Results of Coordinating Research Council MMT Field Test Program

<div class="htmlview paragraph">In this pilot study conducted by the Auto/Oil Air Quality Improvement Research Program, engine-out and tailpipe speciated hydrocarbon emissions were obtained for three vehicles operated over the Federal Test Procedure on two different fuels, both of which were speciated. The fates of the fuel species were traced across the engine and across the catalyst, and relationships were developed between engine-out and tailpipe hydrocarbon emissions and fuel composition. These relationships allowed separating the fuel's contribution to engine-out and tailpipe hydrocarbon emissions into two parts, unreacted fuel and partial oxidation products. Specific ozone reactivities and toxic air pollutants were analyzed for both engine-out and tailpipe emissions. Vehicle-to-vehicle, fuel-to-fuel, and bag-to-bag differences have been highlighted.</div>

<div class="section abstract"><div class="htmlview paragraph">An experimental study on effects of high-pressure injections in conjunction with split fuel injections were conducted on an AVL single cylinder DI diesel engine. Various injection schemes were studied through the use of an electronically controlled, common rail injection system capable of injection pressures up to 200 MPa and a maximum of six injections per combustion event.</div><div class="htmlview paragraph">Up to 100 MPa of the fuel injection pressure, the higher injection pressures create faster combustion rates that result in the higher in-cylinder gas temperatures as compared to conventional low-pressure fuel injection systems. When applying high-pressure injections, particulate emission reductions of up to 50% were observed with no change in hydrocarbon emissions, reductions of CO emissions and only slightly higher NOx emissions.</div><div class="htmlview paragraph">Over 100 MPa, on the other hand, the higher injection pressures still reduced up to almost zero-level of particulate emission, at the same time that the NO emission is reduced greatly. Under these high-pressure injection conditions, strong correlations between soot and CO emissions were observed, which compete for the oxidizing OH species.</div><div class="htmlview paragraph">Multiple or split high-pressure injections also investigated as a means to decrease particulate emissions. As a result, a four-split injection strategy resulted in a 55% reduction in particulates and with little or no penalty on NOx emissions. The high pressure split injection strategy with EGR was more effective in reducing particulate and CO emissions simultaneously.</div></div>

<div class="section abstract"><div class="htmlview paragraph">Increasing concerns due to global warming have led to stringent regulation of greenhouse gas (GHG) emissions from diesel engines. Specifically, for GHG phase-2 regulation (2027), more than 4% improvement is needed when compared to phase-1 regulation (2017) in the light heavy-duty (LHD) diesel engine category. At the same time, California Air Resources Board (CARB) and Environmental Protection Agency (EPA) have proposed the new Low NOx standards that require up to 90% reduction in tailpipe (TP) NOx emissions in comparison to the current TP NOx standards that were implemented in 2010. In addition, CARB and EPA have proposed new certification requirements – Low Load Cycle (LLC) and revised heavy-duty in-use testing (HDIUT) based on the moving average window (MAW) method that would require rigorous thermal management. Hence, strategies for simultaneous reduction in GHG and TP NOx emissions are required to meet future regulations.</div><div class="htmlview paragraph">This paper presents potential pathways to achieve the GHG phase-2 and the ultra-low NOx (ULN) regulations with minimum changes in engine design, while meeting the constraints that need to be considered for engine performance stability, component durability, and vehicle drivability. Experimental evaluations were performed focusing on transient cycles such as heavy-duty Federal Test Procedure (hereafter referred as FTP), LLC, and custom transient cycles for HDIUT assessment. We used a model-year (MY) 2021 production Isuzu diesel engine and an advanced dual-dosing aftertreatment system comprising of a close-coupled SCR (ccSCR), diesel oxidation catalyst (DOC), diesel particulate filter (DPF), selective catalytic reduction (SCR), and Ammonia Slip Catalyst (ASC). Conventional thermal management techniques such as multi-injection, intake, and exhaust throttling were implemented to achieve the emissions targets. In addition to the proposed system design, this paper presents following test results from a full-scale system evaluation: <ol class="list nostyle"><li class="list-item"><span class="li-label">1</span><div class="htmlview paragraph">Achieve rapid and sustained turbine-out exhaust temperatures (>200°C) while meeting the engine-out emissions constraints for soot and total hydrocarbon (THC) emissions.</div></li><li class="list-item"><span class="li-label">2</span><div class="htmlview paragraph">A summary of TP NOx, TP N2O and GHG emissions over a composite FTP and LLC.</div></li><li class="list-item"><span class="li-label">3</span><div class="htmlview paragraph">HDIUT assessment results and observations for LLC and custom transient cycles.</div></li><li class="list-item"><span class="li-label">4</span><div class="htmlview paragraph">Robustness evaluation of TP NOx emissions for composite HDT, LLC and custom transient cycles by imposing component variations.</div></li></ol></div></div>

