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Cimac Congress | Shanghai 2013
cylinders (three ECUs) in preparation. Common ECU SW with
individual functions, e.g. twin air flow and fuel pressure control
(left/right engine bank) for multi ECU systems are configurable in
the SW build process. With SW sharing, the customer can realise
its own SW functions on the supplied ECU HW and SW platform.
Homologation for the most important ship classification societies
for the ECU and a set of common used engine sensors is in
progress. Pre-compliance tests have been performed and the final
compliance test is in preparation. In cooperation with Bosch
Rexroth an interface for the integration of the ECU engine control
management system into the Rexroth ship automation system is
developed. This technical paper will describe the Bosch electronic
engine management system components for the medium- and
high-speed engine applications.
Wednesday May 15th / 15:30 – 17:00
Fundamental Engineering – Thermodynamics 1
Room A
Optimal utilisation of air- and fuel-path flexibility in
medium-speed diesel engines to achieve superior
performance and fuel efficiency
Alexander Knafl, MAN Diesel & Turbo SE, Germany
Gunnar Stiesch, MAN Diesel & Turbo SE, Germany
Markus Friebe, MAN Diesel & Turbo SE, Germany
With the development of common rail fuel injection systems,
variable geometry turbochargers, variable valve timing and
combustion feedback systems, medium-speed diesel engines
offer substantial control flexibility with the potential of significantly
improving performance, fuel economy, emissions
and thus customer value. Engine performance - traditionally
governed solely by the mechanical system - is increasingly dependent
on the interaction of the flexible subsystems and their
proper control. This paper seeks to demonstrate the benefits offered
by variable airpath control in combination with a fully
flexible common rail fuel injection system. System interactions
and optimisation are analysed and performed with design of
experiment (DoE), response surface modelling and constraint
merit functions. Above mentioned method is applied to design
custom-tailored medium-speed engine maps for constant
speed generator, controllable pitch as well as fixed pitch propeller
operation. Engine performance data are obtained via engine
dynamometer experiments augmented with analytical simulations.
With constant speed generator operation, it is shown that
through optimising the engine calibration in accordance with
the typical load profile thereof, specific fuel oil consumption
is reduced by several grams without related engine hardware
changes. The potential of applying engine control maps specifically
tailored to the mode of operation, e.g. fast steaming, slow
steaming or manoeuvring, the operation is assessed and the
potential quantified. This so-called multi-mapping approach
allows for improved performance and reduced emissions over
the entire operating regime of the engine. In addition to steady
state operation, benefits in transient response are demonstrated
by means of optimised air- and fuel-path control. Particularly
load rejection and smoke emissions are substantially improved
over conventional, mechanically rigid systems. Lastly the affect
of Tier III exhaust gas treatment solutions - selective catalytic reduction
(SCR) to reduce NOx and or scrubbers to capture SOx
- on engine performance is investigated. It is shown that Tier III
exhaust gas treatment systems may adversely affect engine performance
through increased exhaust gas backpressure and the
requirement of elevated exhaust gas temperatures. By means of
optimally adjusting the engine control to the new boundary
conditions, it is demonstrated that engine performance and efficiency
can be restored to Tier II levels.
Analysis and optimal design on air intake system of
controllable intake swirl diesel
Guixin Wang, Harbin Engineering University, China
Xiaobo Li, Harbin Engineering University, China
Gongmin Liu, Harbin Engineering University, China
Xiaoli Yang, Harbin Engineering University, China
Xiaoxiao Niu, Harbin Engineering University, China
Choosing one marine controllable intake swirl diesel as the research
object, this paper does some calculation and analysis on
the intake flow field by using a 3D flow field analysis software,
obtains the swirl ratio and the flow coefficient of the target diesel
in different valve lifts and intake baffle angles, and finds that the
intake swirl of the diesel has a two-stage characteristics, namely
the value of the swirl changes from high to low. On the basis of
the calculation and analysis of the diesel air intake system flow
field, this article completes the structure optimisation design of
the diesel intake, and gets the laws of the swirl ratio and the flow
coefficient influenced by the structure of the diesel intake. At the
same time, this paper verifies the calculating results through using
the steady flow test of the diesel air intake system, and ensures the
accuracy and reliability of the diesel air intake system calculating
analysis and design optimisation.
Investigation of extreme mean effective and
maximum cylinder pressures in medium-speed diesel
engines
Peter Eilts, Technical University Braunschweig, Germany
Claude-Pascal Stoeber-Schmidt, Technical University Braunschweig, Germany
The current level of mean effective pressure (mep) of mediumspeed
diesel engines is 25 to 28 bar. Maximum pressure (pmax)
is about 230 bar. At the Technical University Hamburg Harburg, a
research engine with a mep of 40 bar and a pmax of 350 bar has
been operated successfully with good results. This led the authors
to investigate what can be expected when operating at even higher
pressures. In a theoretical study the mep of a 320mm bore medium-speed
engine was increased up to 80 bar. A zero dimensional
cycle simulation program was used for the calculations. Compression
ratio, stoichiometric air ratio, valve timing and mechanical
efficiency were kept constant. Several strategies concerning combustion
and turbocharging efficiency (etaTC) were investigated.
Some results: With a constant etaTC of 70% and constant rate
of heat release (ROHR) an increase of mep above 60 bar is not
possible, because the scavenge pressure difference becomes negative.
Specific fuel oil consumption (sfoc) increases slightly. The
exhaust temperature before turbine (TbT) rises significantly. With
constant ROHR and a constant ratio of pressure before turbine
and charge air pressure a mep of 80 bar is possible. TbT decreases
slightly, sfoc decreases by 5%. The required etaTC is above 80%.
Thermal load of course increases significantly. In all cases the
required charge air pressure (pch) and pmax rise approximately
proportional to mep. For a mep of 80 bar, the first reaches 15 to
16 bar and the latter 750 to 800 bar. Using a jet mixing model,
two strategies for injection and combustion were investigated. In
both the injection duration was kept constant. If the nozzle area is
increased proportional to the injected fuel mass, the ROHR is unchanged
and so are the operating data. The nozzle hole diameters
become very large so smoke problems have to be expected. Injection
pressure rises only moderately. If the nozzle area is increased
60 SPECIAL
Schiff&Hafen | Ship&Offshore | May 2013