Large Particles in Modern Diesel Engine Exhaust

2012 ◽  
Author(s):  
John Hoard ◽  
Tejas Chafekar ◽  
Mehdi Abarham ◽  
Riley Schwader ◽  
Steven Upplegger ◽  
...  
Keyword(s):  
Diesel Engine ◽  
Test System ◽  
Test Stand ◽  
Particulate Filter ◽  
Exhaust Pipe ◽  
Engine Exhaust ◽  
Large Particles ◽  
Valve Sealing ◽  
Egr Cooler ◽  
Deposit Layer

During research on diesel engine EGR cooler fouling a test stand giving visual access to the building deposit layer has been developed. Initial experiments reveal the presence of large particles in the exhaust. While conventional wisdom is that diesel particulates typically have log-normal size distributions ranging approximately 10–200 nm, the tests reported here observe small numbers of particles with sizes on the order of tens of μm. Such particles are not generally reported in the literature because exhaust particle sizing instruments typically have inertial separators to remove particles larger than ∼1 μm in order to avoid fouling of the nanoparticle measurement system. The test stand provides exhaust or heated air flow over a cooled surface with Reynolds number, pressure, and surface temperature typical of an EGR cooler. A window allows observation using a digital microscope camera. Starting from a clean surface, a rapid build of a deposit layer is observed. A few large particles are observed. These may land on the surface and remain for long times, although occasionally a particle blows away. In order to study these particles further, an exhaust sample was passed over a fiberglass filter, and the resulting filtered particles were analyzed. Samples were taken at the engine EGR passage, and also in the test stand tubing just before the visualization fixture. The resulting images indicate that the particles are not artifacts of the test system, but rather are present in engine exhaust. MATLAB routines were developed to analyze the filter images taken on the microscope camera. Particles were identified, counted, and sized by the software. It is not possible to take isokinetic samples and give quantitative measurement of the number and size distribution of the particles because the particles are large enough that inertial and gravitational effects will cause them to at least partially settle out of the flows. Nonetheless, the presence of particles tens of μm is documented. Such particles are probably the result of in-cylinder and exhaust pipe deposits flaking. While these larger particles would be captured by the diesel particulate filter (DPF), they can affect intake and exhaust valve seating, EGR cooler fouling, EGR valve sealing, and other factors.

scholarly journals Parametric Study on EGR Cooler Fouling Mechanism Using Model Gas and Light-Duty Diesel Engine Exhaust Gas

Energies ◽  
2018 ◽  
Vol 11 (11) ◽  
pp. 3161 ◽  
Author(s):  
Sangjun Park ◽  
Kyo Lee ◽  
Jungsoo Park
Keyword(s):  
Heat Exchanger ◽  
Diesel Engine ◽  
Laboratory Experiment ◽  
Flow Rate ◽  
Parametric Study ◽  
Gas Flow ◽  
Exhaust Gas ◽  
Gas Flow Rate ◽  
Engine Exhaust ◽  
Egr Cooler

Exhaust gas recirculation (EGR) and high-pressure fuel injection are key technologies for reducing diesel engine emissions in the face of reinforced regulations. With the increasing need for advanced EGR technologies to achieve low-temperature combustion and low emission, the adverse etableffects of EGR must be addressed. One of the main problems is fouling of the EGR cooler, which involves the deposition of particulate matter (PM) due to the thermophoretic force between the cooler wall and flow field. A large amount of deposited PM can reduce the effectiveness of the heat exchanger in the EGR cooler and the de-NOx efficiency. In the present study, the effects of the variables that affect EGR cooler fouling are investigated by a comparison of laboratory-based and engine-based experiments. In the laboratory experiment, a soot generator that could readily provide separate control of the variables was used to generate the model EGR gas. Through control of the soot generator, it was possible to perform a parametric study by varying the particle size, the EGR gas flow rate, and the coolant temperature as the dominant parameters. A decrease in these factors caused an increase in the mass of the deposit and a drop in the effectiveness of the heat exchanger, related to fouling of the EGR cooler. In the engine-based experiment, engine-like conditions were provided to analyze real exhaust gas without a soot generator. Different variables were found to induce fouling of the EGR cooler, and the results of the engine-based experiment differed from those of the laboratory experiment. For example, in the engine-based experiment, a decrease in the EGR gas flow rate did not lead to a more pronounced drop in the effectiveness of the heat exchanger because of the increase in the concentration of PM in the EGR gas. This result shows that the conditions of the engine exhaust gas are different from those of the soot generator.

