Effects of EGR transient operation on emissions and performance of automotive engines during RDE cycles

Research output: ThesisDoctoral Thesis

Abstract

World wide awareness of pollutant emissions from automotive industry has become a hot topic these days. As a repercussion of this, the emission regulations are getting more stringent. New methods of homologation are being considered other than standardized cycles considering the real driving behavior on the road. EGR is one of the proven and well tested strategies in steady state within the specific operating range of the engine. However, taking into account the challenges from the emission point of view of upcoming real driving emissions, new strategies are needed to develop with respect to dynamic operations.
This dissertation focuses on implementation of different EGR systems during dynamic operations of turbocharged diesel engine. Driving cycle analysis is
carried out to identify the specific and frequent transient operations on newly developed dynamic cycles like WLTC and RDE. Those transients are imitated individually on the diesel engine test bench. This study reveals the dynamic behavior of a turbocharged diesel engine during transient operation with and without EGR of different types. High frequency gas analyzers are used to
track the instantaneous CO2 and NOx concentration respectively at the in- take and exhaust lines of the engine. Trends in the pollutant formation are
determined. Studies reveled that, implementation of EGR can reduce around 20-60% of NOx emission during transients with less than 5% of torque penalty. The LPEGR is more effective at the full load as well as transient operations. A parametric study is carried out with EGR valve actuation during various type of transients, quantifying the transportation delays, NOx concentration and particulate matter. The best suited valve control is proposed, which can
be helpful for transient calibration of a turbocharged diesel engine. The trade- off between the performance and emission during EGR transients is pointed
out after all. Additionally, EGR split optimization using 1D simulations is
carried out to find the best operating condition with minimum pollutant for- mation. The faster algorithm to find out the optimum split is proposed to
reduce around 80% of the time required by traditional approaches like DOE or genetic algorithm. Finally, the simple quasi steady NOx model is proposed to predict the transient emissions in real driving conditions to support the research line.
Original languageEnglish
QualificationPhD
Awarding Institution
  • Universitat Politecnica de Valencia
Supervisors/Advisors
  • Galindo, Jose, Supervisor, External person
Place of PublicationValencia, Spain
Publication statusPublished - 2020

Keywords

  • EGR
  • emissions
  • transient operation
  • automotive engines
  • RDE cycles

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