Emission Control Systems Research Articles

A new methodology for automatic fault tree construction based on component and mark libraries

During the design stage of the development of a new system, automated fault tree construction would produce results a lot sooner than the manual process and hence be highly beneficial in order to modify the system design based on identified weakest areas. Although much work has been performed in this area, the construction of fault trees is still generally done manually. In this paper, a new methodology of constructing fault trees from a system description is proposed. Multi-state input/output tables are introduced, which have the capability to capture output deviations during the normal operation of a component as well as under the influence of abnormality or failure. Two libraries, namely, a component library and a mark library, are introduced. The former stores component models and the latter stores a range of marks. The main purpose of a mark is to identify a certain feature of the system, such as a feedback loop or multiple redundancies. These two libraries are used to redraw the system in a graphical environment where the designer can witness the system come together and also input the necessary failure data for each component. An algorithm has been developed, that uses input/output tables and marks, to automatically construct fault trees for failure modes of interest. In order to demonstrate this methodology, it is applied to an automotive emission control system, and a fault tree is generated using the algorithm developed in this work.

New Aspects to Greenhouse Gas Mitigation Policies for Low Carbon Cities

Methane (CH4) is an important greenhouse gas emitted by vehicles. This study provides estimates of emissions of this important and often not well characterized greenhouse gas (GHG) emission related to transportation energy use. It aims to assist urban community planners and policymakers to prioritize and choose implementation strategies for low carbon cities. The paper focuses on emissions of CH4 from vehicles. Unlike emissions of CO2, which are relatively easy to estimate, emissions of CH4 are a function of many complex aspects of combustion dynamics and depend on the type of emission control systems used. In this context, they cannot be derived easily and instead must be determined through the use of published emission factors for each combination of fuel, end-use technology, combustion conditions, and emission control systems. Emissions of CH4 play a significant role with regards to the relative CO2–equivalent GHG emissions of the use of alternative transportation fuels, in comparison with the use of conventional fuels. By analyzing a database based on literature review this study analyzes all the factors affecting the creation of CH4 emissions from different vehicle types. Statistical analysis indicated “r” values ranging from 0.10 to 0.85 for all vehicles.

Structural Fire Experimental Capabilities at the NIST National Fire Research Laboratory

The NIST National Fire Research Laboratory (NFRL) is a unique facility used to conduct real scale fire measurements. In 2015, the NFRL was expanded to enable research on the response of real-scale structural systems to realistic fire and mechanical loading under controlled laboratory conditions. The scientific objectives of the expanded NFRL are to develop an experimental database on the performance of materials, components, connections, assemblies, and systems under fire load. This data can be used by the international research community to validate and verify physics-based predictive models. The lab features two high bay test areas, a 18 m × 27 m strong floor with 1218 anchor points, a 9 m × 18 m strong wall with 420 anchor points, a hydraulic loading system, four large exhaust hoods instrumented for fire calorimetry, an emission control system for scrubbing acid gases and particles generated by real fuels, controlled gas and liquid fuel burners, water suppression systems, overhead cranes and conditioning space. The laboratory expansion was designed to accommodate experiments on real-scale structural systems and components up to two stories in height and 2 bays × 3 bays in plan. Through application of controlled loads, true service conditions can be simulated, and structures can be exposed to controlled and realistic fire conditions that grow, spread and decay with heat release rates as large as 20 MW. Measurement capabilities have been developed to characterize the response of structural systems and components up to failure and to characterize the fire heat release rate and thermal environment in real time. A detailed description of the laboratory is presented with an emphasis on measurement capabilities.

Achieving nano-gold stability through rational design.

When Au is subdivided to the nanoscale its reactivity changes from an inert nature to one of incredible reactivity which is not replicated by other catalysts. When dispersed onto metal oxides such as TiO2, nano-Au has shown high reactivities for a multitude of reduction and oxidation reactions of industrial importance with potential and current uses such as, CO oxidation, NO x reduction, purification of hydrogen for fuel cells, water gas shift reactions, abatement of volatile organic compounds (VOC's) as well as pollution and emission control systems such as autocatalysts. However, many industrially important reactions and applications operate under harsh conditions where the catalyst is exposed to high temperatures and further needs to operate for extended periods of time. These conditions cause Au nanoparticle sintering whereby small, highly active clusters form large clusters which are catalytically inactive. For this reason, research into stabilizing Au nanoparticles has abounded with a goal of producing durable, thermally stable catalysts for industrial applications. Here we show a durable, thermally stable Au-TiO2 catalyst which has been developed by rational design. The catalyst exhibits a 3-dimensional, radially aligned nanorod structure, already locked into the thermodynamically stable polymorph, via a scalable and facile synthesis, with Au nanoparticles isolated on the support structure. As the Au nanoparticles are highly stable the new catalyst is able to maintain light-off for CO oxidation below 115 °C even after multiple cycles at 800 °C. This ability of the catalyst to resist multiple thermal cycles to high temperature while remaining active at low temperatures shows promise for various industrial applications. The thermal stability of the catalyst is investigated and characterized through morphological and structural studies.

