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Technical Paper

Performance and Emissions of an LPG Lean-Burn Engine for Heavy Duty Vehicles

1999-05-03
1999-01-1513
Performance and emissions of an LPG lean burn engine for heavy duty vehicles were measured. The piston cavity, swirl ratio, propane - butane fuel ratio, and EGR were varied to investigate their effects on combustion, and thus engine performance. Three piston cavities were tested: a circular flat-bottomed cavity with sloped walls (called the “bathtub” cavity), a round bottomed cavity (called the “dog dish” cavity), and a special high-turbulence cavity (called the “nebula” cavity). Compared to the bathtub and dog dish cavities, the nebula type cavity showed the best performance in terms of cyclic variation and combustion duration. It was capable of maintaining leaner combustion, thus resulting in the lowest NOx emissions. High swirl improved combustion by achieving a high thermal efficiency and low NOx emissions. In general, as the propane composition increased, cyclic variation fell, NOx emissions increased, and thermal efficiency was improved.
Technical Paper

Emissions from Buses with DDC 6V92 Engines Using Synthetic Diesel Fuel

1999-05-03
1999-01-1512
Synthetic diesel fuel can be made from a variety of feedstocks, including coal, natural gas and biomass. Synthetic diesel fuels can have very low sulfur and aromatic content, and excellent autoignition characteristics. Moreover, synthetic diesel fuels may also be economically competitive with California diesel fuel if produced in large volumes. Previous engine laboratory and field tests using a heavy-duty chassis dynamometer indicate that synthetic diesel fuel made using the Fischer-Tropsch (F-T) catalytic conversion process is a promising alternative fuel because it can be used in unmodified diesel engines, and can reduce exhaust emissions substantially. The objective of this study was a preliminary assessment of the emissions from older model transit operated on Mossgas synthetic diesel fuel. The study compared emissions from transit buses operating on Federal no. 2 Diesel fuel, Mossgas synthetic diesel (MGSD), and a 50/50 blend of the two fuels.
Technical Paper

Influence of Fuel Aromatics Type on the Particulate Matter and NOx Emissions of a Heavy-Duty Diesel Engine

2000-06-19
2000-01-1856
The influence of fuel aromatics type on the particulate matter (PM) and NOx exhaust emissions of a heavy-duty, single-cylinder, DI diesel engine was investigated. Eight fuels were blended from conventional and oil sands crude oil sources to form five fuel pairs with similar densities but with different poly-aromatic (1.6 to 14.6%) or total aromatic (14.3 to 39.0%) levels. The engine was tuned to meet the U.S. EPA 1994 emission standards. An eight-mode, steady-state simulation of the U.S. EPA heavy-duty transient test procedure was followed. The experimental results show that there were no statistically significant differences in the PM and NOx emissions of the five fuel pairs after removing the fuel sulphur content effect on PM emissions. However, there was a definite trend towards higher NOx emissions as the fuel density, poly-aromatic and total aromatic levels of the test fuels increased.
Technical Paper

AQUAZOLE™: An Original Emulsified Water-Diesel Fuel for Heavy-Duty Applications

2000-06-19
2000-01-1861
1 Since 1997 the ELF group has been working on a new fuel designed in priority for use with urban services (buses, lorries). Basically, it is a diesel/water emulsion stabilised by a series of new additives. A lot of testing programmes on engine and vehicles test benches was carried out. They have clearly shown that with this new fuel there is a reduction of nitrogen oxide emissions by up to 30% and black smoke by up to 80%, without any technological modifications being necessary as against EN 590 diesel fuel marketed normally. The water content is, however, the cause of a certain loss in engine performances. Nevertheless, hydrocarbon consumption is reduced by up to 4%. The use of an oxidation catalyst is compatible with a water-diesel emulsified fuel and results in larger emission benefits. Furthermore, a 50 ppm sulphur emulsion with a continuously regenerating particle filter give a particle reduction of 90%.
Technical Paper

New Quiescent Combustion System for Heavy–Duty Diesel Engines to Overcome Exhaust Emissions and Fuel Consumption Trade–Off

