CIMAC Congress - Schiff & Hafen

CIMAC CONGRESS | BERGEN 2010
actuation systems are key characteristics of this technology. From
Wärtsilä side, the RT-flex family of engines has been designed,
providing performance and operational advantages to ship owners
and operators alike. The engines are equipped with an accumulator
type fuel system where the injection pressure and start of injection can
be individually selected at each operational point. Moreover, the
timing of the exhaust valve movement is fully controlled through a
dedicated actuation system providing additional operational flexibility.
It has already been demonstrated that this flexibility provides
significant advantages throughout the engine operational envelope.
This flexibility will become even more significant in the future as the
variability of fuel types and fuel quality are increasing and the exhaust
gas emission legislation becomes more severe. Based on the current
field experiences and the available technological advancements, new
system architectures are proposed in the 30 cm to 50 cm bore segment.
The systems are designed for low lifetime costs and high reliability.
Stringent emission requirements can be fulfilled, with the engines
fully prepared for future IMO Tier 3 emission legislation, without
modifications of the above mentioned systems. Additionally, it is
possible to make full use of existing system components and subsystems
which have demonstrated reliability and lifetime in other
marine applications, using the same type of marine fuels and at severe
operational conditions. This is important due to the challenging
development schedules for the systems of new engine programs.
The fuel system is characterized by:
• Two injectors per cylinder, each with embedded single circuit
solenoid valve
• Injection timing and quantity control embedded in the injector
• An accumulator (common rail) system based on a volume
optimized, multi-element, double wall rail
• A fuel supply system based on engine driven, inlet throttle
controlled, multi-element pumps validated for two-stroke
applications
• System pressure which is potentially up to 50% higher than those
currently applied on two-stroke engines.
The exhaust valve actuation is characterized by:
• A 300 bar servo- oil actuating medium
• Optimized solenoid valve actuation allowing continuous control
of exhaust valve closure.
Both fuel and valve actuation systems are supported by a new electronic
control system.
The proposed paper presents our experiences from the development
of these critical systems by providing a detailed insight on the
following:
• The market requirements and their fulfilment;
• The advancement between the current RT- flex technology on
larger bore segments and the new system;
• The major sizing, design and development challenges;
• The hydraulic system analysis used for the complete, multicylinder
engine;
• The system integration at engine level;
• The overall system and component performance.
Valve train with learning control features
M. Herranen, T. Virvalo, K. Huhtala, Tampere
University of Technology, Finland,
T. Glader, I. Kallio, Wärtsilä Finland Oy, Finland
The electro-hydraulic valve actuator (EHVA) system of a diesel engine
has a fully controllable gas exchange valve lift and valve timing. The
EHVA system can be utilized to follow existing valve lift profiles and
provides possibility for utilization of modified or new valve lift profiles.
Fast testing of different camshaft profiles is beneficial when new
combustion concepts are tested or when new valve timing specifications
needs to be studied or optimized with existing components.
Comparison and testing of the different profiles with EHVA system is
efficient, since all necessary changes can be done electrically. Therefore
the system should be able to follow the pregenerated valve lift curves
as precise as possible. It is known, that traditional controllers are
having problems to achieve reasonable good tracking due to dynamics
of the hydraulic system. This can be improved by using more complex
and advanced controllers, but tuning of parameters of such controller
is very time consuming. One solution is to use an adaptive or a learning
controller. In this study a controller with a learning feature is
investigated and introduced. The modification of the reference signal
is based on the detected errors during the valve event, which is suitable
method for a repeating work cycle. Performance of the controller is
simulated and some experimental tests are presented. The EHVA
system is additionally integrated with security features for stopping
and starting control processes when needed. The lift profiles of the gas
exchange valves can be changed or modified without need of stopping
the engine. If only opening and closing moment needs to be adjusted,
the controller system allows this without influence to curve shape. The
controller was found capable to keep the tracking error of the gas
exchange valve lift within acceptable range and capable to respond to
changes in the running conditions within adequate time.
10:30 June 17th Room Scene GH
(3–2) Environment, Fuel & Combustion –
Diesel Engines – Fuels II
Medium speed diesel engines operated
on alternative fuels: Lessons learned and
remaining questions
S. Verhelst, R. Sierens, Ghent University, Belgium, L.
Vervaeke, T. Berckmoes, L. Duyck, Anglo Belgian
Corporation nv, Belgium
Rudolf Diesel demonstrated his compression ignition engine at the
World Fair in Paris in 1900, with the engine running on peanut oil.
One year earlier, the first diesel engine outside of Germany was built
under license by the Carels Brothers in Ghent, Belgium. In 1912, this
license was brought into the founding of the Anglo Belgian Corporation
(ABC). Diesel engines have undergone tremendous progress since
then, which has gone hand in hand with the development of fuel
standards, both for light and heavy fuels. Currently, with increasing
focus on noxious emissions, energy security and greenhouse gas
emissions, there is great interest in the use of alternative fuels, mostly
biofuels (biodiesel, straight vegetable oils, animal fats, . . . ). However,
it is unclear what the specifications for these fuels should be. Ghent
University has recently started research to define suitable fuel
specifications for the current and future engine technologies, in
correspondence with one of the priorities set by the European Biofuels
Technology Platform (BTP). Working group 3 of the BTP focuses on
the R&D needs concerning the end-use of the biofuels. It states that a
systematic verification and profound knowledge of the impact of the
fuel properties on the fueling system, engine technology, exhaust gas
aftertreatment etc., is an absolute prerequisite for the formulation of
fuel standards. Diesel engine manufacturer ABC, also located in Ghent,
has done pioneering work in demonstrating the use of several biofuels,
including biogases, with installations running on palm oil, frying oil,
tallow, biodiesel, pitch, bone fat, syngas, etc., and has gathered data
from long-term tests. Ghent University and ABC are cooperating in
analyzing this data and correlating it with the biofuels’ chemical and
physical properties. Furthermore, a constant volume combustion
chamber is being set up to study the spray and combustion
characteristics of these fuels. This paper discusses the initial findings
when operating on different kinds of biofuels – which problems were
encountered and how they were solved – using several case studies.
90 Ship & Offshore | 2010 | No. 3