A Theoretical Performance of MR-DeDuster as a Fine Dust Emission Control System

The theoretical performance of a newly developed multi-cyclone system known as MR-deDuster was investigated in term of its collection efficiency tested on a different type of particles. In addition, the performance of the system was also evaluated based on the various diameter of its vortex finder. A modified version of semi-empirical equations introduced by Lapple was used in the prediction. The results showed that the collection efficiency of the system increases with the diameter of vortex finder and density of particles. Details of the finding are discussed and presented in this paper.

Emission Projections for Long-Haul Freight Trucks and Rail in the United States through 2050.

This work develops an integrated model approach for estimating emissions from long-haul freight truck and rail transport in the United States between 2010 and 2050. We connect models of macroeconomic activity, freight demand by commodity, transportation networks, and emission technology to represent different pathways of future freight emissions. Emissions of particulate matter (PM), carbon monoxide (CO), nitrogen oxides (NOx), and total hydrocarbon (THC) decrease by 60%-70% from 2010 to 2030, as older vehicles built to less-stringent emission standards retire. Climate policy, in the form of carbon tax that increases apparent fuel prices, causes a shift from truck to rail, resulting in a 30% reduction in fuel consumption and a 10%-28% reduction in pollutant emissions by 2050, if rail capacity is sufficient. Eliminating high-emitting conditions in the truck fleet affects air pollutants by 20% to 65%; although these estimates are highly uncertain, they indicate the importance of durability in vehicle engines and emission control systems. Future infrastructure investment will be required both to meet transport demand and to enable actions that reduce emissions of air and climate pollutants. By driving the integrated model framework with two macroeconomic scenarios, we show that the effect of carbon tax on air pollution is robust regardless of growth levels.

Soot Oxidation Kinetics of Different Ceria Nanoparticle Catalysts

Catalysts for direct soot oxidation in catalyzed diesel particulate filters (CDPFs) consist typically of various mixed oxide compositions (frequently with CeO2 as the dominant component) that assist soot oxidation by enhancing the supply of oxygen from the catalyst to the soot. Apart from the composition, the material morphological characteristics may also contribute to the catalytic activity and this is the motivation for the present study. Different CeO2 nanoparticle catalysts have been obtained employing aerosol-based synthesis (ABS) and sol–gel methods. The obtained catalyst particles have been characterized with respect to their physical and morphological properties as well as with respect to their catalytic soot oxidation activity. The results have been analyzed with the aid of a multi-population kinetics model where soot is found to consist of three fractions reacting with different activation energies, namely 120, 180, and 240 kJ/mol. The occurrence of these three fractions is attributed to the formation of distinct families of surface oxygen complexes (SOCs) on the carbon surface which are subsequently gasified and hence cause soot oxidation, in agreement with accepted mechanisms of soot oxidation in the literature. The CeO2 nanoparticles oxidize catalytically all three fractions of soot, but with different “enhancement factors,” while the activation energies during catalytic oxidation remain the same. A comparison of the catalytic pre-exponentials to those of plain soot shows, in most cases, enhancements, which for some catalysts, can be up to ∼4.5, 6.5, and 2 times larger than those of plain soot, reflecting the relative capacity of the catalyst to generate more of the respective SOCs. The developed approach provides a more detailed but tractable way to describe soot oxidation (plain and catalytic), which can be readily incorporated into simulations of actual emission control systems to increase their reliability.

Emissions of polychlorinated diphenyl ethers from a municipal solid waste incinerator during the start-up operation

This study examines the emissions of polychlorinated diphenyl ethers (PCDEs) during the start-up processes of a municipal solid waste incinerator (MSWI). Both normal and modified emission control start-ups were tested. Fifteen samples were taken from the flue gas with increasing furnace temperature. Peak PCDE concentrations of 1.48–10.3ng/Nm3 were observed at 8–11h after the start of combustion, when the furnace temperature was in the range of 267–440°C, that also needed for PCDD/F formation by de novo synthesis. The PCDE emissions could thus, be reduced by current control techniques. Furthermore, the modified control strategies inhibited PCDE formation at the beginning of combustion, and led to an 86% reduction in the maximum PCDE concentration. The overall start-up emissions were calculated as 1.01–3.08mg, while the annual PCDE emissions with one start-up operation were found to be 7.48–9.64mg. However, total PCDE emissions will increase by 12–69% if the number of start-up runs increases to between two and eight times per year. Consequently, the prevention of the unnecessary start-ups and advanced activation of the related emission control system are both efficient ways to reduce PCDE emissions.