2000-06-19
2000-01-1811
In the next few years, the USA, EU, and Japan plan to introduce very stringent exhaust emissions regulations for heavy–duty diesel engines, in order to enhance the protection air quality. This builds upon the heavy–duty diesel engine exhaust emissions regulations already in effect. At the same time, improvement in fuel consumption of heavy–duty diesel engines will be very important for lowering vehicle operating costs, conserving fossil fuel resources, and reduction of CO2 (greenhouse gas) levels. This paper presents a detailed review of a quiescent combustion system for a heavy–duty diesel engine, which offers breakthrough performance in terms of the exhaust emissions – fuel consumption trade–off, compared with the more conventional swirl supported combustion system. This conclusion is supported by experimental results comparing quiescent and swirl supported versions of various combustion system configurations.
Technical Paper

Measurement and Analysis of Commercial Vehicle Air Dryer Efficiency

1999-11-15
1999-01-3774
The measurement of pressure dew point is a well-known method of describing air quality, however this value seldom assists commercial vehicle OEM’s and operators in establishing specific air drying requirements for their vehicles. This paper describes the method and examines the results of using the dryer capacity method specified in SAE document J2384, section 5.2, for determining air dryer performance, and compares the results of various air-drying techniques and the impact on vehicle system design to give the most efficient solution. The paper further goes on to discuss how the drying capacity can also be influenced by the design of the air dryer to meet a wide range of vehicle applications both in Europe and North America. Since J2384 excludes continuous flow air dryers from the scope of the document, they will likewise be excluded from discussion here.
Technical Paper

Electronic Compressor and Air Dryer Control

1999-11-15
1999-01-3771
The paper details opportunities for electronic control of the pneumatic charging system of an air braked vehicle. Electronic control of the charging and drying functions can result in increased fuel efficiency and improved air quality. Control functions can be used to identify and warn of in-service issues, provide prioritized system charging for faster drive-away, and signal required preventative maintenance. The first portion of the paper describes current industry practice, as well as common issues that can result from those practices. This is followed by presentation of areas of improvement, where specialized control features result in energy savings, air quality increases and maintenance/downtime savings. This portion will focus on adaptive control of components used today, and will briefly discuss opportunities for the next generation of charging system devices. The final section of the paper presents the control logic and vehicle interface allowing for system integration.
Technical Paper

A Three Year Comparison of Natural Gas and Diesel Transit Buses

1999-11-15
1999-01-3738
This report details the experiences of two California public transit agencies that replaced aging diesel buses with new compressed natural gas (CNG) buses in 1994. The operating characteristics and costs of 170 natural gas buses are compared with 73 older diesel buses. The natural gas bus fleets have operated well and led to cost reductions in both fleets. The findings are particularly significant because both Sacramento Regional Transit District (RT) and SunLine Transit Agency have been using the same engine-chassis configuration, thus enabling a valid method to combine cost data for a large sample fleet of buses. The data indicate that labor for diesel equipment was almost twice that for CNG vehicles, parts were 25% more and fuel costs were nearly double. In 1997, CNG buses saved RT over $1 million in fuel, maintenance, parts and hazardous waste disposal, a 38% per mile reduction over the cost of their older diesel buses.
Technical Paper

Urea-SCR System Demonstration and Evaluation for Heavy-Duty Diesel Trucks

1999-11-15
1999-01-3722
The Institute of Transportation Studies at the University of California, Davis (ITS-Davis) has brought together a group of public and industrial partners to demonstrate and evaluate the Siemens-Westinghouse Urea-Selective Catalyst Reduction System (SINOx™). The SINOx System has the potential to generate major reductions in nitrogen oxides (NOx) and the volatile organic fraction (VOF) of particulate (PM) from heavy-duty diesel engines, without increasing fuel consumption and carbon dioxide (CO2) emissions. This demonstration began with engine bench testing at Detroit Diesel Corporation to calibrate the system to attain 1 g/bhp-hr NOx emissions in the transient portion of the US-FTP on a 1999 Series 60 engine that has a 4 g/bhp-hr emission level. The second phase of the project entails an on-highway demonstration of a set of ten, Freightliner Class 8 heavy-duty diesel vehicles. These vehicles are part of the Valley Material Transport fleet based in French Camp, California.
Technical Paper

