The scope of this work is to propose a methodology to define multicomponent surrogate mixtures which describe the main evaporation characteristics of real gasoline fuels. Since real fuels are commonly complex mixtures with hundreds or thousands of hydrocarbons, their exact composition is generally not known. Only global characteristics are standardized. An accurate modeling of such complex mixtures in 3D-CFD requires the definition of a suitable surrogate. So far, surrogate mixtures have mostly been defined based on their combustion properties, such as ignition delay or burning velocity, irrespective of their evaporation characteristics. For this reason, in this work, a systematic study is carried out to develop a methodology to define mixtures of representative components that mimic the evaporation behavior of real fuels. Specifically, the following aspects are analyzed: the necessary number and type of the surrogate components, the definition of optimization targets representing the real fuel properties of interest (i.e. the vapor pressure and the distillation curve), the formulation of an appropriate numerical model to evaluate these quantities and the choice of a suitable optimization algorithm to obtain the optimal surrogate composition. It is shown that these different aspects can influence the surrogate definition, potentially leading to a non-optimal representation of the real fuel target properties. This investigation is carried out for four representative real fuels, for which experimental data on their vapor pressure and distillation curve are available. Finally, suitable surrogates are proposed for all fuels.

Pati, Andrea, Gierth, Sandro, Haspel, Philip, Hasse, Christian, Munier, Jerome

The Development of Low Temperature Three-Way Catalysts for High Efficiency Gasoline Engines of the Future: Part II

2018-01-09394/3/2018

It is anticipated that future gasoline engines will have improved mechanical efficiency and consequently lower exhaust temperatures at low load conditions, although the exhaust temperatures at high load conditions are expected to remain the same or even increase due to the increasing use of downsized turbocharged engines. In 2014, a collaborative project was initiated at Ford Motor Company, Oak Ridge National Lab, and the University of Michigan to develop three-way catalysts with improved performance at low temperatures while maintaining the durability of current TWCs. This project is funded by the U.S. Department of Energy and is intended to show progress toward the USDRIVE target of 90% conversion of hydrocarbons (HC), carbon monoxide (CO), and nitrogen oxides (NOx) at 150 °C after high mileage aging. The testing protocols specified by the USDRIVE ACEC team for stoichiometric S-GDI engines were utilized during the evaluation of experimental catalysts at all three facilities. This paper summarizes work performed at Ford on the development of a catalyst formulation with significantly lower lightoff temperatures than a current production TWC after aging on a high temperature 4-mode durability cycle. The new catalyst consists of rhodium post-impregnated onto an overlayer of titanium deposited onto a silica-stabilized Al2O3 support. A rhodium loading study revealed that the lowest T90 s after 4-mode aging were obtained with 0.5% Rh. A titanium loading study showed that that the best performance after 4-mode aging was obtained with 8% titanium, which corresponded to the monolayer coverage of titanium. TEM analysis confirmed that the titanium monolayer remained well dispersed after the high temperature aging. A fresh sample of the optimized catalyst was evaluated after sulfur poisoning and after a stoichiometric desulfation.

Theis, Joseph R., Getsoian, Andrew (Bean), Lambert, Christine K.

Efficiency and Emissions Characteristics of an HCCI Engine Fueled by Primary Reference Fuels

2018-01-12554/3/2018

This article investigates the effects of various primary reference fuel (PRF) blends, compression ratios, and intake temperatures on the thermodynamics and performance of homogeneous charge compression ignition (HCCI) combustion in a Cooperative Fuels Research (CFR) engine. Combustion phasing was kept constant at a CA50 phasing of 5° after top dead center (aTDC) and the equivalence ratio was kept constant at 0.3. Meanwhile, the compression ratio varied from 8:1 to 15:1 as the PRF blends ranged from pure n-heptane to nearly pure isooctane. The intake temperature was used to match CA50 phasing. In addition to the experimental results, a GT-Power model was constructed to simulate the experimental engine and the model was validated against the experimental data. The GT-Power model and simulation results were used to help analyze the energy flows and thermodynamic conditions tested in the experiment. The results indicate that an increase of compression ratio causes higher thermal efficiency and fuel conversion efficiency; however, at the same compression ratio, an increase in PRF number results in lower efficiency due to the required increase in intake temperature and the associated decrease in charge density. While the efficiency does increase with compression ratio, the results show that the effect of increased expansion work is partially offset by higher heat transfer losses and lower ratios of specific heats at higher compression ratios. The results indicate that the maximum pressure rise rate (MPRR) in HCCI significantly increases with compression ratio. Combustion efficiency shows a strong trend with peak temperature regardless of the PRF number or compression ratio, indicating that the CO-to-CO2 conversion is independent of the parent fuel chemistry in the case of the PRFs, whereas the unburned hydrocarbon emissions showed the opposite trend, depending mostly on the parent fuel’s autoignition tendency.

Yang, Ruinan, Hariharan, Deivanayagam, Zilg, Steven, Lawler, Benjamin, Mamalis, Sotirios

Experimental and Kinetic Modeling of Degreened and Aged Three-way Catalysts: Aging Impact on Oxygen Storage Capacity and Catalyst Performance

2018-01-09504/3/2018

The aging impact on oxygen storage capacity (OSC) and catalyst performance was investigated on one degreened and one aged (hydrothermally aged at 955 °C for 50 h) commercial three-way catalyst (TWC) by experiments and modeling. The difference of OSC between the degreened and aged TWCs was dependent on catalyst temperature. The largest difference was found at 600 °C, at which the amount of OSC decreased by 45.5%. Catalyst performance was evaluated through lightoff tests at two simulated engine exhaust conditions (lean and rich) on a micro-reactor. The aging impact on the catalyst performance was different under lean and rich environments and investigated separately. At the lean condition, oxidation of CO and C3H6 was significantly suppressed while oxidation of C3H8 was relatively less degraded. At the rich condition, the inhibition effect was more pronounced on the aged TWC and inhibiting hydrocarbon species from C3H6 partial oxidation can survive at temperatures up to 450 °C. However, NO reduction activity declined less compared to CO and C3H6 oxidation. More NH3 formed at low temperature and N2O formation was suppressed on the aged TWC. A generic TWC model including a dual-site oxygen storage sub-model and PGM kinetics was developed to predict the aging impact on dynamic OSC and catalyst performance. The PGM kinetics include oxidation of H2, CO, and hydrocarbons as well as water-gas shift (WGS) and hydrocarbon steam reforming. NO reduction kinetics including N2O and NH3 formation and decomposition were also considered. The TWC models were calibrated on the degreened and aged TWCs separately based on experimental data. With the dual-site OSC model and calibrated kinetics, the dynamic OSC and lightoff performance on the fresh and aged TWCs were successfully predicted. The resulting changes of the OSC as well as lightoff performance due to aging were quantified and discussed with the help of the TWC models.

