Influence of Ethanol and Cetane Number (CN) Improver on the Ignition Delay of a Direct-Injection Diesel Engine

Recent increases in petroleum fuel costs, corporate average fuel economy (CAFE) regulations, and environmental concerns about CO2 emissions from petroleum based fuels have created an increased opportunity for diesel engines and non-petroleum renewable fuels such as biodiesel. Additionally, the Environmental Protection Agencies Tier II heavy duty and light duty emissions regulations require significant reductions in NOx and diesel particulate matter emissions for diesel engines. As a result, the diesel engine and aftertreatment system is a highly calibrated system that is sensitive to fuel characteristics. This study focuses on the impact of soy methyl ester biodiesel blends on combustion performance, NOx, and carbonaceous soot matter emissions. Tests were completed using a 1.9 L, turbocharged direct injection diesel engine using commercially available 15 ppm ultra low sulfur (ULS) diesel, a soy methyl ester B20 biodiesel blend (20 vol % B100 and 80 vol % ULS diesel), and a pure soy methyl ester biodiesel. Results show a reduction in NOx and carbonaceous soot matter emissions, and an increase in brake specific fuel consumption with the use of biodiesel. Further, traditional methodology assumes that diesel fuels with a high cetane number have a reduced ignition delay. However, results from this study show the cetane number is not the only parameter effecting ignition delay due to increased diffusion burn.

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Effect of Fuel Cetane Numbers on Reducing the Ignition Delay Period and Exhaust Emissions from DI Diesel Engine

10.37394/232012.2020.15.13 ◽

2020 ◽

Vol 15 ◽

Keyword(s):

Diesel Engine ◽

Ignition Delay ◽

Direct Injection ◽

Cetane Number ◽

Injection Pressure ◽

Exhaust Emissions ◽

Combustion Efficiency ◽

Operating Conditions ◽

Engine Torque ◽

Di Diesel Engine

In this present study a theoretical investigation is used to examine the effect of different fuel cetane numbers (CNs) on reducing the ignition delay and exhaust emissions from diesel engine at certain operating conditions. The operating conditions for such diesel engine include compression ratios, engine speeds and intake pressures and temperatures. For this purpose, the fuels with 40 and 50 CN were tested in a four cycle, four cylinders direct injection (DI) diesel engine. Theoretical analyses were conducted for the standard injection pressures (150 bars); the exhaust emissions were tested at engine speeds from 4500 min-1 to 1000 min-1 at full engine load. The results showed that, at all operating conditions, the ignition delay decreases as the cetane number, compression ratio, engine speed, intake pressure and temperature are increased so that combustion efficiency is improved. Also the exhaust emissions NOX, SO2 and CO are reduced when the fuel CN is increased from 40 to 50 for the standard injection pressure (150 bars). Increases in engine torque and power output were observed when the CN is increased.

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