scholarly journals Effect of LP-EGR on the Emission Characteristics of GDI Engine

Machines ◽  
2021 ◽  
Vol 10 (1) ◽  
pp. 7
Author(s):  
Diming Lou ◽  
Guokang Lou ◽  
Bo Wang ◽  
Liang Fang ◽  
Yunhua Zhang
Keyword(s):  
High Speed ◽  
Load Condition ◽  
Exhaust Gas Recirculation ◽  
Gasoline Direct Injection ◽  
Emission Characteristic ◽  
Exhaust Gas ◽  
Particulate Emission ◽  
Gdi Engine ◽  
Gas Recirculation ◽  
Co Emission

Exhaust gas recirculation (EGR) can improve the fuel economy of gasoline direct-injection (GDI) engines, but at the same time it will have a significant impact on emissions. In this paper, the effects of low-pressure exhaust gas recirculation (LP-EGR) and its rate on the main gaseous and particulate emission characteristic of a GDI engine were investigated. The results showed that the particle size distribution of the GDI engine presented bimodal peaks in nucleation and accumulation mode, and the nucleation mode particles comprised the vast majority of the total particles. The effect of LP-EGR on emissions depended on the engine conditions. At low and medium speed, the particle emissions increased with the increase in the EGR rate, while at high speed, a reduction in the particle emission was observed. When the engine operated in full load condition, an increase in the EGR rate reduced the particle number (PN) concentration significantly, but increased the particle mass (PM) concentration. In terms of the gaseous emission, the EGR could reduce as much as 80% of the NOx emission; however, the total hydrocarbons (THC) emission presented an increased trend, and the maximum increase reached 23.5%. At low and medium loads, the EGR could reduce the CO emission, but at high load, the CO emission worsened with the EGR.

Characterization of temporal variations and feedback timescales of exhaust gas recirculation gas properties using high-speed diode laser absorption spectroscopy for next-cycle control of cyclic variability

2018 ◽  
Vol 20 (8-9) ◽  
pp. 945-952
Author(s):  
Gurneesh S Jatana ◽  
Brian C Kaul
Keyword(s):  
High Speed ◽  
Control Strategies ◽  
Direct Injection ◽  
Exhaust Gas Recirculation ◽  
Gasoline Direct Injection ◽  
Exhaust Gas ◽  
Recirculation Flow ◽  
Cyclic Variability ◽  
Laser Absorption ◽  
Gas Recirculation

Dilute combustion offers efficiency gains in boosted gasoline direct injection engines both through knock-limit extension and thermodynamic advantages (i.e. the effect of γ on cycle efficiency), but is limited by cyclic variability at high dilution levels. Past studies have shown that the cycle-to-cycle dynamics are a combination of deterministic and stochastic effects. The deterministic causes of cyclic variations, which arise from feedback due to exhaust gas recirculation, imply the possibility of using active control strategies for dilution limit extension. While internal exhaust gas recirculation will largely provide a next-cycle effect (short-timescale feedback), the feedback of external exhaust gas recirculation will have an effect after a delay of several cycles (long timescale). Therefore, control strategies aiming to improve engine stability at dilution limit may have to account for both short- and long-timescale feedback pathways. This study shows the results of a study examining the extent to which variations in exhaust gas recirculation composition are preserved along the exhaust gas recirculation flow path and thus the relative importance and information content of the long-timescale feedback pathway. To characterize the filtering or retention of cycle-resolved feedback information, high-speed (1–5 kHz) CO2 concentration measurements were performed simultaneously at three different locations along the low-pressure external exhaust gas recirculation loop of a four-cylinder General Motors gasoline direct injection engine using a multiplexed two-color diode laser absorption spectroscopy sensor system during steady-state and transient engine operation at various exhaust gas recirculation levels. It was determined that cycle-resolved feedback propagates through internal residual gases but is filtered out by the low-pressure exhaust gas recirculation flow system and do not reach the intake manifold. Intermediate variations driven by flow rate and compositional changes are also distinguished and identified.

scholarly journals Utilizing One-Way Valve to Optimize Turbocharger Performance on a Blended EGR Engine

