Browse Topic: Emissions control

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Emissions-Related OBD Systems: A Design OverviewC0708.Multi7/8/2021
On-board diagnostics, required by governmental regulations, provide a means for reducing harmful pollutants into the environment. Since being mandated in 1996, the regulations have continued to evolve and require engineers to design systems that meet strict guidelines. This one day seminar is designed to provide an overview of the fundamental design objectives and the features needed to achieve those objectives for generic on-board diagnostics. The basic structure of an on-board diagnostic will be described along with the system definitions needed for successful implementation. Please note that because of proprietary considerations, this class does not provide details of algorithm design, algorithm performance, or algorithm application. The class will cover general OBD algorithm designs and the features required to promote sound OBD system design. Individuals desiring a more in-depth look at On-Board Diagnostics should consider attending SAE seminar ID# C0707 Designing On-Board Diagnostics for Light and Medium Duty Emissions Control Systems. By attending this seminar, you will be able to: Articulate the underlying design objectives of on-board diagnostic systems Apply the design features that all diagnostics need for successful implementation Apply basic design techniques to deal with variation Use a diagnostic design template in the development of an on-board diagnostic 1 Day .7 CEUs
Impact of Non-Thermal Plasma on Particulate Emissions in Application in a Diesel Engine Exhaust DuctSAE-PP-001611/26/2021
Particulates and nitrogen oxides comprise the main emission components of the Diesel combustion and therefore are subject to exhaust emission legislation in respective applications. Yet, with ever more stringent emission standards and test-procedures, such as in passenger vehicle applications, resulting exhaust gas after-treatment systems are quite complex and costly. Hence, new technologies for emission control have to be explored. The application of non-thermal plasma (NTP) as a means to perform exhaust gas after-treatment is one such promising technology. In several publications dealing with NTP exhaust gas after-treatment the plasma state was generated via dielectric barrier discharges. Another way to generate a NTP is by a corona high-frequency discharge. Hence, in contrast to earlier publications, the experiments in this publication were conducted on an operated series-production Diesel engine with an industrial pilottype corona ignition system. Originally developed as an alternative for a spark-plug system in SI engines its attributed properties, such as large penetrated volume and high radical concentration, may also be utilized in the exhaust gas stream. To investigate the effects of a corona discharge on Diesel engine emissions, four igniters were integrated in the exhaust duct of a common-rail direct-injection 2.0 liter diesel engine equipped with a diesel particulate filter (DPF). The impact on particulate number, size distribution as well as on nitrogen oxides has been studied for various operational parameters of the corona system. The particulate number was measured downstream of the DPF to observe the level of improvement for remaining unfiltered nanoparticulates. In this first series of tests, a reduction in particulate number of up to 10 % was achieved depending on engine load. Particulate size distribution was then measured upstream of the DPF. In this case, the highest reduction of 10 % was observed in the midrange particulate size of about 60 nm. No increase in other particulate size ranges has been observed.
MobrxivNonAdmin, Lindsay
Impact of Non-Thermal Plasma on Particulate Emissions in Application in a Diesel Engine Exhaust DuctSAE-PP-001561/25/2021
Particulates and nitrogen oxides comprise the main emission components of the Diesel combustion and therefore are subject to exhaust emission legislation in respective applications. Yet, with ever more stringent emission standards and test-procedures, such as in passenger vehicle applications, resulting exhaust gas after-treatment systems are quite complex and costly. Hence, new technologies for emission control have to be explored. The application of non-thermal plasma (NTP) as a means to perform exhaust gas after-treatment is one such promising technology. In several publications dealing with NTP exhaust gas after-treatment the plasma state was generated via dielectric barrier discharges. Another way to generate a NTP is by a corona high-frequency discharge. Hence, in contrast to earlier publications, the experiments in this publication were conducted on an operated series-production Diesel engine with an industrial pilottype corona ignition system. Originally developed as an alternative for a spark-plug system in SI engines its attributed properties, such as large penetrated volume and high radical concentration, may also be utilized in the exhaust gas stream. To investigate the effects of a corona discharge on Diesel engine emissions, four igniters were integrated in the exhaust duct of a common-rail direct-injection 2.0 liter diesel engine equipped with a diesel particulate filter (DPF). The impact on particulate number, size distribution as well as on nitrogen oxides has been studied for various operational parameters of the corona system. The particulate number was measured downstream of the DPF to observe the level of improvement for remaining unfiltered nanoparticulates. In this first series of tests, a reduction in particulate number of up to 10 % was achieved depending on engine load. Particulate size distribution was then measured upstream of the DPF. In this case, the highest reduction of 10 % was observed in the midrange particulate size of about 60 nm. No increase in other particulate size ranges has been observed.
MobrxivNonAdmin, Lindsay
011 - State-of-Health Online Estimation for Li-Ion BatterySAE-PP-001231/21/2021
To realize a fast and high-precision online state-of-health (SOH) estimation of lithium-ion (Li-Ion) battery, this article proposes a novel SOH estimation method. This method consists of a new SOH model and parameters identification method based on an improved genetic algorithm (Improved-GA). The new SOH model combines the equivalent circuit model (ECM) and the data-driven model. The advantages lie in keeping the physical meaning of the ECM while improving its dynamic characteristics and accuracy. The improved-GA can effectively avoid falling into a local optimal problem and improve the convergence speed and search accuracy. So the advantages of the SOH estimation method proposed in this article are that it only relies on battery management systems (BMS) monitoring data and removes many assumptions in some other traditional ECM-based SOH estimation methods, so it is closer to the actual needs for electric vehicle (EV). By comparing with the traditional ECM-based SOH estimation method, the algorithm proposed in this article has higher accuracy, fewer identification parameters, and lower computational complexity.
MobrxivNonAdmin, Lindsay
Medium/Heavy-Duty E/E Systems Diagnosis NomenclatureJ2403_202008 (Historical)8/3/2020
This SAE Recommended Practice is applicable to all E/E systems on MD and HD vehicles. The terms defined are largely focused on compression-ignited and spark-ignited engines. Specific applications of this document include diagnostic, service and repair manuals, bulletins and updates, training manuals, repair data bases, under-hood emission labels, and emission certification applications. This document focuses on diagnostic terms, definitions, abbreviations, and acronyms applicable to E/E systems. It also covers mechanical systems which require definition. Nothing in this document should be construed as prohibiting the introduction of a term, abbreviation, or acronym not covered by this document. The use and appropriate updating of this document is strongly encouraged. Certain terms have already been in common use and are readily understood by manufacturers and technicians, but do not follow the methodology of this document. These terms fall into three categories: a Acronyms that do not logically fit the term. b Acronyms existing at the component level (i.e., their terms contain the base word or noun that describes the generic item that is being further defined). c Acronyms for terms that appear to contain the base word, but are frequently used as a modifier to another base word. (This use may possibly be thought of as following the methodology, since the acronym is normally used as a modifier.)
Truck Bus Control and Communications Network Committee
A Calculation Methodology for Predicting Exhaust Mass Flows and Exhaust Temperature Profiles for Heavy-Duty Vehicles02-13-02-00097/20/2020
The predictive control of commercial vehicle energy management systems, such as vehicle thermal management or waste heat recovery (WHR) systems, are discussed on the basis of information sources from the field of environment recognition and in combination with the determination of the vehicle system condition. In this article, a mathematical method for predicting the exhaust gas mass flow and the exhaust gas temperature is presented based on driving data of a heavy-duty vehicle. The prediction refers to the conditions of the exhaust gas at the inlet of the exhaust gas recirculation (EGR) cooler and at the outlet of the exhaust gas aftertreatment system (EAT). The heavy-duty vehicle was operated on the motorway to investigate the characteristic operational profile. In addition to the use of road gradient profile data, an evaluation of the continuously recorded distance signal, which represents the distance between the test vehicle and the road user ahead, is included in the prediction model. Using a Fourier analysis, the trajectory of the vehicle speed is determined for a defined prediction horizon. To verify the method, a holistic simulation model consisting of several hierarchically structured submodels has been developed. A map-based submodel of a combustion engine is used to determine the EGR and EAT exhaust gas mass flows and exhaust gas temperature profiles. All simulation results are validated on the basis of the recorded vehicle and environmental data. Deviations from the predicted values are analyzed and discussed.
Kreyer, Jörg, Müller, Marvin, Esch, Thomas
Characteristics of Transient NOx Emissions of HEV under Real Road Driving2020-01-03804/14/2020
To meet the request of China National 6b emission regulations which will be officially implemented in China, firstly including the RDE emission test limits, the transient emissions on real road condition are paid more attention. A non-plug-in hybrid light-duty gasoline vehicles (HEV) sold in the Chinese market was selected to study real road emissions employed fast response NOx analyzer from Cambustion Ltd. with a sampling frequency of 100Hz, which can measure the missing NO peaks by standard RDE gas analyzer now. Emissions from PEMS were also recorded and compared with the results from fast response NOx analyzer. The concentration of NOx emissions before and after the Three Way Catalyst (TWC) of the hybrid vehicle were also sampled and analyzed, and the working efficiency of the TWC in real road driving process was investigated. It is found that when the engine is at high-speed and heavy-load conditions, especially when fuel is injected after fuel cut, instantaneous spikes in tailpipe NO emissions could be observed, which means that traffic positions such as crosswalks, speed bumps, expressway entrances, traffic lights, would lead to higher NOx emissions, because the instantaneous fuel cut-off occurs during the acceleration shifting process, the TWC is in an oxygen-rich state. Obvious transient effects were revealed and the results could be used for further reducing NOx emissions from automotive RDE and engine calibration of RDE.