<div class="section abstract"><div class="htmlview paragraph">Today turbo-diesel powertrains offering low fuel consumption and good low-end torque comprise a significant fraction of the light-duty vehicle market in Europe. Global CO₂ regulation and customer fuel prices are expected to continue providing pressure for powertrain fuel efficiency. However, regulated emissions for NO</div><div class="htmlview paragraph"> and particulate matter have the potential to further expand the incremental cost of diesel powertrain applications. Vehicle segments with the most cost sensitivity like compacts under 1400 kg weight look for alternatives to meet the CO₂ challenge but maintain an attractive customer offering. In this paper the concepts of downsizing and downspeeding gasoline engines are explored while meeting performance needs through increased BMEP to maintain good driveability and vehicle launch dynamics. A critical enabler for the solution is adoption of gasoline direct injection (GDi) fuel systems. GDi provides the ability to utilize increased scavenging without sacrificing hydrocarbon emissions because fueling and air controls can be separated. In-cylinder injection with GDi also provides charge cooling benefit yielding the knock reduction necessary for turbocharged applications. Several options within GDi are explored including multi-hole and single pintle spray generators, as well as side-mount versus central-mount applications. Both 3-cylinder and 4-cylinder base engine configurations are explored for turbocharged engines downsized to 1.2 L. Improvements in hydrocarbon emissions, heat losses and scavenging favor fewer cylinders. This is re-enforced by packaging and cost considerations. The next system aspect considered is emissions aftertreatment. Stoichiometric turbocharged GDi provides the lowest cost using the established 3-way catalyst. Stratified GDi is expected to require a lean NO</div><div class="htmlview paragraph"> trap (LNT) and diesel Euro 6 systems require addition of a diesel particulate filter (DPF) and possibly NO</div><div class="htmlview paragraph"> aftertreatment. Although the aftertreatment system to meet Euro 6 NO</div><div class="htmlview paragraph"> requirement is not known today, addition of a DPF, DPF with LNT, or DPF with urea selective catalytic reduction (SCR) represent significant cost and packaging challenges. The analysis concludes by comparing the 3-cylinder turbocharged GDi to other offerings in the context of value tradeoff of CO₂ reduction to system on-cost. Stratified 3-cylinder turbocharged GDi systems offer up to 22% CO₂ reduction compared to a baseline port-fuel-injected 4-cylinder engine. CO₂ reduction of 18% is possible for a stoichiometric GDi mechanization that employs variable valve actuation (VVA) and a conventional 3-way catalytic converter. At Euro 6 emission levels, stoichiometric 3-cylinder turbocharged GDi powertrains offer excellent value. The 3-cylinder turbo-diesel offers similar value if it is capable of meeting the NO</div><div class="htmlview paragraph"> emissions standard without lean aftertreatment. Powertrains with higher engine-out NO</div><div class="htmlview paragraph"> levels that require lean aftertreatment are significantly disadvantaged. Based on the price sensitivity of the compact car segment, the value analysis predicts the 3-cylinder turbocharged GDi engine as the powertrain of choice.</div></div>

