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Technical Paper

Demonstration of Single-Fuel Reactivity Controlled Compression Ignition Using Reformed Exhaust Gas Recirculation

2018-04-03
2018-01-0262
A key challenge for the practical introduction of dual-fuel reactivity controlled compression ignition (RCCI) combustion modes in diesel engines is the requirement to store two fuels on-board. This work demonstrates that partially reforming diesel fuel into less reactive products is a promising method to allow RCCI to be implemented with a single stored fuel. Experiments were conducted using a thermally integrated reforming reactor in a reformed exhaust gas recirculation (R-EGR) configuration to achieve RCCI combustion using a light-duty diesel engine. The engine was operated at a low engine load and two reformed fuel percentages over ranges of exhaust gas recirculation (EGR) rate and main diesel fuel injection timing. Results show that RCCI-like emissions of NOx and soot were achieved load using the R-EGR configuration. It was also shown that complete fuel conversion in the reforming reactor is not necessary to achieve sufficiently low fuel reactivity for RCCI combustion.
Technical Paper

Investigation of Species from Negative Valve Overlap Reforming Using a Stochastic Reactor Model

2017-03-28
2017-01-0529
Fuel reforming during a Negative Valve Overlap (NVO) period is an effective approach to control Low Temperature Gasoline Combustion (LTGC) ignition. Previous work has shown through experiments that primary reference fuels reform easily and produce several species that drastically affect ignition characteristics. However, our previous research has been unable to accurately predict measured reformate composition at the end of the NVO period using simple single-zone models. In this work, we use a stochastic reactor model (SRM) closed cycle engine simulation to predict reformate composition accounting for in-cylinder temperature and mixture stratification. The SRM model is less computationally intensive than CFD simulations while still allowing the use of large chemical mechanisms to predict intermediate species formation rates.
Journal Article

Energy Analysis of Low-Load Low-Temperature Gasoline Combustion with Auxiliary-Fueled Negative Valve Overlap

2017-03-28
2017-01-0729
In-cylinder reforming of injected fuel during an auxiliary negative valve overlap (NVO) period can be used to optimize main-cycle auto-ignition phasing for low-load Low-Temperature Gasoline Combustion (LTGC), where highly dilute mixtures can lead to poor combustion stability. When mixed with fresh intake charge and fuel, these reformate streams can alter overall charge reactivity characteristics. The central issue remains large parasitic heat losses from the retention and compression of hot exhaust gases along with modest pumping losses that result from mixing hot NVO-period gases with the cooler intake charge. Accurate determination of total cycle energy utilization is complicated by the fact that NVO-period retained fuel energy is consumed during the subsequent main combustion period. For the present study, a full-cycle energy analysis was performed for a single-cylinder research engine undergoing LTGC with varying NVO auxiliary fueling rates and injection timing.
Technical Paper

Exploration of Dual Fuel Diesel Engine Operation with On-Board Fuel Reforming

2017-03-28
2017-01-0757
Many dual fuel technologies have been proposed for diesel engines. Implementing dual fuel modes can lead to emissions reductions or increased efficiency through using partially premixed combustion and fuel reactivity control. All dual fuel systems have the practical disadvantage that a secondary fuel storage and delivery system must be included. Reforming the primary diesel to a less reactive vaporized fuel on-board has potential to overcome this key disadvantage. Most previous research regarding on-board fuel reforming has been focused on producing significant quantities of hydrogen. However, only partially reforming the primary fuel is sufficient to vaporize and create a less volatile fuel that can be fumigated into an engine intake. At lower conversion efficiency and higher equivalence ratio, reforming reactors retain higher percentage of the inlet fuel’s heating value thus allowing for greater overall engine system efficiency.
Journal Article

Investigation of Fuel Effects on In-Cylinder Reforming Chemistry Using Gas Chromatography

2016-04-05
2016-01-0753
Negative Valve Overlap (NVO) is a potential control strategy for enabling Low-Temperature Gasoline Combustion (LTGC) at low loads. While the thermal effects of NVO fueling on main combustion are well-understood, the chemical effects of NVO in-cylinder fuel reforming have not been extensively studied. The objective of this work is to examine the effects of fuel molecular structure on NVO fuel reforming using gas sampling and detailed speciation by gas chromatography. Engine gas samples were collected from a single-cylinder research engine at the end of the NVO period using a custom dump-valve apparatus. Six fuel components were studied at two injection timings: (1) iso-octane, (2) n-heptane, (3) ethanol, (4) 1-hexene, (5) cyclohexane, and (6) toluene. All fuel components were studied neat except for toluene - toluene was blended with 18.9% nheptane by liquid volume to increase the fuel reactivity.
Journal Article