Zhang, Yonghao, Deng, Jun, Li, Qiang, Liu, Yintong, He, Bo, Hu, Zongjie, Bo, Shi, Li, Liguang
Relevance of Exhaust Aftertreatment System Degradation for EU7 Gasoline Engine Applications2020-01-03824/14/2020
Exhaust aftertreatment systems must function sufficiently over the full useful life of a vehicle. In Europe this is currently defined as 160.000 km. With the introduction of Euro 7 it is expected that the required mileage will be extended to 240.000 km. This will then be consistent with the US legislation. In order to quantify the emission impact of exhaust system degradation, an Euro 7 exhaust aftertreatment system is aged by different accelerated approaches: application of the Standard Bench Cycle, the ZDAKW cycle, a novel ash loading method and borderline aging. The results depict the impact of oil ash on the oxygen storage capacity. For tailpipe emissions, the maximum peak temperatures are the dominant aging factor. The cold start performance is effected by both, thermal degradation and ash accumulation. An evaluation of this emission increase requires appropriate benchmarks. For this purpose, an analysis of the emission impacts of ambient temperatures, driving modes and particulate filter regenerations follows. The comparison shows the severe impact of very low ambient conditions. Considering the high statistical relevance of catalyst degradation however, full useful life optimization requires special attention for Euro 7 gasoline engine applications.
Sterlepper, Stefan, Claßen, Johannes, Pischinger, Stefan, Görgen, Michael, Cox, Jim, Nijs, Martin, Scharf, Johannes
Effects of Using an Electrically Heated Catalyst on the State of Charge of the Battery Pack for Series Hybrid Electric Vehicles at Cold Start2020-01-04444/14/2020
Battery models are being developed as a component of the powertrain systems of hybrid electric vehicles (HEVs) to predict the state of charge (SOC) accurately. Electrically heated catalysts (EHCs) can be employed in the powertrains of HEVs to reach the catalyst light off temperature in advance. However, EHCs draw power from the battery pack and hence sufficient energy needs to be stored to power auxiliary components. In series HEVs, the engine is primarily used to charge the battery pack. Therefore, it is important to develop a control strategy that triggers engine start/stop conditions and reduces the frequency of engine operation to minimize the equivalent fuel consumption. In this study, a battery pack model was constructed in MATLAB-Simulink to investigate the SOC variation of a high-power lithium ion battery during extreme engine cold start conditions (-7°C) with/without application of an EHC. The EHC was simulated in MATLAB to determine the energy required to heat the catalyst during cold start conditions. The effect of the EHC in emissions purification at -7°C was studied using a three-way catalyst (TWC) model. The EHC was operated only during the initial few seconds before the engine start to increase the bed temperature of the catalyst. This was found to have a significant impact on exhaust gas emissions even under cold start conditions. However, powering the EHC lowered the SOC of the battery pack, triggering the engine to run and consume more fuel. Hence, an engine ON/OFF control strategy was proposed to control the engine operation conditions and effectively charge the battery pack. The SOC variation of the battery pack and the effects on emissions and fuel consumption were simulated and compared with/without the EHC. The battery model was validated with a control strategy proposed in simulations at 23°C and a parameter study was conducted at -7°C.
Sivakumar, Suchitra, Shingyouchi, Hajime, Yan, Xieyang, Okajima, Toshinori, Yamaguchi, Kyohei, Kusaka, Jin, Nagata, Makoto
Motor Vehicle Emission Control Quality Monitoring for On-Road Driving: Dynamic Signature Recognition of NO x & NH 3 Emissions2020-01-03724/14/2020
Motor vehicle emission testing during on-road driving is important to assess a vehicle’s exhaust emission control design, its compliance with Federal regulations and its impact on air quality. The U.S. Environmental Protection Agency (EPA) has been developing new approaches to screen the characteristics of vehicle dynamic emission control behaviors (its operating signature) while driving both on-road and on-dynamometer. The so-called “signature device” used for this testing is equipped with an O2/NOx sensor, thermocouple and GPS to record dynamic exhaust NOx concentration, air fuel ratio-controlled tailpipe lambda (λ), tailpipe temperature and vehicle speed (acceleration). In the early EPA research, signature screening was used to characterize a vehicle’s PCM control behaviors (cause/effect bijectivity), which help distinguish operation in normal control state-space and abnormal state-space. Currently, signature devices are being used to recognize when ammonia (NH3) has been emitted and to estimate the presence of NOx and NH3 within on-road and on-dyno driving. The presence of NH3 is observed by the signature device’s NOx sensor at times when tailpipe lambda readings are biased rich, after the engine three-way-catalyst (TWC) has warmed up. To study the production of NH3, EPA established a vehicle test program to gather and evaluate the emissions from on-road driving conditions. The same driving conditions were then replicated on an indoor chassis dynamometer (dyno) while using a bag analyzer bench, a raw exhaust modal bench, and a signature device to measure vehicle emissions and control behaviors. EPA ascertained, under certain operating conditions, that stoichiometric engine exhaust passing through a TWC can create hydrogen (CO+H2O→H2), which is then available to produce unregulated ammonia (CO+NO+H2→NH3). These reactions can accelerate when the engine operates with slightly rich-biased lambda introduced either by control or by calibration design. Under current Light-Duty Tier 3 emission regulations, NOx and NMOG emissions are counted together, creating an “opportunity” for more of this type of engine operation.
Tang, Xiaoguo, Kargul, John, McBryde, Dan
RDE-Compliant PEMS Testing of a Gasoline Euro 6d-TEMP Passenger Car at Two Ambient Temperatures with a Focus on the Cold Start Effect2020-01-03794/14/2020
European Union RDE (real driving emissions) legislation requires that new vehicles be subjected to emissions tests on public roads. Performing emissions testing outside a laboratory setting immediately raises the question of the impact of ambient conditions - especially temperature - on the results. In the spirit of RDE legislation, a wide range of ambient temperatures are permissible, with mathematical moderation (correction) of the results only permissible for ambient temperatures <0°C and >+30°C. Within the standard range of temperatures (0°C to +30°C), no correction for temperature is applied to emissions results and the applicable emissions limits have to be met. Given the well-known link between the thermal state of an engine and its emissions following cold start, ambient temperature can be of great importance in determining whether a vehicle meets emissions requirements during an RDE test. This paper reports the results of full RDE-compliant on-road emissions tests performed on a Euro 6d-TEMP passenger car with a direct injection spark ignition engine and a gasoline particle filter. Testing was performed at two temperatures, both lying within the “standard” temperature range for RDE testing: +25°C and +8°C. Regulated gaseous emissions, particle number and CO2/fuel consumption results are presented and discussed. Overall, as expected, emissions following cold start were significantly higher at the lower test temperature. Nevertheless, the long distance covered during RDE tests (~70-100 km) and their urban phases (>16 km, often ~25 km) weakens the impact of this effect. Some simple mathematical analyses of the results from various portions of the trip are presented.
Bielaczyc, Piotr, Merkisz, Jerzy, Pielecha, Jacek, Woodburn, Joseph
Investigations of the Emissions of Fuels with different Compositions and Renewable Fuel Components in a GDI Engine2020-01-02854/14/2020
Investigations were performed, in which fuels and fuel components were compared regarding gaseous as well as particulate number (PN) emissions. The focus on the selection of the fuel components was set on the possibility of renewable production, which lead to Ethanol, as the classic bio-fuel, Isopropanol, Isobutanol and methyl tert-butyl ether (MTBE). As fuels, a Euro 6 (EU6) reference fuel, an anti-spark-fouling (ASF) fuel, a European Super Plus (RON 98) in-field fuel and a potentially completely renewable fuel, which was designed by Porsche AG (named POSYN), were chosen. The composition of the fuels differs significantly which results in large differences in the exhaust gas emissions. The fuels, except ASF, are compliant with the European fuel standard EN 228.The experiments chosen were a variation of the start of injection (SOI) at different load points at a constant engine speed of 2000 rpm, amongst others. The influence of the fuel properties like boiling characteristics, fuel composition (e. g. the content of aromatic compounds), viscosity and enthalpy of vaporization were considered for interpreting the gaseous and PN emissions and efficiencies of the fuels. The results show decreased NO emissions, when the oxygen content increases. Based on these observations, a 0D/1D model was calibrated with the engine data of the EU6 fuel. The model was used to calculate the NO emissions using the Zeldovich mechanism. For each fuel, the only difference in the model was the definition of the fuel, which includes the (theoretical) molecular formula, heat of vaporization, heating value, density and the enthalpy. In addition to that, the burn rate was determined by a three-pressure-analysis (TPA) and was put into the full engine model. The results show, that the influence of the fuel on the NO emissions can be described well by calculations performed.
