Influence of structure and other characteristics of substitute fuel components in petrol on engine efficiency and pollution

European Commission Directorate-General For The Information Society And Media Directorate-General For Research And Innovation

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Energy research

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• Publié par: EUROPEAN-COMMISSION-DIRECTORATE-GENERAL-FOR-THE-INFORMATION-SOCIETY-AND-MEDIA-DI
• Nombre de lectures: 12
• Langue: English
• Poids de l'ouvrage: 2 Mo

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Commission of the European Communities
energy
INFLUENCE OF STRUCTURE
AND OTHER CHARACTERISTICS
OF SUBSTITUTE FUEL COMPONENTS
IN PETROL ON ENGINE EFFICIENCY
AND POLLUTION
Report
EUR 13157 EN
Blow-up from microfiche original Commission of the European Communities
energy
INFLUENCE OF STRUCTURE
AND OTHER CHARACTERISTICS
OF SUBSTITUTE FUEL COMPONENTS
IN PETROL ON ENGINE EFFICIENCY
AND POLLUTION
S. STOURNASH, E. LOIS(1), P. POLYSSIS(1), A. SERDARI(1),
J. SWITHENBANK(2), G.H. PRIESTMAN(2), M. PAPACHRISTOS(2)
(1) Fuels and Lubricants Laboratory
National Technical University
42 Patission St.
GR­106 82 Athens
(2) Chemical Engineering and Fuel Technology
Department of Mechanical and Process Engineering
University of Sheffield, Mappin Street
UK­Sheffield S1 3JD
Contract No. EN3E­0053­GR (T. T.) and EN3E­0054­UK (H)
01.04.86­01.11.89
FINAL REPORT
Research financed
by the Commission of the European Communities within the frame
of the Non­Nuclear Energy R + D Programme
PARL. ÏV.H0?. Blblioth.
Directorate­General
Science, Research and Development N.C./CCM.SS'iXf
1991 CLEUR 13157 EN
Λ/vJVA "l· 6 £££ Published by the
COMMISSION OF THE EUROPEAN COMMUNITIES
Directorate-General
Telecommunications, Information Industries and Innovation
L-2920 LUXEMBOURG
LEGAL NOTICE
Neither the Commission of the European Communities nor any person acting on behalf
of then is responsible for the use which might be made of the following
information
Catalogue number: CD-NA-13157-EN-C
© ECSC — EEC — EAEC, Brussels - Luxembourg, 1991 III
CONTENTS
Page
1. SUMMARY 1
2. OBJECTIVES 4
3. INTRODUCTION
4. CONCLUSIONS 6
5. SYMBOLS AND DEFINITIONS 7
6. RESEARCH ACTIVITIES 8
6.1 MODEL FUEL PREPARATION
6.2 SYNTHESIS OF NOVEL FUEL COMPONENTS 9
6.3 EXPERIMENTAL PROCEDURES 19
7. RESULTS AND DISCUSSION 32
7.1 BASE FUEL BLENDING
7.2 NOVEL FUEL COMPONENTS: SYNTHETIC ASPECTS 40
7.3LL: ANTI-KNOCK PERFORMANCE AND
STRUCTURE-ACTIVITY CORRELATIONS4
7.4 EFFECTS OF ENGINE AND FUEL-SUPPLEMENT VARIABLES ON
THE EXHAUST EMISSIONS OF THE CFR ENGINE 66
7.5S OF ENGINE ANDTS ON
THE PERFORMANCE AND EXHAUST EMISSIONS OF A MULTICYLINDER
SI ENGINE 7
8. FUTURE WORK 137
9. REFERENCES9
APPENDIX : 143
APPENDIX A: COMPOSITION OF BASE FUELS 145 X B: INSTRUMENTS SPECIFICATIONS6
APPENDIX C: EXHAUST GAS ANALYSERS SPECIFICATIONS 152 X D: FORMALDEHYSE MEASUREMENT 15
APPENDIX E: MOLECULAR STRUCTURES OF HBA's7 1. SUMMARY
As set out in the timetable of the research programme, the
initial activities dealt with the preparation of base fuels and
the assessment of their behaviour in the presence of additives
and fuel extenders. After extensively testing and standardizing
the CFR engine, the first two such base fuels (BF1 and BF2) were
prepared, the former containing five hydrocarbon components and
the latter seven. Their main difference lies in the presence of
unsaturate and naphthenic components in BF2, thus making it
similar to actual petrol in composition.
This difference was confirmed in the responce patterns of
the two base fuels after blending with standard oxygenate
extenders, which showed that BF2 resembles actual petrol in being
less susceptible to octane number increase.
The pool of standardized base fuels was eventually expanded
to five, including a base fuel (BF5) that contained MTBE as a
standard component; this allowed testing for additive synergistic
effects.
These base fuels were used to rapidly screen the novel fuel
components and additives in the various stages of the programme
and thus make optimal use of the time consuming octane number
measuring procedure.
In the second stage of the programme, a number of novel
compounds were prepared and consequently tested, in various
proportions, with the base fuels. Simultaneously, commercially
available but untested chemical structures were also examined.
Our approach was to investigate various families of compounds
and examine their changes in BRON performance, by slightly
altering the basic molecule, e.g. adding or subtracting known
groups to a specified position of the structure. Such groups of
compounds included equivalent alcohols and amines in addition to
