Diesel fuel

This article is about the fuel. For other uses see diesel (disambiguation)

Diesel or Diesel fuel is a specific fractional distillate of fuel oil (mostly petroleum) that is used as fuel in a diesel engine invented by German engineer Rudolf Diesel. The term typically refers to fuel that has been processed from petroleum, but increasingly, alternatives such as biodiesel or biomass to liquid (BTL) or gas to liquid (GTL) diesel that are not derived from petroleum are being developed.

Petroleum diesel

File:Diesel station.jpg

A vintage diesel station in a factory's yard

Diesel is produced from petroleum, and is sometimes called petrodiesel (or, less seriously, dinodiesel) when there is a need to distinguish it from diesel obtained from other sources. As a hydrocarbon mixture, it is obtained in the fractional distillation of crude oil between 250 °C and 350 °C at atmospheric pressure. Petro Diesel is considered to be a fuel oil and is about 18% heavier than gasoline.

Diesel typically weighs about 7.1 pounds (lb) per US gallon (gal.) (850 grams per liter (g/l)), whereas gasoline weighs about 6.0 lb per US gal. (720 g/l), or about 15% less. When burnt diesel typically releases about 147,000 British thermal units (BTU) per US gal. (40.9 megajoules (MJ) per liter), whereas gasoline releases 125,000 BTUs per US gal. (34.8 MJ/l), also about 15% less. Diesel is generally simpler to refine than gasoline and often costs less (although price fluctuations often mean that the inverse is true; for example, the cost of diesel traditionally rises during colder months as demand for heating oil, which is refined much the same way, rises).

Diesel fuel, however, often contains higher quantities of sulfur. In Europe, emission standards and preferential taxation have both forced oil refineries to dramatically reduce the level of sulfur in diesel fuels. In contrast, the United States has long had "dirtier" diesel, although more stringent emission standards have been adopted with the transition to ultra-low sulfur diesel (ULSD) occurring in 2006 (see also diesel exhaust). US diesel fuel typically also has a lower cetane number (a measure of ignition quality) than European diesel, resulting in worse cold weather performance and some increase in emissions.

High levels of sulfur in diesel are harmful for the environment. It prevents the use of catalytic diesel particulate filters to control diesel particulate emissions, as well as more advanced technologies, such as nitrogen oxide (NOx) adsorbers (still under development), to reduce emissions. However, lowering sulfur also reduces the lubricity of the fuel, meaning that additives must be put into the fuel to help lubricate engines. Biodiesel is an effective lubricity additive.

Diesel contains approximately 18% more energy per unit of volume than gasoline, which, along with the greater efficiency of diesel engines, contributes to fuel economy (distance traveled per volume of fuel consumed).

In the maritime field various grades of diesel fuel are used.

Chemical composition

Petroleum derived diesel is composed of about 75% saturated hydrocarbons (primarily paraffins including n, iso, and cycloparaffins), and 25% aromatic hydrocarbons (including naphthalenes and alkylbenzenes).^[1]

Synthetic diesel

Wood, straw, corn, garbage, and sewage-sludge may be dried and gasified. After purification the so called Fischer Tropsch process is used to produce synthetic diesel. ^[2] Other attempts use enzymatic processes and are also economic in case of high oil prices. Synthetic diesel may also be produced out of natural gas in the GTL process. Such synthetic diesel has 30% less particulate emissions than conventional diesel (US- California) ^[3].

Biodiesel

Biodiesel can be obtained from vegetable oil and animal fats (bio-lipids, using transesterification). Biodiesel is a non-fossil fuel alternative to petrodiesel. It can also be mixed with petrodiesel in any amount in modern engines, though it is a strong solvent and can cause problems in some cases. There have been reports that a diesel-biodiesel mix results in lower emissions than either can achieve alone. A small percentage of biodiesel can be used as an additive in low-sulfur formulations of diesel to increase the lubricating ability that is lost when the sulfur is removed.

Chemically, biodiesel consists of alkyl (usually methyl) esters instead of the alkanes and aromatic hydrocarbons of petroleum derived diesel. However, biodiesel has combustion properties very similar to regular diesel, including combustion energy and cetane ratings.

Uses

Diesel fuel is very similar to heating oil which used in central heating. In both Europe and the United States, taxes on diesel fuel are higher than on heating oil, and in those areas, heating oil is marked with dye and trace chemicals to prevent and detect tax fraud. Similarly, "untaxed" diesel is available in the United States, which is available for use primarily in agricultural applications such as for tractor fuel. This untaxed diesel is also dyed red for identification purposes, and should a person be found to be using this untaxed diesel fuel for a typically taxed purpose (such as "over-the-road", or driving use), the user can be fined $10,000 USD on the spot. Also, in the United Kingdom and Ireland it is known as red diesel, and is also used by agricultural vehicles. The term DERV (short for "diesel engined road vehicle") is also used in the UK as a synonym for diesel fuel.

Diesel is used in diesel engines, a type of internal combustion engine. Rudolf Diesel originally designed the diesel engine to use coal dust as a fuel, but oil proved more effective. Diesel engines are used in cars, trucks, motorcycles, boats and locomotives.

Packard diesel motors were used in aircraft as early as 1927, and Charles Lindbergh flew a Stinson SM1B with a Packard Diesel in 1928. A Packard diesel motor designed by L.M. Woolson was fitted to a Stinson X7654, and in 1929 it was flown 1000 km non-stop from Detroit to Langley, VA. In 1931, Walter Lees and Fredrick Brossy set the nonstop flight record flying a Bellanca powered by a Packard Diesel for 84h 32m.

The very first diesel-engine automobile trip was completed on January 6, 1930. The trip was from Indianapolis to New York City - a distance of nearly 800 miles (1300 km). This feat helped to prove the usefulness of the internal combustion engine. The following year Dave Evans drove his Cummins Diesel Special to a nonstop finish in the Indianapolis 500, the first time a car had completed the race without a pit stop. That car and a later Cummins Diesel Special are on display at the Indianapolis Motor Speedway Hall of Fame Museum^[4].

Westport claims to have invented a process called Westport-Cycle ^[5] with comparable efficiency using natural gas and petrodiesel.

Notes

^ Agency for Toxic Substances and Disease Registry (ATSDR). 1995. Toxicological profile for fuel oils. Atlanta, GA: U.S. Department of Health and Human Services, Public Health Service
^ "http://www.fas.usda.gov/pecad/highlights/2005/01/btl0104/syntheticdiesel.htm". December 5. {{cite web}}: Check date values in: |date= and |year= / |date= mismatch (help); External link in |title= (help)
^ "SYNTHETIC DIESEL FUEL". December 5. {{cite web}}: Check date values in: |date= and |year= / |date= mismatch (help)
^ "Indianapolis Motor Speedway". December 5. {{cite web}}: Check date values in: |date= and |year= / |date= mismatch (help)
^ "http://www.westport.com/expertise/westport_cycle.php". December 5. {{cite web}}: Check date values in: |date= and |year= / |date= mismatch (help); External link in |title= (help)

External links