Scientists Study Fuel Combustion Features to Create New Engines

Samara University scientists together with foreign colleagues discovered previously unknown mechanisms for the growth of aromatic molecules.  This will help to create environmentally friendly and energy-efficient combustion chambers for gas turbine engines in aviation, shipbuilding and industry, the university press service said. The formation mechanism  of non-planar polyaromatic hydrocarbons (PAHs) is described in "Physical Chemistry Chemical Physics" article.

Aromatic chemical compounds are among the harmful pollutants and are present in the exhaust of any engine using hydrocarbon fuels. It is often noticeable that black smoke comes from the car exhaust pipes – these are soot particles consisting of soldered aromatic six-membered (C6) and five-membered (C5) rings.

Soot formation begins with the simplest aromatic compound –  benzene. The completion of new six-membered rings leads to the formation of flat structures (like two-dimensional graphene material). If five-membered rings are added to them, the flat shape of the structure is violated. Non-planar PAHs are found both in interstellar space (for example, in meteorites) and in terrestrial conditions – among combustion products, in the combustion chambers of aircraft and automobile engines. Samara University employees under the guidance of Professor of Florida International University Alexander Mebel are creating an experimental setup to study combustion reactions as part of a megagrant of the Russian government.

"Unfortunately, many existing experimental methods are not applicable for the study of fast reactions in temperature conditions up to 2000 ° C, achieved in the combustion chambers of modern engines. We used a high-temperature microreactor, where the reactions under our consideration are started, with sampling in a molecular beam and analyzing them in a photoionization mass spectrometer",  –  Chief Researcher of Samara University, Deputy Director of  Samara branch of P.N. Lebedev Physical Institute of the Russian Academy of Sciences Valeriy Azyazov said to RIA Novosti.

Using theoretical and experimental studies, the scientists found out how a five-membered ring of PAHs is added to a six-membered one, which, in turn, leads to the release of PAHs from the plane.

Previously it was believed that exclusively high-temperature environments, above 700 ° C, which are in the combustion chambers of aircraft and automobile engines, as well as in the circumstellar shells of some stars, are necessary for the formation and growth of PAHs. However, Samara University scientists have proved that PAHs can also be formed at very low temperatures in the hydrocarbon-rich atmospheres of planets and their moons, such as, for example, the satellite of Saturn –  Titan (-183 ° С).

The scientists have also calculated reaction rates that can be used to model and develop kinetic models of soot and PAH growth in aircraft combustion chambers.

In the future, the team intends to reveal detailed reaction mechanisms leading to the enlargement of aromatic compounds. According to the scientists, the data obtained will be used at the design stage of gas turbine engines development in aviation, shipbuilding and industry.

Source: ria.ru