Oxygen Enhanced Exhaust Gas Recirculation for Compression Ignition Engines

2011 ◽  
Vol 134 (3) ◽  
Author(s):  
T. Salt ◽  
D. R. Tree ◽  
C. Kim
Keyword(s):  
Direct Injection ◽  
Flame Temperature ◽  
Exhaust System ◽  
Water Concentration ◽  
Particulate Emissions ◽  
Cylinder Pressure ◽  
Engine Operation ◽  
Water Emulsion ◽  
Specific Heats ◽  
Oxygen Enhancement

The benefits of oxygen enhancement in conjunction with EGR on emissions were investigated in a single-cylinder direct injection diesel engine. Cylinder pressure, NOx, and particulate were measured for EGR sweeps with and without oxygen enhancement. In all cases, the total flow of oxygen to the cylinder was maintained constant. This was achieved by increasing cylinder pressure for typical EGR (N-EGR) and by adding oxygen to the intake stream for oxygen-enhanced EGR (O-EGR). The results show that O-EGR produced a substantially better combination of NOx and particulate than N-EGR. In the N-EGR cases, the EGR dilutes the oxidizer causing lower NOx and higher particulate. In O-EGR, flame temperature reduction leading to lower NOx is achieved by a combination of higher molar specific heats of CO2 and H2O and dilution. Particulate emissions decreased or remain constant with increasing O-EGR. In addition to the obvious challenge of providing a source of oxygen to an engine, two operational challenges were encountered. First, as O-EGR was increased, the ratio of specific heats (Cp/Cv) of the cylinder intake charge decreased and decreased the compression temperature, causing significant changes in ignition delay. These changes were compensated for in the experiments by increasing intake temperature but would be challenging to manage in transient engine operation. Second, the increased water concentration in the exhaust created difficulties in the exhaust system and was suspected to have produced a water emulsion in the oil.

Oxygen Enhanced Exhaust Gas Recirculation for Compression Ignition Engines

2009 ◽  
Author(s):  
Tom Salt ◽  
Dale R. Tree ◽  
Chiwon Kim
Keyword(s):  
Direct Injection ◽  
Flame Temperature ◽  
Exhaust System ◽  
Water Concentration ◽  
Particulate Emissions ◽  
Cylinder Pressure ◽  
Engine Operation ◽  
Water Emulsion ◽  
Specific Heats ◽  
Oxygen Enhancement

The benefits of oxygen enhancement in conjunction with EGR on emissions were investigated in a single-cylinder direct injection diesel engine. Cylinder pressure, NOx, and particulate were measured for EGR sweeps with and without oxygen enhancement. In all cases, the total flow of oxygen to the cylinder was maintained constant. This was achieved by increasing cylinder pressure for typical EGR (N-EGR) and by adding oxygen to the intake stream for oxygen-enhanced EGR (O-EGR). The results show that O-EGR produced a substantially better combination of NOx and particulate than N-EGR. In the N-EGR cases, the EGR dilutes the oxidizer causing lower NOx and higher particulate. In O-EGR, flame temperature reduction leading to lower NOx is achieved by a combination of higher molar specific heats of CO2 and H2O and dilution. Particulate emissions decreased or remain constant with increasing O-EGR. In addition to the obvious challenge of providing a source oxygen to an engine, two operational challenges were encountered. First, as EGR was increased, the ratio of specific heats (Cp/Cv) of the cylinder intake charge decreased and decreased the compression temperature, causing significant changes in ignition delay. These changes were compensated for in the experiments by increasing intake temperature but would be challenging to manage in transient engine operation. Second, the increased water concentration in the exhaust created difficulties in the exhaust system and was suspected to have produced a water emulsion in the oil.

