SOME EXPERIMENTAL STUDIES ON NOx REDUCTION IN CI ENGINE USING WATER IN DIESEL EMULSION

Abstract

Diesel engines have high fuel efficiency and long record of reliability but these engines emit a significant amount of Oxides of Nitrogen (NOx) and Particulate Matter into the atmosphere. NOx is a combined term for the Mono-nitrogen oxides NO and NO2 (nitric oxide and nitrogen dioxide). These are produced from the reaction of Nitrogen, Oxygen and even Hydrocarbons (during combustion), especially at high temperatures. At high temperature usually above 1600 oC molecular Nitrogen (N2) and Oxygen (O2) in the combustion air disassociate into their atomic states and participate in a series of reactions. Technologies such as Exhaust Gas Recirculation (EGR) and Selective Catalytic Reduction (SCR) can be used to reduce the NOx emission. But to achieve the present emission norms without increasing the cost of the vehicles water in diesel emulsion is the most suitable strategy. In this strategy, some modification in the fuel is done and this can be used along with EGR or SCR to achieve the present emission standards. Water in Diesel emulsion (WiDE) fuel has potential to significantly reduce the formation of NOx and PM in the diesel engine. The emulsion fuel contains water, diesel fuel, and surfactants, to stabilize the system. Reduction of NOx is originated from the reduction of local high temperature due to vaporized water during combustion. The reduction of local high temperature may cause the reduction of reaction rate, which has a possibility of affording a mixing time for better combustion for reducing PM. Formation of Hydroxyl (OH) radical is also helpful to reduce the NOx in the case of water in diesel emulsion. In this study WiDE fuels are prepared by using surfactants (sorbitan monolaurate, polyoxyethylene sorbitan monolaurate, sorbitan monopalmitate, sorbitan monooleate), a major concern is the long-term stability of the emulsion. Emulsion fuels were prepared by using 1%, 2%, 4% of water and 0.5% of surfactant by weight. The Physico-chemical properties were evaluated and experimental procedure conducted using a Kirloskar single cylinder diesel engine. The results are presented by using the graphs which shows the comparison of the emulsion fuels properties with baseline data. Recommendations are given for further studies, including improving the emulsion fuels and considerations for long-term testing as well.