Aerosols produced by combustion processes have a relevant impact on the chemistry and physics of the atmosphere and on human health. Soot particles are one of the main constituents of the elemental carbon present in the atmosphere, but the role of combustion processes in the formation of organic carbon, which is more abundant than the elemental one in the atmosphere, is less well characterized. Nanoparticles of Organic Carbon (NOC) have been detected in laminar flames employing a variety of experimental diagnostics and some of their chemical and physical properties have been characterized. NOC are not easily detected at the exhausts of practical combustion devices like vehicles equipped with spark ignition or diesel engines because the current available instrumentations do not allow detection of nanoparticles smaller than 3 nm. Also, the number concentration of nanoparticles smaller than 10 nm is strongly variable with temperatures and flow rates of the exhaust products. The purpose of this paper is to review the characteristics of NOC and to show that these particles are also emitted from commercial combustion devices. Different measurement techniques are used to analyze the size and mass concentrations of particulates including UV-visible absorption spectroscopy and Atomic Force Microscopy. These techniques have been applied in laboratory flames and at the exhausts of vehicles equipped with a common-rail diesel engine and a fuel port injection S.I. engine. On the basis of the results obtained, we advance some hypothesis on the role of NOC on the nucleation burst in polluted atmosphere.
Combustion-generated nanoparticles of organic carbon in flames and engine exhausts
Borghese A;
2005
Abstract
Aerosols produced by combustion processes have a relevant impact on the chemistry and physics of the atmosphere and on human health. Soot particles are one of the main constituents of the elemental carbon present in the atmosphere, but the role of combustion processes in the formation of organic carbon, which is more abundant than the elemental one in the atmosphere, is less well characterized. Nanoparticles of Organic Carbon (NOC) have been detected in laminar flames employing a variety of experimental diagnostics and some of their chemical and physical properties have been characterized. NOC are not easily detected at the exhausts of practical combustion devices like vehicles equipped with spark ignition or diesel engines because the current available instrumentations do not allow detection of nanoparticles smaller than 3 nm. Also, the number concentration of nanoparticles smaller than 10 nm is strongly variable with temperatures and flow rates of the exhaust products. The purpose of this paper is to review the characteristics of NOC and to show that these particles are also emitted from commercial combustion devices. Different measurement techniques are used to analyze the size and mass concentrations of particulates including UV-visible absorption spectroscopy and Atomic Force Microscopy. These techniques have been applied in laboratory flames and at the exhausts of vehicles equipped with a common-rail diesel engine and a fuel port injection S.I. engine. On the basis of the results obtained, we advance some hypothesis on the role of NOC on the nucleation burst in polluted atmosphere.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
