Effect of Ultra-Cooled EGR and Retarded Injection Timing on Low Temperature Combustion in CI Engines IIT Bombay, Mumbai-400 076, India

Format:

Conference/Event

Author/Creator:

Brijesh, Brijesh, author.

Contributor:

Chowdhury, A.

Sreedhara, S.

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 work, optimization of various parameters, such asinjection timing, compression ratio (CR) and amount of ultra-cooledexhaust gas recirculation (EGR) has been done for a variablecompression ratio engine. The CR can be adjusted dynamically bychanging the clearance volume through a tilting cylinder blockarrangement. An EGR system, suitable for achieving ultra-cooled aswell as treated EGR and large range of flow rates, has beenimplemented. Taguchi analysis was employed to carry out minimumnumber of experimental runs and still get the essence of largenumber of test cases. Effect of these parameters on engineperformance and exhaust emissions has also been studied with thehelp of signal to noise (SN) ratio analysis. Flatter and wider HRRtraces were observed in previous work of Brijesh and others, indicatinga low temperature combustion (LTC) mode for the runs havingoptimized input parameters. Simultaneous reduction ofNOx and PM were achieved for runs with optimizedparameters in the first stage, but HC and CO emissions wereslightly higher compared to the base run.During the current study, second stage of optimization has beencarried out for further reduction in emissions with improvedperformance. Combination of input parameters selected for run 4 ofsecond stage optimization, id est, -15 CAD aTDC injection timing, 18CR, 220 bar injection pressure and 25% ultra-cooled EGR seems to bethe optimum set of operating parameters for this engine. LTC modehas been achieved with these optimum operating parameters. Brakethermal efficiency was also improved by around 12% compared to thatwith the base operating parameters. The optimization methodindicates that LTC achieved by the combination of retardedinjection timings and moderate rate of ultra-cooled EGR, alsoprovides better efficiency even with low injection pressure (~ 220bar). Increase in HC and CO emissions had been reported as a majorissue with LTC in various literatures. But in the present work,reduction in CO and only a slight increase in HC emissions wereobserved even with LTC mode of combustion. It was mainly possibledue to moderate use of ultra-cooled EGR. Compared to conventionalEGR, lower amounts of ultra-cooled EGR were sufficient to achievesimilar reduction in NOx and PM with reduced HC, CO. Useof ultra-cooled EGR is beneficial in achieving LTC even at higherload conditions. Additionally, decrease in pressure rise rate (PRR)and hence engine noise was also observed

Notes:

Vendor supplied data

Publisher Number:

2013-01-0321

Access Restriction:

Restricted for use by site license