This content is not included in your SAE MOBILUS subscription, or you are not logged in.
Transient Emission Characteristics of a Light Duty Commercial Vehicle Powered by a Low Compression Ratio Diesel Engine
ISSN: 0148-7191, e-ISSN: 2688-3627
Published July 21, 2021 by SAE International in United States
Adopting low compression ratio (LCR) can be a viable approach to meet the stringent emission regulations since it can simultaneously reduce the oxides of nitrogen (NOx) and soot emissions. However, major shortcomings with the LCR approach include higher unburned hydrocarbon (HC) and carbon monoxide (CO) emissions, and fuel economy penalty. Further, poor combustion stability of LCR engines at cold ambient and part load conditions may worsen the transient emission characteristics which are least explored in the literature. In the present work, the effects of implementing the low compression ratio (LCR) approach in a mass production light duty vehicle powered by a single cylinder diesel engine are investigated with a major focus on transient emission characteristics. The experimental investigations were conducted in a chassis dynamometer with a stock compression ratio of 18:1 followed by reduced compression ratio of 14:1 and the results have been quantified for the regulatory modified Indian drive cycle (MIDC). The results obtained show that the LCR approach lead to a significant reduction of 25% and 72% in NOx and soot emissions, respectively along with an increase in the HC and CO emissions by a factor of 10 and 2, respectively. Further, there is a fuel economy penalty of upto 11.7% during the overall cycle. The HC, CO and fuel economy penalty are extremely high in the initial phase of the MIDC cycle when the engine is not warmed-up. By optimizing the injection settings, the HC and CO emission penalty could be contained to 94% and 54%, respectively. Moreover, the fuel economy penalty could also be reduced to 5.5%. The paper provides a detailed overview of the transient emission and fuel consumption results of the MIDC cycle along with the reasoning behind the observed results.