Albrecht, Michael, Deeg, Hans-Peter, Schwarzenthal, Dietmar, Eilts, Peter
Vehicle Emission Solutions for China 6b and Euro 72020-01-06544/14/2020
Combinations of CC1 TWC and CC2 coated gasoline particulate filters (cGPF) were aged by 4-mode and fuel cut aging to simulate 200K kilometers of in-use aging in China and Europe, respectively. Separate combinations of catalysts were then evaluated on two low emission engines using the WLTC driving cycle. Catalyst volume and PGM mass were varied in the CC1. OSC/washcoat amounts were varied at constant PGM loading in the GPF. For the Chinese application, after the four-mode aging, it was found that the CC1 TWC catalyst volume should be greater than 1.0 L. High levels of OSC were needed in the GPF to meet CO and NOx emission targets. For the European application, after fuel cut aging, Euro 6d emissions were met with any combination of TWC and GPF catalysts. If the gaseous regulations for Euro 7 are similar to China 6b, the CC1 TWC catalyst should also be great than 1.0 L in order to meet CO and NOx emissions. Over all, results imply that CC1 TWC design is most critical for gaseous emissions. More washcoat (i.e., bigger volume) in the CC1 is more effective for emission reduction than increased PGM. GPFs in the CC2 position may need high OSC/washcoat levels to achieve the CO and NOx emissions regulations for China 6b and Euro 7. The PN measurements for all GPFs were well within current regulations.
Ball, Douglas, Meng, Xiangwei, Weiwei, Gu, Meng, Xiangwei, Weiwei, Gu
Development of Three-Way Catalyst with Advanced Coating Layer2020-01-06534/14/2020
Further improvements in catalyst performance are required to help protect the atmospheric environment. However, from the viewpoint of resource availability, it is also necessary to decrease the amount of precious metals used at the active sites of the catalyst. Therefore, a high-performance three-way catalyst with an advanced coating layer has been developed to lower the amount of precious metal usage. Fuel efficiency improvement technologies such as high compression ratios and a large-volume exhaust gas recirculation (EGR) generally tend to increase the ratio of hydrocarbons (HC) to nitrogen oxides (NOx) in exhaust gas. This research focused on the palladium (Pd) loading depth in the coating layer with the aim of improving the hydrocarbon (HC) conversion activity of the catalyst. Contact between Pd, which has a high degree of HC conversion activity, and the exhaust gas can be facilitated by controlling the loading depth on the surface of the coating layer, enabling efficient conversion even under high space velocity (SV) conditions. Subsequently, this research focused on the coating structure to maximize the conversion activity and oxygen storage capacity (OSC) performance and improve gas diffusivity in the coating layer. The particle size of each coating material was controlled to maximize the heat resistance and OSC performance. The coating thickness was controlled by applying finer alumina and fabricating connected pores. This coating structure ensures excellent gas diffusivity without affecting the pressure drop. As a result, the developed catalyst achieves high conversion activity with nearly 20% less precious metal usage. This catalyst will start to be introduced in vehicles from 2020.
Saito, Yoshinori, Chinzei, Isao, Morikawa, Akira, Ito, Minoru, Oishi, Shunsuke, Okuda, Takuya
A Novel Solid Oxide Fuel Cell Based Catalytic Converter Replacement for Enhanced Emission Control and Power Generation in Automotive Exhaust2020-01-03534/14/2020
Increased concerns over climate change, limited fossil fuel resources, emissions, and poor air quality has created a greater need for sustainable energy systems. The need for increased sustainable energy systems has created largely two cooperative movements: 1) technologies that are considered renewable or more environmentally friendly and 2) higher efficiency. The automotive industry has long been a target for increasing efficiency and decreasing emissions. Current emission control systems rely heavily on the usage of precious metal based catalytic converters. Traditional catalytic converters convert incomplete combustion products into carbon dioxide and water vapor. During this conversion, any remaining chemical energy within the exhaust is lost to waste heat production. In order to achieve increased efficiency and reduced pollutant emission, the remaining chemical energy in the exhaust must be transformed into usable energy. A Solid Oxide Fuel Cell (SOFC) stack is therefore integrated into the exhaust system of a traditional internal combustion engine in place of the current upstream catalytic converter. A SOFC stack would eliminate the need to maintain stoichiometric exhaust conditions, and would allow the recovery of any remaining chemical energy in the exhaust stream. The SOFC stack creates the potential for electrical power generation from the exhaust, while significantly improving emission reduction in a lean environment when compared to the traditional catalytic converter. Initial testing indicates that a typical internal combustion engine operating at stoichiometric conditions results in an exhaust composition of ~2-3% H2 and CO and ~1% mixed hydrocarbons. These exhaust constituents may be used by the SOFC for electrical power generation. Simultaneously, the SOFC stack has demonstrated an ability to decrease hydrocarbon, carbon monoxide, and nitrogen oxide emission by up to 50% when compared to a traditional platinum foil based catalytic converter.
Welles, Thomas S., Ahn, Jeongmin
Nonlinear Identification Modeling for PCCI Engine Emissions Prediction Using Unsupervised Learning and Neural Networks2020-01-05584/14/2020
Premixed charged compression ignition (PCCI) is an advanced combustion strategy, which has the potential to achieve ultra-low nitrogen oxide and soot emissions at high thermal efficiencies. PCCI combustion is characterized by a complex nonlinear chemical-physical process, which indicates that a physical description involves significant development times and also high computation cost. This paper presents a method to use cylinder pressure data and engine operations parameters for prediction of PCCI engine emissions by unsupervised learning and nonlinear identification techniques. The proposed method first uses principal component analysis (PCA) to reduce the dimension of the cylinder-pressure data. Based on the PCA analysis, a multi-input multi-out model was developed for nitrogen oxide and soot emission prediction by multi-layer perceptron (MLP) neural network. Before the training process, a second principal component analysis was done to reduce the input dimension with hyper-parameters thereby reducing memory requirements of the models. The algorithm is applied to an experimental data set from a single-cylinder light-duty engine with piezo injection system. By comparing the model predictions with experimental results, it is shown that the neural network coupling with the unsupervised learning method can successfully capture the nonlinear relationship between the state parameters and the emissions of PCCI combustion system.
Pan, Wang, Korkmaz, Metin, Beeckmann, Joachim, Pitsch, Heinz
Deep Optimization of Catalyst Layer Composition via Data-Driven Machine Learning Approach2020-01-08594/14/2020
Proton exchange membrane fuel cell (PEMFC) provides a promising future low carbon automotive powertrain solution. The catalyst layer (CL) is its core component which directly influences the output performance. PEMFC performance can be greatly improved by the effective optimization of CL composition. This work demonstrates a deep optimization of CL composition for improving the PEMFC performance, including the platinum (Pt) loading, Pt percentage of carbon-supported Pt and ionomer to carbon ratio of the anode and the cathode,. The simulation results by a PEMFC three-dimensional (3D) computation fluid dynamics (CFD) model coupled with the CL agglomerate model is used to train the artificial neural network (ANN) which can efficiently predict the current density under different CL composition. Squared correlation coefficient (R-square) and mean percentage error in the training set and validation set are 0.9867, 0.2635% and 0.9543, 1.1275%, respectively. It illustrates that the well-trained ANN has a comparable accuracy with the physical model. Then, the ANN is utilized as the fitness function in the genetic algorithm (GA) to search the optimal CL composition for maximizing the current density. For verification, the optimal solution of CL composition is returned to the physical model and the comparison between the ANN predicted current density and the physical model simulated current density is provided. The percentage error is only 2.418% which can illustrate the validity of this work.
Wang, Bowen, Xie, Biao, Xuan, Jin, Gu, Wen, Zhao, Dezong, Jiao, Kui
Numerical Optimization of a SCR System Based on the Injection of Pure Gaseous Ammonia for the NOx Reduction in Light-Duty Diesel Engines2020-01-03564/14/2020
Selective Catalytic Reduction (SCR) systems are nowadays widely applied for the reduction of NOx emitted from Diesel engines. The typical process is based on the injection of aqueous urea in the exhaust gases before the SCR catalyst, which determines the production of the ammonia needed for the catalytic reduction of NOx. However, this technology is affected by two main limitations: a) the evaporation of the urea water solution (UWS) requires a sufficiently high temperature of the exhaust gases and b) the formation of solid deposits during the UWS evaporation is a frequent phenomenon which compromise the correct operation of the system. In this context, to overcome these issues, a technology based on the injection of gaseous ammonia has been recently proposed: in this case, ammonia is stored at the solid state in a cartridge containing a Strontium Chloride salt and it is desorbed by means of electrical heating. In this work, an after-treatment system based on the injection of gaseous ammonia in the SCR system is considered. Numerical 1D and 3D CFD simulations are applied in order to optimize the NOx reduction process. In particular, CFD methodology is applied to study in details the process of injection of the gaseous ammonia in the main exhaust gas stream and the effectiveness of the mixing process. Different geometrical layouts are compared to evaluate their performances in terms of uniformity of the NH3 distribution across the inlet section of the catalyst and pressure drop introduced in the exhaust line. Moreover, a 1D simulation tool is applied to evaluate the performances of the entire exhaust after-treatment system. The 1D model is calibrated on the basis of the information coming from detailed CFD simulations, in particular for what concerns the modeling of the effects of the different mixer geometries in terms on NH3 distribution. In this case, a simplified 3D catalyst is simulated, to take into account the maldistribution of ammonia at the inlet cross section and to evaluate its impact on the global deNOx performance of the system for different dosing strategies and for different levels of the ammonia maldistribution.