Gong, Jian, Wang, Di, Li, Junhui, Kamasamudram, Krishna, Currier, Neal, Yezerets, Aleksey

Considerations for CFD Simulations of a Refueling Pump Nozzle with Application to the Computer Aided Engineering of a Vehicle Refueling System

2018-01-04894/3/2018

A vehicle’s refueling system including components, which make up the onboard refueling vapor recovery (ORVR) system, must be designed to meet federally set evaporative hydrocarbon emission regulations and other performance issues inherent to the refueling process, such as premature click-off and spit-back. A Computational Fluid Dynamics (CFD) model able to predict the performance of a vehicle’s refueling system could be a valuable tool towards the development of future designs, saving the Original Equipment Manufacturer’s (OEM) time and money in the research and development phases. To create an adequate model required for Computer Aided Engineering (CAE) of a modern refueling system, it is paramount to accurately predict the fluid dynamics through and out of a gasoline refueling nozzle, as this is a key inlet condition of any refueling system. This study aims to validate CFD simulations, which predict the fluid dynamics through a refueling gasoline pump nozzle. The commercial CFD software Star-CCM+ was used to model gasoline flow through two gasoline nozzle geometries. The CFD domain for a Husky X1 and an OPW 11B were created using PTC Creo Parametric. Computer Aided Drafting (CAD) models created from physical measurements taken of the deconstructed nozzles. Experiments were conducted and compared to the CFD results. It was found that the OPW 11B produced a divergent/fanning spray pattern, whereas the Husky X1 delivered a narrow jet-like fuel spray. It was found that modeling of the fluid dynamics through the air entrainment and shut-off port geometries within the nozzles were needed to accurately capture fuel spray behavior as demonstrated by experiments. Mesh independence and time independence studies were conducted, as well as different inlet techniques to simulate air entrainment present in the nozzles. The study acts as a guide for future simulations involving fuel filling necks and tanks, and serves to suggest mesh, time step, and solver settings to achieve the highest quality simulation.

Dake, Mangesh Rajendra, FitzWilliam, Joseph, Henderson, Marc, Shaw, Joshua, Swanson, Matthew, Windom, Bret

Exploring the NOx Reduction Potential of Miller Cycle and EGR on a HD Diesel Engine Operating at Full Load

2018-01-02434/3/2018

The reduction in nitrogen oxides (NOx) emissions from heavy-duty diesel engines requires the development of more advanced combustion and control technologies to minimize the total cost of ownership (TCO), which includes both the diesel fuel consumption and the aqueous urea solution used in the selective catalytic reduction (SCR) aftertreatment system. This drives an increased need for highly efficient and clean internal combustion engines. One promising combustion strategy that can curb NOx emissions with a low fuel consumption penalty is to simultaneously reduce the in-cylinder gas temperature and pressure. This can be achieved with Miller cycle and by lowering the in-cylinder oxygen concentration via exhaust gas recirculation (EGR). The combination of Miller cycle and EGR can enable a low TCO by minimizing both the diesel fuel and urea consumptions. In this work, Miller cycle with late intake valve closing (IVC) and EGR technology were investigated on a single cylinder common rail heavy-duty diesel engine at high load operation of 24 bar net indicated mean effective pressure. The experiments were performed with a constant intake manifold pressure of 3 bar while optimizing the start of diesel injection to keep the peak in-cylinder pressure limit of 180 bar. The aqueous urea solution consumption in the SCR aftertreatment system was estimated to evaluate the effectiveness of the strategies in terms of TCO. The calculation was based on the engine-out NOx emissions and the Euro VI NOx limit. The results revealed that the use of the Miller cycle without EGR reduced NOx emissions by 35% and the net indicated efficiency by 4% when compared to the case with the baseline IVC at −178 crank angle degrees (CAD) after top dead center (ATDC). The introduction of 8%EGR decreased the levels of NOx by 54% while maintaining similar net indicated efficiency at the baseline IVC. The combination of Miller cycle with an IVC at −127 CAD ATDC and an EGR rate of 8% achieved the best trade-off between NOx and ISFC, decreasing the NOx levels by 57% and the fuel consumption by 1.6% compared to the baseline case. Soot emissions were maintained below the Euro VI limit of 0.01 g/kW h. Carbon monoxide emissions were maintained at low levels except for the combination of an IVC at −114 and an EGR rate of 8%. Unburned hydrocarbon emissions were slightly decreased with EGR and late IVCs likely due to relatively longer ignition delays and higher exhaust gas temperature. Overall, the analysis showed that the combination of Miller cycle with an IVC at −127 CAD ATDC and 8%EGR achieved the lowest total fluid consumption despite the reduction in net indicated thermal efficiency.

Guan, Wei, Pedrozo, Vinícius, Zhao, Hua, Ban, Zhibo, Lin, Tiejian

Evaluation of Diesel Spray-Wall Interaction and Morphology around Impingement Location

2018-01-02764/3/2018

The necessity to study spray-wall interaction in internal combustion engines is driven by the evidence that fuel sprays impinge on chamber and piston surfaces resulting in the formation of wall films. This, in turn, may influence the air-fuel mixing and increase the hydrocarbon and particulate matter emissions. This work reports an experimental and numerical study on spray-wall impingement and liquid film formation in a constant volume combustion vessel. Diesel and n-heptane were selected as test fuels and injected from a side-mounted single-hole diesel injector at injection pressures of 120, 150, and 180 MPa on a flat transparent window. Ambient and plate temperatures were set at 423 K, the fuel temperature at 363 K, and the ambient densities at 14.8, 22.8, and 30 kg/m3. Simultaneous Mie scattering and schlieren imaging were carried out in the experiment to perform a visual tracking of the spray-wall interaction process from different perspectives. The experiments provided the spatial distribution and time-resolved evolution of the spray impingement on the wall, as well as the post-impingement global spray characteristics under various operating conditions. A previously validated Lagrangian-Eulerian CFD model based on a Reynolds-Averaged Navier-Stokes (RANS) formulation was used to characterize the spray interaction with the surrounding gas and impinged wall, and the numerical results were compared against the available experimental measurements. Subsequently, local spray quantities were extracted at different locations in the vicinity of the impingement point where the spray was characterized in terms of Reynolds and Weber numbers. The cumulative distributions of these local quantities with respect to parcel mass were then compared for increasing number of injected parcels. It was shown that convergence of the global spray quantities does not necessarily imply convergence of local quantities in the impingement area unless a very large number of parcel is used to describe the spray.

Zhao, Le, Torelli, Roberto, Zhu, Xiucheng, Naber, Jeffrey, Lee, Seong-Young, Som, Sibendu, Scarcelli, Riccardo, Raessi, Mehdi

Cold-Start Hydrocarbon Speciation and Trap Materials for Gasoline Engines

2018-01-09404/3/2018

Efficient hydrocarbon (HC) trap materials have been developed to trap the major emitting HC compounds from gasoline direct injection engines. Online FTIR measurements on different test cycles and catalytic systems showed that AHC, C5 compounds, and CH4 were the most emitted species at cold-start phase (up to 100 sec). Making AHC and C5 as targets for improving the HC light-off, lab scale reactor set-up was established with toluene and iso-pentane feed pumping system along with propane-propene mixture. TGA screening experiments conducted with ex-situ toluene adsorption and the results revealed that BEA type materials have moderate to higher HC trapping temperature and HC storage capacity. In the present investigation, BEA-HS exhibited outstanding stability and trapping ability even after 850 °C hydrothermal aging. PGM and TM based BEA materials were evaluated for HC-TPD experiments with TWC gas composition. Interestingly, adsorption properties of the samples at various aging temperatures are well correlated with pore size and structure. Functionalized micro-pore materials with transition based metals showed substantial improvement on toluene desorption temperature. Based on these studies and the test results, advanced HC trap catalysts have been designed which demonstrated potential advantage over conventional TWC.