Local fuel concentration, ignition and combustion in a stratified charge spark combustion in a stratified charge spark ignited direct injection engine: Spectroscopic, imaging and pressure-based measurements

2003 ◽  
Vol 4 (2) ◽  
pp. 61-86 ◽  
Author(s):  
T. D. Fansler ◽  
M. C. Drake ◽  
B Stojkovic ◽  
M. E. Rosalik
Keyword(s):  
High Speed ◽  
Equivalence Ratio ◽  
Direct Injection ◽  
Injection Timing ◽  
Cylinder Pressure ◽  
Engine Operation ◽  
Stratified Charge ◽  
Fuel Concentration ◽  
Spark Gap ◽  
Ignition And Combustion

A recently developed spark emission spec-troscopy technique has been used to measure the effects of fuel injection timing, spark timing and intake swirl level on the individual-cycle fuel concentration at the spark gap in a wall-guided spark ignited direct injection (SIDI) engine. The fuel-concentration measurements were made simultaneously with measurements of individual-cycle spark discharge energy and cylinder pressure. Endoscopic imaging of the fuel spray and high-speed imaging of combustion (both broadband and spectrally resolved) augment these quantitative data. For optimum engine operation, the fuel-air equivalence ratio at the spark gap just after spark breakdown is rich on average (〈φ〉 ≈1.4–1.5) and varies widely from cycle to cycle (∼25 per cent). The evolution with crank angle of the mean equivalence ratio and its cycle-to-cycle fluctuations are correlated with the cylinder pressure, heat release and imaging data to provide insights into fuel transport and mixture preparation that are important to understanding and optimizing ignition and combustion in SIDI engines. For example, causes of misfires and partial burns have been determined.

Some Studies on NOX Reduction From a Diesel Engine Using Stabilized Emulsion

2018 ◽  
Author(s):  
Naveen Kumar ◽  
Harveer Singh Pali ◽  
Sidharth Bansal
Keyword(s):  
Diesel Engine ◽  
Water Content ◽  
Volume Fraction ◽  
Nox Reduction ◽  
Flame Temperature ◽  
Water Volume ◽  
Nox Emissions ◽  
Oxides Of Nitrogen ◽  
Engine Operation ◽  
Water Emulsion

The twentieth century has seen a rapid twenty-fold increase in the use of fossil fuels. Personal and commercial transportation consumes 2% of the total world energy. The main products of combustion of fossil fuel are carbon mono oxide (CO), unburned hydrocarbons (HC), Carbon dioxide (CO2), oxides of sulfur (SOx), oxides of nitrogen (NOx) and particulate matter. Oxides of nitrogen (NOx) are the major diesel engine pollutants and referred to as mixtures of nitric oxide (NO) and nitrogen dioxide (NO2). NOx emissions are required to be controlled because NO and NO2 contribute to the formation of smog, an environmental and human health hazard. NO2 is also directly of concern as a human lung aggravation. To reduce NOx emissions from a diesel engine, the introduction of water in the combustion chamber of a diesel engine is a promising option as vaporization of water reduces adiabatic flame temperature and micro-explosion phenomena lead to improved mixing. In the present study, stable D/W emulsion, with varying water content, up to 3% were prepared using span 80 as a surfactant. The results indicated a reduction in NOx and smoke with increasing water volume fraction in the emulsion compared to diesel baseline. However, beyond 2% water content led to increased ignition delay and higher diffusion phase heat release resulting in noisy engine operation. Therefore, it can be concluded that diesel-water emulsion with 2% water could be used for significant reduction of NOx emissions from diesel and biodiesel operation of a CI Engine.

scholarly journals Investigating the impact of gasoline composition on PN in GDI engines using an improved measurement method

2020 ◽  
pp. 146808742097037
Author(s):  
Charles Bokor ◽  
Behzad Rohani ◽  
Charlie Humphries ◽  
Denise Morrey ◽  
Fabrizio Bonatesta
Keyword(s):  
Direct Injection ◽  
Exhaust System ◽  
Injection Pressure ◽  
Gasoline Direct Injection ◽  
Engine Operation ◽  
Accuracy Of Measurements ◽  
Particulate Number ◽  
Grade Performance ◽  
Gdi Engines ◽  
The Impact