Simultaneous Visualisation of Spray and Flame Propagation in a Heavy-Duty Transparent-Engine with Common-Rail Injection System

2000-06-19
2000-01-1797
The transport of goods is mainly realised by the use of heavy-duty vehicles equipped with diesel engines as a drive assembly. Considering the high flexibility and reliability as well as the growing interest in saving environmental resources, a further optimisation of DI-diesel engines regarding fuel consumption and exhaust emissions is necessary. Current discussions on the application of different injection systems for passenger cars (distributor pump, common-rail, …) are also of great significance with regard to heavy-duty vehicles. Optical measurement techniques are a valuable tool to evaluate the quality and the potential of modern DI-diesel injection systems. In this work a conventional heavy-duty engine (MAN) was modified to carry out optical investigations inside the combustion bowl, concerning spray propagation and flame luminosity for different injection nozzles. With respect to the current discussions, it was equipped with a modern common-rail system.
Technical Paper

Relative Impact on Environment and Health from the Introduction of Low Emission City Buses in Sweden

2000-06-19
2000-01-1882
This paper is focusing on the technical measures that have been implemented during the last decade to reduce the emissions from heavy-duty buses in Sweden. The emission tests carried out on these buses have been evaluated in order to assess the impact on the environment and on several health effects from switching to improved technology and to alternative fuels. Emission factors for the most important emission components (regulated and unregulated) have been determined for each option. Several effects from the emission components have been calculated using weighting factors for each component. Acidification, eutrophication, ozone forming potential, cancer risk, greenhouse gases and several other effects have been evaluated. The analysis showed considerable improvements by reformulation of the diesel fuel and by fitting aftertreatment devices. Particulate emissions and its effects are probably the most severe emission component from the diesel engines.
Technical Paper

Particulate Traps Used in City-Buses in Switzerland

2000-06-19
2000-01-1927
1 Switzerland is enforcing the use of particulate traps for offroad applications like construction as well as for occupational health applications like tunneling. This decision is based on the results of the VERT-project (1994-1999), which included basic aerosol research, bench screening and field testing of promising solutions as well as the development of implementation tools like trap specification, certification scheems and field control measures. On the other hand there is no corresponding regulation for city-buses yet although PM 10 is about 2× above limit in most Swiss cities. Public pressure however is growing and city transport authorities have reacted by retrofitting Diesel city-buses instead of waiting for cleaner engine technology or CNG-conversions. The favored trap system with about 200 retrofits so far is the CRT.
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

Particulate Traps for Construction Machines Properties and Field Experience

2000-06-19
2000-01-1923
1 Occupational Health Authorities in Germany and Switzerland require the use of particulate traps (PT) on construction machines used in underground and in tunneling since 1994. Swiss EPA has extended this requirement 1998 to all construction sites which are in or close to cities. During the VERT*-project, [1, 2, 3, 4, 5]**, traps systems were evaluated for this purpose and only those providing efficiencies over 95% for ultrafine particles < 200 nm have received official recommendation. 10 trap-systems are very popular now for these application, most of them for retrofitting existing engines. Efficiency data will be given as well as experience during a 2-years authority-controlled field test. LIEBHERR, producing their own Diesel engines in Switzerland and construction machines in Germany is the first company worldwide supplying particulate traps as OEM-feature (Original Equipment Manufacturing) on customers request.
Technical Paper

Evaluation of Water-blend Fuels in a City Bus and an Assessment of Performance with Emission Control Devices

2000-06-19
2000-01-1915
The UK government offered a tax incentive to introduce ultra-low sulphur diesel (ULSD) fuels into the market place. This has led rapidly to the use of such a fuel with a consequent reduction in emissions, notably particulates and permits the use of some exhaust after-treatment devices that were formerly precluded. A water-blend fuel technology has been developed to substantially reduce engine out emissions relative to ULSD and is currently under market evaluation. Use of the fuel requires no engine modifications. To further evaluate the emissions performance of the technology, a trial was conducted with the Millbrook testing facility, Bedfordshire, England. The trial also considered the impact of such water-blend fuels on existing/future exhaust emission control technology. On the Millbrook London Transport Bus (MLTB) cycle, the water-blend fuels tested achieved significant reductions in nitrogen oxides (NOx) and particulates over that attained by ULSD.
Technical Paper