Narayana Rao, Komateedi, Kim, Mi-Young, Song, Jinwoo, Na, SeungChul, Han, Hyun Sik

A Combustion Model for Multi-Component Fuels Based on Reactivity Concept and Single-Surrogate Chemistry Representation

2018-01-02604/3/2018

High fidelity engine simulation requires realistic fuel models. Although typical automotive fuels consist of more than few hundreds of hydrocarbon species, researches show that the physical and chemical properties of the real fuels could be represented by appropriate surrogate fuel models. It is desirable to represent the fuel using the same set of physical and chemical surrogate components. However, when the reaction mechanisms for a certain physical surrogate component is not available, the chemistry of the unmatched physical component is described using that of a similar chemical surrogate component at the expense of accuracy. In order to reduce the prediction error while maintaining the computational efficiency, a method of on-the-fly reactivity adjustment (ReAd) of chemical reaction mechanism along with fuel re-distribution based on reactivity is presented and tested in this study. The method is applied to simulate engine combustion with multi-component fuel sprays and its performance is compared to that of simulations with a reaction mechanism that considers the full set of physical/chemical surrogate components. The results show that the ReAd method improves the accuracy of combustion prediction using a single chemistry surrogate, while maintaining superb computational efficiency.

Jamali, Arash, Ra, Youngchul, Park, Wonah, Cho, Gyubaek

2021-12-29.TEST Study of CO ₂ /Hydrocarbons Mixture as the Working Fluids for Engine Waste Heat Recovery

2018-01-0049

4/3/2018

Transcritical Rankine cycle (TRC) is a promising technology for the engine waste heat recovery due to its good temperature matching ability for the waste heat sources. As for the high-temperature engine exhaust, working fluids selection has been an essential issue without a good solution. It was found in this research that mixtures of CO2 and small molecule hydrocarbons are the potential working fluids for the engine waste heat recovery, since they have good chemical stability and thermal performance. Besides, CO2 can be used as the retardant to suppress the flammability of hydrocarbons to ensure safety. In this research, CO2 mixed with five small molecule hydrocarbons are proposed as the working fluids. A thermodynamic model of TRC system is established to evaluate the thermal performance of those mixtures. The effects of mass fraction of CO2, turbine inlet temperature and pressure are investigated. The influence of composition shift is also discussed. The results show that, 65% CO2 in the mixtures is a tremendous improvement for the system safety, comparing to pure hydrocarbons. Compared with the pure CO2 TRC system, the thermal performance of the system can be effectively improved by mixing appropriate hydrocarbons with CO2, and the operation pressure can be decreased, which is beneficial for the future application. Take CO2/n-Pentane for example, the thermal efficiency and net power output can reach up to 16.4% and 16.06 kW, increasing by 34.4% and 13.3% compared with pure CO2. And the composition shift of those mixtures has little effect on the performance of TRC, but can improve the TRC system safety.

Shu, Ge-Qun, Yan, Nanhua, Zhao, Mingru, Li, Linqing

Reformed Fuel Substitution for Transient Peak Soot Reduction

2018-01-02674/3/2018

Advancements in catalytic reforming have demonstrated the ability to generate syngas (a mixture of CO and hydrogen) from a single hydrocarbon stream. This syngas mixture can then be used to replace diesel fuel and enable dual-fuel combustion strategies. The role of port-fuel injected syngas, comprised of equal parts hydrogen and carbon monoxide by volume was investigated experimentally for soot reduction benefits under a transient load change at constant speed. The syngas used for the experiments was presumed to be formed via a partial oxidation on-board fuel reforming process and delivered through gaseous injectors using a custom gas rail supplied with bottle gas, mounted in the swirl runner of the intake manifold. Time-based ramping of the direct-injected fuel with constant syngas fuel mass delivery from 2 to 8 bar brake mean effective pressure was performed on a multi-cylinder, turbocharged, light-duty engine to determine the effects of syngas on transient soot emissions. A Cambustion fNOx400 high-speed emissions analyzer and an AVL 439 opacimeter were used to quantify emissions under the load change to provide sub-cycle and cycle resolved resolution, respectively. Results show substantial soot reduction benefits with modest levels of syngas without significant increases in NOx emissions under the chosen conditions.

Dal Forno Chuahy, Flavio, Olk, Jamen, Kokjohn, Sage

Benefits of Pd Doped Zeolites for Cold Start HC/NOx Emission Reductions for Gasoline and E85 Fueled Vehicles

2018-01-09484/3/2018

In the development of HC traps (HCT) for reducing vehicle cold start hydrocarbon (HC)/nitrogen oxide (NOx) emissions, zeolite-based adsorbent materials were studied as key components for the capture and release of the main gasoline-type HC/NOx species in the vehicle exhaust gas. Typical zeolite materials capture and release certain HC and NOx species at low temperatures (<200°C), which is lower than the light-off temperature of a typical three-way catalyst (TWC) (≥250°C). Therefore, a zeolite alone is not effective in enhancing cold start HC/NOx emission control. We have found that a small amount of Pd (<0.5 wt%) dispersed in the zeolite (i.e., BEA) can significantly increase the conversion efficiency of certain HC/NOx species by increasing their release temperature. Pd was also found to modify the adsorption process from pure physisorption to chemisorption and may have played a role in the transformation of the adsorbed HCs to higher molecular weight species. Both these processes led to desorption at higher temperatures and more efficient conversion. Laboratory studies on BEA zeolite, with and without Pd, are described. These studies show the benefits of Pd-zeolite on the capture and release of HC/NOx species such as ethanol, ethylene, propylene, and toluene. It was also observed that the benefit of Pd in the zeolite was not stable under high-temperature rich conditions. This indicates a possible limitation for the application of Pd-beta in stoichiometric engine exhaust. A base metal was also added to the Pd-zeolite that stabilized emissions trapping after high-temperature rich aging conditions. Parallel vehicle emission test results also confirmed the benefits of the base metal-stabilized Pd-BEA zeolite in reducing cold start HC emissions.

Xu, Lifeng, Lupescu, Jason, Ura, Justin, Harwell, Amy, Paxton, William A., Nunan, John, Alltizer, Chad

Passive Hydrocarbon Trap to Enable SULEV-30 Tailpipe Emissions from a Flex-Fuel Vehicle on E85 Fuel

2018-01-09444/3/2018

Future LEV-III tailpipe (TP) emission regulations pose an enormous challenge forcing the fleet average of light-duty vehicles produced in the 2025 model year to perform at the super ultralow emission vehicle (SULEV-30) certification levels (versus less than 20% produced today). To achieve SULEV-30, regulated TP emissions of non-methane organic gas (NMOG) hydrocarbons (HCs) and oxygenates plus oxides of nitrogen (NOx) must be below a combined 30 mg/mi (18.6 mg/km) standard as measured on the federal emissions certification cycle (FTP-75). However, when flex-fuel vehicles use E85 fuel instead of gasoline, NMOG emissions at cold start are nearly doubled, before the catalytic converter is active. Passive HC traps (HCTs) are a potential solution to reduce TP NMOG emissions. The conventional HCT design was modified by changing the zeolite chemistry so as to improve HC retention coupled with more efficient combustion during the desorption phase. Increased trapping efficiently was achieved by (a) modifying the acidic properties of the zeolite, (b) inclusion of Pd in order to more efficiently trap alkenes and NOx, and (c) the introduction of a new redox function that promoted HC combustion prior to the full desorption phase of the trap. A 2.0 L direct-injection Ford Focus with E85 fuel, utilizing the newly designed HCT developed by Ford and Umicore and having a significantly reduced platinum group metal (PGM) loading of only 0.53 g/L, was able to lower NMOG emissions by about 60% compared to the baseline underbody three-way catalyst (TWC). This in turn achieved combined NMOG + NOx emissions at an average of 19 mg/mi (11.8 mg/km), just below the SULEV-20 limit. The new trap formulation not only improved HC storage and conversion efficiency but substantially decreased the PGM content in line with current LEV-II partial zero-emission vehicle (PZEV) underbody loadings and will ensure continued sales of future flex-fuel vehicles.

