ABSTRACT

DI diesel engine is better than petrol engine in terms of fuel consumption and CO₂  emission. But diesel engine has higher emissions like NOx, PM and exhaust odor. Among the various exhaust emission problems of DI diesel engine, odor is still a prominent exhaust emission problem. Reduction of exhaust odor can be done mainly in three ways. One of them is to optimize the engine parameters. The other is that the use of alternative fuels. The last one is exhaust gas after treatment. It is also of two types. One is to use the catalyst system. The catalyst system works only at high temperature condition, i.e. when the vehicle is in running condition (under load). The other is the non-catalytic type system like charcoal-absorption system, water-washing system, air-dilution system or others. Water washing system is a good option of odor reduction at idling. Last few years thesis report on odor reduction by water washing system showed that water washing system can reduce exhaust odor around 0.75 points. This thesis report focuses on the temperature and pressure effect of the water washing system. The experiment was performed with 20 liter and 112 liter water washing system in which cold water was used and the odor was reduced about 0.5 points for smaller one and more than 0.75 points for larger one. Some combination of water washing and air dilution systems were also used. It was found that odor was reduced about 1 points with the air dilution system combined with water washing system. It was also found that odor level was reduced about 1.25 points with the use of water washing system first then air dilution system. The combination of water washing system and air dilution system not only reduces odorous component but also reduces other emission components like CO, NOx, etc. It also increases eye irritation time which also indicates reduction in irritating components. It was found that CO, NOx, odor and eye irritation were reduced about 90%, 93%, 1.25 points and 96% respectively with the combination of these two systems. 

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