Possibilities of Simultaneous In‐Cylinder Reduction of Soot and NO_x Emissions for Diesel Engines with Direct Injection

Abstract

Recommended by Toshinori WatanabeUp to now, diesel engines with direct fuel injection are the propulsion systems with the highest efficiency for mobile applications. Future targets in reducing CO 2 -emissions with regard to global warming effects can be met with the help of these engines. A major disadvantage of diesel engines is the high soot and nitrogen oxide emissions which cannot be reduced completely with only engine measures today. The present paper describes two different possibilities for the simultaneous in-cylinder reduction of soot and nitrogen oxide emissions. One possibility is the optimization of the injection process with a new injection strategy the other one is the use of water diesel emulsions with the conventional injection system. The new injection strategy for this experimental part of the study overcomes the problem of increased soot emissions with pilot injection by separating the injections spatially and therefore on the one hand reduces the soot formation during the early stages of the combustion and on the other hand increases the soot oxidation later during the combustion. Another method to reduce the emissions is the introduction of water into the combustion chamber. Emulsions of water and fuel offer the potential to simultaneously reduce NO x and soot emissions while maintaining a high-thermal efficiency. This article presents a theoretical investigation of the use of fuel-water emulsions in DI-Diesel engines. The numerical simulations are carried out with the 3D-CFD code KIVA3V. The use of different water diesel emulsions is investigated and assessed with the numerical model.

Experimental Assessment on Exploiting Low Carbon Ethanol Fuel in a Light-Duty Dual-Fuel Compression Ignition Engine

“…First, as shown in Figure 6, a longer premixed phase allowed better PM oxidation. The locally available oxygen content was a key parameter to allow the PM oxidation during combustion process as also reported by Wagner et al [30]. The use of oxygenated biofuels [31], like ethanol, combined with the high level of FSR achieved (Figure 6) led to less fuel-rich zones hence to a limited PM formation [32].…”

Comparison of Water-in-Oil Emulsion Atomization Characteristics for Low- And High-Capacity Pressure-Swirl Nozzles

“…One of the main advantages of using water in combustion is that it reduces combustion temperatures, and as a result, NO x emissions, by its large enthalpy of va- (Wagner et al, 2008). This helps reduce thermal stress on the components and prolongs the integrity of the materials in the combustion system (Tsenev, 1983).…”

Optimization of methanol powered diesel engine: A CFD approach

“…On the other side, water particles are converted in the shape of tiny particles, which passes to improve air fuel mixing. Simultaneously, soot emissions get also reduced due to proper air fuel mixing [32][33][34][35][36][37][38] and enhanced air fuel mixing reduces CO and HC mass fraction, see Fig. 7(b).…”

“…In some studies, NO and soot emissions can be brought down simultaneously by water emulsion method [33][34][35]. The basic cause of emission reduction is the better air fuel mixing due to micro combustion of water particles followed by spray optimization [36][37][38]. Although, water emulsion has been used widely with pure diesel for emission reduction, but it will be interesting to analyze the micro explosion property of water in diesel -methanol blended diesel engine.…”