Modifying the Classical 1D Catalyst Model to Include Axial Conduction and Diffusion

2012 ◽  
Author(s):  
Sudarshan Loya ◽  
Christopher Depcik
Keyword(s):  
Equations Of Motion ◽  
Chemical Species ◽  
Earth Metal ◽  
Space Velocity ◽  
Low Flow ◽  
Lean Nox Trap ◽  
Oxides Of Nitrogen ◽  
Engine Operation ◽  
Axial Conduction ◽  
And Diffusion

Lean NOx Trap (LNT) catalytic aftertreatment devices are one potential option for the reduction of oxides of nitrogen (NOx) in the exhaust of Compression Ignition engines. They work through a controlled modulation between a storage phase that captures NOx over an alkali earth metal and a regeneration phase that reduces the stored nitrates on the surface using a rich pulse of injected fuel or via stoichiometric engine operation. This rich phase has an associated fuel penalty while being relatively difficult to control through temperature and chemical species. In order to improve system efficiency, a number of researchers have proposed dual leg LNT systems using two LNTs, of which one is always storing while the other is undergoing regeneration. The majority of the exhaust flows through the storage LNT while only a small fraction (low space velocity) advects across the regeneration LNT. This increases the regeneration residence time, improving effectiveness and decreasing the amount of fuel used. From an LNT simulation standpoint, most researchers utilize the classical one-dimensional (1D) aftertreatment model constructed from the Euler equations of motion that neglects axial conduction and diffusion. This paper explores the applicability of this model under low flow situations prevalent in a dual leg LNT system through a carbon monoxide light-off experiment. The authors chose this type of experiment in order to focus purely on fluid mechanics and not the choice of LNT reaction mechanism. The results suggest that a Navier-Stokes (N-S) version of the 1D aftertreatment model is preferred for the regeneration leg of a dual LNT system. Moreover, the authors provide the solution of such a model within this paper.

Modifying the Classical One-Dimensional Catalyst Model to Include Axial Conduction and Diffusion

2013 ◽  
Vol 135 (9) ◽  
Author(s):  
Sudarshan Loya ◽  
Christopher Depcik
Keyword(s):  
Chemical Species ◽  
Earth Metal ◽  
Space Velocity ◽  
Low Flow ◽  
Lean Nox Trap ◽  
Oxides Of Nitrogen ◽  
Engine Operation ◽  
Axial Conduction ◽  
One Dimensional ◽  
And Diffusion

Lean NOx trap (LNT) catalytic aftertreatment devices are one potential option for the reduction of oxides of nitrogen (NOx) in the exhaust of compression ignition engines. They work through a controlled modulation between a storage phase that captures NOx over an alkali earth metal and a regeneration phase that reduces the stored nitrates on the surface using a rich pulse of injected fuel or via stoichiometric engine operation. This rich phase has an associated fuel penalty while being relatively difficult to control through temperature and chemical species. In order to improve system efficiency, a number of researchers have proposed dual leg LNT systems using two LNTs, one of which is always storing while the other is undergoing regeneration. The majority of the exhaust flows through the storage LNT while only a small fraction (low space velocity) advects across the regeneration LNT. This increases the regeneration residence time, improving effectiveness and decreasing the amount of fuel used. From an LNT simulation standpoint, most researchers utilize the classical one-dimensional (1D) aftertreatment model constructed from the Euler equations of motion that neglect axial conduction and diffusion. This paper explores the applicability of this model under low flow situations prevalent in a dual leg LNT system through a carbon monoxide light-off experiment. The authors chose this type of experiment in order to focus purely on fluid mechanics and not the choice of LNT reaction mechanism. The results suggest that a Navier–Stokes (N–S) version of the 1D aftertreatment model is preferred for the regeneration leg of a dual LNT system. Moreover, the authors provide the solution of such a model within this paper.

