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Research Papers: Internal Combustion Engines

# Hydrogen-Enhanced Gasoline Stratified Combustion in SI-DI Engines

[+] Author and Article Information
Enrico Conte

Aerothermochemistry and Combustion Systems Laboratory, ETH, Zurich 8092, Switzerlandenrico.conte@alumni.ethz.ch

Konstantinos Boulouchos

Aerothermochemistry and Combustion Systems Laboratory, ETH, Zurich 8092, Switzerland

J. Eng. Gas Turbines Power 130(2), 022801 (Jan 22, 2008) (9 pages) doi:10.1115/1.2795764 History: Received May 18, 2006; Revised September 10, 2007; Published January 22, 2008

## Abstract

Experimental investigations were carried out to assess the use of hydrogen in a gasoline direct injection (GDI) engine. Injection of small amounts of hydrogen (up to 27% on energy basis) in the intake port creates a reactive homogeneous background for the direct injection of gasoline in the cylinder. In this way, it is possible to operate the engine with high exhaust gas recirculation (EGR) rates and, in certain conditions, to delay the ignition timing as compared to standard GDI operation, in order to reduce NOx and HC emissions to very low levels and possibly soot emissions. The results confirmed that high EGR rates can be achieved and NOx and HC emissions reduced, showed significant advantage in terms of combustion efficiency and gave unexpected results relative to the delaying of ignition, which only partly confirmed the expected behavior. A realistic application would make use of hydrogen-containing reformer gas produced on board the vehicle, but safety restrictions did not allow using carbon monoxide in the test facility. Thus, pure hydrogen was used for a best-case investigation. The expected difference in the use of the two gases is briefly discussed.

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## Figures

Figure 11

Heat release rate for stratified operation, without EGR. For comparison, also the heat release rate at homogeneous operation is plotted

Figure 9

NOx–HC trade-off for some combinations of hydrogen enrichment and EGR rates

Figure 8

NOx–COV trade-off for some combinations of hydrogen enrichment and EGR rates

Figure 7

Comparison of NOx emission for different EGR rates and hydrogen enrichment degrees

Figure 6

NOx emissions versus engine stability (COVIMEP) at 3bar IMEP, without EGR

Figure 5

NOx versus HC emissions at 3bar IMEP, without EGR

Figure 3

Qualitative evolution of the mixture stoichiometry with time at the location of the ignition source, for gasoline and hydrogen additions, at low load

Figure 2

IMEP and COVIMEP versus ignition timing at gasoline operation, 17% and 27% hydrogen enrichments, without EGR

Figure 1

Figure 21

Heat release rate at 5bar IMEP, without EGR

Figure 20

Indicated efficiency versus NOx emissions, for increasing hydrogen enrichment degree. 5bar IMEP, without EGR

Figure 19

Figure 18

Figure 17

NOx and HC emissions, 5bar IMEP, without EGR

Figure 16

Qualitative evolution of the mixture stoichiometry with time at the location of the ignition source, for gasoline and hydrogen additions, at high load

Figure 15

IMEP and COV versus ignition timing at gasoline operation, 17 and 27% hydrogen additions, without EGR, 5bar IMEP

Figure 14

Duration of the 50–90% combustion phase at different degrees of hydrogen enrichment, without EGR

Figure 13

Duration of the 5–50% combustion phase at different degrees of hydrogen enrichment, without EGR

Figure 12

Duration of the 0–5% combustion phase at different degrees of hydrogen enrichment, without EGR

Figure 10

Trade-off between indicated efficiency and NOx for some combinations of hydrogen enrichment and EGR rates

Figure 4

NOx and HC emissions versus ignition timing at 3bar IMEP, without EGR

## Errata

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