Lupescu, Jason, Xu, Lifeng, Nunan, John, Alltizer, Chad

A New Catalyzed HC Trap Technology that Enhances the Conversion of Gasoline Fuel Cold-Start Emissions

2018-01-09384/3/2018

Passive in-line catalyzed hydrocarbon (HC) traps have been used by some manufacturers in the automotive industry to reduce regulated tailpipe (TP) emissions of non-methane organic gas (NMOG) during engine cold-start conditions. However, most NMOG molecules produced during gasoline combustion are only weakly adsorbed via physisorption onto the zeolites typically used in a HC trap. As a consequence, NMOG desorption occurs at low temperatures resulting in the use of very high platinum group metal (PGM) loadings in an effort to combust NMOG before it escapes from a HC trap. In the current study, a 2.0 L direct-injection (DI) Ford Focus running on gasoline fuel was evaluated with full useful life aftertreatment where the underbody converter was either a three-way catalyst (TWC) or a HC trap. A new HC trap technology developed by Ford and Umicore demonstrated reduced TP NMOG emissions of 50% over the TWC-only system without any increase in oxides of oxygen (NOx) emissions. Other HC trap technologies had at best a 25% NMOG emission reduction. Parallel laboratory reactor studies were conducted in an effort to understand the improved trapping and NMOG combustion features of the newly developed HC trap. Increased trapping efficiency of certain aromatics (toluene) and alkenes (2-methylpropene) was assigned to rapid and efficient polymerization of these species due to a combination of strong Brønsted acidity, precious metal (i.e., Pd), and base redox active metals. During the emissions desorption phase, the combustion of the adsorbed NMOG occurred without gas-phase oxygen due to the delayed desorption of the large NMOG molecules coupled with the high activity of the base redox active metal in the presence of steam. Besides acting as a source of oxygen during combustion, the ion-exchanged form of the base metal also stabilized Pd against sintering during the hot, four-mode aging process.

Lupescu, Jason, Xu, Lifeng, Jen, Hung-Wen, Harwell, Amy, Nunan, John, Alltizer, Chad, Denison, Gregory

Intermediate Combustion Modes between Conventional Diesel and RCCI

2018-01-02494/3/2018

In recent years, several unconventional fueling modes have been developed for dual-fuel compression ignition (CI) engines. One such mode is reactivity controlled compression ignition (RCCI), which utilizes both a low-reactivity fuel (LRF) and a high-reactivity fuel (HRF) via separate injection systems. RCCI has been tested with many fuels, but there have been relatively few tests on the intermediate modes that exist in between RCCI and conventional diesel combustion (CDC). For this purpose, a quantitative classification system of fueling modes was created and used to test incremental changes in the fueling mode of a 1.9L General Motors (GM) turbodiesel engine, shifting between CDC and RCCI at a single speed/load point. This engine used a 5:2 mass ratio blend of propane and dimethyl ether (DME) as its LRF and ultra-low-sulfur diesel (ULSD) as its HRF. The results confirm previous findings that RCCI can achieve improvements in thermal efficiency, nitrogen oxide (NOx) emissions, and soot emissions simultaneously, at the expense of degradations in peak pressure, max pressure rise rate (PRR), and hydrocarbon emissions. The new developments made were the evaluation and analysis of the intermediate fueling modes between CDC and RCCI, which are herein termed partially premixed compression ignition (PPCI), conventional dual-fuel (CDF), and premixed dual-fuel combustion (PDFC). PDFC in particular appears promising as an intermediate “bridge” between CDC and RCCI, and under the correct conditions, PDFC can produce improvements in thermal efficiency, NOx, and soot emissions similar to RCCI, but without the high peak pressures and PRRs associated with RCCI.

Martin, Jonathan, Boehman, Andre, Topkar, Rutvik, Chopra, Sumit, Subramaniam, Uday, Chen, Heng

Assessment of Engine Control Parameters Effect to Minimize GHG Emissions in a Dual Fuel NG/Diesel Light Duty Engine

2018-01-02664/3/2018

The interest in Natural Gas (NG) as alternative fuel for transportation is constantly growing, mostly due to its large availability and lower environmental impact with respect to gasoline or diesel fuel. In this scenario, the application of the Dual Fuel (DF) Diesel- Natural Gas (NG) combustion concept to light duty engines can represent an important route to increment the diffusion of natural gas use. Many studies have proven the benefits of DF with respect to conventional diesel combustion in terms of CO2, NOx, PM and PN emissions, with the main drawback of high unburned hydrocarbon, mainly at low/partial engine loads. This last aspect still prevents the application of DF mode to small displacement engines. In the present work, a 2.0 L Euro 5 compliant diesel engine, equipped with an advanced electronic closed-loop combustion control (CLCC) system, has been set up to operate in DF mode and tested on a dyno test bench. The experimental campaign was performed in steady-state engine conditions and organized in two phases. Firstly, the aim was to identify optimal values of NG substitution ratios in several engine operating points. Secondly, a thorough analysis of the effects of many engine control parameters (e.g. NG substitution ratio, diesel pilot injection strategies, EGR) on DF combustion evolution was performed, at low and medium engine load. A strong potential on THC emissions control was assessed for parameters like combustion phasing and EGR, giving rise to wider margins of engine recalibration, in comparison with the standard Diesel calibration. The research activity will permit to identify an optimized DF working map, tailored for an automotive multi-cylinder Diesel engine, and to evaluate the actual applicability of the DF configuration on the selected combustion system.

Guido, Chiara, Napolitano, Pierpaolo, Fraioli, Valentina, Beatrice, Carlo, Del Giacomo, Nicola

System and Second Law Analysis of the Effects of Reformed Fuel Composition in “Single” Fuel RCCI Combustion

2018-01-02644/3/2018

Dual-fuel reactivity controlled compression ignition (RCCI) combustion is a promising method to achieve high efficiency with near-zero NOx and soot emissions; however, the requirement to carry two fuels on board limits practical application. Advancements in catalytic reforming have demonstrated the ability to generate syngas (a mixture of CO and hydrogen) from a single hydrocarbon stream. This syngas mixture can then be used as the low reactivity fuel stream to enable single fuel RCCI combustion. The present effort uses a combination of engine experiments and system level modeling to investigate reformed fuel RCCI combustion. The impact of reformer composition is investigated by varying the syngas composition from 10% H2 to approximately 80% H2. The results of the investigation show that reformed fuel RCCI combustion is possible over a wide range of H2/CO ratios. A system level and second law analysis are performed on the highest efficiency operating points, and comparisons are made between partial oxidation reforming, steam reforming, and conventional diesel. The results show that endothermic reforming (steam reforming) can achieve comparable system level efficiency to conventional diesel operation by recovering exhaust energy at similar system-out NOx emissions and near-zero soot emissions. An autoignition integral approach combined with reformer equilibrium modeling shows that in order to achieve higher system level efficiencies, lower H/C ratios of the parent fuel are necessary. Typical H/C ratio ranges for diesel fuels limit the range of operation of the engine to high hydrogen fractions, limiting the system level efficiency due to high heat transfer rates associated with these conditions.