<div class="htmlview paragraph">Species analyses have been performed on engine-out and tailpipe hydrocarbon mass emissions to help understand why fuels with increasing amounts of heavy hydrocarbon constituents produce significantly higher tailpipe hydrocarbon emissions. Mass and speciated hydrocarbon emissions were acquired for a fleet of ten 1989 model year vehicles operating on twenty-six fuels of differing heavy hydrocarbon composition. These fuels formed two statistically designed matrices: one examining the effects of medium, heavy, and tail reformate and medium and heavy catalytically cracked components; and the other examining the effects of heavy paraffinic versus heavy aromatic components and the effects of the 50% distillation temperature.</div> <div class="htmlview paragraph">In this paper the fates of fuel species were traced across the engine and across the catalyst, and correlations were developed between engine-out and tailpipe hydrocarbon species emissions and fuel composition. Engine-out and tailpipe specific ozone reactivities were examined in light of the engine-out and tailpipe speciation, and correlations were developed between these specific reactivities and fuel composition.</div>

<div class="section abstract"><div class="htmlview paragraph">In this paper, 20%H₂ (20% hydrogen in natural gas-hydrogen blends, by volume) is selected as the test fuel, and the ignition timing and EGR ratio are adjusted to optimize the performance, combustion, and emissions of a natural gas-hydrogen engine. An experimental investigation on the effect of ignition timings, EGR ratios on combustion behaviors and emissions of a spark-ignition engine fuelled with natural-gas and hydrogen blends was conducted.</div><div class="htmlview paragraph">When increasing the ignition timing at specified EGR ratio, engine power output will give its peak value at MBT timing. Large EGR introduction decreases engine power output and increases combustion duration. Effective thermal efficiency shows an increasing trend at the small EGR ratio and a decreasing trend with further increasing EGR ratio.</div><div class="htmlview paragraph">With advancing the ignition timing, the flame development duration is increased, and the rapid combustion duration and total combustion duration are decreased. All of these three kinds of combustion duration are increased with the increase of EGR ratio.</div><div class="htmlview paragraph">HC concentration is decreased and NOx concentration is increased with advancing the ignition timing while CO emission varies little with the ignition timing. NOx concentration is decreased with the increase of EGR ratio. HC emission is increased with the increase of EGR ratio. CO and CO₂ emissions show little variations with the EGR ratio and ignition timing.</div><div class="htmlview paragraph">Based on the above analysis, a MAP containing ignition timings and EGR ratios for 20%H₂ fuel blend is presented, and this will provide the reference and guidance to engine designers and engineers. In addition, through optimizing ignition timing and EGR ratio, high efficiency and low emission spark-ignition engine can be realized fueled with natural gas-hydrogen blends.</div></div>

<div class="htmlview paragraph">The exhaust emissions produced by the combustion of methyl ester of rapeseed oil (biofuel) have been compared with the ones obtained using a commercial diesel fuel. The tests have been carried out on a Direct Injection Turbocharged (DITC) diesel engine according respectively to the ECE 15, to a non standard STOP and GO test cycle and to the European 13 MODE test procedure. Similar engines running at the same injection timing have been adopted in performing the transient and the steady tests. PAH emissions have been measured on transient cycles.</div> <div class="htmlview paragraph">The effects of injection timing and of Exhaust Gas Recirculation (EGR) on the emission in steady state tests has been evaluated too. In particular an exhaust oxydating catalyst has been employed in presence of EGR.</div> <div class="htmlview paragraph">The tests carried out indicate that, at the same injection timing, methyl ester promotes a rise in NOx emission, a decrease in HC and CO as well as a strong reduction of smoke. Particulate matter produced by methyl ester in transient cycles is higher than that obtained with diesel fuel. Anyway a general trend to the PAH reduction has been recognized.</div> <div class="htmlview paragraph">Finally experiments have shown that NOx, HC and CO emission of biofuel may be reduced, with low effects on particulate, by the adoption of EGR in presence of an exhaust oxydating catalyst.</div>

