In-cylinder studies of the effects of CO2 in exhaust gas recirculation on diesel combustion and emissions

2000 ◽  
Vol 214 (4) ◽  
pp. 405-419 ◽  
Author(s):  
H Zhao ◽  
J Hu ◽  
N Ladommatos
Keyword(s):  
High Speed ◽  
Measurement Techniques ◽  
Dilution Effect ◽  
Exhaust Gas Recirculation ◽  
Exhaust Emission ◽  
Exhaust Gas ◽  
Diesel Combustion ◽  
Combustion Chambers ◽  
Emission Analysis ◽  
Gas Recirculation

This paper reports the results of the effects of CO2 in exhaust gas recirculation (EGR) on diesel combustion and emissions. The experiments were carried out on a specially designed single-cylinder diesel engine. In-cylinder measurements were obtained from the optically accessible swirl chamber using high-speed shadowgraphy, the two-colour method and laser extinction. Furthermore, in-cylinder pressure measurements from the combustion chambers were used to derive the heat release rates during combustion. Two experiments were carried out on the effects of CO2 on diesel combustion and pollutant formation. In the first series of experiments, CO2 was used to replace some of the oxygen in the intake mixture, which simulated the dilution effect of conventional EGR. This so-called replacement EGR method was characterized by the typical NOx and smoke trade-off, where NOx reduction was accomplished at the expense of exhaust smoke. In the second series of tests, CO2 was added to the intake charge so that the oxygen concentration in the combustion chamber was not affected. In this additional EGR method, CO2 was found to suppress both NOx and smoke emissions. The mechanisms of these two different EGR modes on diesel combustion and emissions were examined using the above in-cylinder measurement techniques and exhaust emission analysis.

The effects of carbon dioxide in exhaust gas recirculation on diesel engine emissions

1998 ◽  
Vol 212 (1) ◽  
pp. 25-42 ◽  
Author(s):  
N Ladommatos ◽  
S M Adelhalim ◽  
H Zhao ◽  
Z Hu
Keyword(s):  
Carbon Dioxide ◽  
Diesel Engine ◽  
High Speed ◽  
Combustion Process ◽  
Dilution Effect ◽  
Exhaust Gas Recirculation ◽  
Chemical Effect ◽  
Particulate Emissions ◽  
Exhaust Gas ◽  
Gas Recirculation

The investigation was conducted on a high-speed direct injection diesel engine and was concerned with the effects of exhaust gas recirculation (EGR) on diesel engine combustion and emissions. In particular, the effects of carbon dioxide (CO2), a principal constituent of EGR, on combustion and emissions were analysed and quantified experimentally. The use of CO2 to displace oxygen (O2) in the inlet air resulted in: reduction in the O2 supplied to the engine (dilution effect), increased inlet charge thermal capacity (thermal effect), and, potentially, participation of the CO2 in the combustion process (chemical effect). In a separate series of tests the temperature of the engine inlet charge was raised gradually in order to simulate the effect of mixing hot EGR with engine inlet air. Finally, tests were carried out during which the CO2 added to the engine air flow increased the charge mass flowrate to the engine, rather than displacing some of the O2 in the inlet air. It was found that when CO2 displaced O2 in the inlet charge, both the chemical and thermal effects on exhaust emissions were small. However, the dilution effect was substantial, and resulted in very large reductions in exhaust oxides of nitrogen (NO x) at the expense of higher particulate and unburned hydrocarbon (uHC) emissions. Higher inlet charge temperature increased exhaust NO x and particulate emissions, but reduced uHC emissions. Finally, when CO2 was additional to the inlet air charge (rather than displacing O2), large reductions in NOx were recorded with little increase in particulate emissions.

In-cylinder stratification of external exhaust gas recirculation for controlling diesel combustion

2009 ◽  
Vol 11 (1) ◽  
pp. 1-15 ◽  
Author(s):  
T Fuyuto ◽  
M Nagata ◽  
Y Hotta ◽  
K Inagaki ◽  
K Nakakita ◽  
...  
Keyword(s):  
Exhaust Gas Recirculation ◽  
Exhaust Gas ◽  
Diesel Combustion ◽  
Gas Recirculation

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.

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

Effect of balance valve on an asymmetric twin-scroll turbine for heavy-duty diesel engine

2020 ◽  
pp. 146808742093016
Author(s):  
Jianjiao Jin ◽  
Jianfeng Pan ◽  
Zhigang Lu ◽  
Qingrui Wu ◽  
Lizhong Xu
Keyword(s):  
Fuel Economy ◽  
High Speed ◽  
Engine Speed ◽  
Flow Parameter ◽  
Engine Performance ◽  
Exhaust Gas Recirculation ◽  
Exhaust Gas ◽  
Engine Fuel ◽  
Recirculation Rate ◽  
Gas Recirculation

A conventional asymmetric twin-scroll turbine with wastegate is capable of effectively tackling down the contradiction between fuel economy degradation and low nitrogen oxide emissions. However, as the engine speed has been rising at middle- and high-speed ranges, the pressure of small scroll inlet will be increasingly higher as compared with the intake pressure, thereby worsening fuel economy. In this study, a novel turbocharging technology of asymmetric twin-scroll turbine with a balance valve was first analyzed to more effectively balance the engine fuel economy and emission. The experiments on turbine test rig and engine performance were performed to explore the effects of balance valve on turbine performance, asymmetric ratio, exhaust gas recirculation rate, as well as engine performance. As the balance valve open degree was elevated, the turbine flow parameter was being extended, while the turbine efficiency was enhanced. Moreover, a lower asymmetric ratio could lead to a broader flow parameter range between that of partial admission and equal admission, thereby resulting in a broader regulating range of exhaust gas recirculation rate. In contrast with the asymmetric twin-scroll turbine with wastegate, the turbine running efficiency of asymmetric twin-scroll turbine with balance valve was enhanced by nearly 2%–11% at middle and high engine speed ranges, while the fuel economy was improved by nearly 1.5%–8%.

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.

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