Diesel fuel is any fuel used to power a diesel engine. Like gasoline, diesel fuel can be made from petroleum, but diesel fuel operates very differently within an engine. Diesel fuel is injected directly into the cylinders of an engine, where the compression and high temperatures inside the engine cause the fuel to burn. Because diesel fuel is not ignited with a spark as is gasoline, it requires certain components for ensuring that it will ignite inside a diesel engine. Those components can vary depending on the needs of the engine.
The form of fuel most commonly associated with the term diesel, more accurately called petroleum diesel or petrodiesel, is produced from fractional distillation of crude oil. In this process, the crude is heated between 200 and 350 degrees Celsius. At those temperatures, the crude oil breaks down into its component parts and can be further refined to produce many types of fuel oil, including petroleum diesel.
Model Engine Diesel
Small diesel engines are a popular power source for models such as radio-controlled cars, trucks and aircraft. Fuel for those vehicles can be made in the home, provided that safe conditions are created and that careful preparation is practised. The base for model diesel fuel is kerosene. Oil is mixed in with the kerosene to both lubricate and seal the engine parts as well as prevent corrosion. The type of oil used can vary, and both mineral oils and vegetable oils are common ingredients for model diesel oil. Ether is also added to lower the ignition temperature of the mix, improving the efficiency with which a small model engine can burn the fuel at its relatively low operating temperatures. An ignition improver, such as amyl nitrate or isopropyl nitrate, is also added to increase the speed of ignition and further lower the temperature at which model diesel fuel combusts.
Biodiesel is made from methanol, lye and oil. The type of oil used is what grants this fuel's claim to the "bio" prefix, as vegetable or other cooking oil is the primary ingredient. Often, used cooking oil is collected from restaurants or other large food preparation establishments where an abundance of waste oil is produced. The methanol and lye are mixed with the used oil, using titration to determine the amounts needed. Ethanol can be substituted for methanol.