NO_x REDUCTION OF A MEDIUM SPEED DIESEL ENGINE USING A CHARGE AIR MOISTURIZER SYSTEM

摘要

It is well known that water can be used to prevent NO_x formation during a combustion process. It is based on the principle by decreasing flame temperature with increasing the specific heat capacity of combustion air by adding water to a combustion chamber. Introducing water into a charge air enables much more water addition into a combustion chamber than other methods, which can reduce NO_x emission to lower level than the others. The method has also the advantage of low installation cost. In a general water injection system for a charge air only hot water is sprayed into the charge air and vaporized, but more effective means to introduce water into the charge air is needed because only small amount of water is evaporated in hot water injection system. In this study, steam and hot moisturizing water are injected simultaneously. The steam supplies steady additional energy for evaporation of the water and can be vapor by itself. The new method was evaluated for NO_x reduction performance on a medium speed diesel engine. NO_x emission was reduced to 10~38% on the 27~59gram water per kilogram dry air.