Autoignition Characteristics of JP8, ULSD, Synthetic and Biodiesel Fuels, including during Cold Start

Work performed in several connected projects are collected in this entry, beginning from 2008 and completed by 2012.

Our goal is to improve survivability and mobility of military vehicles by prompt and reliable engine start using different fuels, without the emission of white smoke, under low ambient temperatures in the field. The objectives include:

• Determine the autoignition characteristics of JP8, Biodiesel and ULSD fuels, as measured by the length of the ignition delay (ID) under different operating conditions.
• Develop a correlation between the ID, charge temperature, charge pressure and the global activation energy for the autoignition reactions of each fuel.
• Compare the combustion characteristics of the three fuels and their impact on engine power output and the emissions, particularly the white smoke during cold start.
• Develop fuel delivery strategies to reduce the cranking period, combustion instability and white smoke emitted during the cold start of the engine at normal and lower ambient temperatures.

The autoignition process and its length have a direct impact on the combustion process and resulting torque, peak pressure, cycle temperature, thermal efficiency and fuel economy. Military engines are required to operate on JP8 that has a wide range of ignition qualities (Cetane Numbers) while commercial diesel fuel that has narrower specifications. The use of JP-8 of low CN close to 30 has been found to cause serious engine problems. In addition military ground vehicles may need to operate on synthetic fuels and renewable fuels or their mixtures with JP-8, with no data on the ignition delay of these fuels. This work is also motivated by the need to reduce cold start problems such as failure of starting, hesitation and emission of white smoke in engines when alternative fuels, such as JP8, with the wide range of CN, and biodiesel, are used.

Our approach includes using CFD diesel cycle simulation and experimental investigations conducted under controlled conditions on commercial truck engines. The goal is to determine autoignition characteristics of fuels, as measured by the length of the ignition delay (ID) under different operating conditions, and find correlation between the ID, charge temperature, charge pressure and the global activation energy for the autoignition reactions of each fuel. Then determine effects on engine power output and emissions, particularly white smoke during cold start.

The database for the autoignition and combustion characteristics of alternative fuels, JP8 and biodiesel produced from this program enables ARMY scientists and engineers to develop strategies to control diesel engines to achieve prompt starting without hesitation using fuels of different properties. The same codes can be used by industry to reduce the unburned fuel and partial or military and commercial diesel oxidation products characteristic to diesel engine exhaust during starting in low ambient temperature environment.

Publications:

• Kaushik Acharya, Mufaddel Dahodwala, Walter Bryzik, Naeim A. Henein and Nathan Sova, “Effect of different Biodiesel blends on Auto ignition, Combustion, Performance and Engine-Out Emissions in a single cylinder HSDI Diesel Engine,” SAE Technical Paper No. 2009-01-0489, 2009.
• Vinay Nagaraju, Mufaddel Dahodwala, Kaushik Acharya, Walter Bryzik, and Naeim A. Henein, “Effect of Swirl Ratio and Injection Pressure on Autoignition, Combustion and Emissions in a High Speed Direct Injection Diesel Engine Fueled with Biodiesel (B-20),” presented at Proceedings of the ASME Internal Combustion Engine Division 2009 Spring Technical Conference ICES2009.
• Jagdish Nargunde, Chandrasekharan Jayakumar, Anubhav Sinha, Walter Bryzik, Naeim Henein, Kaushik Acharya, “Comparison between autoignition, Combustion and Emissions between JP-8 and Ultra Low Sulphur Diesel in a Single Cylinder Diesel Engine” SAE 2010-01-1123,  SP-2289, 2010. doi:10.4271/2010-01-1123
• Sinha, A., Jayakumar, C., Nargunde, J., Acharya, K., Bryzik, W. and Henein, N. A., “Effect of Biodiesel and its Blends on Particulate Emissions from HSDI Diesel Engine,” SAE 2010 World Congress, paper No 2010-01-0789, SP-2289, 2010. doi:10.4271/2010-01-0789
• Jayakumar, C, Nargunde, J., A Sinha, A., Bryzik, W. and Henein, N. A. and Sattler, E.,”Effect of Biodiesel, JP8, and ULSD fuel on autoignition, combustion, performance and emissions in a Single-cylinder Diesel Engine,” ASME ICEF2010-35060 pp. 149-162. doi:10.1115/ICEF2010-35060
• Nargunde, J., Jayakumar, C, A Sinha, A., Bryzik, W. and Henein, N. A. and Sattler, E.,”Effect of Swirl and Injection Pressure on Performance and Emissions of JP-8 Fueled High Speed Single-Cylinder Diesel engine,” ASME ICEF2010-35073 pp. 163-173. doi:10.1115/ICEF2010-35073
• Jayakomer, C, Zheng, Z., Joshi, U., Bryzik, W., Henein, N. and Sattler, E., ”Effect of Inlet Air Temperature on Auto-ignition of Fuels with Different CN and Volatility”, Proceedings ASME ICEF2011-60141, pp. 261-272, 2011. doi:10.1115/ICEF2011-60141
• Jayakomer, C., Zheng, Z., Joshi, U., Bryzik, W., Henein, N. and Sattler, E., “Effect of Intake Pressure and Injection Strategy on the Auto-Ignition of Fuels with Different CN and Volatility,” SAE 2012-01-1317. doi:10.4271/2012-01-1317