FEA Simulation Model in Support of the Mechanical Reliability of Automotive Exhaust Gas Temperature Sensors

Automotive exhaust gas temperature sensors are fitted to monitor the performance of a vehicle emission control system. The aggressive working environment is a big challenge in sensor design. This paper introduces an FEA simulation model developed to support the mechanical reliability of new sensor designs. The simulation model was validated by laboratory tests. Suggestions for optimising sensor reliability are given based on the simulation results.

직접분사식 LPG의 분무 및 연소 특성에 관한 연구

As advantages of LPG-DI engine, LPG is directly injected into combustion chamber during compression stroke to reduce compression temperature, prevent knock and spontaneous combustion, and adjust engine output using the amount of directly injected fuel, thereby reducing pumping loss caused by throttle valve. Stratified charge can be supplied nearby spark plugs to allow for overall lean combustion, which improves thermal efficiency and can cope with problems regarding emission regulations. In addition, it is characterized by free designing of intake manifold. Despite the fact that LPG-DI has many advantages as described above, there is lack of detailed investigation and study on spray characteristics, combustion flame characteristics, and ignition probability. In this study, a visualization experiment system that consists of visualization combustion chamber, air supply control system, emission control system, LPG fuel supply system, electronic control system and image data acquisition system was designed and manufactured. For supply of stratified charge in the combustion chamber, alignment of injector and spark plugs was made linear.

Electrochemical Characterization of Electrode Materials for Mixed-Potential Sensors

The Sensors and Electrochemical Devices group at LANL along with Electro-Science Laboratories (ESL) have developed a reproducible mixed potential NOx sensor for application in automotive emission control systems. The pre-commercial sensor has a perovskite working electrode (La1-xSrxCrO3) and a platinum counter electrode, and an Yttrium Stabilized Zirconium (YSZ) electrolyte layer on one side; with a resistive platinum heater on the other side. While the planar sensor that was developed has been extensively studied, several fundamental questions still need to be answered. This study will attempt to answer the question as to how the performance of the sensor changes as the composition of the working electrode is varied. This study uses a button cell in place of the stick sensor. This cell is constructed using the same materials and processes that formed the stick sensors except that it uses a dense YSZ disk with the electrodes on printed on opposite sides. The rationale for using the button cell is so that there is a reference electrode, in this case the platinum electrode, exposed to a controlled reference gas. In this study, we will investigate the change in the sensitivity and selectivity when the Strontium content of the perovskite electrode is changed. The changes will be characterized by using various electrochemical techniques. Information obtained from characterizing varying electrode materials in the button cell configuration will provide insight for tuning selectivity and sensitivity of future planar mixed-potential sensors.

Development of Emission Control Systems to Enable High NOx Conversion on Heavy Duty Diesel Engines

Development of Emission Control Systems to Enable High NO_x Conversion on Heavy Duty Diesel Engines

Computer Simulation of Automotive Emission Control Systems

Computer Simulation of Automotive Emission Control Systems

The Design of Exhaust Gas Cooler for Diesel Particulate Bag Filter

Currently, the application of bag-filter technology in controlling diesel exhaust particulate emissions has been close to practical stage. As one of the key links in bag-filter technology, engine exhaust cooling can directly influence working safety of the entire exhaust particulate filter system. Thermodynamic calculations and experimental research of water-cooled chiller has provided a feasible basis for water cooler to be used in actual diesel exhaust particulate emission control system. The cooler can make engine exhaust temperature drop from 400 to 180 . Even when engine works in high-speed and high-load condition, inlet exhaust temperature of cooler can descend from 500 to 190 or so after cooling, which can still meet bag-filter system requirement of below 200 .

Deactivation mechanisms of iron-exchanged zeolites for NH3-SCR applications

Emissions of nitrogen oxides (NOX) from internal combustion engines are a major contributor to global air pollution, and with more stringent environmental legislations, the need for more efficient and durable NOX emission control systems increases. In the present paper, experimental results of hydrothermal deactivation and regeneration using hydrogen, and chemical deactivation due to phosphorous and potassium exposure of Fe-BEA as NH3-SCR catalyst are summarized. Based on the experimental results, a multi-site kinetic model is developed to predict deactivation of Fe-BEA. The kinetic model predicts deactivation well by decreasing the number of active sites in the model representing loss of active iron sites due to migration or chemical blockage of the sites. It is discussed that by performing a systematic study of different deactivation mechanisms, a deactivation expression for the active sites could be formulated.