Stabilizing Excessive EGR With an Oxidation Catalyst on a Modern Diesel Engine

2002 ◽  
Author(s):  
Ming Zheng ◽  
David K. Irick ◽  
Jeffrey Hodgson
Keyword(s):  
Diesel Engine ◽  
Oxidation Catalyst ◽  
Stable Operation ◽  
Exhaust Gas ◽  
Oxides Of Nitrogen ◽  
Engine Operation ◽  
Turbocharged Diesel Engine ◽  
New Approach ◽  
Cyclic Variations ◽  
Gas Recirculation

For diesel engines (CIDI) the excessive use of exhaust gas recirculation (EGR) can reduce in-cylinder oxides of nitrogen (NOx) generation dramatically, but engine operation can also approach zones with high instabilities, usually accompanied with high cycle-to-cycle variations and deteriorated emissions of total hydrocarbon (THC), carbon monoxide (CO), and soot. A new approach has been proposed and tested to eliminate the influences of recycled combustibles on such instabilities, by applying an oxidation catalyst in the high-pressure EGR loop of a turbocharged diesel engine. The testing was directed to identifying the thresholds of stable operation at high rates of EGR without causing cycle-to-cycle variations associated with untreated recycled combustibles. The elimination of recycled combustibles using the oxidation catalyst showed significant influences on stabilizing the cyclic variations, so that the EGR applicable limits are effectively extended. The attainability of low NOx emissions with the catalytically oxidized EGR is also evaluated.

scholarly journals Chemical Impact on Heat and Mass Transfer Flow in Presence of Radiation and Rotation with Variable Temperature and Concentration

2019 ◽  
Vol 8 (4) ◽  
pp. 1966-1970
Keyword(s):  
Mass Transfer ◽  
Variable Temperature ◽  
Equations Of Motion ◽  
Porous Plate ◽  
Chemical Species ◽  
Viscous Drag ◽  
Electrically Conducting ◽  
Electrically Conducting Fluid ◽  
Transfer Flow ◽  
Chemical Reaction Parameter

A parametric study to investigate the effect of chemical reaction parameter on an MHD mixed convective mass transfer flow of an incompressible viscous electrically conducting fluid past an infinite vertical porous plate. The equations of motion are work out by assuming Laplace Transform approach. The velocity profile, temperature, concentration, viscous drag, Nusselt number and the rate of mass transfer are discussed graphically by assuming some arbitrary criterion given in the present paper and physical descriptions are made. It is emphasized from the graphical portion that chemical species retards the fluid flow

Computational Analysis of an Early Direct Injected HCCI Engine with Turbocharger Using Bio Ethanol and Diesel Blends

2015 ◽  
Vol 812 ◽  
pp. 70-78
Author(s):  
S. Natarajan ◽  
A.U. Meeanakshi Sundareswaran ◽  
S. Arun Kumar ◽  
N.V. Mahalakshmi
Keyword(s):  
Chemical Kinetics ◽  
Computational Analysis ◽  
Reaction Path ◽  
Chemical Species ◽  
Operating Conditions ◽  
Injection Time ◽  
Engine Operation ◽  
Hcci Engine ◽  
Hcci Combustion ◽  
Auto Ignition

In this paper the work deals with the computational analysis of early direct injected HCCI engine with turbocharger using the CHEMKIN-PRO software. The computational analysis was carried out in the base of auto ignition chemistry by means of reduced chemical kinetics. For this study the neat diesel and Bio ethanol diesel blend (E20) were used as fuel. The inlet pressure was increased to 1.2 bar to simulate the turbocharged engine operation. The injection time was advanced to 18° before top dead centre (BTDC) i.e., 5° BTDC than normal injection time of 23° BTDC. The equivalence ratio was kept at 0.6 (ɸ=0.6) and the combustion, emission characteristics and chemical kinetics of the combustion reaction were studied. Since pressure and temperature profiles plays a very important role in reaction path at certain operating conditions, an attempt had been made here to present a complete reaction path investigation on the formation/destruction of chemical species at peak temperature and pressure conditions. The result showed that main draw backs of HCCI combustion like higher levels of unburned hydrocarbon emissions and carbon monoxide emissions are reduced in the turbocharged operation of the HCCI engine when compared to normal HCCI engine operation without turbocharger.