An Aerosolization Method for Characterizing Particle Contaminants in Diesel Fuel

2013-10-14
2013-01-2668
Diesel fuel injection systems are operating at increasingly higher pressure (up to 250 MPa) with smaller clearances, making them more sensitive to diesel fuel contaminants. Most liquid particle counters have difficulty detecting particles <4 μm in diameter and are unable to distinguish between solid and semi-solid materials. The low conductivity of diesel fuel limits the use of the Coulter counter. This raises the need for a new method to characterize small (<4 μm) fuel contaminants. We propose and evaluate an aerosolization method for characterizing solid particulate matter in diesel fuel that can detect particles as small as 0.5 μm. The particle sizing and concentration performance of the method were calibrated and validated by the use of seed particles added to filtered diesel fuel. A size dependent correction method was developed to account for the preferential atomization and subsequent aerosol conditioning processes to obtain the liquid-borne particle concentration.
Technical Paper

Hydrogen as a Combustion Modifier of Ethanol in Compression Ignition Engines

2009-11-02
2009-01-2814
Ethanol, used widely as a spark-ignition (SI) engine fuel, has seen minimal success as a compression ignition (CI) engine fuel. The lack of success of ethanol in CI engines is mainly due to ethanol's very low cetane number and its poor lubricity properties. Past researchers have utilized nearly pure ethanol in a CI engine by either increasing the compression ratio which requires extensive engine modification and/or using an expensive ignition improver. The objective of this work was to demonstrate the ability of a hydrogen port fuel injection (PFI) system to facilitate the combustion of ethanol in a CI engine. Non-denatured anhydrous ethanol, mixed with a lubricity additive, was used in a variable compression ratio CI engine. Testing was conducted by varying the amount of bottled hydrogen gas injected into the intake manifold via a PFI system. The hydrogen flowrates were varied from 0 - 10 slpm.
Technical Paper

Particle and Gaseous Emission Characteristics of a Formula SAE Race Car Engine

2009-04-20
2009-01-1400
The focus of this work was the physical characterization of exhaust aerosol from the University of Minnesota Formula SAE team's engine. This was done using two competition fuels, 100 octane race fuel and E85. Three engine conditions were evaluated: 6000 RPM 75% throttle, 8000 RPM 50% throttle, and 8000 RPM 100% throttle. Dilute emissions were characterized using a Scanning Mobility Particle Sizer (SMPS) and a Condensation Particle Counter (CPC). E85 fuel produced more power and had lower particulate matter emissions at all test conditions, but more fuel was consumed.
Technical Paper

Off-shoring EMS and the Barrier of Test-in-Reliability

2008-10-07
2008-01-2712
The history of off-road equipment manufacturing has been based on proven designs and long times between model updates. In sharp contrast with this strategy is the electronic manufacturing services (EMS) industry. The EMS industry is driven by the larger consumer product industry's continuing pressure for lower costs. Because of this, EMS tools, processes, and practices have evolved to support rapid technology and component changes. However the increasing consumer demand for features like better user-interfaces, more efficient fuel consumption, and the desire for increased operational controls in equipment have forced the off-road industry to increase the frequency of product updates to meet customers' needs. Equipment manufacturers make running changes leading to a “Learning-by-doing” development and manufacturing process. But rapid changes sometimes have an unpredictable impact on the reliability of the final product.
Journal Article

Emissions Effects of Hydrogen as a Supplemental Fuel with Diesel and Biodiesel

2008-04-14
2008-01-0648
A 1.9 liter Volkswagen TDI engine has been modified to accomodate the addition of hydrogen into the intake manifold via timed port fuel injection. Engine out particulate matter and the emissions of oxides of nitrogen were investigated. Two fuels,low sulfur diesel fuel (BP50) and soy methyl ester (SME) biodiesel (B99), were tested with supplemental hydrogen fueling. Three test conditions were selected to represent a range of engine operating modes. The tests were executed at 20, 40, and 60 % rated load with a constant engine speed o 1700 RPM. At each test condition the percentage of power from hydrogen energy was varied from 0 to 40 %. This corresponds to hydrogen flow rates ranging from 7 to 85 liters per minute. Particulate matter (PM) emissions were measured using a scaning mobility particle sizer (SMPS) and a two stage micro dilution system. Oxides of nitrogen were also monitored.
Journal Article

Late Intake Valve Closing as an Emissions Control Strategy at Tier 2 Bin 5 Engine-Out NOx Level

