Lean Burn Versus EGR S. I. Engine 951902

Lean burn and EGR concepts are being used increasingly in spark-ignition engines. Compared with a stoichiometric petrol engine, however, these dilution concepts are said to give a certain reduction in power output, in particular with higher EGR ratios or under lean mixtures near the minimum flammability limit. Some of the reduction can be recovered by correctly optimizing the MBT, and increasing the intake pressure which in addition reduces the pumping losses. In this work, experimental and theoretical studies of engine performance and emissions have been carried out with special emphasis on the combustion process. These have been analyzed from both combustion images in the early stages of the flame kernel development, and from the pressure-time history. Simultaneous measurements of engine operating conditions, pressure traces and sequences of combustion images have been made in a single-cylinder four-stroke engine. The early stages of the combustion have been analyzed using image analysis techniques. From the pressure time history the actual instantaneous flame speed has been derived for the main burn phase. The experimental part includes stoichiometric and lean burn operating conditions, while the simulation extends the scope into th studying of EGR. The detailed spark ignition engine simulation predicts the effects of EGR ratio, flame speeds, ignition timing and the lean equivalence ratio on the engine performance and on the emissions of CO, HC and NOx.


Subscribers can view annotate, and download all of SAE's content. Learn More »


Members save up to 17% off list price.
Login to see discount.
Special Offer: Download multiple Technical Papers each year? TechSelect is a cost-effective subscription option to select and download 12-100 full-text Technical Papers per year. Find more information here.
We also recommend:

Direct Visualization of Combustion in an E85-Fueled DISI Engine under Various Operation Conditions


View Details


Cyclic Variations of Initial Flame Kernel Growth in a Honda VTEC-E Lean-Burn Spark-Ignition Engine


View Details


A Study on Natural Gas Fueled Homogeneous Charge Compression Ignition Engine - Expanding the Operating Range and Combustion Mode Switching


View Details