Impact of exhaust gas recirculation on production of nitrogen oxides in natural gas combustion

2018 ◽  
Author(s):  
Mária Čarnogurská ◽  
Miroslav Příhoda
Keyword(s):  
Natural Gas ◽  
Nitrogen Oxides ◽  
Exhaust Gas Recirculation ◽  
Exhaust Gas ◽  
Gas Combustion ◽  
Natural Gas Combustion ◽  
Gas Recirculation

scholarly journals Ensuring Requirements for Emissions of Harmful Substances of Diesel Engines

2020 ◽  
Vol 19 (4) ◽  
pp. 305-310
Author(s):  
G. M. Kuharonak ◽  
D. V. Kapskiy ◽  
V. I. Berezun
Keyword(s):  
Diesel Engine ◽  
Nitrogen Oxides ◽  
Fuel Consumption ◽  
Exhaust Gas Recirculation ◽  
Exhaust Gas ◽  
Average Temperature ◽  
Dispersed Particles ◽  
Harmful Substances ◽  
Gas Recirculation ◽  
Emissions Of Harmful Substances

The purpose of this work is to consider the requirements for emissions of harmful substances of diesel engines by selecting design and adjustment parameters that determine the organization of the workflow, and the exhaust gas cleaning system, taking into account the reduction of fuel consumption. Design elements and geometric characteristics of structures for a turbocharged diesel engine of Д-245 series produced by JSC HMC Minsk Motor Plant (4ЧН11/12.5) with a capacity of 90 kW equipped with an electronically controlled battery fuel injection have been developed: exhaust gas recirculation along the high pressure circuit, shape and dimensions of the combustion chamber, the number and angular arrangement of the nozzle openings in a nozzle atomizer, and inlet channels of the cylinder head. Methods for organizing a workflow are proposed that take into account the shape of the indicator diagrams and affect the emissions of nitrogen oxides and dispersed particles differently. Their implementation allows us to determine the boundary ranges of changes in the control parameters of the fuel supply and exhaust gas recirculation systems when determining the area of minimizing the specific effective fuel consumption and the range of studies for the environmental performance of a diesel engine. The paper presents results of the study on the ways to meet  the requirements for emissions of harmful substances, obtained by considering options for the organization of working processes, taking into account the reduction in specific effective fuel consumption, changes in the average temperature of the exhaust gases and diesel equipment. To evaluate these methods, the following indicators have been identified: changes in specific fuel consumption and average temperature of the toxicity cycle relative to the base cycle, the necessary degree of conversion of the purification system for dispersed particles and NOx. Recommendations are given on choosing a diesel engine to meet Stage 4 emission standards for nitrogen oxides and dispersed particles.

Homogeneous Ignition Delay, Flame Propagation Rate and End-Gas Autoignition Fraction Measurements of Natural Gas and Exhaust Gas Recirculation Blends in a Rapid Compression Machine

2020 ◽  
Author(s):  
Jeffrey Mohr ◽  
Bret Windom ◽  
Daniel B. Olsen ◽  
Anthony J. Marchese
Keyword(s):  
Natural Gas ◽  
Flame Propagation ◽  
Ignition Delay ◽  
Exhaust Gas Recirculation ◽  
Propagation Rate ◽  
Delay Period ◽  
Exhaust Gas ◽  
Rapid Compression Machine ◽  
Gas Recirculation ◽  
Ignition Delay Period

Abstract To evaluate the effect of exhaust gas recirculation (EGR) and variable fuel reactivity on knock and misfire in spark ignited national gas engines, experiments were conducted in a rapid compression machine to measure homogeneous ignition delay, flame propagation rate, and end-gas autoignition fraction for stoichiometric natural gas/oxidizer/EGR blends. Natural gas with a range of chemical reactivity was simulated using mixtures of CH4, C2H6, and C3H8. Reactive exhaust gas recirculation (R-EGR) gases were simulated with mixtures of Ar, CO2, CO, and NO and non-reactive exhaust gas recirculation gases (NR-EGR) were simulated with mixtures of AR and CO2. Homogeneous ignition delay period, flame propagation rate and end-gas autoignition fraction were measured at compressed pressures and temperatures of 30.2 to 34.0 bar and 667 to 980 K, respectively. Flame propagation rate decreased with both R-EGR and NR-EGR substitution. The substitution of R-EGR increased the end-gas autoignition fraction, whereas NR-EGR substitution decreased the end-gas autoignition fraction. The results indicate that the presence of the reactive species NO in the R-EGR has a strong impact on end-gas autoignition fraction. An 82-species reduced chemical kinetic mechanism was also developed that reproduces measured homogeneous ignition delay period with a total average relative error of 11.0%.

