Internal and External Measures for Catalyst Light-Off Support

Laible, Thomas; Pischinger, Stefan; Holderbaum, Bastian

doi:10.4271/2015-24-2501

Cited by 3 publications

(1 citation statement)

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“…The last strategy for increasing the EGT is using external heating measures. Dosing liquid fuel or HC directly in the exhaust line upstream of the DOC device 15,16 and using electrically heated catalyst 17,18 have been used for exhaust thermal management. However, the cost and complexity of the electrically heated catalyst limited their use in large volumes.…”

Section: Introductionmentioning

confidence: 99%

Exploring alternative combustion control strategies for low-load exhaust gas temperature management of a heavy-duty diesel engine

Guan

Zhao

Ban

et al. 2018

International Journal of Engine Research

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6The employment of aftertreatment systems in modern diesel engines has become indispensable 7 in order to meet the stringent emissions regulations. However, a minimum exhaust gas 8 temperature (EGT) of approximately 200°C must be reached to initiate the emissions control 9 operations. Low load engine operations usually result in relatively low EGT, which lead to 10 reduced or no exhaust emissions conversion. In this context, this study investigated the use of 11 different combustion control strategies to explore the trade-off between EGT, fuel efficiency 12 and exhaust emissions. 13 14The experiments were carried out on a single cylinder common rail heavy-duty diesel engine 15 at a light load of 2.2 bar indicated mean effective pressure. Strategies include the late intake 16 valve closure (LIVC) timing, intake throttling, late injection timing (Tinj), lower injection 17 pressure (Pinj), and internal exhaust gas recirculation (iEGR) as well as external EGR (eEGR) 18 were investigated. Results showed that the use of eEGR and lower Pinj were not effective in 19 increasing EGT. Although the use of late Tinj could result in a higher EGT, the delayed 20 combustion phase led to the highest fuel efficiency penalty. Intake throttling and iEGR allowed 21 for an increase in EGT by 42°C and 52°C at the expense of 7.2% and 17% fuel consumption 22 penalties, respectively. In comparison, LIVC strategy achieved the best trade-off between EGT 23 and ISFC, increasing the EGT by 52°C and the fuel consumption penalty by 5.3% while 24 reducing NOx and soot emissions simultaneously. When the IVC timing was delayed to after 25 -107 CAD ATDC, however, the combustion efficiency deteriorated, and hence very high HC 26 and CO emissions. This could be overcome by combining iEGR with LIVC to increase the in-27 cylinder combustion temperature for a more complete combustion. The results demonstrated 28 that the "LIVC + iEGR" strategy can be the most effective means, increasing the EGT by 62°C 29 with small penalty in the fuel consumption of 4.6% and soot emission reduction by 85%. 30 Meanwhile, maintaining high combustion efficiency as well as low HC and CO emissions of 31 diesel engines. 32 Keywords 33 Heavy-duty diesel engine, variable valve actuation, late intake valve closing, internal EGR, 34 exhaust temperature, exhaust emissions 35 36 42 combustion produces a large amount of particulate matter (PM) in the fuel rich burning region 43 and high concentration of nitrogen oxide (NOx) in the high temperature zones [1]. In order to 44 meet the Euro VI or equivalent emission regulations of 0.4 g/kW•h NOx and 0.010 g/kW•h PM 45 [2], significant reduction of these pollutants by in-cylinder combustion technologies and 46 emission control aftertreatment systems are required. 47 48 Advanced combustion modes such as Homogeneous Charge Compression Ignition (HCCI), 49 Pre-mixed Charge Compression Ignition (PCCI), and Low Temperature Combustion (LTC) 50 are able to achieve a reduction in NOx and soot simultaneously, through reducing the peak in-51...

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