2008-04-14
2008-01-0637
A fully flexible valve actuation (FFVA) system was developed for a single cylinder research engine to investigate high efficiency clean combustion (HECC) in a diesel engine. The main objectives of the study were to examine the emissions, performance, and combustion characteristics of the engine using late intake valve closing (LIVC) to determine the benefits and limitations of this strategy to meet Tier 2 Bin 5 NOx requirements without after-treatment. The most significant benefit of LIVC is a reduction in particulates due to the longer ignition delay time and a subsequent reduction in local fuel rich combustion zones. More than a 95% reduction in particulates was observed at some operating conditions. Combustion noise was also reduced at low and medium loads due to slower heat release. Although it is difficult to assess the fuel economy benefits of LIVC using a single cylinder engine, LIVC shows the potential to improve the fuel economy through several approaches.
Technical Paper

Improving Air Quality by Using Biodiesel in Generators

2004-10-25
2004-01-3032
A biodiesel / petroleum fuel blend and practical low-cost methods of emission control were sought to obtain reductions in emissions from diesel generators. Little direct testing of biodiesel in diesel-powered electric generators has been done. Laboratory and field evaluations were conducted to determine the influence of using biodiesel on diesel exhaust emissions. B20 (20% biodiesel / 80% petroleum diesel) was chosen because of previously successful studies with this blend level, and there is evidence that the NOx emissions increase that result from using B20 can be controlled using existing technology. B85 was selected because it is a “high blend,” which promised to give a large decrease in PM at the expense of a larger increase in NOx than B20, but still within the range of control with existing technology. Charge-air cooling and a fuel additive were tested as NOx controls. For PM, CO, and HC reduction, a diesel oxidation catalyst (DOC) was evaluated.
Technical Paper

The Emission Performance of a GTL Diesel Fuel - a Japanese Market Study

2003-05-19
2003-01-1946
Comparative exhaust emission tests were performed on Japanese light- and heavy-duty vehicles fuelled with a Fischer-Tropsch diesel derived from natural gas and two crude oil-derived reference diesels. Both vehicles were tested without and with an oxidation catalyst fitted to the engine. In the case of the light-duty vehicle a current Japanese specification diesel and a future specification low sulphur diesel were used as reference while in the case of the heavy-duty vehicle only the low sulphur diesel was used as reference. The emission tests were performed using the standard Japanese emission test cycle applicable to that vehicle type. In addition certain selected modes from a special test cycle representative of congested traffic patterns encountered in the Tokyo inner city environment were used for both the light- and heavy-duty vehicles. In general, Fischer-Tropsch diesel reduced all the regulated emissions compared to both crude derived diesels.
Technical Paper

Exhaust Particle Number and Size Distributions with Conventional and Fischer-Tropsch Diesel Fuels

2002-10-21
2002-01-2727
Diesel exhaust particle number concentrations and size distributions, as well as gaseous and particulate mass emissions, were measured during steady-state tests on a US heavy-duty engine and a European passenger car engine. Two fuels were compared, namely a Fischer-Tropsch diesel fuel manufactured from natural gas, and a US D2 on-highway diesel fuel. With both engines, the Fischer-Tropsch fuel showed a considerable reduction in the number of particles formed by nucleation, when compared with the D2 fuel. At most test modes, particle number emissions were dominated by nucleation mode particles. Consequently, there were generally large reductions (up to 93%) in the total particle number emissions with the Fischer-Tropsch fuel. It is thought that the most probable cause for the reduction in nucleation mode particles is the negligible sulphur content of the Fischer-Tropsch fuel. In general, there were also reductions in all the regulated emissions with the Fischer-Tropsch fuel.
Technical Paper

Characterisation of the Injection-Combustion Process in a Common Rail D.I. Diesel Engine Running with Sasol Fischer-Tropsch Fuel

2000-06-19
2000-01-1803
Regulatory standards on diesel engines emissions will decidedly become more restrictive in coming years. This has led to the development and implementation of alternative fuels. The objective of this paper is to evaluate the potential of Sasol Fischer-Tropsch (FT) diesel fuel to improve the reduction of emissions in a direct injection diesel engine with a high pressure common-rail injection system (HDI engine from PSA Peugeot-Citroën). In principle, FT diesel fuel shows significant advantages in reducing emissions over a standard diesel fuel due to its low aromaticity, high cetane rating and high H/C rating. Initial tests with two 406 HDI Euro 2 vehicles with standard calibration showed very favourable trends on exhaust emissions in comparaison with reference fuel (CEC RF73-A-93 type). Sasol FT diesel fuel gave significant improvement on specific fuel consumption, and decreased the HC, CO, CO2 and particulate emissions without degrading NOx emissions.
Technical Paper