Combustion Mode Switching Characteristics of a Medium-Duty Engine Operated in Compression Ignition/PCCI Combustion Modes

2018 ◽  
Vol 140 (9) ◽  
Author(s):  
Akhilendra Pratap Singh ◽  
Nikhil Bajpai ◽  
Avinash Kumar Agarwal
Keyword(s):  
Combustion Engine ◽  
Mode Switching ◽  
Exhaust Gas ◽  
Compression Ignition ◽  
Oxides Of Nitrogen ◽  
Combustion Mode ◽  
Engine Operation ◽  
Combustion Modes ◽  
Brake Mean Effective Pressure ◽  
Study Results

Premixed charge compression ignition (PCCI) combustion is a novel combustion concept, which reduces oxides of nitrogen (NOx) and particulate matter (PM) emissions simultaneously. However, PCCI combustion cannot be implemented in commercial engines due to its handicap in operating at high engine loads. This study is focused on the development of hybrid combustion engine in which engine can be operated in both combustion modes, namely, PCCI and compression ignition (CI). Up to medium loads, engine was operated in PCCI combustion and at higher loads, the engine control unit (ECU) automatically switched the engine operation to CI combustion mode. These combustion modes can be automatically switched by varying the fuel injection parameters and exhaust gas recirculation (EGR) by an open ECU. The experiments were carried out at constant engine speed (1500 rpm) and the load was varied from idling to full load (5.5 bar brake mean effective pressure (BMEP)). To investigate the emission and particulate characteristics during different combustion modes and mode switching, continuous sampling of the exhaust gas was done for a 300 s cycle, which was specifically designed for this study. Results showed that PCCI combustion resulted in significantly lower NOx and PM emissions compared to the CI combustion. Lower exhaust gas temperature (EGT) in the PCCI combustion mode resulted in slightly inferior engine performance. Slightly higher concentration of unregulated emission species such as sulfur dioxide (SO2) and formaldehyde (HCHO) in PCCI combustion mode was another important observation from this study. Lower concentration of aromatic compounds in PCCI combustion compared to CI combustion reflected relatively lower toxicity of the exhaust gas. Particulate number-size distribution showed that most particulates emitted in PCCI combustion mode were in the accumulation mode particle (AMP) size range, however, CI combustion emitted relatively smaller sized particles, which were more harmful to the human health. Overall, this study indicated that mode switching has significant potential for application of PCCI combustion mode in production grade engines for automotive sector, which would result in relatively cleaner engine exhaust compared to CI combustion mode engines.

Comparison of Emissions and Efficiency of a Turbocharged Lean-Burn Natural Gas and Hythane-Fueled Engine

1997 ◽  
Vol 119 (1) ◽  
pp. 218-226 ◽  
Author(s):  
J. F. Larsen ◽  
J. S. Wallace
Keyword(s):  
Natural Gas ◽  
Specific Energy Consumption ◽  
Oxides Of Nitrogen ◽  
Heavy Duty ◽  
Lean Burn ◽  
Clear Trend ◽  
Engine Operation ◽  
Spark Timing ◽  
Test Engine ◽  
Carbon Dioxide Co2

An experiment was conducted to evaluate the potential for reduced exhaust emissions and improved efficiency, by way of lean-burn engine fuelling with hydrogen supplemented natural gas (Hythane). The emissions and efficiency of the Hythane fuel (15 percent hydrogen, 85 percent natural gas by volume), were compared to the emissions and efficiency of pure natural gas using a turbocharged, spark ignition, 3.1 L, V-6 engine. The feasibility of heavy duty engine fueling with Hythane was assessed through testing conducted at engine speed and load combinations typical of heavy-duty engine operation. Comparison of the efficiency and emissions at MBT spark timing revealed that Hythane fueling of the test engine resulted in consistently lower brake specific energy consumption and emissions of total hydrocarbons (THC), carbon monoxide (CO), and carbon dioxide (CO2), at a given equivalence ratio. There was no clear trend with respect to MBT oxides of nitrogen (NOx) emissions. It was also discovered that an improved NOx-THC tradeoff resulted when Hythane was used to fuel the test engine. Consequently, Hythane engine operating parameters can be adjusted to achieve a concurrent reduction in NOx and THC emissions relative to natural gas fueling.