Dal Forno Chuahy, Flavio, Kokjohn, Sage

Fuel Effects on Particulate Matter Emissions Variability from a Gasoline Direct Injection Engine

2018-01-03554/3/2018

Particulate matter emissions from gasoline direct injection engines are a concern due to the health effects associated with ultrafine particles. This experimental study investigated sources of particulate matter emissions variability observed in previous tests and also examined the effect of ethanol content in gasoline on particle number (PN) concentrations and particle mass (PM) emissions. FTIR measurements of gas phase hydrocarbon emissions provided evidence that changes in fuel composition were responsible for the variability. Exhaust emissions of toluene and ethanol correlated positively with emitted PN concentrations, while emissions of isobutylene correlated negatively. Exhaust emissions of toluene and isobutylene were interpreted as markers of gasoline aromatic content and gasoline volatility respectively. Tests conducted with gasoline containing added toluene (10%) supported this hypothesis and led to the overall conclusion that the emissions variability observed in PN concentrations can be attributed to changes in the composition of the pump gasoline being used. Tests conducted with gasoline containing added ethanol (10% and 30%) found that increasing ethanol fuel content increased emitted PN concentrations at steady-state operation.

Ramos, Manuel J.M.G., Wallace, James S.

Optimized PFI+DI Operation For Minimizing DI Gasoline Engine Particulates

2018-01-14154/3/2018

Direct Injection (DI) fueled gasoline engines provide higher efficiency than port fueled injected (PFI) engines. However, emission of small particulates is greatly increased when DI is used. Particulate mass emission is increased by more than a factor of 10 and particulate number is increased by a factor of 10-100 relative to PFI engines leading to health concerns and to implementation and consideration of new regulations. Optimized combinations of PFI and DI can greatly reduce DI-generated particulate emissions without compromising efficiency and performance. A DI enhanced PFI mode of engine operation is employed where PFI is the dominant means in dual-injection fueling over a drive cycle, and the fuel fraction that is directly injected is reduced/minimized while still preventing knock at high loads. Further reduction can be obtained by optimal use of spark retard. The already low particulate emissions are further reduced by decreasing the percentage of DI fuel that results in particulate generation from wall wetting; this is accomplished by adjustment of injection timing, injection rate and pulse length. We have developed a computational model of DI-generated particulates over the torque and speed map for gasoline engine operation with combined PFI and DI. The computational model includes models for knock suppression and for particulate generation from wall wetting. These models are calibrated using experimental data. We have used this computational approach to determine illustrative reductions in DI generated particulates for turbocharged gasoline engines various drive cycles. These reductions in DI-generated particulates for the US06 and UDDS cycles are greater than 20 and 50 times, respectively relative to the use of DI alone. An optimized PFI+DI system could be used in combination with a GPF for even further particulate reduction while also reducing GPF cost and the efficiency loss from GPF back pressure.

Bromberg, Leslie, Cohn, Daniel

Soot and PAH Formation Characteristics of Methanol-Gasoline Belnds in Laminar Coflow Diffusion Flames

2018-01-03574/3/2018

Particulate matter emissions are becoming a big issue for GDI engines as the emission regulations being more stringent. Methanol has been considered to be an important alternative fuel to reduce soot emissions. To understand the effect of methanol addition on soot and polycyclic aromatic hydrocarbons (PAHs) formation, the 2-D distributions of soot volume fraction and different size PAHs relative concentrations in methanol/gasoline laminar diffusion flames were measured by TC-LII and PLIF techniques. The effect of methanol was investigated under the conditions of the same carbon flow and the same flame height. The methanol volume fraction was set as M0/20/40/60/80. The results showed that the natural luminescent flame lift-off height and soot lift-off height increases consistently with the increasing methanol content due to the increase of outlet velocity of fuel vapor. Methanol addition is able to inhibit the soot and PAHs formations significantly, which may be largely due to the dilution of aromatics and methanol molecular structure. The effect of methanol on reducing soot is weakened with the increasing methanol ratio. Under the same flame height condition, the peak soot volume fraction in the M20, M40, M60, and M80 flames reduces by 35.6%, 58.7%, 74.9% and 88.5%. The PAHs concentration of four different scales decrease with the increasing methanol content, and the largest aromatic ring (450 nm) decrease the most. As the number of rings of aromatics increases, it peaks at a higher height, and its highly concentrated area gradually moves from the center of the flame to the two wings of the flame. The initial height of soot formation increases with the increasing methanol ratio, which increases more significantly under the same flame height condition than that under the same carbon flow condition.

Hua, Yang, Liu, Fushui, Wu, Han, Kang, Ning, Shi, Zhongjie

Development of Highly Durable Zeolites as Hydrocarbon Trap Materials for Automotive Catalysts

2018-01-09474/3/2018

Low-temperature activity is an important requirement for automotive catalysts. In particular, most of the tailpipe emissions occur right after the engine starts (cold emissions). These emissions can be effectively reduced by using a trap material such as zeolite for hydrocarbon (HC) adsorption [1, 2, 3, 4, 5, 6, 7, 8, 9]. However, using zeolite as a trap material in automotive catalyst is limited due to its low durability under hydrothermal aging conditions. That is the reason why zeolites can be often used for diesel engines which usually run at lower temperature than the gasoline engines during entire mode driving. In most cases, zeolites need to be placed away from large thermal loads in order to take advantage of their adsorption abilities. In general, the thermal endurance of close-coupled catalysts for gasoline powered vehicles proceeds at about 1000 °C in the presence of water. Under these conditions, the zeolite structure would be decomposed by the dissociation of aluminum from the zeolite frameworks [10]. Through this study, we show that the hydrothermal durability of zeolite can be dramatically improved by chemical modification of zeolite with zirconium phosphate. This improvement strategy works well, especially for β-type zeolites (BEAs) with low SiO2/Al2O3 ratio, which can be easily decomposed by hydrothermal aging at around 1000 °C. We also found that this modified BEA worked well as HC trap material and showed an enormous reduction of cold HC emissions with Pd/Rh three-way catalyst (TWC). In the engine test evaluations with the close-coupled TWC + TWC and TWC + HC trap system as aged catalysts, effects of this HC trap catalyst on cold emissions were observed. It is found that HC emission decrease by up to 43% when compared to those from the corresponding TWC + TWC system which does not have any zeolite. In addition, a detailed analysis of this effect proved this improvement to be due to the adsorption-desorption process of zeolite and the purification process by TWCs.

Endo, Yoshinori, Nishikawa, Joe, Iwakura, Hironori, Inamura, Masaaki, Wakabayashi, Takashi, Nakahara, Yuunosuke, Ogasawara, Masataka, Kato, Sumio

Sensor Droplets Enable Cheaper, Faster Food Testing

TBMG-281701/1/2018

The foodborne pathogen Escherichia coli O157 causes an estimated 73,000 illnesses and 60 deaths every year in the United States. Better safety tests could help avoid some of the illnesses caused by this strain of E. coli and other harmful bacteria.

Aluminum Alloy for High-Temperature Applications

TBMG-2800012/1/2017

NASA’s Marshall Space Flight Center originally developed a high-performance piston alloy to meet U.S. legislative restrictions on vehicular exhaust hydrocarbon emissions. NASA 398 aluminum alloy exhibits excellent tensile and fatigue strength at elevated temperatures. NASA 398 alloy also offers superior wear resistance, surface hardness, dimensional stability, and lower thermal expansion compared to conventional aluminum alloys.

Effects of Aromatic and Olefin on the Formations of PAHs in GDI Engine

2017-01-239010/8/2017

In this paper, the impacts of Aromatic and Olefin on the formation of poly-aromatic hydrocarbons (PAHs) in the gasoline direct injection (GDI) engine were experimentally and numerically investigated. The objective of this study is to describe the formation process of the soot precursors including one ring to four ring aromatics (A1-A4). In order to better understand the effects of the fuel properties on the formations of PAHs. Three types of fuels, namely base gasoline, gasoline with higher aromatics content, and gasoline with higher olefin content were experimentally studied. At the same time, these aspects were also numerically investigated in the CHEMKIN code by using premixed laminar flame model and surrogated fuels. The results show that higher aromatics content in gasoline will lead to much higher PAHs formation. Similar trend was also found in the gasoline with higher olefin content. This study indicats that reducing the aromatic and olefin contents are efficient methods in decreasing the PAHs emissions.

