The physical origin of injector coking in diesel engines has been clarified and the most critical design parameters and operating variables pertaining to the occurrence of the phenomenon have been identified. Fouling has been shown to be affected by many factors, such as injector temperature, nozzle configuration, hole diameter and conicity as well as fuel composition. Optical and scanning electron microscope (SEM) analyses have been conducted both inside and outside injectors of different type and four locations have been identified as the main deposition sites. Furthermore, different coking typologies, i.e., dry and wet coking, have been assessed and discussed. Energy Dispersive X-ray (EDX) spectroscopy images of the deposits on the spray hole walls have revealed that minute quantities of Zn catalyze the coking reactions to a great extent. Significant quantities of Zn have also been found in the injector deposits. An extensive experimental test campaign has been carried out at the engine test bench with different nozzle setups in order to evaluate performance deterioration after different ageing procedures. The effects of both the Zn concentration in the fuel and running time have been assessed separately on the fouling rate. Injection rate time histories have been acquired at the hydraulic test rig, under different working conditions, for both new and aged injectors. The experimental changes in the EVI profiles subsequent to fouling have been analyzed and related to the corresponding variations in engine power measured at the engine test bench. A previously developed combustion multi-zone diagnostic model has also been applied to gain a further insight into the cause and effect relationships between the experimental in-cylinder pressure time histories and engine-out emissions.

References

References
1.
Pundir
,
B. P.
,
Singal
,
S. K.
, and
Gondal
,
A. K.
, 1994, “
Diesel Fuel Quality. Engine Performance and Emissions
,” SAE Paper No. 942020.
2.
Watkinson
,
A. P.
, 1988, “
Critical Review of Organic Fluid Fouling
,” Argonne National Laboratory Report No. ANL/ CNSV-TM-208.
3.
Wooten
,
D.
,
Stehouwer
,
D. M.
,
Fang
,
H. L.
, and
Martin
,
H.
, 2003, “
Interaction between Fuel Additive and Oil Contaminant: (I) Field Experiences
,” SAE Paper No. 2003-01-3139.
4.
Fang
,
H. L.
,
Stehouwer
,
D. M.
, and
Wang
,
J. C.
, 2003, “
Interaction Between Fuel Additive and Oil Contaminant: (II) Its Impact on Fuel Stability and Filter Plugging Mechanism
,” SAE Paper No. 2003-01-3140.
5.
Mikkonen
,
S.
, and
Tenhunen
,
E.
, 1987, “
Deposits in Diesel-Injection Pumps Caused by the Incompatibility of Fuel and Oil Additives
,” SAE Paper No. 872119.
6.
Caprotti
,
R.
, 1998, “
Harm Free Use of Diesel Additives
,” SAE Paper No. 982569.
7.
Caprotti
,
R.
,
Graham
,
B.
,
Ullmann
,
J.
,
Geduldig
,
M.
, and
Stutzenberger
,
H. A.
, 2008, “
Investigation on the Formation and Prevention of Internal Diesel Injector Deposits
,” SAE Paper No. 2008-01-0926.
8.
Tang
,
J.
,
Pischinger
,
S.
,
Lamping
,
M.
,
Korfer
,
T.
,
Tatur
,
M.
, and
Tomazic
,
D.
, 2009, “
Coking Phenomena in Nozzle Orifices of DI-Diesel Engines
,” SAE Paper No. 2009-01-0837.
9.
Caprotti
,
R.
,
Bhatti
,
N.
, and
Balfour
,
G.
, 2010, “
Deposit Control in Modern Diesel Fuel Injection Systems
,” SAE Paper No. 2010-01-2250.
10.
Caprotti
,
R.
,
Breakspear
,
A.
,
Graupner
,
O.
,
Klaua
,
T.
,
Schik
,
A.
, and
Rouff
,
C.
, 2005, “
Injector Deposit Test For Modern Diesel Engines
,”
Proceedings of the TAE Symposium 2005
,
Esslingen
,
Germany
.
11.
Caprotti
,
R.
,
Breakspear
,
A.
,
Graupner
,
O.
, and
Klaua
,
T.
, 2005, “
Detergency Requirements of Future Diesel Injection Systems
,” SAE Paper No. 2005-01-3901.
12.
Caprotti
,
R.
,
Leedham
,
A.
,
Graupner
,
O.
, and
Klaua
,
T.
, 2004, “
Impact of Fuel Additives on Diesel Injector Deposits
,” SAE Paper No. 2004-01-2935.
13.
Klaua
,
T.
, 2006, “
Diesel Injector Deposits Potential in Future Fueling Systems
,” SAE Paper No. 2006-01-3359.
14.
Winterbone
,
D. E.
,
Clough
,
E.
