Effects of Charge Density and Oxygen Concentration on Combustion Process: Efficiency and Emissions in a High Load Operation Diesel Engine State Key Laboratory of Engines, Tianjin

Format:

Conference/Event

Author/Creator:

Lu, Lu, author.

Contributor:

Pei, Yiqiang

Su, Wanhua

Yu, Wenbin

Conference Name:

SAE 2013 World Congress & Exhibition (2013-04-16 : Detroit, Michigan, United States)

Language:

English

Physical Description:

1 online resource

Place of Publication:

Warrendale, PA SAE International 2013

Summary:

In this study, experimental and simulation investigations on theroles of charge density (ρtdc),temperature (Τtdc) at the top deadcenter and oxygen concentration (φO2) on the combustion paths,emissions and thermal efficiency of a high load operation dieselengine were conducted. Experimental engine was a modifiedsingle-cylinder engine equipped with variable mechanisms of boost,exhaust gas recirculation (EGR) and intake valve closing timing(IVCT) to regulate the Ptdc, φO2and Τtdc. Simulations of enginecombustion processes were performed with an ECFM-3Z combustionmodel.The results revealed that higherPtdc, leading to lower overallfuel/oxygen equivalence ratio (Φm), enhanced the rate ofmixing and chemical reaction and benefited improvement of thethermal efficiency. It was found that increasing charge densityplayed two opposite roles in NOx formation: one wasinhibiting combustion temperature rise due to increased total heatcapacity of the charge and another was increasing the airentrainment rate resulting mainly in raising mixture temperature.The role of reduced φ\dO₂ by using EGR was essentially to decreasethe chemical reactivity of the fuel/gas mixture and to retard thephase of heat release rather than to increase heat capacity and tolower mixing rate. A phenomenon of formation and maintenance of alarge amount of incomplete combustion products, id est, CO, was foundin the high load operation engine during the combustion process andwas named as "cold storage of carbon-monoxide," whichretarded the heat release phase and decreased the burning gastemperature, which led to decreased NOx emissions. Itwas also found that the engine exhaust soot correlated with theamount of the "cold storage of CO"

Notes:

Vendor supplied data

Publisher Number:

2013-01-0895

Access Restriction:

Restricted for use by site license