<div class="htmlview paragraph">A model has been developed which predicts engine-out hydrocarbon (HC) emissions for spark-ignition engines. The model consists of a set of scaling laws that describe the individual processes that contribute to HC emissions. The model inputs are the critical engine design and operating variables. This set of individual process scaling relations was then calibrated using production spark-ignition engine data at a fixed light-load operating point. The data base consisted of engine-out HC emissions from two-valve and four-valve engine designs with variations in spark timing, valve timing, coolant temperature, crevice volume, and EGR, for five different engines. The model was calibrated separately for the three different engines to accommodate differences in engine design details and to determine the relative magnitudes of each of the major sources. A good fit to this database was obtained.</div> <div class="htmlview paragraph">The model provides insight into the individual phenomena involved in the total HC mechanism and how each individual process is affected by model inputs. The model results showed that the fuel sources (oil layers, deposits, and liquid fuel) and fuel-air sources (crevices and quench layers) contributed approximately equally to the engine-out HC emissions. Typical in-cylinder post combustion HC oxidation levels were 68% for fuel-air sources and close to zero for fuel sources. For all sources, about 25% of the unoxidized HC were retained in the cylinder, and exhaust port HC oxidation was about 35%. The model predicted that the fuel source contribution to the engine-out HC emissions was most affected by changes in coolant temperature, compression ratio, EGR, and spark timing, whereas the contribution from the fuel-air sources was affected most by crevice volume, spark timing and compression ratio, and only slightly by EGR, valve overlap and coolant temperature. The model was used to establish relative sensitivities of HC emissions to critical design and operating parameters by determining the magnitude of individual parameter changes that produced a 10% decrease in HC emissions.</div>

<div class="htmlview paragraph">Advances in integrated circuit technology over the past few years have led to the development of a group of technologies that have been classed as smart power. These new technologies now allow the semiconductor manufacturer to include logic and analog control on the same monolithic device with power transistors capable of controlling many Watts of output power. Recently developed devices have the capability to control up to 400 Watts of power delivered to the load with a single monolithic integrated circuit.</div> <div class="htmlview paragraph">Many of the Smart Power technologies are compatible with the automotive environment and may be used to fabricate devices for power actuation in an automotive multiplex control system. This paper gives a brief overview of four smart power technologies and their applications in an automotive multiplex control system for body electric. Two specific devices recently developed in these technologies are introduced.</div>

<div class="section abstract"> <div class="htmlview paragraph">This SAE Recommended Practice is applicable to all light duty and medium duty passenger vehicles and trucks with feedback fuel control system. Specific applications of this document include diagnostic, service and repair manuals, repair data bases, and off-board readout devices.</div> <div class="htmlview paragraph">This document focuses on a diagnostic code format and code messages for automotive electronic control systems.</div> <div class="htmlview paragraph">The use and appropriate updating of this document is strongly encouraged; however, this document does not prohibit the use of additional codes for additional diagnostics.</div></div>

