75. An illustration of the various technologies under investigation is shown below.
Accomplishments —
- Moderate intake throttling can be used to increase exhaust gas temperature without increasing HC emissions. Test data obtained at 1,200 rpm and 1.7 bar BMEP demonstrated a 50°C increase in turbine-out temperature for only a 5-percent increase in engine-out HC emissions.
- High-temperature glow plugs with improved temperature control can provide significant HC reductions. Engine-out HC emissions were reduced by more than 50 percent from the stock glow plugs during both steady-state and transient tests with glow plug temperatures at or above 1,200°C.
- Proper tuning of the multiple injection parameters can result in an improved trade-off between exhaust gas temperature and engine-out HC emissions.
- The use of high EGR idle during the idle period between the first and second hills of the FTP75 was shown to result in a 30°C higher close-coupled catalyst temperature with a negligible HC emission increase after the DPF.
- A low HC calibration map was made that combined the above engine tuning technologies, which resulted in an additional 20 percent reduction in HC emissions and a higher closed-coupled catalyst temperature history. However, the new calibration map has higher NOx, so future testing with a close-coupled LNT must be conducted to determine the acceptable level of engine-out NOx.
