CIMAC Congress - Schiff & Hafen

Tuesday, 15 June Wednesday, 16 June Thursday, 17 June
Monday, 14 June
the specifications of the PC plug and the flame ignition mechanism
has not been clarified. Hence the purpose of this study is to improve
the thermal efficiency of the engine up to the target value after
clarifying the specification of the PC plug which up to this point has
not yet been specified.
• For this purpose, the combustion mechanism of the PC plug
was verified using a visible engine and CFD analysis.
Based on these test results, prototypes of the PC plugs were made
and then combustion period, COV, and thermal efficiency were
compared using a supercharged single cylinder engine.
• Based on the results, it has been concluded that internal volume,
diameter of orifice and sparking position greatly contribute to the
combustion characteristics of the engine. The PC plug with the
optimum combination of the above mentioned there factors
achieved a thermal efficiency value 1% higher than a conventional
plug under 1.9Mpa of Pmi. In addition, it enhances lean limit value
ramda from 1.8 to 1.85.
• Enlarging the internal volume can allow the proper amount of
fuel to flow into the prechamber. Reducing diameter of orifice
increases the power of the flame jet. An optimized spark position
was able to eliminate the influence of the residual gas forecasted by
CFD, which ultimatly resulted in high ignitability.
• The above results show that the PC plug can be designed to
reach the targeted thermal efficiency level in an open-chamber
engine. However, because combustion characters differ, the next
target is to achieve a wider coverage of engines with minimum
changes to the PC plug.
The gas engine of the future – Innovative
combustion and high compression ratios for
highest efficiencies
J. Klausner, C. Trapp, H. Schaumberger, M. Haidn,
J. Lang, GE Jenbacher GmbH, Austria
engine. The present work illustrates a predictive model for cylinder oil
stress in low speed two-stroke diesel engines based on the results from
several enginetest campaigns. The experimental investigation has been
carried out on Wärtsilä large bore marine diesel engines equipped
with several lubrication oil systems and on the Bolnes 3(1) DNL
170/600 research engine from Shell Global Solutions (Deutschland)
GmbH. Acquired experimental data regarded both cylinder oil
sampling techniques, chemical and physical laboratory analysis of the
oil samples and optical technique to quantify the amount of oil blown
off though the inlet ports from the piston ring pack. Relevant differences
in used cylinder lube oil properties between samples gathered with
different techniques have been found. The paper will describe these
findings and will propose an innovative way of looking at oil stress
analysis in two-stroke engines.
The piston-running behaviour monitoring of
large bore low-speed marine diesel engine
at sea by measurement of piston ring oil
film thickness and iron content in cylinder
drain oil
Y. Saito, T. Yamada, IHI Corporation, Japan,
K. Moriyama, Diesel United, Ltd., Japan
In low speed two stroke diesel engines, the scuffing problem of the
cylinder liners and the piston rings is one of the most important
subjects in order to secure reliability due to the high cylinder pressure
and the low quality fuels in these days. On the other hand, the
reduction of cylinder oil feeding rate is required because of the
reduction of ship operation cost. Therefore, achieving coexisting of
Gas engines are expected to play an increasingly important role
within a trend towards decentralized energy supply worldwide.
Today’s gas engines have already reached a high level of efficiency
thanks to lean burn combustion strategy and Miller/Atkinson valve
timing in combination with steadily increasing compression ratios.
However, the pressing need to further increase engine efficiency,
with the target to maximize the energy harvest from various types of
gas, requires further progress. This paper describes a new highpressure
turbo charging approach with advanced Miller/Atkinson
timing. By increasing the turbo charger efficiency and pressure ratio,
the Miller/Atkinson cycle’s potential is more fully exploited than
was hitherto possible. The paper describes the modular changes in
charging, valve timing, gas exchange, ignition and combustion of
the development engines.
15:30 June 14th Room Klokkeklang
(4–2) Diesel Engines – Tribology II
Cylinder lubrication – understanding oil
stress in the low speed two-stroke diesel
engine
J. Hammett, J. L. Garcia, Shell Global Solutions GmbH,
Germany,
F. Micali, M. F. Weber, Wärtsilä Switzerland Ltd.,
Switzerland,
A. De Risi, University of Salento, Italy
The concept of oil stress in a low speed two-stroke diesel engine has yet
to be tackled in the same way or depth as it has been in the four-stroke
No. 3 | 2010 | Ship & Offshore 35