Põlemis

Põlemis, the Estonian term for combustion, is a chemical process in which a fuel reacts with an oxidizer, typically oxygen in air, releasing heat and often light. It occurs under conditions of sufficient temperature, confinement, and fuel-oxidizer contact and is fundamental to many natural and engineered processes.

In its ideal form, complete combustion of a hydrocarbon with oxygen yields carbon dioxide and water, with energy released as heat. Incomplete combustion occurs when the oxidizer is limited or temperatures are not high enough, producing carbon monoxide, soot, and other partially oxidized species, with lower energy yield and greater pollutant formation. The reaction can be rapid, as in flames, or slow, as in smoldering solid fuels.

A useful way to understand combustion is the fire triangle: heat, fuel, and an oxidizer. Removing any one element prevents the process. Ignition temperature or autoignition temperature is needed to start combustion; once initiated, heat release from the reaction sustains it. Combustion can occur in premixed flames, where fuel and oxidizer mix before ignition, or in diffusion flames, where they meet at the flame front.

Efficiency, stability, and emissions depend on factors such as mixture composition, pressure, temperature, and the design of the combustion system (for example, engines, boilers, or industrial burners). Applications span energy generation, propulsion, metallurgy, and waste incineration, among others. Environmental concerns focus on emissions of carbon dioxide, carbon monoxide, nitrogen and sulfur oxides, and particulates, driving ongoing research into cleaner, more efficient combustion technologies. Safety considerations emphasize fire and explosion hazards, proper ventilation, and adherence to regulations.