Experimental analysis of NOx reduction through water addition and comparison with exhaust gas recycling

• Published in: Energy (Oxford) Vol. 168; pp. 737 - 752
• Main Authors: Serrano, J., Jiménez-Espadafor, F.J., Lora, A., Modesto-López, L., Gañán-Calvo, A., López-Serrano, J.
• Format: Journal Article
• Language: English
• Published: Oxford Elsevier Ltd 01.02.2019; Elsevier BV
• Subjects: Air pollution control; Blurring; Carbon monoxide; Combustion chambers; Combustion products; Dependence; Diesel; Diesel engine; Diesel engines; EGR; Emission standards; Engine performance; Exhaust emissions; Exhaust gases; Heat release; Heat release rate; Heat transfer; Injection; Intake manifolds; Nitrogen oxides; Particulate emissions; Particulate matter; Pollutant emissions; Real gases; Reduction; Soot; Thermal capacity; Water injection; Water injection; EGR; Pollutant emissions; Diesel engine; Heat release; Engine performance
• ISSN: 0360-5442; 1873-6785
• DOI: 10.1016/j.energy.2018.11.136

The diesel engine requirements regarding the reduction of exhaust emissions, especially nitrogen oxide (NOx) and particulate matter (PM) are becoming more stringent year by year. A current method used for NOx control is exhaust gas recirculation (EGR). However, this approach significantly increases the production of soot for medium and high rates. Water addition can also be used for NOx control, achieving 50% NOx reduction rates in relation to EGR with a lower production of soot and without additional carbon monoxide (CO) and hydrocarbons (HC) substantially. This paper analyses the weaknesses and the strengths of adding water into the intake manifold with a flow-blurring injector for NOx reduction on a current technology diesel engine with multiple injection thorough a proprietary tool for heat release rate that considered real gas properties. A reduction of NOx emissions around 60–70% was achieved with water injection at different loads and speeds. Besides, a clear relationship was established between the minimum attainable NOx emission and the thermal capacity of the load (air plus water), this result stablish the hard relationship between NOx formation and combustion chamber temperature and therefore shows the strong dependence of the Zeldovich mechanism. •Effects of adding water into the intake manifold with a flow-blurring injector.•NOx reduction on a current technology diesel engine with multiple injection.•The NOx emission was reduced by adding water in comparison to the EGR.•A reduction of NOx emissions around 60–70% was achieved with water injection.•The minimum attainable NOx emission and the thermal capacity are related.