Zhao, Hongxue, Jing, Daliang, Wang, Yinhui, Shuai, Shi-jin, PANG, Changle

Regulated and Unregulated Emissions from a Spark Ignition Engine Fueled with Acetone-Butanol-Ethanol (ABE)-Gasoline Blends

2017-01-232810/8/2017

Bio-butanol has been widely investigated as a promising alternative fuel. However, the main issues preventing the industrial-scale production of butanol is its relatively low production efficiency and high cost of production. Acetone-butanol-ethanol (ABE), the intermediate product in the ABE fermentation process for producing bio-butanol, has attracted a lot of interest as an alternative fuel because it not only preserves the advantages of oxygenated fuels, but also lowers the cost of fuel recovery for individual component during fermentation. If ABE could be directly used for clean combustion, the separation costs would be eliminated which save an enormous amount of time and money in the production chain of bio-butanol. In this respect, this study is focused on investigating the regulated and unregulated emissions of a single cylinder port-fuel injection spark ignition engine fueled with ABE and gasoline blends. 30 vol.% ABE fuels with different component volumetric ratios (A:B:E of 3:6:1 and 6:3:1) were blended with 70 vol.% gasoline, which were represented as ABE(361)30, ABE(631)30 respectively, were tested. Experiments were conducted at an engine speed of 1200 rpm, and at engine loads corresponding to brake mean effective pressures (BMEP) of 3 bar and 5 bar and under various equivalence ratios (Φ=0.83-1.25). Exhaust gases were measured including nitrogen oxides (NOx), carbon monoxide (CO) and unburned hydrocarbons (UHC). Additionally, aromatic hydrocarbons emissions such as benzene, ethylbenzene, toluene and xylenes (BTEX) concentrations were also measured by a gas chromatograph coupled with a mass spectrometer (GC/MS) and a gas chromatograph with a flame ionization detection (GC/FID).

Li, Yuanxu, Nithyanandan, Karthik, Ning, Zhi, Lee, Chia-Fon, Wu, Han

Lubricity of Diesel Fuel Hydrocarbons and Surrogate Fuels

2017-01-2292

10/8/2017

The aim of this study is to investigate the lubricity of hydrocarbons that constitute components of petroleum diesel fuel. A number of typical hydrocarbon compounds were selected as representative of the group types of alkanes (paraffins), cycloalkanes (naphthenes) and aromatics, similar to those that are present in diesel fuel. The lubricity of these substances was examined in a High Frequency Reciprocating Rig (HFRR) apparatus according to the ISO 12156-1 standard method. Thereafter, a series of diesel surrogate fuel were prepared from the above substances based on literature data for diesel fuel composition and on the previously obtained results. These model fuels were assessed regarding their lubricating performance in order to evaluate how each individual component can affect the lubricity of the final fuel. In addition to this, commercial, additive-free diesel fuel samples were analyzed per the previously mentioned procedure and were used as reference fuels for a comparative assessment.

Dodos, George S., Vassileiou, Florentia, Karonis, Dimitrios

Effect of the Structure of Radial Vane Cavity on Performance of Turbine Inter-Vane Burner Based on Jet-Vortex Flow

2017-01-228410/8/2017

The potential benefits of reheat burner placed between turbine stages for propulsion system have been recognized for nearly a century. Compared to the conventional non-reheat engines, the turbine inter-guide-vane burner (TIB) engines by using jet-swirl flow scheme (high-G loading) are shown to have a higher specific thrust with no or only small increase in thrust specific fuel consumption. But, it is a known fact that the G loading in the circumferential cavity is inversely proportional to the radius of the circumferential cavity. If one needs to scale this configuration for a larger spool of turbine components, the effeciency of the high G operation and obtained benefits on flame speed will reduce and hence the performance will de-grade. Hence to make a universal TIB, an alternate approach was proposed using a trapped vortex cavity to replace the jet-swirl flow combustion to enhance mixing rates via a jet-vortex flow in the cavity, followed by further mixing of the free stream air through the guide vane with a notch. The various structures of radial vane cavity are focused on in this study to research effect of this cavity structure on performance of turbine inter-vane burner based on jet-vortex flow, such as straight cavity; hypsokinesis cavity; fore-rake cavity; circle cavity; half cavity, and to cover the shortage of co-relational research in the field of turbine inter-vane burner. And the Scale-Adaptive Simulation (SAS) turbulence model is used in the simulation process. Finally, compared with the other models, various performance parameters in term of combustion efficiency (η), total pressure loss (dp/p), pollutant emissions of CO, and unburned hydrocarbons (UHC) for the model-3 is much better, and the application of turbine inter-vane burner technology based on jet-vortex flow in gas turbine engine is the effective solution to these bottleneck problems traditional for traditional civilian aero-engine.

Zheng, Haifei

Blending Octane Number of Ethanol on a Volume and Molar Basis in SI and HCCI Combustion Modes

2017-01-225610/8/2017

The blending behavior of ethanol in five different hydrocarbon base fuels with octane numbers of approximately 70 and 84 was examined under Spark-Ignited (SI) and Homogeneous Charge Compression Ignited (HCCI) operating conditions. The Blending octane number (BON) was used to characterize the blending behavior on both a volume and molar basis. Previous studies have shown that the blending behavior of ethanol generally follows several well-established rules. In particular, non-linear blending effects are generally observed on a volume basis (i.e. BON > RON or MON of pure ethanol; 108 and 89, respectively), while linear blending effects are generally observed on a molar basis (i.e. BON = RON or MON of pure ethanol). This work firstly demonstrates that the non-linear volumetric blending effects traditionally observed under SI operating conditions are also observed under HCCI operating conditions. In keeping with previous studies, the degree of this non-linearity is shown to be a function of the base fuel composition and octane number. By contrast, the molar blending approach is shown to behave differently depending on the chosen combustion mode, with some non-linearity observed under HCCI operating conditions (i.e. BON ≠ RON or MON of pure ethanol). This suggests that the well-established blending rules for SI operating conditions may not always be relevant to other combustion modes that operate with globally lean or diluted air-fuel mixtures. This has implications for the design of future fuel specifications.

Waqas, Muhammad Umer, Morganti, Kai, Masurier, Jean-Baptiste, Johansson, Bengt

Numerical Simulations of Mixture Formation in Combustion Chambers of Lean-Burn Natural Gas Engines Incorporating a Sub-Chamber

2017-01-228010/8/2017

The aim of this study is to clarify the mixture formation in the combustion chamber of our developed natural gas engine incorporating the sub-chamber injection system, in which natural gas is directly injected into a combustion sub-chamber in order to completely separate rich mixture in the sub-chamber, suitable for ignition, from ultra-lean mixture in the main chamber. Mixture distributions in chambers with and without sub-chamber were numerically simulated at a variety of operating conditions. The commercial software of Fluent 16.0 was used to conduct simulations based on Reynolds averaged Navier-Stokes equations in an axial 2 dimensional numerical domain considering movements of piston. Non-reactive flow in the combustion chamber was simulated before the ignition timing at an engine speed of 2000 rpm. The turbulence model employed here is standard k-ε model. Air-fuel ratio is set with a lean condition of 30. The results obtained from the numerical simulations demonstrate higher equivalence ratio in the sub-chamber than that in the main chamber, which extends the lean limit at engine operations. Furthermore, existing probability of mixture with low equivalence ratio is higher than that without the sub-chamber, which is an evidence of lower NOx emissions from test engines incorporating the sub-chamber. On the other hand, high equivalence ratio mixture remains in the squish area of the main chamber when the sub-chamber is installed. The unburned fuels in the squish area probably cause high hydrocarbon emissions from engines, observed during engine tests. In addition, the retarded timing of injection end results in the accumulation of fuel in the sub-chamber, increasing the equivalence ratio of mixture existing in the sub-chamber. The high hydrocarbon emissions observed during engine tests under retard conditions are due to the deterioration of ignitability resulting from the richer mixture.

