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  WP5 Single Cylinder Engine Testing

Activities in WP 5 concentrated on investigating the potential of improvements for engine attributes like performance and emissions by testing BtL fuels and appropriate blends. The Diesel engines used for these investigations represented the most advanced engine technology to meet future legal emission limits, fuel consumption savings and power output expectations. In order to derive the optimum fuel out of a number of fuels to be tested it was planned to use single cylinder (SC) engines for these tests since due to a higher flexibility they are much easier to handle than full size engines. However, the outcome of the SC engine investigations have been demonstrated on multicylinder engines afterwards.

Achievements:

  • 13 fuels of the 2 fuel matrixes have been tested and evaluated
    - Reference fuel
    - 8 BtL-Like compounds
    - 4 XtL blends
  • Based upon the results of the screening tests 6 XtL blends were defined
  • Single cylinder tests in WP 5 with diesel blends were performed according to plan. Due to the delay in BtL supply, the material compatibility tests and single cylinder testing with naphtha blends have been postponed.
  • Based upon the results 3 Diesel fuel blends were defined for WP6 full engine tests

D.5.1 - Screening fuel matrix and orientations for the formulation of the optimized blends

D.5.2 - First appraisal of the impact of fuel characteristics on the performance and the emissions of advanced single cylinder Diesel research engine - Test and Synthesis Report

D.5.4/D5.5. - Assessment of single Cylinder advanced Diesel engine tests- Experimental Report and determination of fuels to be tested in full engine


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Based on the literature study and IFP Energies nouvelles expertise, the components n-alkanes, iso-alkanes and naphthenes, each with a high and a low boiling range, were selected as blend components for the first screening tests at IFP Energies nouvelles.

Single cylinder engine tests of 8 test fuels (20%...40% admixture) and 1 reference fuel were performed and 4 additional blends are planned to be evaluated. The screening tests showed that CN and distillation range have little effect on engine performance in the respective investigated range. The results showed that the chemical composition, in particular low aromatic content and a high content on n- alkanes and iso-alkanes seem to reduce smoke emissions.

  • Full load:  Improvement in max. power achieved (+1.5%) with low aromatic fuels with high CN
  • Mid load: Influence of CN and boiling range on combustion. These parameters and the aromatic content impact smoke emissions. After optimization, similar engine outputs are obtained with a reduction of ISFC (2.5% @ 11bar up to 8% @ 6bar) for low aromatic fuels
  • Light load: CN and boiling range modify the combustion processes but similar engine outputs are achieved once settings optimized

Single cylinder testing with most promising fuel blends have started at Ford and VW.



Single Cylinder tests for conventional diesel engine operation

Based upon the IFP Energies nouvelle results the WP4 / WP5 partners defined the fuel matrix for the single cylinder tests with conventional diesel combustion to be conducted at VW and Ford. The fuel matrix includes 2 reference fuels (CEC and WWFC4) and 6 fuel blends containing of 20%-40% Btl-like components. The BtL components were replaced by XtL components delivered by a third party fuel blender.


Single Cylinder tests for HCCI engine operation

In addition to the investigations based on conventional diesel combustion the objective of WP 5.3 was the assessment of BtL-blend fuel composition for HCCI engine operating mode. The agreed fuel matrix includes 1 reference fuel and 4 naphtha blends containing of 20%-40% BtL-like components. Due to lack of BtL, XtL components delivered by a third party fuel blender were used for blending.

Due to lower content of aromatic hydro carbons the blends show lower soot emissions in comparison with the CEC fuel. The naphtha blends with admixture of low boiling kerosene show the highest potential for reducing soot emissions. Tests indicate a similar trend for CO emissions during HCCI operation. CO emissions decrease with decreasing boiling characteristic. The 20% XtL kerosene blend exhibits for HCCI operation lowest CO emission. Due to lower ignitibility of the test fuels all naphtha blends show higher HC and NOx emissions than the CEC reference fuel, especially for the 20% blends.  In regard to the efficiency of combustion no significant differences between the fuels were observed. CO2 emissions and volumetric fuel consumption are mainly driven by fuel - density and- lower heating value.

Oil dilution

The defined test matrix fuels contain a high rate of paraffinic fuels from a Fischer- Tropsch process. Thus, an experimental
study was performed by IFP Energies nouvelles focused on effects of paraffinic fuels on the engine durability.

The main objective of this study was the evaluation of the impact of "BtL-like" blends on the oil dilution in a multi-cylinder Diesel engine via a radionuclide technique enabling on-line measurements. The 2 test fuels were EN590 Diesel fuel and a 60/40 blend of a EN590 diesel and a Fischer-Tropsch fuel in a high boiling distillation range similar to the EN590 diesel fuel.


The obtained results show that the 60/40 XtL fuel blend with similar boiling range as standard diesel fuel tested in this study, does not have any detrimental impact regarding engine oil dilution compared to the standard diesel fuel.