Della Torre, Augusto, Montenegro, Gianluca, Onorati, Angelo, Cerri, Tarcisio, Tronconi, Enrico, Nova, Isabella
Effects of Sub-Chamber Configuration on Heat Release Rate in a Constant Volume Chamber simulating Lean-burn Natural Gas Engines2019-32-05511/24/2020
Sub-chamber is a useful device with regard to sustaining stable operation of compressed natural gas (CNG) engines under lean burn conditions. In our previous studies, we applied a sub-chamber injection system to CNG engines, in which a single injector and a spark plug are mounted in a small sub-chamber. The aim of this study is to investigate the effect of the sub-chamber configuration on heat release in the main combustion chamber. 11 types of sub-chamber with different nozzle number, nozzle diameter, and sub-chamber volume were examined under a condition that pressure is 2.3 MPa, and global equivalence ratio is 0.6. When the sub-chamber with smaller nozzles are used, the penetration velocity of burned gas jet increases. In addition, the velocity also increases with an increasing sub-chamber volume. The high-speed penetration of burned gas jet shortens the period of initial flame development. This is because the high-temperature burned gas quickly reaches to side wall of main chamber, and immediately ignites lean mixtures existing in the main chamber. Consequently, combustion duration time until heat release reaches 90 % is also shortened. On the other hand, the velocity difference between the jets from sub-chambers with different nozzle numbers is small. To predict the penetration velocity, we proposed an empirical formula based on the volume, nozzle diameter and nozzle number of sub-chamber. The jet intensity evaluated from the formula shows correlations with duration times of combustion periods as well as penetration velocities of burned gas jets.
Nada, Yuzuru, Kidoguchi, Yoshiyuki, Yamashita, Yuto, Furukawa, Ryo, Kaya, Ryu, Nakano, Hideaki, Kobayashi, Shinichi
Application of Porous Material as Heat Storage Medium to a Turbocharged Gasoline Engine2019-32-05411/24/2020
Porous materials, which have large surface areas, have been used for heat storage. However, porous Si-SiC material, as heat storage medium to be applied to a turbocharged gasoline engine has not been investigated extensively. In this study, porous Si-SiC material was used in the upstream of the turbine as heat storage medium and a model was thereby developed for further study. Substrate surface area and substrate volume of Si-SiC were calculated for structure model calibration. Following these calculations and test results, the pressure loss and thermal model were validated. Results show that the weaken exhaust gas pulsation amplitude by porous Si-SiC leads to better turbine performance and BSFC in steady engine condition for a turbocharged gasoline engine. In addition, its transient operation response needs to be improved under transient engine conditions. Hence the possibility of improving the transient response is investigated with characteristics of porous Si-SiC material. It was observed that less time was required for the engine to reach the target torque in transient conditions.
Dong, Dongsheng, Moriyoshi, Yasuo, Kuboyama, Tatsuya, Shen, Fuchao, Hasegawa, Naohiro
Rework of an in-line two-cylinder engine for the application in Formula Student2019-32-05321/24/2020
Formula Student is an international design competition, where students all over the world develop, design and build their own race car and afterwards compete with each other at different disciplines at events worldwide. The development process includes every module of the race car and the team of joanneum racing graz has focused on the powertrain since the beginning. The following paper contains an overview of the reworking process of an in-line two-cylinder engine for the application in Formula Student. The intention was to increase the BMEP and at the same time reach a desired power/weight ratio of the engine. The process of selecting the most appropriate turbocharger by means of experimental testing on an engine dynamometer, as well as its optimization by means of numerical simulation, is outlined. Subsequently, the paper discusses the challenges regarding valve timing and finding the best trade-off between power and residual gas with the help of 1D-simulations. The necessary implementation of an intercooler and its efficiency optimization is also addressed. Finally, the calibration and optimization of the setup on the engine test bed is presented. After the selection of the most suitable turbocharger for the engine and the reworking of its compressor side, it was possible to achieve a maximum boost pressure of 2.76 bar absolute. Charge air cooling and closed loop boost control guaranteed fast boost pressure build up. Together with the optimized cam timing, which reduced residual gas, and an increased compression ratio, the overall torque output of the engine resulted in 135 Nm at 4000 rpm and a maximum power of 63 kW at 6000 to 6500 rpm. The overall target of increasing the BMEP of the selected engine and at the same time achieving a lower power/weight ratio than the previous engine (FS133) was accomplished with a final value of 0.81 kW/kg.
Feigl B.Sc, Michael, Rößmann B.Sc, Dominik, Michael Trzesniowski, FH-Prof. DI
Calcium in Oil Effects on Pre-ignition of Two-stroke Engine2019-32-05791/24/2020
Investigations of the influence of calcium on pre-ignition in a two-stroke engine have shown that the lower the calcium concentration, the lower the frequency of pre-ignition. Pre-ignition problems can occur in small, air-cooled, two-stroke engines such as a chainsaw. In contrast, in a supercharged automobile engine, it has been reported that calcium, which is a detergent component in engine oil, causes low-speed pre-ignition. The oil for two-stroke engines also contains calcium and is mixed with the fuel and lubricated before being supplied to the combustion chamber. This makes, two-stroke engines more likely to be affected by oil components. Based on this, we investigated the influence of calcium on pre-ignition of a two-stroke engine. First, we investigated driving conditions in which pre-ignition is likely to occur, such as warming up the engine. Under this condition, oil with calcium concentrations ranging from 0 ppm to 1,500 ppm were tested at a mixing ratio of 2%. The results show that the lower the calcium concentration, the lower the incidence rate of pre-ignition. Which could also occur at 0 ppm. The incidence rate was 4.6% at 1,500 ppm and 2.3% at 0 ppm.
Eto, Kuniyoshi, Kihara, Masaki
An Effect of Utilization B30 from Various Blends of B0:FAME and HVO on Emissions, Fuel Consumption and Power of Euro4 Vehicle Technology2019-01-218912/19/2019
Indonesia has implemented mandatory for utilization of high ratio biodiesel starting from B10 (10% of biodiesel and 90% of diesel fuel by volume) in 2013 then it gradually increased to B20 in 2016 and B30 in 2020. On the other hand, Indonesian Government will also strengthen vehicle emission regulation from Euro 2 to Euro4 in 2021. Therefore, B0 (low sulfur diesel fuel) and B100 (biodiesel) fuel properties as blended fuel for B30 must be improved to comply with Euro4 vehicle emission regulation. In this study various formulation of B30 were investigated, in which the B100 was varied from FAME (fatty Acid Methyl Ester), HVO (Hydrotreated Vegetable oil), and blend of FAME and HVO. The test was conducted under Euro4 vehicle technology to investigate their effect on emissions, fuel consumption and power. In this experiment, emission, fuel consumption and power were tested using UN-ECE R83-05 regulation, UN-ECE R101 and acceleration method respectively. The results showed that B30 has lower CO, HC and particulate emission compared with B0. However, NOx emission for some formulation slightly increased. Moreover, B30 could comply with emission limit, as stated under Euro4 regulation. Fuel consumption for B30 with some formulation was 2-3% higher than that of B0, but it was about the same between B0 and B30 with optimization ratio of FAME and HVO.
Setiapraja, Hari, Yubaidah, Siti, Ekasari, Mutia, Haspriyanti, Nita, Rustyawan, Wawan, Rochim, Abdul
Development of Diesel Particulate NOx Reduction DPNR System for Simultaneous Reduction of PM and NOx in Diesel Engines2019-28-255411/21/2019
The Diesel Particulate NOx Reduction (DPNR) system is used for simultaneous reduction of PM and NOx in diesel engine. DPF is used to trap particulate matter in diesel engines. NOx absorber technology removes NOx in a lean (i.e. oxygen rich) exhaust environment for both diesel and gasoline lean-burn GDI engines. The NOx storage and reduction catalyst is uniformly coated on the wall surface and in the fine pores of a highly porous filter substrate. Combination of these two components in the DPNR results in a compact size of the system. The base diesel engine model validated with pressure crank angle diagram and performance parameters such as Indicated mean effective pressure. This base engine’s exhaust emission is given as an input to the DPNR system. The surface reaction is connected to the DPF through chemcon template. The surface reaction is NOx storage and reduction chemical kinetics like Lean NOx Trap. The modelling of DPNR and Base engine is done using GT-SUITE. This paper describes about the 1D simulation of DPNR system with base diesel engine model and the percentage reduction of PM and NOx from the base model.