Emission reduction through internal and low-pressure loop exhaust gas recirculation configuration with negative valve overlap and late intake valve closing strategy in a compression ignition engine

2017 ◽  
Vol 18 (10) ◽  
pp. 973-990 ◽  
Author(s):  
Jaeheun Kim ◽  
Choongsik Bae
Keyword(s):  
High Pressure ◽  
Nitrogen Oxides ◽  
Exhaust Gas Recirculation ◽  
Low Pressure ◽  
Exhaust Gas ◽  
Effective Pressure ◽  
Intake Valve ◽  
Trade Off ◽  
Indicated Mean Effective Pressure ◽  
Gas Recirculation

An investigation was carried out to examine the feasibility of replacing the conventional high-pressure loop/low-pressure loop exhaust gas recirculation with a combination of internal and low-pressure loop exhaust gas recirculation. The main objective of this alternative exhaust gas recirculation path configuration is to extend the limits of the late intake valve closing strategy, without the concern of backpressure caused by the high-pressure loop exhaust gas recirculation. The late intake valve closing strategy improved the conventional trade-off relation between nitrogen oxides and smoke emissions. The gross indicated mean effective pressure was maintained at a similar level, as long as the intake boosting pressure kept changing with respect to the intake valve closing timing. Applying the high-pressure loop exhaust gas recirculation in the boosted conditions yielded concern of the exhaust backpressure increase. The presence of high-pressure loop exhaust gas recirculation limited further intake valve closing retardation when the negative effect of increased pumping work cancelled out the positive effect of improving the emissions’ trade-off. Replacing high-pressure loop exhaust gas recirculation with internal exhaust gas recirculation reduced the burden of such exhaust backpressure and the pumping loss. However, a simple feasibility analysis indicated that a high-efficiency turbocharger was required to make the pumping work close to zero. The internal exhaust gas recirculation strategy was able to control the nitrogen oxides emissions at a low level with much lower O2 concentration, even though the initial in-cylinder temperature was high due to hot residual gas. Retardation of intake valve closing timing and intake boosting contributed to increasing the charge density; therefore, the smoke emission reduced due to the higher air–fuel ratio value exceeding 25. The combination of internal and low pressure loop loop exhaust gas recirculation with late intake valve closing strategy exhibited an improvement on the trade-off relation between nitrogen oxides and smoke emissions, while maintaining the gross indicated mean effective pressure at a comparable level with that of the high-pressure loop exhaust gas recirculation configuration.

Hydrogen enrichment: A way to maintain combustion stability in a natural gas fuelled engine with exhaust gas recirculation, the potential of fuel reforming

2001 ◽  
Vol 215 (3) ◽  
pp. 405-418 ◽  
Author(s):  
S. Allenby ◽  
W-C. Chang ◽  
A. Megaritis ◽  
M. L. Wyszyński
Keyword(s):  
Natural Gas ◽  
Exhaust Gas Recirculation ◽  
Combustion Stability ◽  
Exhaust Gas ◽  
Fuel Reforming ◽  
Rapid Reduction ◽  
Indicated Mean Effective Pressure ◽  
Hydrogen Enrichment ◽  
Gas Recirculation ◽  
Operating Points

An experimental study was carried out to evaluate the potential of hydrogen enrichment to increase the tolerance of a stoichiometrically fuelled natural gas engine to high levels of dilution by exhaust gas recirculation (EGR). This provides significant gains in terms of exhaust emissions without the rapid reduction in combustion stability typically seen when applying EGR to a methane-fuelled engine. Presented results give the envelope of benefits from hydrogen enrichment. In parallel, the performance of a catalytic exhaust gas reforming reactor was investigated in order that it could be used as an onboard source of hydrogen-rich EGR. It was shown that sufficient hydrogen was generated with currently available prototype catalysts to allow the engine, at the operating points considered, to tolerate up to 25 per cent EGR, while maintaining a coefficient of variability of indicated mean effective pressure below 5 per cent. This level of EGR gives a reduction in NO emissions greater than 80 per cent in all test cases.

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