Analysis of ship propulsion system performance is often performed using detailed hydrodynamic models to assess load changes, which are subsequently compared to static engine limits, or by detailed engine models that are rarely integrated with sufficiently detailed propulsion models for load change estimation. To investigate the dynamic engine (overloading) behaviour and ship propulsion performance under various heavy operating conditions, a Mean Value First Principle Parametric (MVFPP) engine model is integrated into a ship propulsion system model in this paper. An upgraded thermodynamic-based MVFPP model for two-stroke marine diesel engines is presented, in particular a newly developed MVFPP gas exchange model. Based on the integrated propulsion system model of a benchmark ocean-going chemical tanker, the engine dynamic behaviour during ship acceleration, deceleration and crash stop has been investigated. Results show that, during dynamic processes, the engine could be thermally overloaded even if the engine power trajectory is inside the static engine operating envelope. The paper contributes to finding proper indicators for thermal overloading of modern two-stroke marine diesel engines. It is demonstrated that when matching the engine with the propeller and designing the ship propulsion control system, not only the static engine operating envelope, but also the dynamic engine behaviour should be considered.

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Current EEDI (Energy Efficiency Design Index) regulations striving to reduce the installed engine power on new ships for a low EEDI may lead to underpowered ships having insufficient power when operating in adverse sea conditions. In this paper, the operational safety of a low-powered ocean-going cargo ship operating in adverse sea conditions has been investigated using an integrated ship propulsion, manoeuvring and sea state model. The ship propulsion and manoeuvring performance, especially the dynamic engine behaviour, when the ship is sailing in heavy weather and turning into head sea, have been studied. According to the results, the dynamic engine behaviour should be considered when assessing the ship operational safety, as the static engine operating envelope is inadequate for the safety assessment. The impact of PTO/PTI (power-take-off/in) operation and changing propeller pitch on the ship thrust availability in adverse sea conditions have also been investigated. To protect the engine from mechanical and thermal overloading, compressor surge and over-speeding during dynamic ship operations and/or in high sea states, the engine and propeller should be carefully controlled. The paper shows that if in (heavy) adverse weather the propeller pitch can be reduced or if the shaft generator can work as a motor (PTI), more thrust can be developed which can significantly improve the operational safety of the ship.

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The shipping industry, which remains the backbone of international merchandise trade, is striving to reduce its operational cost and more importantly its environment impact. New ships need meet the EEDI (Energy Efficiency Design Index) requirements of IMO (International Maritime Organization). However, the current EEDI is not able to accurately evaluate the real lifetime carbon emissions of the ship. Under the guidance of current EEDI regulation, the ship designers, owners and policymakers could be misled to adopt the configurations that are underperforming or even leading to an increase of CO2 emissions in reality. A technically easy and effective solution to meet the EEDI requirement is to lower the installed engine power and thus the ship design speed. However, reducing the installed engine power could lead to an underpowered ship, which could have insufficient power for propulsion and steering in adverse weather conditions. The main research question addressed in this dissertation is: What is the transport performance of ocean-going cargo ships with small EEDI when sailing in realistic operating conditions; are these ships safe when sailing in heavy operating conditions; and, how to improve both the transport performance and operational safety of ocean-going cargo ships by using the short-term applicable ship propulsion options? The ship transport performance investigated in this dissertation includes the energy conversion performance, fuel consumption performance and emissions performance. The influences of the operational ship speed reduction, propulsion control, PTO (power-take-off)/PTI (power-take-in), and using LNG (liquefied natural gas) as the fuel as well as the combination of these measures on the ship transport performance have been systematically investigated. The operational safety investigated in this dissertation includes both engine operational safety and ship operational safety. The engine dynamic behaviour during ship acceleration, deceleration, crash stop, and turning in normal sea condition have been investigated. The ship propulsion and manoeuvring performance when sailing in head sea, accelerating in head sea and turning to head sea in adverse sea conditions have been investigated. The influences of propeller pitch and PTO/PTI on the ship thrust limit and engine behaviour have also been investigated. As a reflection of the research in this dissertation, suggestions on amendments of IMO’s current EEDI has been provided. The proposal for amending the current EEDI formula tries to make the EEDI calculation more realistic and representative when evaluating ship transport performance at the design stage. Moreover, it can also partly solve the other weakness of the current EEDI with respect to the issues of underpowered ships.@en

Hybrid propulsion and using liquefied natural gas (LNG) as the alternative fuel have been applied on automobiles and some small ships, but research investigating the fuel consumption and emissions over the total voyage of ocean-going cargo ships with a hybrid propulsion and different fuels is limited. This paper tries to fill the knowledge gap by investigating the influence of the ship mission profile, propulsion modes and effects of different fuels on the fuel consumption and emissions of the ship over the whole voyage, including transit in open sea and manoeuvring in close-to-port areas. Results show that propulsion control and electric power generation modes have a notable influence on the ship's fuel consumption and emissions during the voyage. During close-to-port manoeuvres, propelling the ship in power-take-in (PTI) mode and generating the electric power by auxiliary engines rather than the main engine will reduce the local NOx and HC (hydrocarbons) emissions significantly. Sailing the ship on LNG will reduce the fuel consumption, CO₂ and NOx emissions notably while producing higher HC emissions than traditional fuels. The hybridisation of the ship propulsion and using LNG together with ship voyage optimisation, considering the ship mission, ship operations and sea conditions, will improve the ship's fuel consumption and emissions over the whole voyage significantly.

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The increasing economic cost and environmental impact of maritime transportation necessitate the reduction of fossil fuel consumption of ocean-going cargo ships. Although fundamental ship propulsion system theory is well-known and is at a mature stage of development, there is still an enormous variety in the assessment methodology of (environmental) transport performance of ships. Furthermore, calibration of ship propulsion system model parameters with testbed, towing tank and full-scale measurement data is rare, as these measurements are both difficult and expensive. Finally, the effects of different power management strategies on the ultimate energy conversion effectiveness of typical cargo ships have rarely been investigated systematically. In this paper these three issues are discussed, addressed and solved for a representative benchmark chemical tanker. This ship was chosen to investigate the so-called energy conversion effectiveness under various propulsion control and electric power generation modes, as ample real ship data is available. The transport performance assessment of the ship's power plant is generalised for hybrid arrangements with either Power-Take-Off or Power-Take-In. The results show that an optimal combination of propulsion control, power management and voyage planning will further reduce the global fuel consumption and CO₂ emissions produced by the shipping industry.

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Mean value diesel engine models are widely used since they focus on the main engine performance and can operate on a time scale that is longer than one revolution, and as a consequence use time steps that are much longer than crank-angle models. Mean Value First Principle (MVFP) models are not primarily intended for engine development but are used for systems studies that are become more important for engine users. In this paper two new variants of Seiliger processes, which characterize the engine in-cylinder process with finite stages are investigated, in particular their ability to correctly model the heat release by a finite number of combustion parameters. MAN 4L20/27 engine measurements are used and conclusions were drawn which Seiliger variant should be used and how to model the combustion shape for more engines. Then expressions to calculate the combustion parameters have been obtained by using a multivariable regression fitting method. The mean value diesel engine model has been corrected and applied to the simulation of a ship propulsion system which contains a modern MAN 18V32/40 diesel engine in its preliminary design stage and the simulation results have shown the capability of the integration of MVFP model into a larger system.@en