A Finite-Difference Approach for Solving the Gas Dynamics in an Engine Exhaust

1975 ◽  
Vol 17 (3) ◽  
pp. 125-132 ◽  
Author(s):  
J. D. Ledger
Keyword(s):  
Diesel Engine ◽  
Finite Difference ◽  
Boundary Conditions ◽  
Gas Dynamics ◽  
Gas Flow ◽  
Computation Time ◽  
Finite Difference Schemes ◽  
Exhaust Pipe ◽  
Engine Exhaust ◽  
Turbocharged Diesel Engine

Finite-difference schemes have been considered for solving the unsteady, compressible gas flow in the exhaust pipe of a turbocharged diesel engine. The most promising scheme, based on centred differencing, was developed to incorporate the boundary conditions applicable to the exhaust problem. Good comparisons were obtained with results for pipe pressure from characteristics programmes at intermediate and final stages of the development. Recommendations are made for reducing the computation time of the centred-difference programme.

Energy Analysis for Hydrogen Generation with the Waste Heat of Internal Combustion Engine

2012 ◽  
Vol 512-515 ◽  
pp. 1492-1498 ◽  
Author(s):  
Liang Chun Lu ◽  
Jau Huai Lu
Keyword(s):  
Diesel Engine ◽  
Internal Combustion Engine ◽  
Thermal Energy ◽  
Combustion Engine ◽  
Internal Combustion ◽  
Methanol Solution ◽  
Exhaust Pipe ◽  
Hydrogen Yield ◽  
Engine Exhaust ◽  
Production Of Hydrogen

The production of hydrogen with the exhaust energy of an internal combustion engine was investigated in this paper. Steam reforming of methanol is an efficient way to generate hydrogen at relatively low temperature. The reactants of this process are methanol and water, and the hydrogen yield may reach as high as 75% theoretically. However, this is an endothermic reaction, and additional energy has to be provided to this process. If copper oxides and zinc oxides are used as catalyst, the reaction may proceed at the temperature of 270°C. A heat exchanger was designed in this study to use the hot exhaust of a diesel engine to convert methanol to hydrogen. This system is composed of a reformer, a heating chamber, a by-pass valve, and a control valve. Methanol was mixed with pure water at the ratio of 1:1 to form methanol solution. The flow rate of the methanol solution was adjusted according to the engine speed and load such that the thermal energy of engine exhaust may be fully utilized. The reformer is made of copper tubes and compact alumina fins. Pills of catalyst were filled inside copper tubes. Hot exhaust gas flowed through fins and transferred heat to methanol solution. Methanol solution at room temperature was fed into the reformer at a specified rate. It was heated and vaporized inside the copper tube, and then converted to the final products. It was found that in our system the molar fraction of H2 in the reformed gas was 72.6%, while that of CO2 was 23.5%. The exhaust temperature of a diesel engine varies in the range of 250°C~450°C, depending on the load of engine. It is quite sufficient to generate hydrogen with engine exhaust in a methanol reformer. In our system, the hydrogen rate of 17.3 L/min can be obtained in the exhaust pipe of a diesel engine with the displacement volume of 6000c.c. It was found that 49.5% of thermal energy can be recovered, and 92.6% of the recovered energy can be converted. In total, 36.7% of the waste energy can be recovered and stored in the reformed fuel.

Evaluation of a Spark Discharge Particulate Matter Sensor in a Turbocharged Diesel Engine

2007 ◽  
Author(s):  
David P. Gardiner ◽  
William D. Allan ◽  
Marc LaViolette
Keyword(s):  
Particulate Matter ◽  
Diesel Engine ◽  
Oxygen Sensor ◽  
Spark Discharge ◽  
Exhaust Pipe ◽  
Engine Exhaust ◽  
Exhaust Temperature ◽  
Sensor Temperature ◽  
Diagnostic Applications ◽  
The Impact

This paper describes an experimental study of a Particulate Matter (PM) sensor that is intended for on-board control and diagnostic applications in diesel engines. The sensor measures the exhaust PM concentration based upon changes in the voltage waveform of a repetitive, low energy spark discharge. The sensor is electrically heated to prevent carbon fouling from diesel soot and to control its operating temperature. Earlier versions of the sensor were installed directly in the engine exhaust pipe like an Exhaust Gas Oxygen sensor. It was determined that the output of the PM sensor was sensitive to temperature as well as PM concentration, and variations in exhaust temperature made it difficult to maintain the sensor at a constant temperature. In the present study, the sensor was mounted in an electrically heated chamber and a portion of the engine exhaust was bypassed through the chamber. This made it possible to improve the stability of the sensor temperature, thereby reducing the sensitivity of the PM indication to changes in exhaust temperature as the engine load was varied. The PM sensor has been evaluated using a Caterpillar Model 3126 turbocharged 6-cylinder medium duty diesel engine. Small changes in load were used to create minor variations in exhaust PM levels. The PM levels were measured using an AVL 415S smoke meter. Experimental results are presented showing the correlation between the PM sensor signal and the reference PM measurements and the impact of speed and load variations on the correlation.

