저속 2행정기관에의 밀러 사이클 적용에 관한 연구

Abstract

A concern about environmental pollution in advanced countries is rising, since environmental pollution including global warming, which means a gradual increase in the mean temperature of the globe in the past 100 years, ozone depletion and acid rain is becoming severe. As an example, IMO has begun to tighten the regulations on NOx emissions from ships in ECAs since 2016, the ECAs have expanded to a broader range from the coasts of Europe and the US to apply the Tier III regulations more broadly. In addition to NOx emissions, the regulations on SOx, PM and BC emissions are intensifying, as well. With exhaust emission regulation being strict, various studies to reduce air pollution by harmful exhaust are already on the way.

As part of this research, there are various ways, which are water injection, water emulsion, SCR, EGR, etc. An application of the Miller cycle has been known as a solution of these issues on the 4-stroke diesel engines. The way is valve timing to influence to compression rate in substance. In other words, it means that compression stroke starts at closing moment of inhalation valve, equally expansion power finishes at opening moment of exhaust valve in 4-stroke cycle engine. Therefore Miller Cycle is able to get greater valid expansion power as well as reduce friction or resistance loss of compression stroke by adjusting valve timing.

However, it has a problem that hard to apply at 2 stroke marine diesel engine with regard to raise expansion ratio by intake valve since the intake valve isn’t equipped. As a countermeasure, evaluate the Miller effect by using a method for controlling the exhaust valve timing, if the Miller effect can be achieved by changing the exhaust valve timing, may be taken in a variety of performance improvements, such as performance and Emission problems.

Therefore, analyze features are demanded when Miller Cycle is applied to 2 stroke marine diesel engine and set emission valve timing to be optimum conditions at the fuel consumption rate & NOx emission aspect as well as review other factors affecting results. However, due to technical & economical difficulties it was hard to get the datas from existing 2 stroke marine diesel engine hence grasp theoretical features through computer simulation.

This study has its aim to report results of study on the analysis of each factor influencing on the performance of engine and study on the analysis related to methods to enhance efficiency. In addition, this study has applied the Miller's effect by utilizing program predicting emission and performance of large-sized two-stroke engine.