, and
Rao
,
K. K.
, 1992, “
Effect of DI-Nozzle Fouling on Fuel Spray Characteristics
,” SAE Paper No. 922232.
15.
Richards
,
P.
,
Walker
,
R. D.
, and
Williams
,
D.
, 1997, “
Fouling of Two-Stage Injectors: An Investigation into Some Causes and Effects
,” SAE Paper No. 971619.
16.
Wilson
,
S.
, 2010, “
Injector Deposits in High-Load Off-Road Applications
,”
Proceedings of the SAE FFL 220
, San Diego, October 2010.
17.
Pehan
,
S.
,
Jerman
,
M. S.
,
Kegl
,
M.
, and
Kegl
,
B.
, 2009, “
Biodiesel Influence on Tribology Characteristics of a Diesel Engine
,”
Fuel
,
88
, pp.
970
979
.
18.
Caprotti
,
M.
,
Takaharu
,
S.
, and
Masahiro
,
D.
, 2008, “
Impact of Diesel Fuel Additives on Vehicle Performance
,” SAE Paper No. 2008-01-1600.
19.
Caprotti
,
M.
,
Breakspear
,
A.
,
Graupner
,
O.
,
Klaua
,
T.
, and
Kohnen
,
O.
, 2006, “
Diesel Injector Deposits Potential in Future Fueling Systems
,” SAE Paper No. 2006-01-3359.
20.
Caprotti
,
R.
,
Breakspear
,
A.
,
Graupner
,
O.
,
Klaua
,
T.
, and
Kohnen
,
O.
, 2007, “
Beyond 2008: The Challenges for Diesel Detergency
,”
Proceedings of the TAE Symposium 2007
,
Esslingen
,
Germany
.
21.
Arters
,
D. C.
, 2009, “
Investigations into Internal Diesel Injector Deposits
,”
Proceedings of the SAE FFL 209, Diesel Deposit Worhshop, November, 2009
,
San Antonio, TX
.
22.
Argueyrolles
,
B.
,
Dehoux
,
S.
,
Gastaldi
,
P.
,
Grosjean
,
L.
,
Levy
,
F.
,
Michel
,
A.
, and
Passerel
,
D.
, 2007, “
Influence of Injector Nozzle Design and Cavitation on Coking Phenomenon
,” SAE Paper No. 2007-01-1896.
23.
Schwap
,
S. D.
,
Bennett
,
J. J.
,
Dell
,
S. J.
,
Galante
,
J. M.
,
Kuninowski
,
A. M.
, and
Miller
,
K. T.
, 2010, “
Internal Injector Deposits in High-Pressure Common Rail Diesel Engines
,” SAE Paper No. 2010-01-2242.
24.
Panesar
,
A.
,
Martens
,
A.
,
Jansen
,
L.
,
Lal
,
S.
,
Ray
,
D.
, and
Twilley
,
M.
, 2000, “
Development of a New Peugeot XU9 10 Hour Cyclic Test to Evaluate the Nozzle Coking Propensity of Diesel Fuels
,” SAE Paper No. 2000-01-1921.
25.
Quiegly
,
R.
,
Fahey
,
E.
,
Arters
,
D. C.
,
Wetzel
,
W.
, and
Ray
,
J.
, 2011, “
A Study of the Internal Injector Deposit Phenomena
,”
Proceedings of the TAE Symposium 2011
,
Esslingen
,
Germany
.
26.
Birgel
,
A.
,
Ladommatos
,
N.
,
Aleiferis
,
P.
,
Zülch
,
S.
,
Milovanovic
,
N.
,
Lafon
,
V.
,
Orlovic
,
A.
,
Lacey
,
P.
, and
Richards
,
P.
, 2008, “
Deposit Formation in the Holes of Diesel Injector Nozzles: A Critical Review
,” SAE Paper No. 2008-01-2383.
27.
Watkinson
,
A. P.
, and
Wilson
,
D. I.
, 1997, “
Chemical Reaction Fouling: A Review
,”
Exp. Therm. Fluid Sci.
,
14
, pp.
361
374
.
28.
Barbour
,
R.
,
Arters
,
D.
,
Dietz
,
J.
,
Macduff
,
J.
,
Panesar
,
A.
, and
Quigley
,
R.
, 2007, “
Diesel Detergent Additive Responses in Modern, High-Speed, Direct-Injection, Light-Duty Engines
,” SAE Paper No. 2007-01-2001.
29.
Mendoza
,
M.
,
Zhang
,
Q.
,
Hansen
,
A. C.
, and
Reid
,
J. F.
, 2001, “
Injector Nozzle Coking With Oxygenated Diesel
,” SAE Paper No. 2001-01-2016.
30.
Uitz
,
R.
,
Brewer
,
M.