A Physically-Based, Control-Oriented Diesel Oxidation Catalyst (DOC) Model for the Applications of NO/NO2 Ratio Estimation Using a NOx Sensor

2010 ◽  
Author(s):  
Ming-Feng Hsieh ◽  
Junmin Wang
Keyword(s):  
Diesel Engine ◽  
Diesel Oxidation Catalyst ◽  
Oxidation Catalyst ◽  
Particulate Filter ◽  
Exhaust Gas ◽  
Ratio Estimation ◽  
Engine Exhaust ◽  
Diesel Oxidation ◽  
Physically Based ◽  
Aftertreatment Systems

NO and NO2 are generally considered together as NOx in engine emissions. Since NO2/NOx ratio is small in diesel engine exhaust gas, very often, existence of NO2 is ignored in studies/applications. However, current diesel aftertreatment systems generally include diesel oxidation catalysts (DOCs) at upstream of other catalysts such as diesel particulate filter (DPF) and selective catalytic reduction (SCR). DOC can significantly increase the NO2 fraction in the exhaust NOx. Because NO2 and NO have completely different reaction characters within catalysts, e.g. NO2 can assist DPF regeneration while NO cannot, and SCR De-NOx rate can be increased with higher NO2/NOx ratio (no more than 0.5), considerations of NO2 in aftertreatment systems are becoming necessary. Nevertheless, current onboard NOx sensors cannot differentiate NO and NO2 from NOx. This induces an interest in the method of estimating the concentrations of NO and NO2 in the exhaust gas by available measurements. In this paper, a physically-based, DOC control-oriented model which considers the NO and NO2 related dynamics and an engine exhaust NO/NO2 prediction method were proposed for the purposes of NO/NO2 ratio estimation in diesel engine aftertreatment systems, and the developed model was validated with experimental data.

Comparative analysis on the effects of diesel particulate filter and selective catalytic reduction systems on a wide spectrum of chemical species emissions

2018 ◽  
Author(s):  
Z. Gerald Liu ◽  
Devin R. Berg ◽  
Thaddeus A. Swor ◽  
James J. Schauer‡
Keyword(s):  
Diesel Engine ◽  
Selective Catalytic Reduction ◽  
Diesel Particulate Filter ◽  
Catalytic Reduction ◽  
Wide Spectrum ◽  
Chemical Species ◽  
Pollutant Emissions ◽  
Particulate Filter ◽  
Diesel Particulate ◽  
Aftertreatment Systems

Two methods, diesel particulate filter (DPF) and selective catalytic reduction (SCR) systems, for controlling diesel emissions have become widely used, either independently or together, for meeting increasingly stringent emissions regulations world-wide. Each of these systems is designed for the reduction of primary pollutant emissions including particulate matter (PM) for the DPF and nitrogen oxides (NOx) for the SCR. However, there have been growing concerns regarding the secondary reactions that these aftertreatment systems may promote involving unregulated species emissions. This study was performed to gain an understanding of the effects that these aftertreatment systems may have on the emission levels of a wide spectrum of chemical species found in diesel engine exhaust. Samples were extracted using a source dilution sampling system designed to collect exhaust samples representative of real-world emissions. Testing was conducted on a heavy-duty diesel engine with no aftertreatment devices to establish a baseline measurement and also on the same engine equipped first with a DPF system and then a SCR system. Each of the samples was analyzed for a wide variety of chemical species, including elemental and organic carbon, metals, ions, n-alkanes, aldehydes, and polycyclic aromatic hydrocarbons, in addition to the primary pollutants, due to the potential risks they pose to the environment and public health. The results show that the DPF and SCR systems were capable of substantially reducing PM and NOx emissions, respectively. Further, each of the systems significantly reduced the emission levels of the unregulated chemical species, while the notable formation of new chemical species was not observed. It is expected that a combination of the two systems in some future engine applications would reduce both primary and secondary emissions significantly.

Career fire hall exposures to diesel engine exhaust in Ontario, Canada

2019 ◽  
Vol 17 (1) ◽  
pp. 38-46 ◽  
Author(s):  
JuWon Chung ◽  
Paul A. Demers ◽  
Sheila Kalenge ◽  
Tracy L. Kirkham
Keyword(s):  
Diesel Engine ◽  
Engine Exhaust ◽  
Diesel Engine Exhaust
Sign in / Sign up

Export Citation Format

Share Document