The continuous stringent requirements of the environmental regulations along with the LNG fuel 12 penetration and the development of port and bunkering facilities, render the use of the dual fuel 13 engines an attractive alternative of the traditional ship propulsion plants based on Diesel engines 14 running with HFO for reducing both the plant operating cost and environmental footprint. The present 15 study deals with the computational investigation of a large marine dual fuel (DF) engine of the four-16 stroke type for comparing its performance and emissions, in both diesel and gas mode operation by 17 using the commercial software GT-ISE. The engine diesel model was initially set up and calibrated to 18 adequately represent the engine operation. Subsequently, the engine dual fuel model was further 19 developed by considering the injection of two different fuels; methane in the cylinder inlet ports and 20 pilot diesel fuel into the engine cylinders. The derived results were analysed for revealing the 21 differences of the engine performance and emissions at each operating mode. In addition, the 22 turbocharger matching was investigated and discussed to enlighten the turbocharging system 23 challenges due to the completely different air fuel ratio requirements in diesel and gas modes, 24 respectively. Finally, parametric simulations were performed for gas mode operation at different loads 25 by varying pilot fuel injection timing, inlet valve closing and inlet manifold boost pressure, aiming to 26 identify the engine settings that simultaneously reduce CO 2 and NOx emissions considering the 27 ratio operation window limitations. The parametric study results are discussed to infer the 28 engine optimal settings.
Lessons from maritime accidents are conventionally used to inform safety improvements in design and operation of ships. However, this process is only as good as the core understanding derived from accident analysis is. The current explanation of accidents is limited to direct and contributing causal factors, whereas the role of a wider socio-technical context that has given rise to causal mechanisms behind major maritime accidents in recent years is left unexplained. The paper describes analysis results of maritime incidents and accidents occurred over the last decade with passenger ships, with the purpose to illuminate the prevailing causal factors, not least the systemic ones. The results show where the weak links in maritime safety control are (e.g., interactions between ship operators and equipment manufacturers), what their role in accident causation is, and how they can be strengthened. The study seeks to provide valuable input for enhancements in overall maritime safety control and proactive safety management at the ship and shipping company levels.
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