An experimental investigation was carried out to investigate Particulate Number (PN) emissions from a modern, small-capacity Gasoline Direct Injection (GDI) engine. The first part of the study focused on improving measurement repeatability using the Cambustion DMS-500 device. Results showed that sampling near the exhaust valve – while dampening the pressure oscillations in the sampling line – can significantly improve the repeatability. It was also found that uncontrolled phenomena such as deposition in the exhaust system from earlier engine operation can undermine the accuracy of measurements taken at tailpipe level. The second part of the work investigated PN emissions from three types of gasoline fuel, Pump-grade, Performance and Reference. Fuel chemical composition was found to have an appreciable impact on PN, but the magnitude of this effect differs in various operating points, being more pronounced at higher engine load. The Reference fuel was found to have the lowest PN emission tendency, conceivably because of its lower aromatics, olefins and heavy hydrocarbons content. A sweep of operating parameters showed that higher injection pressure reduces PN, but the extent of the reduction depends on fuel physical properties such as volatility.

Measurement of cycle-resolved engine-out soot concentration from a diesel-pilot assisted natural gas direct-injection compression-ignition engine

2021 ◽  
pp. 146808742098626
Author(s):  
Pooyan Kheirkhah ◽  
Patrick Kirchen ◽  
Steven Rogak
Keyword(s):  
Response Time ◽  
Internal Combustion Engines ◽  
Fuel Injection ◽  
Exhaust System ◽  
Cycle Period ◽  
Scanning Mobility Particle Sizer ◽  
Compression Ignition Engine ◽  
Engine Operation ◽  
Exhaust Port ◽  
Exhaust Stream

Exhaust-stream particulate matter (PM) emission from combustion sources such as internal combustion engines are typically characterized with modest temporal resolutions; however, in-cylinder investigations have demonstrated significant variability and the importance of individual cycles in transient PM emissions. Here, using a Fast Exhaust Nephelometer (FEN), a methodology is developed for measuring the cycle-specific PM concentration at the exhaust port of a single-cylinder research engine. The measured FEN light-scattering is converted to cycle-resolved soot mass concentration ([Formula: see text]), and used to characterize the variability of engine-out soot emission. To validate this method, exhaust-port FEN measurements are compared with diluted gravimetric PM mass and scanning mobility particle sizer (SMPS) measurements, resulting in close agreements with an overall root-mean-square deviation of better than 30%. It is noted that when PM is sampled downstream in the exhaust system, the particles are larger by 50–70 nm due to coagulation. The response time of the FEN was characterized using a “skip-firing” scheme, by enabling and disabling the fuel injection during otherwise steady-state operation. The average response time due to sample transfer and mixing times is 55 ms, well below the engine cycle period (100 ms) for the considered engine speeds, thus suitable for single-cycle measurements carried out in this work. Utilizing the fast-response capability of the FEN, it is observed that cycle-specific gross indicated mean effective pressure (GIMEP) and [Formula: see text] are negatively correlated ([Formula: see text]: 0.2–0.7), implying that cycles with lower GIMEP emit more soot. The physical causes of this association deserve further investigation, but are expected to be caused by local fuel-air mixing effects. The averaged exhaust-port [Formula: see text] is similar to the diluted gravimetric measurements, but the cycle-to-cycle variations can only be detected with the FEN. The methodology developed here will be used in future investigations to characterize PM emissions during transient engine operation, and to enable exhaust-stream PM measurements for optical engine experiments.

Effect of Injection Timing on Combustion Characteristics of a DI Diesel Engine Fuelled with Pistacia chinensis Bunge Seed Biodiesel

2012 ◽  
Vol 614-615 ◽  
pp. 337-342
Author(s):  
Li Luo ◽  
Bin Xu ◽  
Zhi Hao Ma ◽  
Jian Wu ◽  
Ming Li
Keyword(s):  
Combustion Temperature ◽  
Fuel Injection ◽  
Direct Injection ◽  
Combustion Characteristics ◽  
Injection Timing ◽  
Brake Specific Fuel Consumption ◽  
Cylinder Pressure ◽  
Combustion Duration ◽  
Di Diesel Engine ◽  
Maximum Combustion Temperature

