Jalotkaasut

Jalotkaasut are gaseous products released during the combustion of fuels in oxidizing environments, typically at elevated temperatures. The term is used in Finnish technical literature to describe the hot, reactive gas mixture formed in flames, furnaces and engines. Jalotkaasut arise from the rapid oxidation of hydrocarbons and other combustibles, with flame chemistry generating a range of species from stable oxides to transient radicals.

The composition of jalotkaasut varies with fuel, air–fuel ratio and temperature. Common components include carbon dioxide and water vapor as primary oxidation products, along with carbon monoxide and residual unburned hydrocarbons in cases of incomplete combustion. Reactive intermediates such as hydrogen, hydroxyl (OH) and other radicals, as well as nitrogen oxides (NOx) formed from atmospheric nitrogen, and sulfur oxides when sulfur-containing fuels are used, are often present. In many flames, soot formation or soot precursors may also be associated with the jalotkaasut, especially under fuel-rich conditions.

Measurement and analysis of jalotkaasut involve a range of techniques. Infrared spectroscopy and Fourier transform infrared spectroscopy are used to quantify major gases like CO2 and H2O, while chemiluminescence and laser-based methods detect NOx and other reactive species. Gas chromatography can identify trace combustion products, and in-situ probes may monitor temperature and gas composition directly within flames or exhaust streams.

The study of jalotkaasut is central to combustion science and engineering. It informs burner design, engine efficiency, and emissions control, and supports environmental assessments and safety analyses in industrial settings. Related topics include flame chemistry, exhaust gas treatment, and combustion optimization.