A Bioinspired Active Micropump

2015 ◽  
Author(s):  
Prashanta Dutta ◽  
Jin Liu
Keyword(s):  
Fluid Flow ◽  
Osmotic Pressure ◽  
Sucrose Solution ◽  
Chemical Species ◽  
Mass Conservation ◽  
Pressure Head ◽  
Proton Gradient ◽  
Low Flow ◽  
Preliminary Design ◽  
Transporter Proteins

A preliminary design concept is provided for a bioinspired active micropump. The proposed micropump uses light energy to activate the transporter proteins (bacteriorhodopsin protein and sucrose/sugar transporter proteins), which create an osmotic pressure gradient and drive the fluid flow. The purpose of the bacteriorhodopsin protein is to pump proton from the pumping section to the sucrose source for a proton gradient. This proton gradient is used by the sucrose transporter proteins to transport sugar molecules from the sucrose solution chamber to the pumping channel, which generates an osmotic pressure in the pumping section. A numerical model is used to evaluate the performance of the micropump where the concentrations of proton and sucrose molecules are calculated using the conservation of chemical species equations. The fluid flow and pressure field are calculated from momentum and mass conservation equations. Simulation results predict that the micropump is capable of generating a pressure head that is comparable to other non-mechanical pumps. The proposed bioinspired self-sustained micropump will be most effective at low flow rate.

Water-Ethanol-Gasoline Blends—Physical Properties, Power, and Pollution Characteristics

1984 ◽  
Vol 106 (4) ◽  
pp. 841-848 ◽  
Author(s):  
S. Rajan
Keyword(s):  
Physical Properties ◽  
Thermal Efficiency ◽  
Spark Ignition ◽  
Spark Ignition Engines ◽  
Oxides Of Nitrogen ◽  
Engine Operation ◽  
Nitrogen Emissions ◽  
Pollution Characteristics ◽  
The Road ◽  
On The Road

Factors relevant to the utilization of nonanhydrous ethanol as a blending component with gasoline for use in current on-the-road spark ignition engines are investigated. Miscibility limits are determined and key physical properties important for proper engine operation are measured. Dynamometer tests on an unmodified production engine with hydrated ethanol-gasoline blends containing varying percentages of water show potential for increased thermal efficiency and reduced oxides of nitrogen emissions.

Sol-gel Processing and Characterization of Alkaline Earth and Rare-earth Fluoride Thin Films

1999 ◽  
Vol 14 (4) ◽  
pp. 1610-1616 ◽  
Author(s):  
Munehiro Tada ◽  
Shinobu Fujihara ◽  
Toshio Kimura
Keyword(s):  
Thin Films ◽  
Rare Earth ◽  
Alkaline Earth ◽  
Heating Temperature ◽  
Sol Gel ◽  
Chemical Species ◽  
Earth Metal ◽  
Homogeneous Solutions ◽  
Rare Earth Fluoride ◽  
Earth Fluoride

Alkaline earth and rare-earth fluoride thin films were prepared on silica glass substrates by a sol-gel process using trifluoroacetic acid (TFA) as a fluorine source. Homogeneous solutions were obtained by stirring a mixture of alkaline earth or rare-earth metal acetates, TFA and H2O, dissolved in isopropanol. The solutions were spin-coated and heated at 300–800 °C. The fluoride thin films were obtained by heat treatment around 400 °C in air. The crystallization behavior, the surface morphology, and the optical properties of the films depended on the heating temperature as well as the chemical species of the metal ions.

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