Parthiban, E., Jain, Aatmesh, Chhaganlal Vora, Kamalkishore
Mahle reveals modular, scalable integrated hybrid powertrain19AUTP11_1011/1/2019
Mahle is developing a complete “fits all, off-the-shelf” modular hybrid-drive propulsion system for a wide range of automakers' models, designed to cut costs, improve packaging and provide a level of electrified-vehicle commonality not seen before in the auto industry. Designated Mahle Modular Hybrid Powertrain (MMHP), the system is modular, scalable and dual-mode (parallel and series). It could be in production within two years, ready to power anything from compact sedans to hefty SUVs. The MMHP integrates an all-new turbocharged gasoline internal-combustion engine in twin- and 3-cylinder forms, customizable gearbox (1-, 2- or 4-speed) and a compact but powerful (choice of power/torque) electric traction motor.
Birch, Stuart
Experimental and Numerical Prediction of the Pressure Drop Reduction of Catalytic Converter under Various Mass Flow Rate of Exhaust Gas for a Naturally Aspirated Diesel Engine2019-28-003010/11/2019
Nowadays, Diesel emission control strategies are stringent across the globe which caused the rise in need of diesel after treat treatment devices that are more reliable and efficient. The optimized design of the catalytic converter aids in the durability of the product as well as the improvement in efficient operation of the Indian driving cycle. By changing the convergent and divergent cone angles of the catalytic converter, the consequential decrease in pressure drop leads to efficient flow of exhaust gases. The purpose of this study is to design, test, and analyse the catalytic converter in order to reduce the pressure drop in the exhaust system of a naturally aspirated diesel engine using both experimental and CFD techniques. In this study, a Diesel Oxidation Catalyst Catalytic Converter is investigated. For numerical analysis, ANSYS Fluent is used. Validation is done on baseline Catalytic converter pressure drop results obtained both numerically and experimentally for various speeds conditions and it is found that a reasonably good agreement exists. From the analytical calculations, Catalytic converter diameter, length and Cone angle are selected so as to have maximum pressure drop reduction. The modified inlet and outlet cone angles in catalytic converter chosen are 20°, 22°, 26°, and 28° and the porosity value is 0.826 with square shaped pores in monolith. The Cone angle of 26° gives more reduction in pressure drop of 1.7499KPa, which is less than the baseline pressure drop value of 1.85699 KPa. This leads to 7% overall pressure drop as compared to the different cone angle results. It could be concluded that the inlet and outlet cone angles must be in 26° to yield best flow with reduced pressure drop across the catalytic converter for the selected engine configuration and operating conditions when the porosity is 0.826 with the shape of square monolith.
Vinodh Kumar, Kanchi Gopi, Senthilkumar, Sundararaj, Rajasingh, Edison
Comparison of Regulated and Unregulated Emissions and Fuel Economy of SI Engines with Three Fuels: RON95, M15, and E1004-12-03-001310/4/2019
Abstract This article focuses on a comparative research of the emissions discharged from four vehicles equipped with SI engines, which comply with different emission control systems (Euro 6, Euro 5, and Euro 3). The vehicles used for this work were installed with two different fuel injection technologies (direct injection and port fuel injection) and were operated with three different types of fuels (RON 95, M15, and E10). The tests were performed at the Joint Research Center (JRC) in Ispra using a state-of-the-art emissions test facility according to the European emissions legislation. The test bench included a chassis dynamometer and two different driving cycles were used: NEDC and US06. The main conclusions observed by this article are: (1) Emissions levels from vehicles fueled with M15 are similar to or lower than from those fueled with RON95. (2) Using M15 has the potential to decrease carbon dioxide emissions and to save fuel on an energetic basis. (3) PM emissions are lower for gasoline/alcoholic fuels. (4) No statistically significant effects on carbonyl emissions were found with M15.
Goldwine, Gideon, Sher, Eran, Sher, Diana
3D-Printed Liquid Lab-on-a-ChipTBMG-3527910/1/2019
Researchers have 3D-printed an all-liquid device that, with the click of a button, can be repeatedly reconfigured on demand to serve a wide range of applications from making battery materials to screening drug candidates.
Experimental Test on the Feasibility of Passive Regeneration in a Catalytic DPF at the Exhaust of a Light-Duty Diesel Engine2019-24-00459/9/2019
Diesel engines are attractive thanks to good performance in terms of fuel consumption, drivability, power output and efficiency. Nevertheless in the last years, increasing restrictions have been imposed to particulate emissions, concerning both mass (PM) and number (PN). Different technologies have been proposed to meet emissions standards and the wall-flow Diesel Particulate Filter (DPF) is currently the most common after-treatment system used to trap PM from the exhaust gases. This technology exhibits good features such that it can be regenerated to remove any accumulation of PM. However, this process involves oxidation of the filtered PM at a high temperature through after and post fuel injection strategies, which results in an increase of fuel consumption and may lead to physical damages of the filter in the long term. This work deals with the experimental testing of a catalytic silicon carbide (SiC) wall flow DPF, aiming at decreasing the soot oxidation temperature. The catalyst (CuFe2O4) was deposited on the filter by means of an optimized procedure based on a preliminary controlled chemical erosion of the SiC porous structure. In this way, a uniform distribution of the catalyst on the surface of the filter and in its internal porosities can be obtained. The experimental tests were performed at the exhaust of a EURO V light duty Diesel engine, operating at different speed/load conditions. The results evidence a filtration efficiency higher than 96%, throughout the soot accumulation phase, and, more importantly, a constant value of pressure drop (meaning that the soot oxidation rate equals its deposition rate) at the temperature of 320°C. A further increase of the temperature up to 340 °C, achievable by a small adjustment of engine load, a decrease of the pressure drop is observed, thus evidencing the occurrence of passive regeneration.
Rossomando, Bruno, Arsie, Ivan, Meloni, Eugenio, Palma, Vincenzo, Pianese, Cesare
Diesel Vehicle with Ultra-Low NOx Emissions on the Road2019-24-01459/9/2019
The gap between diesel vehicle emissions in laboratory tests compared to those in use has been addressed by the introduction of the Real Driving Emissions (RDE) requirements. Modern diesel technology now demonstrates low emissions on the road over a wide range of driving conditions. This paper further demonstrates that consistent low nitrogen oxide (NOx) and particle number (PN) emissions can be achieved over a wide range of driving conditions beyond Euro 6d RDE requirements, with emission control technologies combined in an integrated approach. An LNT (Lean NOx Trap) is combined with a dual-dosing SCR (Selective Catalytic Reduction) system. Low-load NOx control is achieved by the LNT in combination with a close-coupled SCR coated on the Diesel Particulate Filter (SDPF). High load conditions, on the other hand, are covered by the underfloor SCR system with a second AdBlue® injector. A P0 48V mild-hybrid system is also available to support the NOx control and to ensure good driving performance and fuel efficiency. An advanced control strategy is implemented to ensure optimal interaction between all emission control functionalities. The system was implemented on a C-segment demonstrator vehicle. The paper discusses the emissions tests performed and the results achieved. A combination of tests on the road and in the lab were carried out to cover a wide range of driving conditions. Special attention was paid to the robustness of the emission performance under urban and motorway driving conditions. Results demonstrate that each aftertreatment component contributes to achieving consistently low NOx emissions under all driving conditions. Particulate emissions are effectively controlled by the DPF.
Demuynck, Joachim, Favre, Cecile, Bosteels, Dirk, Bunar, Frank, Spitta, Joachim, Kuhrt, Andreas
Experimental Investigations on Engine-Out Emissions Sensitivity to Fuel Injection Pressure of a High-Performance DISI Single Cylinder Engine2019-24-01699/9/2019
In recent times, complying with increasingly stringent emission regulations has become ever more challenging than before. While an efficient after-treatment system, that includes a gasoline particulate filter, enables compliance with legislation requirements, lowering engine-out emissions by improving the combustion system must be considered as a crucial advantage for both pollutants emission control and performance. In this respect, high-performance enabling contents such as relatively large displacement, flow-capacity oriented intake ports and a limited stroke-to-bore ratio have significant drawbacks on the charge motion quality and, consequently, on mixture formation and homogeneity. As a countermeasure, fuel injection system components, as well as control strategies, need to be substantially improved. The increase of fuel injection pressure, coupled with optimized injection timing and splitting, has proven to be effective in reducing emissions, especially with regard to particulate matter. This paper provides results of an experimental study investigating the effect of different fuel injection strategies on engine-out emissions, with special emphasis on the influence of very high fuel injection pressures (up to 50 MPa) on particulate matter. A multi-hole inwardly-opening fuel injector fitted to a high specific power direct-injection spark ignition (DISI) single cylinder engine, was tested over a wide range of steady state operating conditions, including catalyst heating, part loads and rated power. A fast particle spectrometer was employed along with a PMP-compliant particle counter to fully characterize fuel injection pressure effect on particle number and size distribution. The results show that significant improvements can be achieved over the entire range of investigated engine operating conditions, especially in regard to particulate matter emissions.
