Injection Strategy Optimization for a Light Duty DI Diesel Engine in Medium Load Conditions with High EGR rates

Effects of active species induced by injected NO on the reduction of diesel NO_x emission

“…To understand those experimental results, it is necessary to find what reactions occur in flames with various equivalence ratios. There are a number of detailed studies simulating combustion in diesel engines with exhaust gas recirculation (EGR) (Lee and Huh, 2014, Johansson, et al, 2013, Helmantel and Golovitchev, 2009, but it is difficult to apply their findings to our results because the NO concentrations at the intake were much lower in those studies than the ones in our experiments, and because the oxygen concentration at the engine intake varies with changing EGR ratio. There are also a number of analytical studies about burners, investigating premixed flames with NO initially mixed (Knyazkov, et al, 2009, Feng, et al, 1998, Williams and Fleming, 1994, Branch, et al, 1991, Zabarnick, 1992Etzkorn, et al, 1992).…”

Diesel aerosols and gases in underground mines: guide to exposure assessment and control.

“…In conventional diesel combustion, almost any attempt to lower NO X emissions through incylinder techniques results in an increase in DPM, and the converse is true as well. Referred to as the "NO x /DPM" or "NO X /PM" tradeoff, this correlation is controlled by the fact that NO X formation increases at higher combustion temperatures and lean conditions, while DPM mass formation (driven by increased EC formation), will increase at lower combustion temperatures and rich conditions [Horibe and Ishiyama 2009;Heywood 1988c;Majewski and Khair 2006b;EPA 2001a;Helmantel and Golovitchev 2009;Kook et al 2005]. Because of this correlation, it is very difficult to simultaneously reduce NO X and DPM without combining various in-cylinder and aftertreatment technologies.…”

“…From an emissions perspective, the compression of charge air leads to leaner conditions within the cylinder during combustion (or situations where the fuel to air ratio is low), which promotes efficient, higher temperature oxidation of the fuel. Under these conditions, DPM formation is limited at the expense of increased NO X gas emissions [Helmantel and Golovitchev 2009]. In addition, the compression of charge air may increase turbulence within the cylinder during induction, enhancing the mixing between fuel and air [Majewski and Khair 2006c] and further reducing DPM formation.…”

Potential of multiple injection strategies implementing the after shot and optimized with the design of experiments procedure to improve diesel engine emissions and performance

“…When heavy EGR rates (EGR fractions around 60%) are applied to control NO x , most of the after injection cases generate an increment in the soot and in HC and CO, because the after injected fuel cannot burn well due to the poor oxygen concentration and delayed ignition [28]. This effect is in contrast with the main effect of after injection under moderate EGR rates (EGR fractions in the 25÷40 range).…”