Diisel

Diisel is an occasional alternate spelling of diesel encountered in non-English sources or as a typographical variant. In standard English usage, the conventional spelling is diesel. When diisel appears, it typically refers to the same set of fuels and engines associated with diesel, and can be considered a misspelling or transliteration artifact rather than a distinct category.

Diesel refers to a family of fuels produced from crude oil by distillation and refinement, optimized for compression-ignition engines. Diesel fuel is valued for its energy density and efficiency, making it common in trucks, buses, ships, trains, and stationary generators. Diesel engines operate by compressing air to a temperature high enough to ignite injected fuel, enabling high torque and good fuel economy, especially at low to moderate speeds.

Variations of diesel include biodiesel, renewable or synthetic diesel, and diesel blends. Standards regulate properties such as cetane number and sulfur content to meet emissions and performance requirements. Environmental impacts include emissions of NOx and particulates, and carbon-dioxide output, prompting regulatory and technical efforts to reduce pollutants through cleaner fuels, exhaust after-treatment, and lower-sulfur formulations.

The term diesel honors Rudolf Diesel, who conceived the compression-ignition engine in the 1890s. The spelling diisel is not standard in English, and most technical references use diesel. In linguistic or branding contexts, diisel may appear as an alternative transliteration or product name, but it generally denotes the same class of fuels and engines as diesel.