Rossi, Vincenzo, Silvestri, Nicola, Medda, Massimo
Development of a Dedicated CNG Three-Way Catalyst Model in 1-D Simulation Platforms2019-24-00749/9/2019
A growing interest towards heavy-duty engines powered with NG, dictated by stringent regulations in terms of emissions, has made it essential to study a specific Three-Way Catalyst (TWC). Oxygen storage phenomena characterize the catalytic converter efficiency under real world driving operating conditions and, consequently, during strong dynamics in Air-to-Fuel ratio (AFR). A numerical “quasi-steady” model has been set-up to simulate the chemical process inside the reactor. A dedicated experimental campaign has been performed in order to evaluate the catalyst response to a defined λ variation, thus providing the data necessary for the numerical model validation. In fact, goal of the present research activity was to investigate the effect of very fast composition transitions of the engine exhaust typical of the mentioned driving conditions (including fuel cutoffs etc.) on the catalyst performance and on related emissions. A surface reactions kinetic mechanism, representing CH4, CO, H2 oxidation and NO reduction, has been appropriately calibrated in steady-state operation, using a step-by-step procedure all over the engine operating conditions at different AFRs. Then transient conditions were numerically reproduced, through cyclical and consecutive transitions of variable frequency between rich and lean phases. The model includes a proper calibration of the reactions involving Cerium inside the catalyst, in order to reproduce oxygen storage and oxygen release dynamics. Monitoring the reaction rates of the adopted mechanism permitted to evaluate their impact on the exhaust stream composition in several operating conditions. The proposed model predicts tailpipe conversion/formation of the main chemical species starting from experimental engine-out data and provides a useful tool for evaluation of the catalyst performance.
Di Maio, Dario, Beatrice, Carlo, Fraioli, Valentina, Golini, Stefano, Rutigliano, Francesco Giovanni
Exploring the Potential of Miller Cycle with and without EGR for Maximum Efficiency and Minimum Exhaust Emissions in a Heavy-Duty Diesel Engine03-12-05-00379/3/2019
Abstract In order to improve the fuel conversion efficiency and meet more stringent exhaust emissions regulations, Miller cycle and exhaust gas recirculation (EGR) have been researched as separate means to reduce carbon dioxide (CO2) and pollutant emissions from the internal combustion engines. In this article, an experimental work was carried out to explore the potential benefits of Miller cycle operation via late intake valve closing (LIVC) with and without EGR in a single-cylinder heavy-duty (HD) diesel engine equipped with a variable valve actuation (VVA) system. The overall engine-out emissions, fuel conversion efficiency, and estimated urea consumption in the selective catalytic reduction (SCR) aftertreatment were analysed and compared over the World Harmonized Stationary Cycle (WHSC) for different combustion control strategies. Additionally, the potential of Miller cycle with and without EGR based on the “SCR-only” and “SCR + EGR” technical routes to meet the Euro VI nitrogen oxides (NOx) limit of 0.4 g/kWh was assessed at different NOx aftertreatment efficiencies. When considering the urea consumption in the SCR, the results showed that the introduction of EGR allowed for an engine operation with higher corrected net indicated efficiency (NIEcorr.) or lower specific total fluid consumption than the baseline cases without EGR due to the relatively lower engine-out NOx emissions. However, the use of EGR adversely affected soot and carbon monoxide (CO) emissions when operating with constant intake pressure (Pint) of the baseline case. The application of Miller cycle with and without EGR strategies decreased the NIE and NIEcorr. when operating with the same Pint of the baseline operation. The use of higher Pint helped to improve upon the NIE and NIEcorr. of the Miller cycle cases. The WHSC cycle-averaged analysis showed that different combustion and engine control technologies can be adopted with and without EGR to meet Euro VI NOx limit. A conventional baseline engine operation without EGR would require a high SCR efficiency of 96% in order to curb a cycle-averaged NOx emissions level of 10 g/kWh. Miller cycle operation without EGR achieved the optimum NIEcorr. at the cycle-averaged NOx level of 8 g/kWh. When increasing the Pint, this strategy enabled an increase of 2.6% in the NIEcorr. and reduced the required SCR efficiency to 93.5%, but with a penalty on the NIE of 3.3% when controlling the cycle-averaged NOx level at 6.5 g/kWh. Alternatively, Miller cycle operation with EGR and higher Pint allowed for cycle-averaged NOx levels of 4.0 g/kWh, decreased the total fluid consumption by 8%, and minimised the required SCR efficiency to 90%. Therefore, this study has presented promising cost-effective emission control and fuel efficiency technologies that could be suitable for the “SCR-only” and “SCR + EGR” technical routes for the future HD diesel engines.
Guan, Wei, Pedrozo, Vinícius B., Wang, Xinyan, Zhao, Hua, Ban, Zhibo, Lin, Tiejian
Graphene Lid Extends Photoemission Electron Microscopy to LiquidsTBMG-347537/1/2019
By capping liquids with graphene (an ultrathin sheet of pure carbon), researchers can easily image and analyze liquid interfaces and the surface of nanometer-scale objects immersed in liquids. In the imaging technique known as photoemission electron microscopy (PEEM), ultraviolet light or X-rays bombard a sample, stimulating the material to release electrons from a region at or just beneath its surface. Electric fields act as lenses, focusing the emitted electrons to create an image.
Event-Driven Simulation of Particle-Particle and Particle-Surface Collisions in Ice Crystal Icing2019-01-20146/10/2019
This paper describes an event-driven simulation tool for predicting particle-particle and particle-surface interactions in ice crystal icing (ICI). A new accretion model which is much less empirical than existing models for predicting ICI accretion is also described. Unlike previous models, the new “gouge/bounce model” (GBM) differentiates between (erosion) losses resulting from particle bounce and those resulting from particle gouging. A bounce threshold based on the tangential Stokes number is used to calculate most of the bounce loss. The GBM also predicts ejecta velocities and directions, at least approximately, which is important because most of the mixed-phase mass flux impacting a surface actually bounces off or erodes existing material in ICI, thereby increasing the mass flux downstream. The event-driven simulation tool, denoted COLLIDE, has been applied to two test cases in which accretion growth appeared to be affected by TWC in a manner beyond that which would be expected from the accumulation parameters. An existing correlation-based accretion model (CBM), modified to predict erosion dependence on particle diameter, is also implemented and applied to the test cases. COLLIDE predicted the observed accretion dependence on TWC in a least a qualitative fashion for the majority of model/test case permutations, supporting the hypothesis that collisions between backscattered and incident particles reduces erosion and thereby increases sticking efficiency as observed in experiments with larger particles. The predictions suggest scattering of incident particles by impacts with ejecta is the dominant mechanism responsible for the flux interference effect, not particle size reduction due to particle-particle collisions.
Currie, Thomas Charles
Analysis and Automated Detection of Ice Crystal Icing Conditions Using Geostationary Satellite Datasets and In Situ Ice Water Content Measurements2019-01-19536/10/2019
Recent studies have found that high mass concentrations of ice particles in regions of deep convective storms can adversely impact aircraft engine and air probe (e.g. pitot tube and air temperature) performance. Radar reflectivity in these regions suggests that they are safe for aircraft penetration, yet high ice water content (HIWC) is still encountered. The aviation weather community seeks additional remote sensing methods for delineating where ice particle (or crystal) icing conditions are likely to occur, including products derived from geostationary (GEO) satellite imagery that is now available in near-real time at increasingly high spatio-temporal detail from the global GEO satellite constellation. A recent study using a large sample of co-located GEO satellite and in-situ isokinetic evaporator probe (IKP-2) total water content (TWC) datasets found that optically thick clouds with tops near to or above the tropopause in close proximity (≤ 40 km) to convective updrafts were most likely to contain high TWC (TWC ≥ 1 g m-3). These parameters are detected using automated algorithms and combined to generate a HIWC probability (PHIWC) product at the NASA Langley Research Center (LaRC). Seven NASA DC-8 aircraft flights were conducted in August 2018 over the Gulf of Mexico and the tropical Pacific Ocean during the HIWC Radar II field campaign. The convection sampled during four flights was observed by GOES-16 at 1- or 5-minute intervals, providing the first opportunity to analyze product performance from this new satellite. This paper will (1) present initial comparisons between GOES-16 and IKP-2 datasets during HIWC Radar II, (2) demonstrate GOES-16 products for select periods when high TWC was encountered with an emphasis on three flights with 1-minute imagery, (3) compare GOES observations and derived products from the HIWC Radar I and II campaigns.
Bedka, Kristopher, Yost, Christopher, Nguyen, Louis, Strapp, J. Walter, Ratvasky, Thomas, Khlopenkov, Konstantin, Scarino, Benjamin, Bhatt, Rajendra, Spangenberg, Douglas, Palikonda, Rabindra
Cleaner Trucks Initiative starts NOx-reduction journey19TOFHP06_126/1/2019
The U.S. Environmental Protection Agency (EPA) is in the beginning stages of establishing new NOx regulations for heavy-duty on-highway trucks. The agency is spurred by advances in technology and a desire to streamline the certification process. The EPA last revised NOx standards for on-road heavy-duty trucks and buses in January 2001. The process that culminated in those standards actually started in the late 1990s. Rulemaking takes time, both to understand technology trends and incorporate a wide group of stakeholders. It will take no less time to update those NOx standards under the program called the Cleaner Trucks Initiative (CTI), announced by the EPA in November 2018.
