Investigation on the Effects of Internal EGR by Variable Exhaust Valve Actuation with Post Injection on Auto-ignited Combustion and Emission Performance

Abstract

Variable valve mechanisms are usually applied to a gasoline combustion engine to improve its power performance by controlling the amount of intake air according to the operating load. These mechanisms offer one possibility of resolving the conflict of objectives between a further reduction of raw emissions and an improvement in fuel efficiency. In recent years, variable valve control systems have become extremely important in the diesel combustion engine. Importantly, it has been shown that there are several potential benefits of applying variable valve timing (VVT) to a compression ignition engine. Valve train variability could offer one option to achieve the reduction goals of engine-out emissions and fuel consumption. The aim of this study was to investigate the effects on part load combustion and emission performance of internal exhaust gas recirculation (EGR) by variable exhaust valve lift actuation using a cam-in-cam system, which is an electronically variable valve device with a variable inside cam retarded to about 30 degrees. Numerical simulation based on GT-POWER has been performed to predict the NO x reduction strategy at the part load operating point of 1200 rpm in a four-valve diesel engine. A GT-POWER model of a common-rail direct injection engine with internal EGR was built and verified with experimental data. As a result, large potential for reducing NO x emissions through the use of exhaust valve control has been identified. Namely, it is possible to utilize heat efficiently as recompression of retarded post injection with downscaled specification of the exhaust valve rather than the intake valve, even if the CIC V1 condition with a reduction of the exhaust valve has a higher internal EGR rate of about 2% compared to that of the CIC V2 condition.

Tribological Assessment of Aluminum Cylinder Material for Piston Compressors in Trucks and Buses Brake Systems

“…The set goals could be achieved by applying modern technologies in order to optimize combustion and tribological processes [4][5][6][7][8][9][10].…”

Improving Thermal Efficiency of Internal Combustion Engines: Recent Progress and Remaining Challenges

“…It was also observed that the use of iEGR moderated combustion by delaying the ignition time, thus eliminating the oscillations of the in-cylinder pressure [120]. Cho et al [121] reported that the variable exhaust valve actuation with iEGR in diesel engines was beneficial for post-injection.…”

Numerical Investigation and Multi-Objective Optimization of Internal EGR and Post-Injection Strategies on the Combustion, Emission and Performance of a Single Cylinder, Heavy-Duty Diesel Engine

“…In addition, it has been stated that post-injection improves soot oxidation by increasing the probability of the fuel finding available oxygen. Cho et al [22] numerically studied the effect of iEGR application through recompression by reducing exhaust valve lift and duration and post-injection on emission and performance of a 4-cylinder direct injection diesel engine. Their findings showed that the iEGR by recompression is efficient in utilizing heat energy by increasing the EGR rate by about 10%.…”