Diesel heavy-duty trucks

Table 4 Typical exhaust after-treatment for diesel heavy-duty trucks...

The necessity of having a post catalyst layer which can eliminate slipping ammonia (in addition, since CO and HC also must be eliminated, current catalytic SCR-urea systems applied to diesel engine emissions are composed typically of five catalytic layers, making the size of the catalytic converter quite large and therefore applicable essentially only to heavy-duty trucks and buses). 

Salmeen, I. T., R. A. Gorse, Jr., and W. R. Pierson, Ames Assay Chromatograms of Extracts of Diesel Exhaust Particles from Heavy-Duty Trucks on the Road and from Passenger Cars on a Dynamometer, Environ. Sci. Technol., 19, 270-273 (1985). 

FIGURE 16.42 Measured emissions of (a) particles (PM) and (b) NO, from more than 300 buses and heavy-duty trucks running on compressed natural gas (CNG), two diesel fuels, or alcohol fuels (E93, E95, and M100). The bars are the means and the boxes encompass the 95% confidence intervals. E93 = 93% ethanol, 5% methanol, 2% K-l kerosene E95 = 95% ethanol, 5% gasoline M100 = 100% methanol (adapted from Wang et al., 1997). 

A. Lawson, A. J. Last, A. S. Desphande, and E. W. Simmons, "Heavy-Duty Truck Diesel Engine Operation on Unstabdized Alethanol/Diesel Fuel Emulsion," SAE Paper 810346, (SP-480) Int. Congress and Expo (Detroit, Alich, Feb. 23—27, 1981) Society of Automotive Engineers, Warrendale, Pa. 

The minimum temperature, where the additive filter systems can operate, is in the range of 625 - 650 K. The additive dosage rates to the diesel fuel generally are 30 - 50 ppm metal content on a weight basis. The resulting ash from cerium and iron does not plug the filter, in contrast to copper, where serious filter pluggings are reported. When 25 ppm of cerium additive is used for a typical heavy duty truck, the filler will be 50 % filled after 75,000 to 150,000 miles [5]. Copper is reported to... 

Since the diesel engine is the workhorse of urban buses and heavy-duty trucks, worldwide, and since diesel exhaust poses health concerns, including cancer, emphysema, and other respiratory diseases, the aftertreatment of diesel exhaust is receiving worldwide attention. Both wall-flow filters and catalytic converters are being tested, the former for trapping solid particulates and the latter for converting hydrocarbons by oxidizing the soluble... 

Consider a 10-litcr, 230-hp diesel engine for a medium- to heavy-duty truck for urban areas. We design the total filter volume to be 10 liters, with a microstructure commensurate with 90% filtration efficiency. Based on prior experience we limit the soot loading to 10 g/liter of filter volume to ensure safe regeneration at 2-hr intervals. Then,... 

Among the gaseous hydrocarbon components of diesel exhaust that are individually known to be of toxicologic relevance are the aldehydes (e.g., formaldehyde, acetaldehyde, acrolein), benzene, 1,3-butadiene, and polycyclic aromatic hydrocarbons (PAHs) and nitro-PAHs. Diesel engines are used to power heavy machinery, locomotives, ships, buses, heavy-duty trucks, and some light-duty trucks and passenger cars. 

Since about 1991, diesel oxidation catalysts have been generally applied to passenger cars in the European Union and to some medium and heavy duty trucks in the USA. Their principle of operation is shown in Fig. 101. The amount of carbon monoxide, hydrocarbons and aldehydes is reduced by oxidation of these components to carbon dioxide and water. The mass of particulate matter emitted is reduced by the oxidation of the liquid hydrocarbons, which are adsorbed on the particulates. These liquid hydrocarbons originate both from the fuel and the lubricating oil, and are commonly denoted as the soluble organic fraction (SOF). The adsorbed polynuclear aromatic hydrocarbons are also removed by oxidation. 

The most convenient way to remove particulates from the exhaust gas is combustion. Diesel particulates are, however, relatively unreactive and oxidation occurs moderately at normal exhaust temperatures for both passenger cars and heavy-duty trucks. In the non-catal3rtic as well as the catal3rtic oxidation of soot the reaction rate under all circumstances is rather slow in comparison to the residence time in the exhaust system. To achieve complete oxidation, the reaction... 

Based on our first-pass APU application characterization and screening, hotel loads for long-haul heavy-duty truck / recreational vehicles, refrigerated trucks, police car and contractor utility trucks appear to be good candidates for further analysis. We will start detailed analysis of the long-haul truck cabin loads using petroleum diesel as a fuel. We will work with DOE to agree on the next 1 to 2 applications for detailed study as part of Task 3. 

In the past, exhaust emission standards (limits) have been set in most industrialised countries for passenger cars, light-duty trucks and heavy-duty trucks (gasoline and diesel... 

In addition to their primary fimction of reducing particulate matter, diesel catalysts must convert gas phase CO and HC. Emission limits have come down sharply for U.S. trucks, for example, 2009 standards allow only about 1/10 as much as HC as was permitted in 1994. For CO, 2003/2004 limits for Japanese heavy-duty trucks are about 1/3 of their values in 2000. The much leaner diesel exhaust, compared with gasoline exhaust, helps reduce CO and HC emissions, but diesel exhaust is generally cooler, which suppresses conversion. Low temperature activity is, accordingly, are research priority. Pt, or Pt/Pd, supported on alumina, is standard, but even small changes in thermal stability can confer a competitive advantage. 

With internaJ-combustion engines, automatic transmissions are frequently used these are easily justified when vehicles must make many moves during the day. Smooth as is the control afforded by automatic transmissions, it is neveriheless inferior to that provided by electric trucks, especially those with solid-state controls. Gasoline and diesel power are also used, but mostly for outdoor equipment and very-heavy-duty units. 

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