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Research Papers: Gas Turbines: Combustion, Fuels, and Emissions

# Impact of Very High Injection Pressure on Soot Emissions of Medium Speed Large Diesel Engines

[+] Author and Article Information
Michael Engelmayer

LEC—Large Engines Competence Center,
Graz University of Technology,
Graz 8010, Austria
e-mail: engelmayer@ivt.tugraz.at

Andreas Wimmer

LEC—Large Engines Competence Center,
Graz University of Technology,
Graz 8010, Austria
e-mail: wimmer@ivt.tugraz.at

Gert Taucher

LEC—Large Engines Competence Center,
Graz University of Technology,
Graz 8010, Austria
e-mail: taucher@ivt.tugraz.at

Gernot Hirschl

Virtual Vehicle Research Center,
Graz 8010, Austria
e-mail: gernot.hirschl@v2c2.at

Thomas Kammerdiener

AVL List GmbH,
Graz 8020, Austria
e-mail: thomas.kammerdiener@avl.com

1Corresponding author.

Contributed by the Combustion and Fuels Committee of ASME for publication in the JOURNAL OF ENGINEERING FOR GAS TURBINES AND POWER. Manuscript received March 2, 2015; final manuscript received March 6, 2015; published online April 8, 2015. Editor: David Wisler.

J. Eng. Gas Turbines Power 137(10), 101509 (Oct 01, 2015) (6 pages) Paper No: GTP-15-1072; doi: 10.1115/1.4030096 History: Received March 02, 2015; Revised March 06, 2015; Online April 08, 2015

## Abstract

Measures exist to adjust tailpipe NOx emissions to assigned values, for example cooled exhaust gas recirculation (EGR) or a selective catalytic reduction (SCR) catalyst in conjunction with urea. The situation is quite different with soot when use of a trap is not feasible for reasons of cost, space requirements and maintenance. Due to the highly complex soot formation and oxidation process, soot emissions cannot be targeted as easily as NOx. So, how can soot be kept within the limits? In principle, soot can be controlled by allocating sufficient oxygen and establishing good mixing conditions with vaporized fuel. The most effective measures target the injection system, e.g., increasing injection pressure, applying multiple injections, optimizing nozzle geometry. To investigate the impact of very high injection pressure on soot, an advanced injection system with rail pressure capability up to 3000 bar and a Bosch injector was installed at the Large Engines Competence Center (LEC) in Graz. Full load and part load operating points at constant speed and in accordance with the propeller law were investigated at the test bed to quantify the impact of high injection pressure on soot emissions. Test runs were conducted with both SCR and EGR while varying injection timing and air–fuel ratios. Use of a statistical method, design of experiments (DOE), helped reduce the number of tests. Optical investigations of the spray and combustion were conducted. The goal was to obtain soot concentration history traces with the two color method in order to better understand how soot originates and to be able to calibrate 3D CFD (computational fluid dynamics) FIRE spray models for use with injection pressures of up to 3000 bar. Very low soot emissions can be achieved using high pressure injection, even when EGR is applied. DOE results provide a clear picture of the relationships between the parameters and can be used to optimize set values for the whole speed and load range. A reliable spray break up model can be used in further 3D CFD simulation to investigate how to reduce soot emissions.

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## Figures

Fig. 1

High pressure generation FIE3000

Fig. 2

Engine with optical access

Fig. 3

Rail pressure variation at two injection timings, IMEP = 25 bar, speed = 1000 rev/min, and NOx = 1.5 g/kWh

Fig. 4

ROHR at two injection timings and different rail pressure levels, IMEP = 25 bar, and speed = 1000 rev/min

Fig. 5

Rail pressure variation at two air–fuel ratios, IMEP = 25 bar, speed = 1000 rev/min, and NOx = 1.5 g/kWh

Fig. 6

ROHR at two injection timings and two air–fuel ratios, IMEP = 25 bar, and speed = 1000 rev/min

Fig. 7

Rail pressure variation at two injection timings, IMEP = 12 bar, speed = 888 rev/min, and NOx = 1.5 g/kWh

Fig. 8

ROHR at two injection timings and different rail pressure levels, IMEP = 12 bar, and speed = 888 rev/min

Fig. 9

Rail pressure variation at two air–fuel ratios, IMEP = 12 bar, speed = 888 rev/min, and NOx = 1.5 g/kWh

Fig. 10

Measurement versus prediction, IMEP = 25 bar, speed = 1000 rev/min, rail pressure 1800 to 2800 bar, air–fuel ratio 23 to 30, SOI −15 deg to −5 deg ATC, and NOx = 1.5 g/kWh

Fig. 11

Measurement versus prediction, IMEP = 5 to 25 bar, const. speed = 1000 rev/min, rail pressure 1400 to 2600 bar, air–fuel ratio 28 to 50, and SOI −15 deg to 5 deg ATC

Fig. 12

Measurement versus prediction, IMEP = 10 to 25 bar, speed = 630 to 1000 rev/min, rail pressure 1400 to 2600 bar, air–fuel ratio 24 to 32, and SOI −15 deg to 5 deg ATC

Fig. 13

Spray penetration length at rail pressure 2000 bar

Fig. 14

Injection spray, experiment versus simulation

Fig. 15

ROHR and cylinder pressure at two rail pressure levels IMEP = 25 bar, and speed = 1000 rev/min

Fig. 16

NOx and soot emissions, rail pressure variation, IMEP = 25 bar, and speed = 1000 rev/min

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