Morey, Bruce
Scientists 3D Print All-Liquid ‘Lab on a Chip’TBMG-345526/1/2019
Researchers at DOE's Lawrence Berkeley National Laboratory (Berkeley Lab) have 3D printed an all-liquid device that, with the click of a button, can be repeatedly reconfigured on demand to serve a wide range of applications — from making battery materials to screening drug candidates.
Fuel Reforming and Catalyst Deactivation Investigated in Real Exhaust Environment2019-01-03154/2/2019
Increased in-cylinder hydrogen levels have been shown to improve burn durations, combustion stability, HC emissions and knock resistance which can directly translate into enhanced engine efficiency. External fuel reformation can also be used to increase the hydrogen yield. During the High-Efficiency, Dilute Gasoline Engine (HEDGE) consortium at Southwest Research Institute (SwRI), the potential of increased hydrogen production in a dedicated-exhaust gas recirculation (D-EGR) engine was evaluated exploiting the water gas shift (WGS) and steam reformation (SR) reactions. It was found that neither approach could produce sustained hydrogen enrichment in a real exhaust environment, even while utilizing a lean-rich switching regeneration strategy. Platinum group metal (PGM) and Ni WGS catalysts were tested with a focus on hydrogen production and catalyst durability. Although 4% additional hydrogen was initially produced in the EGR stream, leading to improvements in the coefficient of variation (CoV) and brake specific fuel consumption (BSFC), catalyst activity decreased within a few hours regardless of the regeneration strategy employed. With an SR catalyst, a small amount of hydrogen was produced in the EGR stream via the WGS reaction but not the SR reaction. Similar to the WGS catalyst testing, the SR catalyst deactivated quickly due to coking. While neither of these approaches displayed acceptable long-term performance, the exhaust environment still poses a significant opportunity for the production of hydrogen rich reformate to deliver improvement in engine efficiency.
Bartley, Gordon, Gukelberger, Raphael, Henderson, Robert, Henry, Cary
Deposit Reduction in SCR Aftertreatment Systems by Addition of Ti-Based Coordination Complex to UWS2019-01-03134/2/2019
Formation of urea-derived deposits in selective catalytic reduction (SCR) aftertreatment systems continues to be problematic at temperatures at and below 215 °C. Several consequences of deposit formation include: NOx and NH3 slip, exhaust flow maldistribution, increased engine backpressure, and corrosion of aftertreatment components. Numerous methods have been developed to reduce deposit formation, but to date, there has been no solution for continuous low-temperature dosing of Urea-Water Solution (UWS). This manuscript presents a novel methodology for reducing low-temperature deposit formation in SCR aftertreatment systems. The methodology described herein involves incorporation and dissolution of an HNCO hydrolysis catalyst directly into the UWS. HNCO is a transient species formed by the thermolysis of urea upon injection of UWS into the aftertreatment system. Ideally HNCO undergoes hydrolysis to form NH3 and CO2, but under certain conditions HNCO may polymerize or react with other constituents in the exhaust. Reaction of HNCO with species other than water generally results in the formation of deposits in the aftertreatment system. Addition of an HNCO hydrolysis catalyst directly into the UWS provides maximum contact between catalyst and substrate, thereby improving deposit reduction efficacy. This method of reducing deposits has been shown to reduce deposits by 89% at a 215 °C operating condition.
Hartley, Ryan, Henry, Cary, Eakle, Scott, Tonzetich, Zachary
Study on Improvement of NOx Reduction Performance at Low Temperature Using Urea Reforming Technology in Urea SCR System2019-01-03174/2/2019
To reduce NOx and PM emissions in exhaust gas, after-treatment systems for low NOx emissions are being developed in combination with improvements of engine combustion. In recent years, the exhaust gas temperature has been dropping because of enhanced low-fuel consumption of the engine. Therefore, it is urgent to develop NOx reduction technologies that work at a low temperature under 200degC. Since NOx is reduced by reacting with ammonia supplied to the SCR catalyst, it is necessary to make the urea solution decompose into ammonia using the heat of the exhaust gas to supply sufficient ammonia to the SCR catalyst. However, both the decomposition reaction and hydrolysis reaction of the urea have insufficient exhaust heat, thus making it difficult for urea to decompose and hydrolyze to ammonia at a low temperature. To solve this problem, it focuses on forcibly decomposing the urea solution without depending on the exhaust gas temperature. We selected a urea reforming method in which the urea is directly heated using the glow plug as the heat source. In this study, we have considered further improvement of the NOx reduction performance at a low temperature with a view to improving the ammonia generation efficiency by urea reforming.
Okada, Yuichi, Hirabayashi, Hiroshi, Sato, Shinya, Inoue, Hiroshi
Development and Experimental Validation of a Control Oriented Model of a Catalytic DPF2019-01-09854/2/2019
1 The wall-flow Diesel Particulate Filter (DPF) is currently the most common after-treatment system used to meet the particulate emissions regulations for automotive engines. Today’s technology shows the best balance between filtration efficiency and back-pressure in the engine exhaust pipe. During the accumulation phase the pressure drop across the filter increases, thus requiring periodic regeneration of the DPF through after and post fuel injection strategies. This paper deals with the development of a control oriented model of a catalytic silicon carbide (SiC) wall flow DPFs with CuFe2O4 loading for automotive Diesel engines. The model is intended to be used for the real-time management of the regeneration process, depending on back-pressure and thermal state. In order to ensure suitable computational demand and to realize emissions control and fuel economy objectives, the 0-D model has been developed with the aim of investigating the essential behavior of the system, such as the chemical kinetic of filtered soot oxidation, the thermal and backpressure dynamics along accumulation and regeneration processes. Parameters identification and model validation have been performed vs. experimental data measured on the engine test bench at the exhaust of a EURO 5 light-duty Diesel engine, in different operating conditions. During the accumulation process, engine speed, load and rail pressure are controlled to ensure several levels of trapped soot; on the other hand, the injections pattern, which directly affects the DPF inlet temperature, is handled during regeneration tests. The results show that the model simulates the thermal dynamics and the pressure drop across the filter with good accuracy.
D'Aniello, Federica, Rossomando, Bruno, Arsie, Ivan, Pianese, Cesare
Numerical Modeling Study of Detailed Gas Diffusivity into Catalyst Washcoat for Lean NOx Catalyst2019-01-09934/2/2019
To evaluate the relationship between the exhaust gas purification performance and the catalyst pore properties related to gas diffusion, an elementary reaction model was combined with gas diffusion into catalyst pores, referred to as the pseudo-2D gas diffusion/reaction model. It was constructed for Pt/Al2O3 + CeO2 catalyst as lean NOx catalyst. The gas diffusion was described as macro pore diffusion between the catalyst particles and meso pore diffusion within the particle. The kinetic model was composed of 26 reactions of NO/CO/O2 chemistry including 17 Pt/Al2O3 catalyst reactions and 9 CeO2 reactions. Arrhenius parameters were optimized using activity measurement results from various catalysts with various pore properties, meso pore volume and diameter, macro pore volume and diameter, particle size, and washcoat thickness. Good agreement was achieved between the measured and calculated values. Moreover, as compared to the performance of other catalysts which was not used for reaction model calibration, the simulated results were in good agreement with this experimental data. Using the calibrated reaction model combined with detailed gas diffusion model, a sensitivity analysis for NOx concentration was performed to identify key diffusion parameters of the lean NOx catalyst. In summary, parameters with the highest sensitivity were catalyst particle size, washcoat thickness, CeO2 meso pore volume, and diameter. Also, catalyst macro pore volume and diameter showed no dependence. Consequently, to increase the NOx purification performance, the meso pore parameters and washcoat thickness should be increased, particle size should be decreased. With these changes, the gaseous NOx will easily move to the catalyst surface and into the active site of meso pore, resulting in better performance.
Yamamoto, Osami, Matsuo, Yuichi, Tosa, Shinichi, Okayama, Tatsuya, Zhang, Zhiwei, Tolsma, John
Modeling of Close-Coupled SCR Concepts to Meet Future Cold Start Requirements for Heavy-Duty Engines2019-01-09844/2/2019
The low-NOx standard for heavy-duty trucks proposed by the California Air Resources Board will require rapid warm-up of the aftertreatment system (ATS). Several different aftertreatment architectures and technologies, all based on selective catalytic reduction (SCR), are being considered to meet this need. One of these architectures, the close-coupled SCR (ccSCR), was evaluated in this study using two different physics-based, 1D models; the simulations focused on the first 300 seconds of the cold-start Federal Test Procedure (FTP). The first model, describing a real, EuroVI-compliant engine equipped with series turbochargers, was used to evaluate a ccSCR located either i) immediately downstream of the low-pressure turbine, ii) in between the two turbines, or iii) in a by-pass around the high pressure turbine. These simulations indicate that the location downstream of the low-pressure turbine offers nearly the best NOx conversion, and that the optimal volume of the ccSCR in this location is 25% of a conventional SCR catalyst. The second model describes a conventional heavy-duty aftertreatment system, to which a ccSCR was added. This model was used to examine the performance of the ccSCR in the context of the full ATS. Optimization of the diesel oxidation catalyst (DOC) and SCR catalyst designs in this system was considered, as well as the use of an NH3 storage-based control strategy for DEF dosing to the SCR catalysts.