, and
Williams
,
R.
, 2009, “
Impact of FAME Quality on Injector Nozzle Fouling in a CR Diesel Engine
,” SAE Paper No. 2009-01-2640.
31.
Lepperhoff
,
G.
, and
Houben
,
M.
, 1993, “
Mechanisms of Deposit Formation in Internal Combustion Engines and Heat Exchangers
,” SAE Paper No. 931032.
32.
Loest
,
O.
,
Ullmann
,
J.
, and
Winter
,
J.
, 2007, “
Investigation on the Addition of FAME to Diesel Fuels
,” DGMK Deutsche Wissenschafliche Gesellschaft fur Erdol, Erdgas und Kohle e.V., Research Report No. 639e, Germany.
33.
Stahl
,
M.
,
Damaschke
,
C.
, and
Tropea
,
C.
, 2006, “
Experimental Investigation of Turbulence and Cavitation Inside a Pressure Atomizer and Optical Characterization of the Generated Spray
,” ICLASS, Kyoto.
34.
Payri
,
F.
,
Bermudez
,
V.
,
Payri
,
R.
, and
Salvador
,
F. S.
, 2004, “
The Influence of Cavitation on the Internal Flow and Spray Characteristics in Diesel Injector Nozzles
,”
Fuel
,
83
, pp.
419
431
.
35.
Som
,
S.
, and
Longman
,
D. E.
, 2012, “
Nozzle Flow Characteristics of Alternate Fuels for HCCI Engine Applications
,”
Proceedings of the ASME Spring Technical Conference, ICES2012, May 6–9
,
Torino, Italy
.
36.
Som
,
S.
, and
Aggarwal
,
S. K.
, 2010, “
Effects of Primary Breakup Modeling on Spray and Combustion Characteristics of HCCI Engines
,”
Combust. Flame
,
157
, p.
1179
.
37.
Catania
,
A. E.
,
d’Ambrosio
,
S.
,
Finesso
,
R.
,
Spessa
,
E.
,
Cipolla
,
G.
, and
Vassallo
,
A.
, 2009, “
Combustion System Optimization of a Low Compression-Ratio PCCI Diesel Engine for Light-Duty Application
,”
SAE Int. J. Engines
,
2
, pp.
1314
1326
.
38.
Catania
,
A. E.
,
Ferrari
,
A.
,
Manno
,
M.
, and
Spessa
,
E.
, 2008, “
Experimental Investigation of Dynamics Effects on Multiple Injection Common-Rail System Performance
,”
Trans. ASME J. Eng. Gas Turbines Power
,
130
(
3
), p.
032806
.
39.
Caprotti
,
R.
,
Fowler
,
W. J.
,
Lepperhoff
,
G.
, and
Houben
,
M.
, 1993, “
Diesel Additive Technology Effects on Injector Hole Erosion/Corrosion, Injector Fouling and Particulate Traps
,” SAE Paper No. 932739.
40.
Vassallo
,
A.
, and
Avolio
,
G.
, 2007, “
Coking Phenomena in Diesel Engines
,”
Internal Technical Report
,
General Motor Powertrain Europe
,
Torino
.
41.
Williams
,
R.
, and
Balthazar
,
F.
, 2009, “
Diesel Fuel Degradation and Contamination in Vehicle Systems
,”
Proceedings of the TAE Symposium 2009
.
42.
Baratta
,
M.
,
Catania
,
A. E.
,
Ferrari
,
A.
,
Finesso
,
R.
, and
Spessa
,
E.
, 2011, “
Premixed Diffusive Multi-Zone Model for Combustion Diagnostics in Conventional and PCCI Diesel Engines
,”
Trans. ASME J. Eng. Gas Turbines Power
,
133
, p.
1028011
.
43.
Catania
,
A. E.
,
Ferrari
,
A.
, and
Spessa
,
E.
, 2009, “
Numerical-Experimental Study and Solutions to Reduce the Dwell Time Threshold for Fusion-Free Consecutive Injections in a Multijet Solenoid-Type C.R. System
,”
J. Eng. Gas Turbines Power
131
(
1
), p.
022804
.
44.
Reitz
,
R. D.
, and
Bracco
,
F. V.
, 1979, “
On the Dependence of Spray Angle and Other Spray Parameters on Nozzle Design and Operating Conditions
,” SAE Paper No. 790494.
45.
Heywood
,
J. B.
, 1988,
Fundamentals of Internal Combustion Engines
,
McGraw-Hill
,
New York
.
46.
Kim
,
S.
,
Chung
,
N.
, and
Sunwoo
,
M.
, 2005, “
Injection Rate Estimation of a Piezo-Actuated Injector
,” SAE Paper No. 2005-01-0911.
You do not currently have access to this content.