2021 ◽  
Vol 7 ◽  
Author(s):  
Gaurav Handa ◽  
Bradley Denton ◽  
Sankar Rengarajan ◽  
Christopher Chadwell ◽  
Graham Conway
Keyword(s):  
High Speed ◽  
Internal Combustion Engines ◽  
High Efficiency ◽  
Load Condition ◽  
Exhaust Gas Recirculation ◽  
High Load ◽  
Exhaust Gas ◽  
Personal Transportation ◽  
Gas Recirculation ◽  
Load Conditions

Internal combustion engines will be a part of personal transportation for the foreseeable future. One recent trend for engines has been downsizing which enables the engine to run more favorably over regulatory drive cycles. Another shift due to downsizing is the increase in engine power density which leads to problems with engine knock. One way to reduce the knock propensity of engines is by introducing Exhaust Gas Recirculation (EGR) into the combustion chamber. Exhaust Gas Recirculation also helps improve fuel economy and can reduce NOX emissions. EGR reduces volumetric efficiency which places challenges on the boosting system. LP-EGR helps to lower backpressure and improves scavenging which helps reduce knock and operate at a high efficiency at the low-speed and high-load conditions. At high-speed, and high-load operation however, LP-EGR operation can choke the compressor. This would mean that the turbocharger would need resizing to allow a higher mass flow at these higher speed-load conditions. The HP-EGR helps by reducing the flow rates to the compressor at the higher speed-load conditions which avoids compressor choke and permits a full load performance while retaining a smaller, more transient capable turbocharger. The concept of a one-way valve in the HP-EGR Loop has been explored in this paper. During HP-EGR operation, pressure pulsations drive the intake air back through the HP-EGR Loop and limit the maximum amount of HP-EGR. A one-way valve would prevent any backflow and permit a greater HP-EGR flow for a given average delta pressure. For a given EGR rate, this enables a wider throttle position and thus better controllability at the higher speed-load conditions. Engine testing with the one-way valve suggested that the HP-EGR rate at the high speed/load condition was nearly doubled while reducing the PMEP with an improvement in the Brake Specific Fuel Consumption . Additionally, this led to more reasonable actuator positions in terms of the EGR valve and the intake throttle to ensure better controllability.

A comparative study into the effects of pre and post catalyst exhaust gas recirculation on the onset of knock

2020 ◽  
pp. 146808742096229
Author(s):  
Dominic Parsons ◽  
Simon Orchard ◽  
Nick Evans ◽  
Umud Ozturk ◽  
Richard Burke ◽  
...  
Keyword(s):  
Exhaust Gas Recirculation ◽  
Exhaust Gas ◽  
Engine Combustion ◽  
Low Load ◽  
Fine Control ◽  
Novel Method ◽  
Gdi Engine ◽  
Stochastic Phenomena ◽  
Gas Recirculation ◽  
Onset Angle

Exhaust gas recirculation (EGR) is proven as a valuable technology for controlling knock whilst maintaining lambda one operation, and is also capable of providing efficiency gains at low load. Despite this few studies in the literature address the question of EGR composition effects, namely whether the EGR gas is sourced from before or after the catalyst, and this remains an area which is often overlooked whilst investigating EGR performance. This paper demonstrates a novel method combining experiment air-path emulation and in-depth data processes to compare the effect of EGR catalysis on the angle of knock onset in a 1L GDI engine. Since initial temperature and pressure have a significant impact on knocking behaviour, an artificial boosting rig replaced the turbomachinery. This enabled fine control over the engine boundary conditions to ensure parity between the catalysed and un-catalysed cases. To overcome the difficulty of comparing stochastic phenomena in an inherently variable dataset, a pairing method was combined with Shahlari and Ghandhi’s angle of knock onset determination method to assess the effects of EGR composition on knock onset for EGR rates ranging from 9% to 18%. The air path emulation system stabilised the engine combustion to provide a suitably rich dataset for analysing knock using the pairing method. Catalysed EGR improved the mean knock onset angle by 0.55 CAD, but due to the inherent variability in cylinder pressure data this only equated to a 58.3% chance of a later knock onset angle for catalysed EGR in any given pair of comparative cycles.

scholarly journals Cyclic NO2:NOx ratio from a diesel engine undergoing transient load steps

