A comparative study on mean value modelling of two-stroke marine diesel engine

In the present paper, two mean value modelling approaches of varying complexity, capable of simulating two-stroke marine Diesel engines, are presented. Both approaches were implemented in the computational environment of MATLAB Simulink®. Simulation runs of transient operation cases of a large two-stroke marine Diesel engine were performed. The derived results were validated against previously published data are used for comparing the two modelling approaches and discussing the advantages and drawbacks of each

Modelling and parametric investigation of a large marine two-stroke dual fuel engine

This work deals with the modelling of a large marine two-stroke dual duel engine of the low gas pressure concept by using the GT-PowerTM software. Appropriate models were used to represent the engine processes including combustion, scavenging, heat transfer and friction whereas a knocking model was employed to characterise the engine unstable operation. The model was first validated against the manufacturer data and subsequently, the entire engine envelope in both operating modes was simulated. The derived results were used for analysing and discussing the engine performance and emissions as well as for comparing the two operating modes in terms of the turbocharger matching. In addition, parametric runs were performed and the results were used for identifying the settings that can further optimize the engine operation in the dual fuel mode in terms of CO2 and NOx emissions trade-off

Ship machinery condition monitoring using vibration data through supervised learning

This paper aims to present an integrated methodology for the monitoring of marine machinery using vibration data. Monitoring of machinery is a crucial aspect of maintenance optimisation that is required for the vessel operation to remain sustainable and profitable. The proposed methodology will train models using pre-classified (healthy/faulty) data and then classify new data points using the models developed. For this, vibration points are first acquired, appropriately processed and stored in a database. Specific features are then extracted from the data and stored. These data are then used to train supervised models pertinent to specific machinery components. Finally, new data are compared against the models developed in order to evaluate their condition. The above will provide a flexible but robust framework for the early detection of emerging machinery faults. This will lead to minimisation of ship downtime and increase of the ship’s operability and income through operational enhancement

Investigation of ship cooling system operation for improving energy efficiency

The application of recently introduced IMO regulations for reduction of CO2 gaseous emissions as well as the initiatives for greener shipping, rendered the efforts for improving on-board energy systems performance to be of high priority. This study focuses on the investigation of the on-board operation of the combined sea/fresh water cooling system of a merchant ship. The detailed model of a cooling system is presented based on energy and mass conservation laws. The simulation input data includes the system geometry and arrangement, the operational characteristics of cooling pumps, the control scenarios for the system valves as well as data for calculating the pipes friction and minor losses coefficients, wherefrom the system performance parameters can be calculated. The cooling system energy consumption was estimated considering a typical annual ship operational profile. Two cases were investigated; first, a conventional case of controlling the sea water and fresh water temperatures by using three-way valves and, second, a more sophisticated case of installing variable speed motors for driving the system pumps. The obtained results are compared in terms of annual power consumption leading to conclusions about the system performance. The developed models can be used as an assessment tool for improving shipboard power demand early in the design stage and, also, during operation

Dynamic energy modelling for ship life-cycle performance assessment

This article summarises related work undertaken by the EC-funded Research Project TARGETS, which focuses on assessing energy efficiency by a direct approach. Energy flows onboard ships are considered in the time domain for complete ship energy systems simulation, allowing for interactions at system and component levels and accounting for different configurations, operating profiles, itineraries and environmental conditions. The approach and tools form the basis for life-cycle energy management considerations, addressing design, operation and retrofitting. To demonstrate the methodology leading to the evaluation of performance-based energy efficiency and its anticipated impact on ship design and operation, a case study for containership was carried out. Results are presented and discussed, demonstrating considerable advantage in adopting a more systematic and scientific approach to address Energy Efficiency of ships

Ship machinery and equipment inspection tool development for risk control and decision making