Nada, Yuzuru, Morimoto, So, Kidoguchi, Yoshiyuki, Kaya, Ryu, Nakano, Hideaki, Kobayashi, Shinichi

Absorbent Polymer Reinforcing Fiber

TBMG-2766810/1/2017

Absorbent polymers can be used, for instance, to absorb hydrocarbons from an aqueous medium such as the absorption of oil from water. In some configurations, conventional absorbent polymers are contained within a permeable material; for example, conventional spill “socks” and booms can hold an absorbent polymer within a fabric to enable the absorbent polymer to be applied directly to the site of interest. Moreover, conventional absorbent booms can float on a water surface to help contain a spill from spreading beyond the boom. This application, however, requires the absorbent polymer to be contained within a permeable membrane or fabric.

Simarouba Biodiesel Blends as an Alternative Fuel for Compression Ignition Engine and Its Optimization Using Multiple Regression Analysis on CI Engine Performance (BTE) and Emissions (CO ₂ , HC) Characteristics

2017-01-21369/19/2017

The objective of this work is to optimize the operating parameters of the Direct Injection Single Cylinder (5.2 kw) CI engine with respect to Brake Thermal Efficiency (BTE), Hydrocarbons (HC) and Carbon dioxide (CO2). For this investigation, we used Simarouba Biodiesel as an alternate fuel for diesel fuel which possesses low cetane number which is not sufficient to operate existing diesel engine. However, this could be combined with the diesel fuel in the form of blends. For this investigation four levels and four parameters were selected viz. Injection Pressure (IP), Fuel Fraction (FF), Compression Ratio (CR) and Injection Timing (Before TDC). Taguchi Method is used for minimizing the number of experiments and Multiple Regression Analysis is used to find the optimum condition. Three outputs variables such as; Brake Thermal Efficiency (BTE), content of HC particles and CO2 in the emission are measured and considered its influence on CI Engine performance. The test was carried out at full load condition and the optimized condition are found such as; 18:1 Compression Ratio, 250 bar Injection Pressure, 22° Injection Timing and 20% Fuel Fraction. The optimized condition gives better performance than diesel, HC emission is nearly similar as that for diesel fueled engine but CO2 slightly increases.

Sayyad, Almuddin Rustum, Salunke, Pratik, Jadhav, Sangram

Fast Hybrid Sensor for Soot of Production CI Engines

2017-24-01379/4/2017

During transients, engines tend to produce substantially higher peak emissions like soot - the main fraction of particular matter (PM) - which are the longer the more important as the steady state emissions are better controlled. While Diesel particulate filters are normally able to block them, preventing their occurrence would of course be more important. In order to achieve this goal, however, they must be measurable. While for most emissions commercial sensors of sufficient speed and performance are available, the same is not true for PMs, especially for production engines. Against this background, in the last years the possible use of a full stream 50Hz sensor based on Laser Induced Incandescence (LII) was investigated, and the results were very encouraging, showing that the sensor could recognize transient changes undetected by conventional measurement systems (like the AVL Opacimeter) but confirmed by the analysis of combustion. This was also related to the position of the sensor which can be mounted upstream or downstream of the turbine in a turbocharged CI engine. The measurement is instantaneous, without dilution or transport, and this raises also the question about accuracy, as the variability of the particulate flow near to the sensor will be directly visible in the sensor output. To reduce this effect, we propose a hybrid sensor approach in which the final reading is computed by a suitable combination of the output of the photodiodes and operation information of the engine, e.g. the pressure and temperature near to the sensor location. This paper presents the methodology as well as an experimental assessment. All measurements have been done on a production 2 lt Euro 5 CI engine.

Zhang, Zhen, del Re, Luigi, Fuerhapter, Richard

Application of a Dual Fuel Diesel-CNG Configuration in a Euro 5 Automotive Diesel Engine

2017-01-07693/28/2017

An increasing interest in the use of natural gas in CI engines is currently taking place, due to several reasons: it is cheaper than conventional Diesel fuel, permits a significant reduction of carbon dioxide and is intrinsically clean, being much less prone to soot formation. In this respect, the Dual Fuel concept has already proven to be a viable solution, industrially implemented for several applications in the heavy duty engines category. An experimental research activity was devoted to the analysis of the potentiality offered by the application of a Dual Fuel Diesel-CNG configuration on a light duty 2L Euro 5 automotive diesel engine, equipped with an advanced control system of the combustion. The experimental campaign foresaw to test the engine in dynamic and steady state conditions, comparing engine performance and emissions in conventional Diesel and Dual Fuel combustion modes. To this aim, dynamic engine tests were performed adopting the New European Driving Cycle (NEDC) while eight steady-state operative test points, representative of the engine working during the homologation cycle, were chosen to analyze specific aspects of the Dual Fuel combustion process. The engine was fully instrumented for indicating signal analysis and pollutant emission measurements. The study confirmed the generally assessed results in terms of strong smoke and CO2 reduction and significant total hydrocarbon emissions (mainly methane) increment when a gaseous fuel is burned in Dual Fuel mode. Due to the high methane emissions at low loads that limits the CNG substitution ratio with diesel, the application of the DF concept is still critical for automotive engines. Moreover, the combustion analysis gave important information on the critical and beneficial aspects of the management engine control technology when this innovative combustion concept is adopted.

Napolitano, Pierpaolo, Guido, Chiara, Beatrice, Carlo, Del Giacomo, Nicola

The Development of Low Temperature Three-Way Catalysts for High Efficiency Gasoline Engines of the Future

2017-01-09183/28/2017

In anticipation that future gasoline engines will have improved fuel efficiency and therefore lower exhaust temperatures during low load operation, a project was initiated in 2014 to develop three-way catalysts (TWC) with improved activity at lower temperatures while maintaining the durability of current TWCs. This project is a collaboration between Ford Motor Company, Oak Ridge National Laboratory, and the University of Michigan and is funded by the U.S. Department of Energy. The ultimate goal is to show progress towards the USDRIVE goal of 90% conversion of hydrocarbons (HC), carbon monoxide (CO), and nitrogen oxides (NOx) at 150°C after high mileage aging. A reactor was set up at Ford to follow the catalyst testing protocols established by the USDRIVE ACEC tech team for evaluating catalysts for stoichiometric gasoline direct-injection (S-GDI) engines; this protocol specifies a stoichiometric blend of CO/H2, NO, C3H6, C2H4, C3H8, O2, H2O, and CO2 for the evaluations. This paper summarizes some of the lessons learned from the reactor testing at Ford and also discusses the results on some initial catalyst formulations at Ford that consisted of palladium (Pd) on various oxide supports. The temperature ramp rate had little effect on the lightoff performance, but the O2 level around stoichiometry and interactions between the gas species were found to significantly affect the light off temperatures. Al2O3 and ZrO2 catalysts with 2% Pd were fairly robust to lean aging at 1000°C, but a TiO2 powder with 2% Pd suffered significant degradation after lean aging at only 800°C.

