Abstract
The energy efficiency and environmental friendliness of medium-speed marine diesel engines are to be improved through the application of various measures and technologies. Special attention will be paid to the reduction in NOx in order to comply with the conditions of the MARPOL Convention, Annex VI. The reduction in NOx emissions will be achieved by the application of primary and secondary measures. The primary measures relate to the process in the engine, while the secondary measures are based on the reduction in NOx emissions through the after-treatment of exhaust gases. Some primary measures such as exhaust gas recirculation, adding water to the fuel or injecting water into the cylinder give good results in reducing NOx emissions, but generally lead to an increase in fuel consumption. In contrast to the aforementioned methods, the use of an earlier inlet valve closure, referred to in the literature as the Miller process, not only reduces NOx emissions, but also increases the efficiency of the engine in conjunction with appropriate turbochargers. A previously developed numerical model to simulate diesel engine operation is used to analyse the effects of the Miller process on engine performance. Although the numerical model cannot completely replace experimental research, it is an effective tool for verifying the influence of various input parameters on engine performance. In this paper, the effect of an earlier closing of the intake valve and an increase in inlet manifold pressure on fuel consumption, pressure and temperature in the engine cylinder under steady-state conditions is analysed. The results obtained with the numerical model show the justification for using the Miller processes to reduce NOx emissions and fuel consumption.
Highlights
Maritime transport is extremely important for the exchange of goods at the global level. the transport of goods by sea is the most efficient known mode of transport in terms of energy consumption per mile travelled and per tonne of cargo transported, it faces increasing demands in terms of energy efficiency and the reduction in negative environmental impacts
The primary measures relate to the process in the engine, while the secondary measures are based on the reduction in NOx emissions through the after-treatment of exhaust gases
The NOx emission limits for marine diesel engines with a rated power of more than 130 kW are divided into Tiers I, II and III according to the IMO (International Maritime Organisation)
Summary
Maritime transport is extremely important for the exchange of goods at the global level. CylinderThis by leads increasing the enables approximately constant pressure of theincombustion to lower compression ratio and while simultaneously reducing the which amount of fuel injected per crankshaft maximum pressure a lower maximum temperature, is beneficial because NO x emissions revolution theoretically enables the approximately constant pressure of the combustion process. This leads to lower maximum pressure and a lower maximum temperature, which is beneficial because NOx emissions are largely temperature-dependent. Specific fuel oil consumption and changes in of pressure and temperature in the engine cylinder [3].to zero-dimensional model the four-stroke diesel engine was developed investigate the effects of early inlet valve closure and increased charge pressure on the engine specific. The properties of the working medium are determined according to Woschni [6] and Jankov [7]
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