ELECTRONIC ENGINE CONTROL SYSTEMS IN MODERN VEHICLES IN ASPECT OF USING IT IN MILITARY COMBAT AND LOGISTIC VEHICLES

Because of much more restricted norms about polluting gas emission in modern vehicles, there is a need to make better control of fuel combustion. The process of fuel combustion is controlled by electronic control unit (ECU). The unit is analysing signals from many sensors, and when the control unit is not able to correct mistakes in fuel combustion, it turn on a warning indicator light and alarming a driver that the emission of polluting gas is too high. The problem is, that the hole system is undependable. The level of complicated of the system is high. In military vehicles, suddenly lost of power of an engine, because of some little mistake in emission control system, in combat conditions could be very danger. Off course, some armoured vehicles has special program in ECU, but most of the military vehicles are built on civilian vehicles, without any changes. The paper show potentials danger in modern electronics controls units of engines. The authors has also practice not only in vehicles testing and service, but also in preparing sport vehicles for rally. The sports programs for ECU in rally vehicles, allows for example for drive with the full power of the engine, even if the temperature of the cooling system is very high, and in normal vehicles, the ECU would not allow to work in such a condition.

The Role of the Chemical Sciences Training on the Emission Control Systems in Vehicles

In industrial plants and motor vehicles basic environmental pollutants and trained human factors play a significant role for the reduction of pollution. This paper briefly describes the effect of chemical science, for the various stages used in the automotive technology training, in the Vocational Higher School in Turkish Higher Education System. The methodology used to improve the learning process in the associate degree level to undergraduate, for the automotive technology program unit emission systems course in the internal combustion engine emission laboratory. The aim of this automotive program is the design of products and process that maximize resource and energy efficiency, while minimizing waste, and thus reduces the environmental pollution. In the modern automotive technology, emission analyzers equipped with the skills to develop these sustainable technologies are particularly valuable. At the end of the training; automotive technicians perform laboratory and field tests to monitor environmental resources, and determine the contaminants and sources of environmental pollution. The best job opportunities exist for those with good diagnostic and problem-solving skills and who have been trained in basic electronics skills and new technology systems in the new vehicles.

Progression of Soot Cake Layer Properties During the Systematic Regeneration of Diesel Particulate Filters Measured with Neutron Tomography

Although particulate filters (PFs) have been a key component of the emission control system for modern diesel engines, there remain significant questions about the basic regeneration behavior of the filters and how it changes with accumulation of increasing soot layers. This effort describes a systematic deposition and regeneration of particulate matter in 25-mm diameter × 76-mm long wall-flow PFs composed of silicon carbide (SiC) material. The initial soot distributions were analyzed for soot cake thickness using a nondestructive neutron imaging technique. With the PFs intact, it was then possible to sequentially regenerate the samples and reanalyze them, which was performed after nominal 20, 50, and 70 % regenerations. The loaded samples show a relatively uniform distribution of particulate with an increasing soot cake thickness and nearly identical initial density of 70 mg/cm3. During regeneration, the soot cake thickness initially decreases significantly while the density increases to 80–90 mg/cm3. After ∼50 % regeneration, the soot cake thickness stays relatively constant, but instead, the density decreases as pores open up in the layer (∼35 mg/cm3 at 70 % regeneration). Complete regeneration initially occurs at the rear of the PF channels. With this information, a conceptual model of the regeneration is proposed.

ChemInform Abstract: Oxidation Potentials in Iron and Steel Making

AbstractReview: 20 refs.

NO oxidation on catalyzed soot filters

In addition to its filtration function, a catalyzed soot filter (CSF) also plays a variety of catalytic roles in modern diesel emission control systems. This paper focuses on NO oxidation on CSF for passive filter regeneration and for optimizing the performance of a downstream SCR catalyst. Using a Pt-catalyzed CSF loaded with diesel soot, we conducted a filter regeneration experiment with NO2 and found that soot oxidation started within the filter walls then extended to the soot cake. The NO2 used to oxidize the soot can be continuously regenerated on the filter after it is consumed, i.e. multiple NO turnovers. By inserting a capillary sampling probe into an inlet channel of a soot-free Pt-CSF, we demonstrated that NO2 generated within the filter walls can diffuse back to the inlet channels against the bulk gas flow, which makes the passive regeneration of the soot cake possible. For CSF-catalyzed NO oxidation in a SCR system, we found a large variability in NO conversion on a Pt-CSF resulting from different aging conditions. A Pt/Pd-CSF can reduce the NO conversion variability to a degree. High-temperature calcination of the supported Pt/Pd powder, before the slurry process, can further reduce this variability.