novel ethers, furans, phenols ,and formamides.
It is our belief that this approach is essential for a better
understanding of the effects on the BRON number that are caused
by various groups and their combinations on specific compounds.
Such tests were carried out in BF-1 and BF-2 base fuels, at
concentrations varying from 0.5 to 3% of novel compound.
In order to be able to evaluate the results quickly, a
relative effectiveness scale was introduced, by which all
fuels were compared to the performance of MTBE, both on a molar and on a weight basis; the effectiveness of the latter was taken
as unity. The results were encouraging, since some useful
conclusions could be drawn following this systematic approach.
It is worth noting that even a relatively early stage of the
research work, two hitherto unknown, albeit readily available,
additive structures were identified, whose relative effectiveness
in our base fuels was several times higher than that of MTBE both
on a molar and on a weight basis.
The focus of the investigation continued to be placed upon
the main families of compounds that were originally identified as
promising regarding their potential anti-knock activity. This led
to the identification of new active structures, such as furfuryl
alcohol. In addition, some of the basic findings of previous
reports, such as the pro-knock activity of tertiary nitrogens and
the C-0-CH2-C group, were further verified; however, other
assumptions (such as the higher activity of amines versus
alcohols) were found not to be as universally applicable as
originally assumed.
The investigation also turned to the following new families
of potential anti-knock fuel components:
1. The terpenic derivatives, which were a priori interesting
because of their non-petroleum origin and renewable nature.
2. Materials which can be termed as "super MTBE's", and
consist of highly substituted ethers that have been constructed
according to the molecular guidelines that had been identified
during the course of the research work already carried out.
3. A new class of fuel additives, which approach the
activity of lead alkyls in suppressing engine knock, even though
they contain no metal and are fully organic in their molecular
structure. Blending octane numbers in excess of 1000 were
encountered in two separate occasions; to our knowledge, this Is
the first time that such high BRON values have been reported for
non-metallic, organic anti-knock additives. Of course, these
materials cannot as yet be considered as viable candidates for
additives in petrol, inasmuch as they suffer from two serious
drawbacks, viz. low solubility in hydrocarbons and rather high
instability towards atmospheric oxygen. However, their very high
activity brings fresh hope to the possibility of finding non-
metallic organic antiknock additives that combine high
effectiveness with acceptable solubility and stability. 4. The Mannich base phenols, whose BRON values are not as
high as those of the ylide structures of the previous paragraph,
but which also do not share in the drawbacks of the latter such
as instability and low solubility; their other important
advantage is their relatively easy accessibility in high yield
from readily available and rather low cost starting materials.
Over twenty of these compounds were prepared and tested; the
results that have been obtained allow interesting observations to
be made about structure-activity correlations and point to the
importance of even minor molecular modifications on final
performance.
Another class of materials, the tertiary polyamines, display
very high pro-knock behaviour and thus offer insight to new
structures of additives that could prove very efficient as
ignition improvers in diesel fuels; a more detailed investigation
of these materials, however, lies beyond the scope of this work.
Finally, the CFR engine was used to effect the measurement
of exhaust emissions under variable compression ratios; the
results confirmed the importance of maintaining adequate ignition
quality in petrol not only for engine efficiency purposes but
also in order to avoid incresed emissions and in particular
unburnt hydrocarbons.
The use of a variety of the above materials at the
multicylinder SI engine test rig at Sheffield University pointed
to the possibility of achieving fuel economy and lower exhaust
emissions by judicious choice of the appropriate fuel extenders. 2. OBJECTIVES
The main objectives of this work have been:
1. To develop model fuels that would ensure rational and
reproducible testing operations.
2. To use the CFR engine as the initial screening tool for
improved engine efficiency and pollution abatement.
3. To proceed in a rational