Comparative Emissions Performance of Sasol Fischer-Tropsch Diesel Fuel in Current and Older Technology Heavy-Duty Engines

2000-06-19
2000-01-1912
Comparative exhaust emission tests were performed with five diesel fuels, namely a Sasol Fischer-Tropsch diesel, a fuel meeting the CARB diesel fuel specification, a fuel meeting the US 2-D diesel fuel specification, and two blends of the Fischer-Tropsch diesel and the 2-D diesel. Hot-start and cold-start heavy-duty transient emission tests were performed using a 1999 model year DDC series 60 engine. Regulated exhaust emissions with the Fischer-Tropsch diesel were significantly lower than with the 2-D and CARB diesel fuels, in both the hot-start and cold-start tests. When compared with test results obtained previously with a 1991 engine, it was found that the reduction in NOX with the Fischer-Tropsch fuel was smaller in the 1999 engine, while the reduction in PM was greater.
Technical Paper

Influence of Fuel Additives and Dilution Conditions on the Formation and Emission of Exhaust Particulate Matter from a Direct Injection Spark Ignition Engine

2000-06-19
2000-01-2018
Experiments were performed to measure the number-weighted particle size distributions emitted from a gasoline direct injection (GDI) engine. Measurements were made on a late model vehicle equipped with a direct injection spark ignition engine. The vehicle was placed on a chassis dynamometer, which was used to load the engine to road load at five different vehicle speeds ranging from 15 - 100 km/hr. Dilution of the exhaust aerosol was carried out using a two-stage dilution system in which the first stage dilution occurs as a free jet. Particle size distributions were measured using a TSI 3934 scanning mobility particle sizer. Generally speaking, the presence of the additives did not have a strong, consistent influence on the particle emissions from this engine. The polyether amine demonstrated a reduction in particle number concentration as compared to unadditized base fuel.
Technical Paper

Some Comparative Chemical, Physical and Compatibility Properties of Sasol Slurry Phase Distillate Diesel Fuel

1998-10-19
982488
The Sasol Slurry Phase Distillate (SPD) process provides an opportunity to convert the world's abundant natural gas reserves into a conventional liquid fuel that is easily transportable and marketable. The high quality diesel produced by the Sasol SPD process could either be used on its own or as a blending component. Blending Sasol SPD diesel with crude oil derived diesel will improve the properties of the crude oil derived diesel so that it can meet the more stringent, environment and engine technology driven, diesel quality and emissions specifications. The properties of the Sasol SPD diesel and blends of Sasol SPD diesel and an on-highway, 2D-grade diesel fuel from the USA were compared to current and proposed specifications for high quality diesel which included CARB and Premium Diesel specifications from the USA. The compatibility of the Sasol SPD diesel with various elastomers was found to be similar to other low aromatic diesel fuels.
Technical Paper

Influence of an Iron Fuel Additive on Diesel Combustion

1998-02-23
980536
This program used a 0.6 liter DI NA single cylinder diesel engine to study the influence of ferrocene as a fuel additive on particulate and NOx emissions and heat release rates. Previous Studies1,15 have shown efficiency and particulate emission benefits only after engine conditioning. Two engine configurations were tested: standard aluminum piston with normal engine deposits and a second test with the engine cleaned to “new engine condition”, but with the piston replaced with a thermal barrier coated piston. Particle concentration and size in roughly the 7.5 to 750 nm diameter range were measured with a condensation nucleus counter and an electrical aerosol analyzer. Heat release rates and IMEPs were calculated from in-cylinder pressure data. Particle number concentrations increased substantially when the 250 ppm dose was first started with both engine configuration, but decreased 30% to 50% with conditioning.
Technical Paper

Diesel Exhaust Emissions Using Sasol Slurry Phase Distillate Process Fuels

1997-10-01
972898
Transient emission tests were performed to compare emissions using fuels produced by the Sasol Slurry Phase Distillate Process, to those with US diesel fuels. A heavy-duty, four stroke, 1991 emission level diesel engine was used. Two variations of the Sasol Slurry Phase Distillate (SSPD) fuels were tested, along with fuels meeting the US 2-D and CARB specifications, as well as three blends comprising various concentrations of SSPD fuel in the 2-D fuel. It was found that the SSPD fuels produced significantly lower emissions than the 2-D and CARB fuels in all four regulated emission categories. The blended fuels generally reduced emissions in proportion to the amount of SSPD fuel in the blend. Tests were also performed at retarded injection timing settings with the SSPD fuel, which has a cetane number in excess of 70. It was found that a further reduction in NOx emissions could be obtained, without significantly compromising particulate emissions or specific fuel consumption.
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