抄録
By 2016, under the IMO Tier III rules, NOx emissions from ships sailing in emission control areas (ECA) should decrease by more than 80% relative to IMO Tier I levels. In this study, in order to reduce NOx emissions from marine diesel engines, a low-oxygen and high-humidity system for suction air was connected to the suction line of a high-speed marine diesel engine, and the influence of oxygen density and moisture content in suction air on NOx emission was investigated. The following results were clarified. (1) NOx emission decreases with a decrease in oxygen density for each load factor, and it is necessary to adjust the oxygen density to 17% or less to comply with Tier 3 regulations. (2) NOx emission decreases because oxygen density decreases with an increase in moisture content. The regulations can be complied with by adjusting the humidity of suction air to 16 mol%. (3) NOx emission can be effectively reduced by decreasing both oxygen density and suction air humidity, taking into account the operating conditions of the engine.