In this study, the effect of injection timing on combustion characteristics of a direct injection, electronically controlled, high pressure, common rail, turbocharged and intercooled engine fuelled with different pistacia chinensis bunge seed biodiesel/diesel blends has been experimentally investigated. The results indicated that brake specific fuel consumption reduces with the increasing of fuel injection advance angle and enhances with the increasing of biodiesel content in the blends. The peak of cylinder pressure and maximum combustion temperature increase evidently with the increment of fuel injection advance angle. However, the combustion of biodiesel blends starts earlier than diesel at the same fuel injection advance angle. At both conditions, the combustion duration and the peak of heat release rate are insensitive to the changing of injection timing.

scholarly journals Characterization of a Novel Porous Injector for Multi-Lean Direct Injection (M-LDI) Combustor

2017 ◽  
Author(s):  
Jianing Li ◽  
Umesh Bhayaraju ◽  
San-Mou Jeng
Keyword(s):  
Air Temperature ◽  
Mass Fraction ◽  
Direct Injection ◽  
Flame Temperature ◽  
Gaseous Fuel ◽  
Nox Emissions ◽  
Fuel Injector ◽  
Porous Tube ◽  
Lean Direct Injection ◽  
Air Mixing

A generic novel injector was designed for multi-Lean Direct Injection (M-LDI) combustors. One of the drawbacks of the conventional pressure swirl and prefilming type airblast atomizers is the difficulty of obtaining a uniform symmetric spray under all operating conditions. Micro-channels are needed inside the injector for uniformly distributing the fuel. The problem of non-uniformity is magnified in smaller sized injectors. The non-uniform liquid sheet causes local fuel rich/lean zones leading to higher NOx emissions. To overcome these problems, a novel fuel injector was designed to improve the fuel delivery to the injector by using a porous stainless steel material with 30 μm porosity. The porous tube also acts as a prefilming surface. Liquid and gaseous fuels can be injected through the injector. In the present study, gaseous fuel was injected to investigate injector fuel-air mixing performance. The gaseous fuel was injected through a porous tube between two radial-radial swirling air streams to facilitate fuel-air mixing. The advantage of this injector is that it increases the contact surface area between the fuel-air at the fuel injection point. The increased contact area enhances fuel-air mixing. Fuel-air mixing and combustion studies were carried out for both gaseous and liquid fuel. Flame visualization, and emissions measurements were carried out inside the exit of the combustor. The measurements were carried out at atmospheric conditions under fuel lean conditions. Natural gas was used as a fuel in these experiments. Fuel-air mixing studies were carried out at different equivalence ratios with and without confinement. The mass fraction distributions were measured at different downstream locations from the injector exit. Flame characterization was carried out by chemiluminescence at different equivalence ratios and inlet air temperatures. Symmetry of the flame, flame length and heat release distribution were analyzed from the flame images. The effects of inlet air temperature and combustion flame temperature on emissions was studied. Emissions were corrected to 15% O2 concentration. NOx emissions increase with inlet air temperature and flame temperature. Effect of flame temperature on NOx concentration is more significant than effect of inlet air temperature. Fuel-air mixing profile was used to obtain mass fraction Probability Density Function (pdf). The pdfs were used for simulations in Chemkin Pro. The measured emissions concentrations at the exit of the injector was compared with simulations. In Chemkin model, a network model with several PSRs (perfectly stirred reactor) were utilized, followed by a mixer and a PFR (plug flow reactor). The comparison between the simulations and the experimental results was investigated.

scholarly journals THE EFFECT OF DIESEL-BIODIESEL BLENDS ON THE PERFORMANCE AND EXHAUST EMISSIONS OF A DIRECT INJECTION OFF-ROAD DIESEL ENGINE

Transport ◽  
2014 ◽  
Vol 29 (4) ◽  
pp. 440-448 ◽  
Author(s):  
Tomas Mickevičius ◽  
Stasys Slavinskas ◽  
Slawomir Wierzbicki ◽  
Kamil Duda
Keyword(s):  
Diesel Engine ◽  
Diesel Fuel ◽  
Direct Injection ◽  
Engine Performance ◽  
Exhaust Emissions ◽  
Bench Test ◽  
Maximum Pressure ◽  
Cylinder Pressure ◽  
Biodiesel Blends ◽  
Performance And Emission

