Injection of a H2O2/water solution into the combustion chamber of a direct injection diesel engine and its effect on soot removal

✍ Scribed by Berthold Fanz; Paul Roth

• Publisher: Elsevier Science
• Year: 2000
• Tongue: English
• Weight: 214 KB
• Volume: 28
• Category: Article
• ISSN: 1540-7489
• DOI: 10.1016/s0082-0784(00)80333-1

✦ Synopsis

Hydrogen peroxide (H 2 O 2 ) dissolved in water was injected into the combustion chamber of a direct injection (DI) diesel engine at different crank angles. Its effect on the general combustion characteristics was followed by crank angle (CA) resolved pressure and OH radiation measurements inside the combustion chamber. The influence on soot mass in the exhaust gas flow was measured by the Bosch Smoke Number, which is the standard measurement technique in internal combustion engine research. Additionally, the concentrations of unburned hydrocarbons (HC) and nitric oxides (NO x ) were recorded by a gas analyzer.

For both, the spray of H 2 O 2 /water and pure water, a clear decrease in soot emission was observed for early injection at crank angles ‫04מ‬Њ Ͻ CA Ͻ ‫01מ‬Њ before top dead center (BTDC), which is associated with an increase in the exhaust gas HC concentration. For these conditions, the soot removal is mainly an effect of compressed air cooling, which increases the induction time of the diesel spray, thus resulting in a shift toward more premixed combustion. At injection crank angles CA Ͼ ‫01ם‬Њ, the water and the H 2 O 2 / water sprays show an opposite behavior with respect to the exhaust gas soot. The in-cylinder measurements clearly show an increase of OH radiation during cycles with H 2 O 2 /water injection compared to the standard engine conditions. The H 2 O 2 decomposition product OH influences the chemistry of the in-cylinder soot oxidation, which results in a decrease of the soot mass in the engine exhaust gas flow. Concentrations of HC and NO x are not significantly affected. The addition of pure water causes an increase in the exhaust gas soot for spray injection crank angles CA Ͻ ‫01ם‬Њ.