and lube oil consumption as well
as the capability of burning any
kind of fuel, is the leading guide-
line for the design and develop-
ment. Though for some engine
types V-engines are available, the
general tendency is to feature in-
line engines, especially for marine
application.
Low cylinder numbers or in-line
engines mean a low number of
moving parts. Though today, on
account of improved materials and
experience in design, a high relia-
bility of the different parts can be
achieved, there is no doubt that
the all over reliability is directly
related to the number of parts in-
volved and bear a direct relation
to maintenance and overhaul re-
quirements.
The general trend for reduction
of fuel consumption initiated by
the increasing price of fuels has
resulted in an extensive develop-
ment work in this direction. Today
MaK engines are of the highest ef-
ficiency and in particular cases
leading in this field, achieving up
to 50 percent efficiency.
For more than 15 years the
burning of heavy fuels in medium-
speed four-stroke engines has been
developed with increasing success.
Today even the highest viscosities
can be burned without difficulties,
not only at full but also at part
load. Wear rates of parts exposed
to combustion are in many cases
even lower than experienced with
older engines running on gas oil
Alan C. Barich and Edwin E.
Hodges of Transamerica DeLaval
presented a paper on "Exhaust
Emission Control Techniques of
Today's Large-Bore Medium-Speed
Diesel Engines for Heavy-Fuel
Operation."
Although currently in the em-
bryonic stage for marine applica-
tion, exhaust emissions are in the
process of being regulated for ship
operation in our inland water-
ways, Great Lakes and major U.S.
ports. Control of diesel exhaust
emissions will include changes to
the basic operation of the diesel
engine through such means as to
retard fuel injection timing, charge
air manifold temperatures and use
of exhaust gas recirculation.
The work discussed in this re-
port revealed substantial results.
Injection timing and intake air
manifold cooling show clear reduc-
tions in NOx emissions, but the
extent of the reductions is limited.
Moreover, substantial fuel penal-
ties associated with these tech-
niques were demonstrated. Of the
combustion control techniques
tried, exhaust gas recirculation
was the most effective in achiev-
ing significant NOx reductions with
minimum fuel-consumption pen-
alty. However, the hidden costs as-
sociated with this method are a
major concern at this time. Fur-
ther development work is needed
to improve the EGR system and
thus reduce fouling and related
gas-handling problems. The effect
of EGR on lube oil contamination
and ultimately on engine wear
also needs additional investigation.
Ammonia-injection catalytic re-
duction appears to work well in re-
ducing NOx, but again needs fur-
ther attention. It has not yet
achieved expected percentage re-
ductions, and additional work di-
rected toward the control system
and related hardware is necessary.
Based on results of the experi-
mental program to date, it is ap-
parent that both catalytic reduc-
tion and EGR are deserving of
further attention. No mechanical
experiments with engine redesign
are possible until completion of
the present experimental pro-
gram, but research can be directed
at resolving the problems associ-
ated with EGR.
Until such a time as more work
can be done, it is up to the engine
manufacturer and owner alike to
help reduce NOx by carefully and
precisely sizing auxiliary equip-
ment that will help reduce engine
emissions.
C. E. Rosgren, design manager
for Wartsila Diesel, spoke on "Re-
liable Heavy-Fuel Engine Compo-
nent Designs." This paper deals
with the design aspects of some
critical components in heavy-fuel-
burning diesel engines. The theo-
retical considerations are de-
scribed as well as the practical
outcome of applied engine tests
and field experience.
The heavy fuel experiences re-
ferred to were gained during the
(continued on page 14)
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