This paper presents a comparative analysis of the diesel engine performance and emission characteristics, when operating on diesel fuel and various diesel-biodiesel (B10, B20, B40, B60) blends, at various loads and engine speeds. The experimental tests were performed on a four-stroke, four-cylinder, direct injection, naturally aspirated, 60 kW diesel engine D-243. The in-cylinder pressure data was analysed to determine the ignition delay, the Heat Release Rate (HRR), maximum in-cylinder pressure and maximum pressure gradients. The influence of diesel-biodiesel blends on the Brake Specific Fuel Consumption (bsfc) and exhaust emissions was also investigated. The bench test results showed that when the engine running on blends B60 at full engine load and rated speed, the autoignition delay was 13.5% longer, in comparison with mineral diesel. Maximum cylinder pressure decreased about 1–2% when the amount of Rapeseed Methyl Ester (RME) expanded in the diesel fuel when operating at full load and 1400 min–1 speed. At rated mode, the minimum bsfc increased, when operating on biofuel blends compared to mineral diesel. The maximum brake thermal efficiency sustained at the levels from 0.3% to 6.5% lower in comparison with mineral diesel operating at full (100%) load. When the engine was running at maximum torque mode using diesel – RME fuel blends B10, B20, B40 and B60 the total emissions of nitrogen oxides decreased. At full and moderate load, the emission of carbon monoxide significantly raised as the amount of RME in fuel increased.

Effects of the Injection Parameters on the Emissions of a Heavy Duty Diesel Engine

2009 ◽  
Author(s):  
M. Yılmaz ◽  
M. Zafer Gul ◽  
Y. Yukselenturk ◽  
B. Akay ◽  
H. Koten
Keyword(s):  
Diesel Engine ◽  
Direct Injection ◽  
Combustion Process ◽  
Design Parameters ◽  
Combustion Model ◽  
Particulate Emissions ◽  
Multiphase Model ◽  
Heavy Duty ◽  
Flow Development ◽  
Air Motion

It is estimated by the experts in the automotive industry that diesel engines on the transport market should increase within the years to come due to their high thermal efficiency coupled with low carbon dioxide (CO2) emissions, provided their nitrogen oxides (NOx) and particulate emissions are reduced. At present, adequate after-treatments, NOx and particulates matter (PM) traps are developed and industrialized with still concerns about fuel economy, robustness, sensitivity to fuel sulfur and cost because of their complex and sophisticated control strategy. New combustion processes focused on clean diesel combustion are investigated for their potential to achieve near zero particulate and NOx emissions. Their main drawbacks are increased level of unburned hydrocarbons (HC) and carbon monoxide (CO) emissions, combustion control at high load and limited operating range and power output. In this work, cold flow simulations for a single cylinder of a nine-liter (6 cylinder × 1.5 lt.) diesel engine have been performed to find out flow development and turbulence generation in the piston-cylinder assembly. In this study, the goal is to understand the flow field and the combustion process in order to be able to suggest some improvements on the in-cylinder design of an engine. Therefore combustion simulations of the engine have been performed to find out flow development and emission generation in the cylinder. Moreover, the interaction of air motion with high-pressure fuel spray injected directly into the cylinder has also been carried out. A Lagrangian multiphase model has been applied to the in-cylinder spray-air motion interaction in a heavy-duty CI engine under direct injection conditions. A comprehensive model for atomization of liquid sprays under high injection pressures has been employed. The combustion is modeled via a new combustion model ECFM-3Z (Extended Coherent Flame Model) developed at IFP. Finally, a calculation on an engine configuration with compression, spray injection and combustion in a direct injection Diesel engine is presented. Further investigation has also been performed in-cylinder design parameters in a DI diesel engine that result in low emissions by effect of high turbulence level. The results are widely in agreement qualitatively with the previous experimental and computational studies in the literature.

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