<div class="section abstract"><div class="htmlview paragraph">Achieving zero emissions across transportation is a tremendous challenge. The upcoming Euro 7/VII standards, set to be enforced in 2025, will mandate further reduction in ICEs exhaust emissions. Thus, additional improvements and potential new technologies and fuels are needed to design ultra-low emissions vehicles.</div><div class="htmlview paragraph">Hydrogen seems to be a very attractive fuel, thanks to its high lower heating value, clean combustion, and extremely low pollutant emissions, due to the zero-carbon content. Nevertheless, NOx emissions are still an issue in hydrogen fueled engines and optimized lean-burn combustion and suitable after-treatment NOx reduction are mandatory to reach high specific power and efficiency and near zero NOx emissions, thus enabling H2-ICE powered vehicles to be zero-impact emitting technology solution.</div><div class="htmlview paragraph">Selective Catalytic Reduction by using NH3 as the reducing agent is the most effective control technology for NOx abatement. Nevertheless, ongoing research and innovation are critical in developing new strategies for reducing NOx emissions, to overcome the NH3-SCR system main critical issues (extra equipment for urea storage and dosing, ammonia-slip, deactivation and fouling, low efficiency at low temperature).</div><div class="htmlview paragraph">The SCR of NOx by hydrogen is considered a promising alternative to traditional ammonia-based deNOx technology. The H2-SCR catalysts are suitable for engine exhaust after-treatment during cold-start and urban-driving operations, exhibiting higher catalytic activity for low-temperature NOx emissions conversion (180 – 200 °C). Furthermore, in H2-ICE powered vehicles, the additional tank to store the reducing agent is not needed with a significant simplification of the engine exhaust lay-out.</div><div class="htmlview paragraph">Experimental investigations on different H2-SCR catalysts have demonstrated that the conversion activity is greatly affected by the catalytic system configuration, the adsorption properties of the support material, the H2 spillover, that in turn are affected by H2/NO ratio and exhaust gas composition, temperature and flow rate.</div><div class="htmlview paragraph">In the present paper, a feed-forward neural network model of H2-SCR is presented, with the aim of performing real-time estimation of reduction efficiency and supporting the design of suitable H2 management to achieve maximum NOx reduction and minimum hydrogen consumption. Model training and identification are carried out against a large set of experimental data measured on a H2-SCR small scale prototype at the Synthetic Gas Bench. The experimental tests were designed to reproduce the real conditions expected at the exhaust of a H2-fueled engine.</div></div>

<div class="section abstract"><div class="htmlview paragraph">An unmodified, conventionally fuelled, 2009 Class D vehicle with a 2.0L turbocharged gasoline direct injection engine was operated on a range of gasoline, gasoline-ethanol and gasoline-butanol fuel blends over NEDC drive cycles and WOT power curves on a chassis dynamometer. Engine performance, engine management system parameters and vehicle out emissions were recorded to investigate the response of a current state-of-the-art technology vehicle to various alcohol fuel blends.</div><div class="htmlview paragraph">The vehicle fired on all fuels and was capable of adapting its long term fuelling trim to cope with the increased fuel flow demand for alcohol fuels up to E85. Over the NEDC tests, the volumetric fuel consumption was very strongly related to the calorific content of the fuel. CO and NOx emissions were largely unaffected for the mid alcohol blends, but CO emissions decreased and NOx emissions increased significantly for the high alcohol fuels. THC emissions were largely unaffected. Particulate mass initially reduced as the alcohol content increased, but then increased significantly for the higher alcohols. This was likely due to the poor vaporisation during cold start.</div><div class="htmlview paragraph">During the power curves, WOT performance increased with the oxygen content in the fuel. The performance on 95RON was slightly restricted by occasional activation of the knock controller, which retarded the mean spark timing. The alcohol fuels did not suffer from knocking events but were able to use additional fuel-sourced oxygen to increase the power output and increase the turbine enthalpy.</div></div>