Concerning the successful business competence, strategic planning should be enhanced considering assets availability by involving maintenance and reliability operational aspects. The INCASS (Inspection Capabilities for Enhanced Ship Safety) FP7 EU funded research project aims to tackle the issue of ship inspection, identification of high-risk ships, providing access to information related to ship surveys and incorporate enhanced and harmonized cooperation of maritime stakeholders in order to avoid ship accidents, promote maritime safety and protect the environment. The current research consists of machinery and equipment specifications and stakeholders’ data requirements. Focusing on the methodology perspective, a Machinery Risk Analysis (MRA) model is introduced. All progress and methodology development takes place in Java programm ing language. Overall, the outcomes of this study demonstrate the reliability performance of marine machinery components. Future development include dynamic failure rate variation through time, probabilistic model’s sensitivity analysis and components’ and systems’ interdependencies in a user-friendly Graphical User Interface (GUI) design

Analysis of two stroke marine diesel engine operation including turbocharger cut-out by using a zero-dimensional model

In this article, the operation of a large two-stroke marine diesel engine including various cases with turbocharger cut-out was thoroughly investigated by using a modular zero-dimensional engine model built in MATLAB/Simulink environment. The model was developed by using as a basis an in-house modular mean value engine model, in which the existing cylinder block was replaced by a more detailed one that is capable of representing the scavenging ports-cylinder-exhaust valve processes. Simulation of the engine operation at steady state conditions was performed and the derived engine performance parameters were compared with the respective values obtained by the engine shop trials. The investigation of engine operation under turbocharger cut-out conditions in the region from 10% to 50% load was carried out and the influence of turbocharger cut-out on engine performance including the in-cylinder parameters was comprehensively studied. The recommended schedule for the combination of the turbocharger cut-out and blower activation was discussed for the engine operation under part load conditions. Finally, the influence of engine operating strategies on the annual fuel savings, CO2 emissions reduction and blower operating hours for a Panamax container ship operating at slow steaming conditions is presented and discussed

Sustainability assessment of ship energy systems at the design phase : integrating environmental and economic aspects

Sustainable development of the shipping sector is becoming increasingly important for policy, decisions makers, as well as, academia. A gap in assessing the sustainability of ship systems exists, even though the ship energy systems have the major environmental and economic impacts over the vessel’s operational lifetime. The purpose of this paper is to present the status of sustainability assessment in the shipping sector and introduce a method that can facilitate the integrated assessment of environmental and economic sustainability of ship systems lifetime at the design phase, by taking into consideration the operational and regulatory requirements of the vessel

Open type ferry safety systems design for using LNG fuel

This feasibility study investigates the viability of employing Liquefied Natural Gas (LNG) fuel to an open type Ro-Ro passenger ferry and the potential challenges imposed with regard to the vessel safety systems. The study proposes appropriate methodology for converting the existing ship to run on LNG fuel and discusses all the necessary modifications to the ship’s safety systems; furthermore, the ship’s evacuation analysis is investigated accordingly. The basic requirements that the ship already complies with are initially reported for each safety system while the additional restrictions that need to be taken into consideration for employing LNG fuel are analysed; appropriate actions are proposed. Furthermore, a Hazard Identification Study (HAZID) is also carried out. Overall, the technical feasibility of the investigated scenario is clearly demonstrated; minimal modifications to the ship's safety systems in order to comply with the imposed safety rules are required for the specific type of ship

Techno-economic investigation of alternative propulsion plants for ferries and RoRo ships

In this paper, the main alternative propulsion plants based on reciprocating internal combustion engines of a ferry or RoRo ship operating in routes that include Emission Control Areas (ECAs) are comparatively assessed. Specifically, a dual fuel engine propulsion plant is compared with a conventional Diesel engine plant. For both cases, the installation of a Waste Heat Recovery system, which covers a part of the ship electric energy demand, is also considered. The ship main DF engines are assumed to operate using LNG and a small amount of MDO for initiating combustion, whereas low sulphur MDO was regarded as the fuel for the case of the Diesel engine plant. The installation of selective catalytic reduction (SCR) after-treatment unit for reducing the NOx emissions for the case of Diesel engines plant is also taken into account. The propulsion plants were modelled under steady state conditions, and the simulation results were analysed in order to compare the alternative configurations. Furthermore, the energy efficiency design index (EEDI) values were calculated and the two examined propulsion system cases were compared on EEDI basis. Finally, the Life Cycle Cost for each alternative propulsion plant was calculated and used for completing an economic evaluation of the Dual fuel propulsion plant versus the conventional designs applied in ferries