Measurement of the Number and Size Distribution of Particle Emissions from Heavy Duty Engines

2000-06-19
2000-01-2000
Air quality monitoring of PM10 and associated health studies have focused interest on the size and the number of particles emitted to, and found in, the atmosphere. Automotive sources are one of the important elements in this, and CONCAWE have completed a study of heavy duty diesel particle emissions, complementing their previously reported light duty work. This heavy duty programme, presented here, investigated the nature of particulate emissions from two heavy duty engines (representative of different emissions levels), operating on three marketed fuels, over their respective European legislative heavy duty test cycles. The programme has investigated some of the complexities associated with obtaining credible data (e.g. dilution ratios, system stabilisation time etc.). The number distributions, which were measured over a wide size range (3 to 1000 nm), have been split into two size ranges, representative of nucleation mode and accumulation mode particles.
Technical Paper

Characterization of Particle Size Distribution of a Heavy-Duty Diesel Engine During FTP Transient Cycle Using ELPI

2000-06-19
2000-01-2001
Particle number concentrations and size distributions were measured for the diluted exhaust of a 1991 diesel engine during the US FTP transient cycle for heavy-duty diesel engines. The engine was operated on US 2-D on-highway diesel fuel. The particle measurement system consisted of a full flow dilution tunnel as the primary dilution stage, an air ejector pump as the secondary dilution stage, and an electrical low pressure impactor (ELPI) for particle size distribution measurements. Particle number emission rate was the highest during the Los Angeles Non Freeway (LANF) and the Los Angeles Freeway (LAF) segments of the transient cycle. However, on brake specific number basis the LAF had the lowest emission level. The particle size distribution was monomodal in shape with a mode between 0.084 μm and 0.14 μm. The shape of the size distribution suggested no presence of nanoparticles below the lower detection limit of the instrument (0.032 μm), except during engine idle.
Technical Paper

Similarities and Differences Between ACEA E3, E4 and E5 Specifications and Their Impact on Heavy Duty Diesel Engine Oil Formulations

2000-06-19
2000-01-1986
The increasingly severe emission legislation for heavy duty diesel engines forces engine builders to modify their engine designs drastically. Together with a desire for longer drain intervals, this results in changes in engine oil specifications. Recently, a new ACEA specification for heavy duty diesel engine oils - E5 - has been added to the existing E1-E4 categories, and E1 has been withdrawn. The previous ACEA specifications - E1 through E4 - are sequential in the sense that each next category means an increase in performance. The new ACEA E5 specification, although it resembles an improved E3 product, breaks with this tradition in that it does not fall between the E3 and E4 specifications, but moves in a new direction regarding the formulation requirements. This is due to the inclusion of various API CH-4 tests that put an emphasis on the engine oils capability to handle soot.
Technical Paper

Off-The-Shelf Variable Flow Rate Water-Propylene Glycol Hydraulics

2000-09-11
2000-01-2587
A commercially available axial piston water hydraulic pump (Danfoss PAH 10) was evaluated under a range of pressures, speeds and fluid temperatures. Three candidate fluids were used in this evaluation: filtered tap water (as a baseline), a mixture of tap water and polypropylene glycol based antifreeze, and finally a mixture of synthetic seawater and polypropylene glycol based antifreeze. The effect of the fluids and temperatures on the pump efficiency was observed. The evaluation provides the basis for the design of a non-polluting variable flow water-antifreeze hydraulic power source.
Technical Paper

Off-Highway Noise - Diverging Demands of the Future

2000-09-11
2000-01-2548
Recent years has seen the development of increased restrictions on allowable noise output from Earthmoving equipment within the European Union, Australia, and Japan. At the same time, other environmental issues such as engine emissions have been the prime focus of America. With Europe now adopting a similar approach to emissions, earthmoving equipment manufacturers are anticipating the conflict that this brings in terms of machine design. This paper reviews the changes in recent years, illustrates the methods adopted so far to reduce noise, and considers what the future may hold in order to meet both legislative and customer demands.
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