<div class="section abstract"><div class="htmlview paragraph">The introduction of alternative fuels is crucial to limit greenhouse gases. CNG is regarded as one of the most promising clean fuels given its worldwide availability, its low price and its intrinsic properties (high knocking resistance, low carbon content...). One way to optimize dedicated natural gas engines is to improve the CNG slow burning velocity compared to gasoline fuel and allow lean burn combustion mode. Besides optimization of the combustion chamber design, hydrogen addition to CNG is a promising solution to boost the combustion thanks to its fast burning rate, its wide flammability limits and its low quenching gap.</div><div class="htmlview paragraph">This paper presents an investigation of different methane/hydrogen blends between 0% and 40 vol. % hydrogen ratio for three different combustion modes: stoichiometric, lean-burn and stoichiometric with EGR. The main objectives are to identify the complex mechanisms involved in the combustion process and to define the optimal hydrogen ratio for each combustion mode.</div><div class="htmlview paragraph">The study combines engine tests and 0D modeling. Tests were carried out on a spark-ignited single-cylinder engine adapted to CNG operation with 2 different compression ratios 9,5:1 and 11,5:1. Computations allow studying separately the different phenomena linked to the progressive addition of hydrogen in the fuel. Hence, using 0D modeling, the effects due only to the combustion speed evolution, as a function of hydrogen ratio in the fuel, were then quantified using experimental results as comparison basis.</div><div class="htmlview paragraph">The engine test results reveal that the impact of hydrogen is limited in stoichiometric conditions except for CO₂ savings. A ratio of 10 to 20 vol. % of hydrogen seems to be optimal to reach interesting HC emissions reduction without an excessive lowering of the operation range. The results are more encouraging for lean-burn operation as the lean limit of equivalence ratio is extended for more than 0,125 with 40 vol. % of hydrogen. NOx emissions and consumption were significantly reduced (-92% for NOx) while maintaining constant HC and CO emissions compared to methane operation. Hydrogen stabilizes and speeds up combustion especially in very diluted mixtures. Furthermore, hydrogen increases EGR tolerance for the same reasons as in lean-burn mode: in comparison, identical very-low NOx levels were reached with smaller consumption gains. Finally, the engine test results show that the highest tested ratio of hydrogen (up to 40%) in methane for very diluted mixtures with air or EGR drastically reduce NOx emissions without penalty on engine performances.</div><div class="htmlview paragraph">Computations prove that the evolution in terms of thermodynamic properties of the fuel is not the most important contribution to the evolution of combustion. The effect of hydrogen addition contributes mainly to increase the combustion speed. Moreover, lean burn operation results demonstrate that the increase of combustion speed due to hydrogen addition is enhanced. This can only be explained by the increase of thermo-diffusivity which has an opposite and larger effect than the slowdown of laminar flame velocity conventionally described in the literature.</div></div>

<div class="htmlview paragraph">The performances of four lean-burn gas engines were analyzed using test data and computer simulation. Two engines have swirl initiating inlet ports leading to a high flame speed and the other two engines have no swirl motion in the combustion chamber, which results in a longer heat release.</div> <div class="htmlview paragraph">The US Heavy Duty transient test and the 8-mode test show that hydrocarbon emissions are produced mainly at low load as well as at full load. NOx emissions are formed mainly at full load. In order to attain a minimum HC emission level, the air/fuel ratio must be adjusted accurately, especially at low load, and the valve overlap must be as small as possible, which will reduce the HC emission at part load as well as at full load.</div> <div class="htmlview paragraph">Two computer models have been used for the analysis. When the effective efficiencies measured are corrected for the different engine specifications and settings to a reference engine, the engines considered have an almost equal indicated efficiency. The NOx emissions can be explained by the peak temperatures calculated.</div>

<div class="htmlview paragraph">This work is a joint development project between Chrysler and CFD Research Corporation (CFDRC). The objective of this investigation is to perform a 3D computational heat transfer analysis in a vehicle passenger compartment, for better climate control, under external thermal radiation. One of the major tasks is to simulate the transient temperature variation in the passenger compartment after the AC unit is turned on.</div> <div class="htmlview paragraph">Two physical models were incorporated in the computations, namely, the radiation model and the conjugate heat transfer methodology. The 3D radiation model was employed to evaluate the solar irradiation through the glazed surfaces, namely, the front windshield, the rear window, and the two side windows. Conjugate heat transfer methodology was employed to compute the heat transfer across the glazed surfaces due to heat conduction and convection. These developed models were then integrated and incorporated into the CFD-ACE code, a multi-domain, 2D and 3D combined general equation solver developed by CFDRC.</div> <div class="htmlview paragraph">Comparison shows very reasonable agreement between computational results and experimental data obtained from vehicle hot room cool down tests. This study demonstrates that Computational Fluid Dynamics (CFD) technology can be used as a design and prototyping tool for automotive climate control systems.</div>