Diesel, Diesel Oil, Diesel Fuel, Petrodiesel


Diesel is a heavy oil named after Rudolf Diesel, or Rudolf Christian Karl Diesel, a German engineer who invented the diesel engine (1858-1913). The most common form of diesel is petrodiesel, which is derived from the fractional distillation of petroleum. Diesel is derived from fossil fuels and refined like gasoline.

There are various types of synthetic diesel, such as biodiesel, gas-to-liquid diesel and coal-to-liquid diesel. They are derived from natural wastes like remnants of food, sewage and wood scraps.

The Diesel Engine

France-born mechanical engineer Rudolf Diesel invented the diesel engine in the late nineteenth century. It was designed as an efficient alternative to the steam engine and was used in ships. The mechanism of ignition for the diesel engine is compression, instead of spark ignition. The air inside the diesel engine is compressed to a ratio of 15:1, generating immense heat and pressure. The heat causes the fuel to react with oxygen and converts thermal energy into mechanical work, which pushes the piston downwards.

Nowadays, a low sulfur containing alternative, ultra-low sulfur diesel (ULSD), is used in most parts of America and Europe to reduce environmental pollution.

Uses of Diesel Oil

Diesel oil is used for the following:

  • For running heavy road vehicles, like buses, trucks and tractors
  • For running cars and SUVs
  • For overland shipping
  • In military vehicles, like tanks and trucks
  • To power modes of water transportation, such as ships, tankers, liners, yachts and boats
  • For electricity backup in major industries, hospitals and other telecom industries
  • In power generators
  • In construction and farming equipment
  • For the removal of tar from Bitumen burns

Benefits of Diesel Oil

The many benefits of diesel fuel vis-à-vis gasoline are:

  • More economical
  • Lower emissions and particulate matter
  • Less volatile
  • Higher fuel efficiency
  • Safer
  • Higher mileage

The main disadvantage of using diesel is that at lower temperatures, its viscosity increases, converting it into a non-flowing gel.

How is Diesel Processed?

Petroleum diesel, which is also called petrodiesel or fossil diesel, is produced from the fractional distillation of crude oil (petroleum) at atmospheric pressure, within a temperature range of 200°C to 350°C. This results in a mixture of hydrocarbon chains that contains around 8 to 21 carbon atoms per molecule. The viscosity and the boiling point of the fuel increase with an increase in the number of carbon atoms. This helps in the separation of the various components by distillation.

The chains from C7 to C11 vaporize at temperatures below the boiling point of water and are used as gasoline. The products from the range of C12 to C15 form kerosene, diesel oil and heavier fuel oils. The No. 2 fuel oil is known as diesel oil and is used for running cars, trucks and other vehicles. The lubricating oils follow, ranging from very light to very thick motor oils, gear oils and semi-solid greases. Vaseline also falls in this category. Hydrocarbon chains above the range of C20 form solids, like paraffin wax, tar and asphalted bitumen.