Abstract
Ships, in particular service vessels, need to reduce fuel consumption, emissions and cavitation noise while maintaining manoeuvrability and preventing engine overloading. Diesel mechanical propulsion with controllable pitch propellers can provide high fuel efficiency with good manoeuvrability. However, the conventional control strategy with fixed combinator curves limits control freedom in trading-off performance characteristics. In order to evaluate performance of current state-of-the-art and future alternative propulsion systems and their control, a validated propulsion system model is required. To this end, this paper proposes a propulsion model with a Mean Value First Principle (MVFP) diesel engine model that can be parameterised with publicly available manufacturer data and further calibrated with obligatory FAT measurements. The model uses a novel approach to predict turbocharger performance based on Zinner blowdown, the Büchi power and flow balance and the elliptic law for turbines, and does not require detailed information such as compressor and turbine maps. This model predicts system performance within 5% of actual measurements during Factory Acceptance Tests (FAT) of the diesel engines and Sea Acceptance Tests (SAT) of a case study navy ship. Moreover, this paper proposes measures of performance that objectively quantify the fuel consumption, acceleration rate, engine thermal loading and propeller cavitation during trial, design and off-design conditions in specified benchmark manoeuvres, within an hour simulation time. In our experiments, we find that, depending on the control strategy, up to 30% of fuel can be saved, thermal engine loading can be reduced by 90K, and acceleration time by 50% for a case study Holland class patrol vessel.
Highlights
The green house gas reduction targets set during the United Nations climate change conference 2015 in Paris and acknowledged by the European Union, national governments and the International Maritime Organisation (IMO), require seagoing ships to significantly reduce their fuel consumption and improve their propulsion system efficiency [1,2]
This paper proposes a propulsion model with a Mean Value First Principle (MVFP) diesel engine model that can be parameterised with publicly available manufacturer data and further calibrated with obligatory Factory Acceptance Tests (FAT) measurements
The combinator curve of the transit mode achieves 30% less fuel consumption at 5 kts, 10% less fuel consumption at 10 kts and 2% less fuel consumption at 15 kts compared to the manoeuvring mode
Summary
The green house gas reduction targets set during the United Nations climate change conference 2015 in Paris and acknowledged by the European Union, national governments and the International Maritime Organisation (IMO), require seagoing ships to significantly reduce their fuel consumption and improve their propulsion system efficiency [1,2]. Many types of ships, in particular service vessels, have to accelerate fast and accurately when performing their missions at sea [3]. Diesel mechanical propulsion with controllable pitch propellers can deliver both accurate manoeuvrability and high fuel efficiency during transit. This type of propulsion is often used for the above mentioned vessels and considered in this study.
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