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Diesel Vehicles
Volkwagen Jetta TDI – The Most Fuel Efficient Diesel Car
Advanced diesel vehicles using EPA-mandated ultra-low sulfur diesel (ULSD) fuel are among the most fuel-efficient vehicles available today. Collaborative R&D between DOE, industry and the national laboratories has resulted in improved engine efficiency and very low emissions. Collaboration with the U.S. Environmental Protection Agency, industry, and national laboratories under the DOE Diesel Emission Control Sulfur Effects (DECSE) program provided the supporting data needed to mandate 15 ppm sulfur in diesel fuel as the appropriate level to maintain effectiveness of diesel engine emission control technologies. Most diesel vehicles also can run on biodiesel blends without engine modification.
Diesel Vehicle Classes
Diesel Emissions
Advanced diesel engine technologies combining in-cylinder combustion control for low engine-out emissions with advanced aftertreatment technologies and using ultra-low sulfur diesel (ULSD) fuel can meet EPA emissions standards. Advanced combustion strategies such as exhaust gas recirculation (EGR) lower engine-out NOx emissions. Aftertreatment devices such as NOx adsorbers and selective catalytic reduction (SCR), reduce NOx emissions by up to 90 percent. Diesel particulate filters and oxidation catalysts lower particulate matter emissions by over 95 percent. A combination of these aftertreament technologies is used to meet stringent emissions standards.
Source: Diesel Technology Forum. See DieselNet’s Emission Standards for details.
Diesel Selective Catalytic Reduction
Selective catalytic reduction (SCR) is an advanced emission-control technology that can help light-, medium-, and heavy-duty diesel vehicles meet stringent regulations on nitrogen oxides (NOx) emissions. In an SCR system, a liquid reducing agent composed of urea and water—known as Diesel Exhaust Fluid (DEF)—is combined with engine exhaust in the presence of a catalyst to convert smog-forming NOx into harmless nitrogen and water vapor. See the diagram below.
Source: Diesel Technology Forum—Selective Catalytic Reduction
The process starts with ultra-low sulfur diesel fuel combusted in an optimized diesel engine. Hot exhaust from the engine flows through a diesel particulate filter (which removes particulate matter) toward the SCR catalyst. DEF from a storage tank is injected into the exhaust stream, and the exhaust and finely atomized DEF enter the SCR catalyst chamber together. In the presence of the SCR catalyst, the exhaust and DEF react to convert NOx into nitrogen (N2) and water vapor.
One important requirement of an SCR system is consistently refilling the DEF storage tank. This occurs at approximately the interval of recommended oil changes for light-duty vehicles. The interval varies based on application for medium- and heavy-duty vehicles. A DEF distribution system is being established to meet refilling needs.
Selective catalytic reduction has been used for decades in marine and large stationary diesel engines. The technology is used extensively with heavy-duty highway vehicles in Europe, where the DEF is marketed as AdBlue. The use of SCR in highway and non-road engines has been demonstrated in the United States, and several auto manufacturers are incorporating SCR into their U.S. diesel products. Tests have shown that SCR can reduce NOx emissions by 75% to 90%.
NOx Adsorbers
NOx adsorbers—also known as NOx traps or lean NOx traps—are advanced emission-control technologies that can help diesel vehicles meet stringent nitrogen oxides (NOx) emissions standards. NOx adsorbers trap and store NOx present in the lean (i.e., oxygen-rich) exhaust produced by diesel engines. The stored NOx is transformed into more environmentally benign compounds before these compounds are emitted into the atmosphere. See the diagram below.
Adapted from: APBF-DEC 2,000-Hour Performance of a NOx Adsorber Catalyst and Diesel Particle Filter System for a Medium-Duty, Pick-Up Truck Diesel Engine Platform
The process starts with ultra-low sulfur diesel (ULSD) fuel combusted in an optimized diesel engine. (Use of ULSD minimizes potential poisoning of the NOx adsorber by sulfur compounds.) Lean exhaust from the engine flows into the NOx adsorber; in some configurations, the exhaust flows first through other emission control devices (as shown in the diagram above). With the aid of a noble metal catalyst, NOx is captured and stored within the NOx adsorber substrate.
When the NOx adsorber nears its NOx storage capacity, it begins "regeneration." The engine exhaust is briefly made rich (i.e., fuel rich and oxygen poor) by means such as injecting diesel fuel into the exhaust stream ("In-Exhaust Fuel Injection" in the diagram above) or late-cycle in-cylinder injection. In the presence of this fuel-rich exhaust, the stored NOx is released then reduced to carbon dioxide (CO2), water (H2O), nitrogen (N2), and other nitrogen-containing gases over a noble metal catalyst. These gases are then emitted out the tailpipe.
NOx adsorbers are not a new technology but are just beginning to be seen in vehicle applications. Tests have shown they can reduce automotive NOx emissions by 80% to 90.
List of Top Diesel Cars:
| Sort by: | Model | MPG | Price | Type |
|---|---|---|---|---|
| Volkswagen Touareg 2 TDI | 16 MPG | $39,300 | SUV |
| Volkswagen Jetta TDI | 35 MPG | $21,900 | Sedan |
| BMW 730d | 33 MPG | $198,800 | Sedan |
| BMW 335d BluePerformance | 29 MPG | $44,700 | Sedan |
| 57 MPG | N/A | Sedan | |
| N/A | N/A | Truck | |
| N/A | N/A | SUV |
Similar Posts:
- Light-Duty Diesel Vehicles
- Medium- and Heavy-Duty Diesel Vehicles
- Low-Level Biodiesel Blends
- BMW M Goes Diesel
- Top 5: 2010 Diesel Cars
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[...] control devices soon will be required to meet stringent emissions standards.Learn more about diesel emissions and how technologies such as selective catalytic reduction, Diesel Exhaust Fluid, and NOx adsorbers [...]
[...] control devices soon will be required to meet stringent emissions standards. Learn more about diesel emissions and how technologies such as selective catalytic reduction, Diesel Exhaust Fluid, and NOx adsorbers [...]