Knocking combustion in spark-ignition engines

The review paper summarizes major developments in vehicular emissions regulations and technologies in 2013. First, the paper covers the key regulatory developments in the field, including proposed light-duty (LD) criteria pollutant tightening in the US; and in Europe, the continuing developments towards real-world driving emissions (RDE) standards. Significant shifts are occurring in China and India in addressing their severe air quality problems. The paper then gives a brief, high-level overview of key developments in fuels. Projections are that we are in the early stages of oil supply stability, which could stabilize fuel prices. LD and HD (heavy-duty) engine technology continues showing marked improvements in engine efficiency. Key developments are summarized for gasoline and diesel engines to meet both the emerging NOx and GHG regulations. HD engines are or will soon be demonstrating 50% brake thermal efficiency using common approaches. NOx control technologies are then summarized, including SCR (selective catalytic reduction) systems and SCR filter developments. Emphasis is on low-temperature deNOx and integration of components and control. Diesel PM (particulate matter) reduction technologies are evolving around the behavior of ash deposits and SCR integration. Filters for direct injection gasoline applications are developing very rapidly, and in some cases the back pressure, light-off characteristics, and emissions reductions are very similar to standard three way catalysts (TWCs). Oxidation catalysts mainly involve developments towards stubborn problems, like low-temperature performance with exhaust with high hydrocarbon and CO, and methane oxidation. Finally, the paper discusses some key developments in gasoline gaseous emission control, focusing on matching engine calibration with emissions system characteristics; and on lean burn gasoline emissions control. CITATION: Johnson, T., "Vehicular Emissions in Review," SAE Int. J. Engines 7(3):2014, doi:10.4271/2014-01-1491. 2014-01-1491 Published 04/01/2014 Copyright © 2014 SAE International doi:10.4271/2014-01-1491 saeeng.saejournals.org 1207 This paper is posted on this website with permission from SAE International. It may not be shared, downloaded, duplicated, or transmitted in any manner without prior written permission from SAE.

https://www.corning.com/media/worldwide/cet/documents/SAE_2014-01-1491.pdf

Vehicular Emissions in Review

Smoothing HCCI Heat-Release Rates Using Partial Fuel Stratification with Two-Stage Ignition Fuels

A Scania 13 1 engine modified for single cylinder operations was run using nine fuels in the boiling point range of gasoline, but very different octane number, together with PRF20 and MK1-diesel The eleven fuels were tested in a load sweep between 5 and 26 bar gross IMEP at 1250 rpm and also at idle (25 bar IMEP, 600 rpm) The boost level was proportional to the load while the inlet temperature was held constant at 303 K For each fuel the load sweep was terminated if the ignitibility limit was reached A lower load limit of 15 and 10 bar gross IMEP was found with fuels having an octane number range of 93-100 and 80-89 respectively, while fuels with an octane number below 70 were able to run through the whole load range including idle A careful selection of boost pressure and EGR in the previously specified load range allowed achieving a gross indicated efficiency between 52 and 55% while NOx ranged between 01 and 05 g/kWh At high load, in the worst case, the nine gasolines showed 05 FSN of soot while diesel showed 28 FSN In the paper it is shown that chemical reasons, rather than mixing, are behind this substantial gap With the two best fuels, the brake parameters were estimated It was found that soot was low, and in some cases below both the EU VI and US10 regulations NOx was always below EU VI, and in some cases was only slight above US10 regulations At high loads the estimated brake efficiency was roughly 50% in both cases All the results were achieved keeping the maximum pressure rise rate within acceptable levels (Less)

An advanced internal combustion engine concept for low emissions and high efficiency from idle to max load using gasoline partially premixed combustion

Fuel reforming in internal combustion engines

Dedicated EGR: A New Concept in High Efficiency Engines

Synergies between High EGR Operation and GDI Systems

The Effect of Hydrogen Enrichment on EGR Tolerance in Spark Ignited Engines

Modern gasoline engines face fuel-efficiency challenges due to inherent limitations including knock, pumping losses, and fuel enrichment. The addition of exhaust-gas recirculation (EGR) has been sh...

Cooled exhaust-gas recirculation for fuel economy and emissions improvement in gasoline engines:

SwRI has developed a new technology concept involving the use of high EGR rates coupled with a high-energy ignition system in a gasoline engine to improve fuel economy and emissions. Based on a single-cylinder study [1], this study extends the concept of a high compression ratio gasoline engine with EGR rates > 30% and a high-energy ignition system to a multi-cylinder engine. A 2000 MY Isuzu Duramax 6.6 L 8-cylinder engine was converted to run on gasoline with a diesel pilot ignition system. The engine was run at two compression ratios, 17.5:1 and 12.5:1 and with two different EGR systems - a low-pressure loop and a high pressure loop. A high cetane number (CN) diesel fuel (CN=76) was used as the ignition source and two different octane number (ON) gasolines were investigated - a pump grade 91 ON ((R+M)/2) and a 103 ON ((R+M)/2) racing fuel. The results showed that the stock, 17.5:1 compression ratio (CR) was unsuitable for operation except at light (<50%) loads with the peak BMEP's of 700 kPa on 91 ON fuel and 1000 kPa on 103 ON fuel. The engine-out BSNOx ranged from 0.76 to 2.35 g/kW-hr with brake thermal efficiencies (BTE) between 26-38% over the load range. At 12.5:1 CR, the peak BMEP's were much higher, 1260 kPa on 91 ON and 1720 kPa on 103 ON. The engine-out BSNOx ranged from 0.03 to 2.10 g/kW-hr with BTE's between 23-37% over the load range. With the addition of a 3-way catalyst, made possible by stoichiometric operation, the possibility exists for extremely low emissions at diesel-like fuel economies. These results show that the technology has the potential to return the efficiency of a modern diesel engine (equipped with aftertreatment devices) with the low emissions of a light-duty gasoline engine.

Terry Alger

Papers

Dedicated EGR: A New Concept in High Efficiency Engines

Synergies between High EGR Operation and GDI Systems

The Effect of Hydrogen Enrichment on EGR Tolerance in Spark Ignited Engines

Cooled exhaust-gas recirculation for fuel economy and emissions improvement in gasoline engines:

The Heavy Duty Gasoline Engine - A Multi-Cylinder Study of a High Efficiency, Low Emission Technology