2019 ◽  
Vol 22 (1) ◽  
pp. 284-294 ◽  
Author(s):  
FCP Leach ◽  
MH Davy ◽  
MS Peckham
Keyword(s):  
Diesel Engine ◽  
High Speed ◽  
Exhaust Gas Recirculation ◽  
Operating Conditions ◽  
Formation Mechanisms ◽  
Exhaust Gas ◽  
Work Cycle ◽  
Wide Range ◽  
Gas Recirculation ◽  
Aftertreatment Systems

As the control of real driving emissions continues to increase in importance, the importance of understanding emission formation mechanisms during engine transients similarly increases. Knowledge of the NO2/NOx ratio emitted from a diesel engine is necessary, particularly for ensuring optimum performance of NOx aftertreatment systems. In this work, cycle-to-cycle NO and NOx emissions have been measured using a Cambustion CLD500, and the cyclic NO2/NOx ratio calculated as a high-speed light-duty diesel engine undergoes transient steps in load, while all other engine parameters are held constant across a wide range of operating conditions with and without exhaust gas recirculation. The results show that changes in NO and NOx, and hence NO2/NOx ratio, are instantaneous upon a step change in engine load. NO2/NOx ratios have been observed in line with previously reported results, although at the lightest engine loads and at high levels of exhaust gas recirculation, higher levels of NO2 than have been previously reported in the literature are observed.

scholarly journals Butanol-gasoline blend and exhaust gas recirculation, impact on GDI engine emissions

Fuel ◽  
2017 ◽  
Vol 208 ◽  
pp. 662-672 ◽  
Author(s):  
C. Hergueta ◽  
M. Bogarra ◽  
A. Tsolakis ◽  
K. Essa ◽  
J.M. Herreros
Keyword(s):  
Exhaust Gas Recirculation ◽  
Exhaust Gas ◽  
Engine Emissions ◽  
Gdi Engine ◽  
Gas Recirculation

Extending Lean and Exhaust Gas Recirculation-Dilute Operating Limits of a Modern Gasoline Direct-Injection Engine Using a Low-Energy Transient Plasma Ignition System

2016 ◽  
Vol 138 (11) ◽  
Author(s):  
James Sevik ◽  
Thomas Wallner ◽  
Michael Pamminger ◽  
Riccardo Scarcelli ◽  
Dan Singleton ◽  
...  
Keyword(s):  
Direct Injection ◽  
Exhaust Gas Recirculation ◽  
Low Energy ◽  
Gasoline Direct Injection ◽  
Combustion Stability ◽  
Exhaust Gas ◽  
Ignition System ◽  
Plasma Ignition ◽  
Gas Recirculation ◽  
Transient Plasma

The efficiency improvement and emissions reduction potential of lean and exhaust gas recirculation (EGR)-dilute operation of spark-ignition gasoline engines is well understood and documented. However, dilute operation is generally limited by deteriorating combustion stability with increasing inert gas levels. The combustion stability decreases due to reduced mixture flame speeds resulting in significantly increased combustion initiation periods and burn durations. A study was designed and executed to evaluate the potential to extend lean and EGR-dilute limits using a low-energy transient plasma ignition system. The low-energy transient plasma was generated by nanosecond pulses and its performance compared to a conventional transistorized coil ignition (TCI) system operated on an automotive, gasoline direct-injection (GDI) single-cylinder research engine. The experimental assessment was focused on steady-state experiments at the part load condition of 1500 rpm 5.6 bar indicated mean effective pressure (IMEP), where dilution tolerance is particularly critical to improving efficiency and emission performance. Experimental results suggest that the energy delivery process of the low-energy transient plasma ignition system significantly improves part load dilution tolerance by reducing the early flame development period. Statistical analysis of relevant combustion metrics was performed in order to further investigate the effects of the advanced ignition system on combustion stability. Results confirm that at select operating conditions EGR tolerance and lean limit could be improved by as much as 20% (from 22.7 to 27.1% EGR) and nearly 10% (from λ = 1.55 to 1.7) with the low-energy transient plasma ignition system.

Exhaust gas recirculation trials with high-speed marine and rail diesel engines

MTZ worldwide ◽  
2006 ◽  
Vol 67 (1) ◽  
pp. 6-9
Author(s):  
Dirk Bergmann ◽  
Christian Philipp ◽  
Helmut Rall ◽  
Rolf Traub
Keyword(s):  
Diesel Engines ◽  
High Speed ◽  
Exhaust Gas Recirculation ◽  
Exhaust Gas ◽  
Gas Recirculation
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