Harris, Thomas Miller, Mc Pherson, Kristoffer, Rezaei, Reza, Kovacs, David, Rauch, Hendrik, Huang, Yinyan
Ash Transport and Deposition, Cake Formation and Segregation-A Modeling Study on the Impact of Ash on Particulate Filter Performance2019-01-09884/2/2019
Non-combustible particles, commonly summarized as ash, influence the lifetime performance of wall flow filters. This study aims to investigate this influence by means of simulation. An existing transient 1D+1D wall flow filter model is extended by dedicated transport balances for soot and ash (1), by a discrete cake model describing changing soot and ash compositions over the cake height (2), by a phenomenological cake filtration model (3), by dedicated cake property models (4) and by a phenomenological model capturing the radial mobility of solids within the cake (5). Results of three different types of simulations are shown. First, the various sub-models are assessed in isolated simulation configurations. The combination of these shall serve as theoretical model validation. Second, isolated loading and passive regeneration simulations are performed. This aims to identify the impact of different filtration and cake migration constants on soot and ash segregation (i.e. ash accumulation) and on soot conversion performance. Third, the impact of ash during a combined loading and passive regeneration cycle is investigated. This aims to identify the impact of ash on the formation of a soot balance point.
Wurzenberger, Johann C., Kutschi, Susanne, Nikodem, Astrid
Modeling of Engine Aftertreatment System Cooling for Hybrid Vehicles2019-01-09894/2/2019
Exhaust aftertreatment systems are essential components in modern powertrains, needed to reach the low legislated levels of NOx and soot emissions. A well designed diesel engine exhaust aftertreatment system can have NOx conversion rates above 95%. However, to achieve high conversion the aftertreatment system must be warm. Because of this, large parts of the total NOx emissions come from cold starts where the engine has been turned off long enough for the aftertreatment system to cool down and loose its capacity to reduce NOx. It is therefore important to understand how the aftertreatment cools down when the engine in turned off. Experimental data for a catalyst cool-down process is presented and analyzed. The analysis shows that it is important to capture the spatial distribution of temperatures both in axial and radial directions. The data and analysis are used to design a catalyst thermal model that can be used for model based catalyst temperature monitoring and control.
Holmer, Olov, Blomgren, Fredrik, Eriksson, Lars
High Load Expansion of Catalytic EGR-Loop Reforming under Stoichiometric Conditions for Increased Efficiency in Spark Ignition Engines2019-01-02444/2/2019
The use of fuel reformate from catalytic processes is known to have beneficial effects on the spark-ignited (SI) combustion process through enhanced dilution tolerance and decreased combustion duration, but in many cases reformate generation can incur a significant fuel penalty. In a previous investigation, the researchers showed that, by controlling the boundary conditions of the reforming catalyst, it was possible to minimize the thermodynamic expense of the reforming process, and in some cases, realize thermochemical recuperation (TCR), a form of waste heat recovery where exhaust heat is converted to usable chemical energy. The previous work, however, focused on a relatively light-load engine operating condition of 2000 rpm, 4 bar brake mean effective pressure (BMEP). The present investigation demonstrates that this operating strategy is applicable to higher engine loads, including boosted operation up to 10 bar BMEP. By controlling the reforming catalyst boundary conditions, it is possible to achieve fuel reforming without experiencing high temperature exotherms that could be damaging to the catalyst. Additionally, the thermodynamic air handling consequences of operating a highly dilute strategy at high loads is quantified. The results confirm that this operating strategy provides an efficiency benefit at all conditions investigated, with relative efficiency increases of 3-6%, and is therefore applicable over wider regions of the engine operating map.
Szybist, James P., Pihl, Josh, Huff, Shean, Kaul, Brian
Review of Vehicle Engine Efficiency and Emissions2019-01-03144/2/2019
This review paper covers major regulatory and technology developments in 2018 pertinent to tailpipe emissions of greenhouse gases and criteria pollutants. Europe has proposed ambitious reductions in CO2 limits for both light- and heavy-duty sectors. The challenge is compounded with changing measurement norms and a significant shift away from fuel efficient diesels in the light-duty (LD) space. Both incremental and step changes are being made to advance internal combustion. New studies show that in-use NOx emissions from diesels can be much lower than required by the Euro 6 regulation. Discussions have already started on Euro 7 regulations, and the leading regulatory concepts and proposed technical solutions are provided. In the heavy-duty (HD) sector, the progress is outlined in improving engine and vehicle fuel efficiency through the US Department of Energy’s (DOE’s) SuperTruck II program and other representative studies. Common approaches among the participants include hybridization, waste heat recovery, and both open- and closed cycle incremental improvements. Emissions control focus is on evaluating pathways to achieve California’s contemplated low-NOx standards, recently also supported by the US EPA through the Cleaner Trucks Initiative. The challenge is to reduce cold start and low load emissions, requiring innovative engine and after-treatment system solutions. Leading concepts include close-coupled SCR (selective catalytic reduction), use of passive NOx adsorbers, integration of SCR (selective catalytic reduction) on DPFs (diesel particulate filters), low temperature urea or ammonia injection, dual SCR, and active and passive thermal management to raise exhaust temperatures. Work is also underway on a new low load certification cycle. Continued advancement is made on after-treatment components. Aged three-way catalysts (TWCs) and diesel oxidation catalysts (DOCs) are nearing 90% conversion at 150 °C. SCR catalysts continue to improve both their low temperature conversion as well as high temperature durability. Particulate regulations in Europe, China and India are leading to widespread adoption of gasoline particulate filters (GPFs). Lean burn gasoline engines can offer significant fuel economy benefits. NOx control is a challenge, and passive SCR systems and new catalysts are proposed.
Joshi, Ameya
Optimization of a Diesel Engine with Variable Exhaust Valve Phasing for Fast SCR System Warm-Up2019-01-05844/2/2019
Early exhaust valve opening (eEVO) increases the exhaust gas temperature by faster termination of the power stroke and is considered as a potential warm up strategy for diesel engines aftertreatment thermal management. In this study, first, it is shown that when eEVO is applied, the engine main variables such as the boost pressure, exhaust gas recirculation (EGR) and injection (timing and quantity) must be re-calibrated to develop the required torque, avoid exceeding the exhaust temperature limits and keep the air fuel ratio sufficiently high. Then, a two-step procedure is presented to optimize the engine operation after the eEVO system is introduced, using a validated diesel engine model. In the first step, the engine variables are optimized at a constant eEVO shift. In the second step, optimal eEVO trajectories are calculated using Dynamic Programming (DP) for a transient test cycle. The optimized results indicate that with early EVO, the boost pressure should be increased to provide enough cylinder air charge and to maintain the engine torque. External EGR can be reduced due to increased internal EGR while maintaining the same engine out NOx. An optimal zone to maximize temperature benefit with least impact to BSFC has been observed. The study also shows some of the penalties related to eEVO including increased flow pulsation at the air flow sensor location. Finally, with optimal eEVO, a 6.5% - 11% reduction is observed in the light-off time of the selective catalytic reduction (SCR) catalyst and 45% reduction in tailpipe NOx compared to the baseline operation without eEVO.
Srinivas, Pavan Kumar, Salehi, Rasoul
Engine-Aftertreatment in Closed-Loop Modeling for Heavy Duty Truck Emissions Control2019-01-09864/2/2019
An engine-aftertreatment computational model was developed to support in-loop performance simulations of tailpipe emissions and fuel consumption associated with a range of heavy-duty (HD) truck drive cycles. For purposes of this study, the engine-out exhaust dynamics were simulated with a combination of steady-state engine maps and dynamic correction factors that accounted for recent engine operating history. The engine correction factors were approximated as dynamic first-order lags associated with the thermal inertia of the major engine components and the rate at which engine-out exhaust temperature and composition vary as combustion heat is absorbed or lost to the surroundings. The aftertreatment model included catalytic monolith components for diesel exhaust oxidation, particulate filtration, and selective catalytic reduction of nitrogen oxides (NOx) with urea. Both the engine and aftertreatment models have been calibrated with dynamometer measurements from a commercial 2010-certificated 15-L Cummins diesel engine. The fuel consumption engine map with the reduced data is attached in the appendix. Simulations with the combined engine and aftertreatment models above appear to reveal important trends among the fuel efficiency, emissions control, power demand for HD trucks under realistic drive cycle conditions. Thus, this type of computational simulation appears to have significant value in choosing among options for HD vehicle design and operation.
Gao, Zhiming, Deter, Dean, Smith, David, Pihl, Josh, Daw, C. Stuart, Parks, James
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