Theis, Joseph R., Getsoian, Andrew, Lambert, Christine

Transient Flame Development in a Constant-Volume Vessel Using a Split-Scheme Injection Strategy

2017-01-08153/28/2017

Multiple-injection strategies are characterized by a complex and transient interplay between high- and low-temperature reactions. Tracking low-temperature reaction products such as formaldehyde (CH2O) is particularly important to understand ignition phenomena and the so-called “combustion recession” that is observed in experiments. Experimentally, it is often difficult to discriminate between formaldehyde and other species such as poly-aromatic hydrocarbons, which is why a selective excitation approach is used in this work. Simultaneous high-speed imaging of the chemically-excited hydroxyl radical (OH*) is used to improve indication of flame location and second stage ignition. During experiments in a constant-volume vessel, two 0.5-ms injections of n-dodecane, separated by 0.5-ms dwell time, are injected into a 900-K ambient. The global flame development is characterized based on high-speed diagnostics, followed by an investigation into the spatial distribution of formaldehyde at four different times after start-of-injection (aSOI). Results show significant influence of the first injection on characteristics of the second. Ignition delay and lift-off location of the second injection are prominently reduced, while flame penetration is greatly enhanced by the wake of the first injection. Formaldehyde structure is observed during both end-of-injection transients, reaching as far upstream as 6 mm from the nozzle. Even after the second injection, the flame structure still appears to be influenced by the first, with a shorter lift-off length and compressed formaldehyde structure. Based on the selective excitation procedure, it becomes clear that the interpretation of laser-induced fluorescence (LIF) images obtained by 355-nm excitation alone is prone to ambiguity.

Maes, Noud, Bakker, P.C., Dam, Nico, Somers, Bart

Development and Testing of the Ultera ^® Dual Stage Catalyst System on Gasoline-Fueled Light Duty Vehicles (LDV’s)

2017-01-09203/28/2017

All vehicles sold today are required to meet emissions standards based on specific driving cycles. Emissions standards are getting tighter and the introduction of real driving tests is imminent, potentially calling for improved aftertreatment systems. A dual stage catalyst system, with exhaust temperature control, can provide a robust solution to meet challenging modes of operation such as rapid acceleration and other heavy-duty transients. The Ultera® technology, developed and successfully implemented on stationary natural gas CHP (Combined Heat and Power) engines, introduces a second stage catalyst downstream of a three-way catalyst. Air is injected between the two stages to provide oxygen required for the second stage reaction that removes additional CO and NMOG. Critical to the process is to avoid the reformation of NOx. This is achieved by cooling the exhaust gas prior to the second stage, to a temperature range in which CO and NMOG oxidation is extremely effective, while no new NOx is created. The objective of this research was to apply this technology to vehicle engines, with the primary interest being gasoline-fuel, direct fuel injection, and more dramatic transient loading. Testing of a ULEV compliant light duty truck (LDT) and a European passenger vehicle was conducted using a chassis dynamometer. Optimization of control temperature and air- injection flow was studied. Also examined were customized catalyst formulations for enhanced hydrocarbon reduction. Results showed significant reductions of CO and NMOG, with no negative impact on NOx. There was also no measurable impact on fuel economy, but further study is required to include the parasitic loads of cooling and air injection in order to fully quantify the impact to mpg. Future development work can provide opportunities to further reduce NOx emissions through chemistry and integration with engine operation.

Roy, Jean P., Ghoniem, Ahmed, Panora, Robert, Gehret, Joseph, Falls, Bruce, Wallace, David, Ott, Daniel

Tire Tread Performance Modification Utilizing Polymeric Additives

2017-01-15023/28/2017

Tire manufacturers have long grappled with the challenge of balancing the conflicting tire attributes of traction, rolling resistance, and treadwear. Improvements to one of these “magic triangle” attributes often comes at the expense of the other attributes. Recent regulations have further increased the pressure on manufacturers to produce optimized tires with minimal performance compromises. In order to meet this challenge, the tire industry is looking to new material systems beyond the traditional tire tread components. Polymeric materials beyond the base elastomers and processing oils used in tread provide opportunities to modify the physical and viscoelastic properties of tread. In this study, various polymeric materials were evaluated as additives in a model tire tread formulation. Hydrocarbon resin, high styrene resin, and thermoplastic styrene elastomers were added to the model formulation at various loading levels and through various addition strategies. The thermal behavior of the raw polymeric additives was characterized utilizing differential scanning calorimetry (DSC). The impact of the polymeric additives on the tread compound was assessed by evaluating the cure kinetics, physical properties, and viscoelastic properties of the experimental compounds. The viscoelastic properties, as measured by dynamic mechanical analysis (DMA), were utilized to predict the relative tire tread performance attributes. Each polymeric additive evaluated in this study was predicted to modify the tire tread performance in a unique way. The potential advantages and challenges of utilizing the polymeric additives to optimize tire tread performance will be discussed.

Harper, Madeline, Tardiff, Janice, Haakenson, Daniel, Joandrea, Maria, Knych, Matthew

Investigation on Electronic Assisted Primary Fuel Injection of Compression Ignition Engine Fueled with Waste Cooking Oil as Pilot Fuel for Improved Part Load Efficiency and Effective Waste Utilization

2017-01-0768

3/28/2017

Waste utilization is found to be a challenging task all around the globe. Converting the waste into useful forms of energy is a significant landmark in meeting the demand of world energy requirement. Thus an attempt was made in this study to make use of Waste Cooking Oil (WCO) as a fuel to operate compression ignition engine effectively as it degrades both the environment and human health.WCO was collected form the hostel mess of the author institution. In the first phase of the study, a single cylinder water cooled diesel engine was developed and operated in a single fuel mode with neat diesel and WCO as fuel under various load condition. Engine was modified in the second phase of the work to operate in dual fuel mode with a low reactive fuel like ethanol as primary fuel. In this work ethanol was injected in the intake manifold using newly developed Electronic Primary Fuel Injection System (EPFIS). Experiments were conducted at 80% and 100% load condition with various ethanol energy shares. It was inferred that establishment of the EPFIS increased the brake thermal efficiency of engine fueled with WCO by 5% with additional benefit of drastic reduction in smoke and Oxides of Nitrogen (NOX) emission. Both Unburnt Hydrocarbon (UHC) and Carbon Monoxide (CO) emission were found to be marginally high with the injection system. Thus with the help of EPFIS,WCO can be used effectively in the part load as well as in full load condition in a compression ignition engine with UHC and CO reducing techniques in the future for producing clean and green energy.

Nandagopal, Sasikumar, Masimalai, Senthil Kumar, Subramaniyan, Arul Selvan, Mayakrishnan, JaiKumar

Investigation into Occurrence of Megaknock and Auto-Ignition in GTDI Engines

2017-01-06903/28/2017

The performance of boosted gasoline engines is limited at high loads by knock, stochastic Low Speed Pre-Ignition, and Megaknock. An investigation has been carried out on the occurrence of abnormal combustion and megaknock in a 1.6 L GTDI engine with the aim to determine the causes of such phenomena. A classification of abnormal combustion events and causes is presented in order to facilitate a consistent terminology. The experiments specifically focus on the effects of exhaust residual gas on occurrence of megaknock in multi-cylinder engines. The results showed that while a misfire will not lead to megaknock, a very late combustion in one cycle, in one cylinder may lead to megaknock in the following cycle in the same or adjacent cylinder. Additionally, a recently developed multi-zone model was used to analyze the role of residual gas on auto-ignition. It was found that residual gas from a late combustion event may in fact lead to auto-ignition in the following cycle; the composition of the residual gas and the presence of partially burned hydrocarbon species were found to be critical.

Khosravi, Maziar, Ruhland, Helmut, Lorenz, Thomas, Weber, Carsten

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