Roland Sommer

Application of laser-induced incandescence to suspended carbon black particles

For the first time, to the best of our knowledge, laser-induced incandescence (LII) has successfully been applied to carbon black suspensions. A linear correlation between the experimentally derived signal decay time and the mean primary particle size, determined by transmission electron microscopy, for different carbon black particles was found. Moreover, a nonlinear relation similar to that known from measurements of aerosols was observed for the peak LII signal and the laser fluence. Despite different heat transfer properties, the signal decay time was not influenced by the solvents used.

Chapter 6 Time-Resolved Laser-Induced Incandescence

Abstract Online characterization of nanoscaled particles is an important issue in basic research, e.g., combustion soot formation and oxidation, and in several different technical applications, e.g., in nanoparticle production reactors or in automotive raw exhaust. For the determination of mass concentration and primary particle size, a possible in situ measurement technique is time-resolved laser-induced incandescence (TIRE-LII). The basic principle of this technique is the heating-up of the nanoscaled particles by a high-energetic laser pulse and the subsequent detection and analysis of the spectrally and temporally resolved enhanced thermal radiation. At later times after the laser pulse, heat conduction to the ambient gas is the dominant heat loss mechanism and so particles with different specific surface area cool down differently. From the temporal signal decay, the size distribution of the primary particles can be derived. Furthermore, the signal maximum is proportional to the mass concentration. Here, besides an introduction to the basic principle of this technique, an overview is given on current technical applications using this measurement technique and on its use in basic combustion research, for nanoparticle characterization, with emphasis on carbonaceous particles. Measurements have been performed at different nanoparticle production reactors on the one hand side and directly in the diesel engine raw exhaust and in ambient air on the other hand. Thereby, the results were compared with established measurement methods such as transmission electron microscopy (TEM), conventional adsorption analysis and gravimetrical techniques. Furthermore, a new approach is shown applying this technique also in liquids for suspended particles.

Time-resolved selective particle characterization for the evaluation of ultra low emission vehicles

Time-resolved selective particle characterization of ultra low emission vehicles is crucial for evaluating after-treatment systems and systematic engine optimization. In the framework of a research project in which beyond others, the Chair of Technical Thermodynamics of the University Erlangen-Nurnberg and the RWTUV Essen were involved, a laser based sensor (LI2SA) for online soot determination in the exhaust of different engines was deployed.

Temporally resolved characterization of iron nanoparticles using a time-resolved laser technique

For the first time, time-resolved laser-induced incandescence (TiRe-LII) has been used to investigate the metal-organic chemical vapor deposition (MOCVD) process of iron in a fluidized bed reactor characterizing nanoparticles deposited on a substrate surface.

Laseroptische Charakterisierung von gasgetragenen Nanoteilchen mit der zeitaufgelösten laserinduzierten Glühtechnik (TIRE-LII) (Laser-Optical Characterization of Air-Borne Nanoparticles by Time-Resolved Laser-Induced Incandescence (TIRE-LII))

Abstract Die Charakterisierung gasgetragener Nanoteilchen ist für eine Vielzahl industrieller und natürlicher Prozesse von entscheidender Bedeutung. Insbesondere die Überwachung von in Verbrennungssystemen erzeugten Rußteilchen und die für die Nanoteilchentechnologie notwendige Produktcharakterisierung und Prozesssteuerung benötigen in zunehmendem Maße geeignete Analysenmesstechniken, die schnelle, empfindliche und zuverlässige Aussagen über eine Vielzahl von Messgrößen zulässt. Mit der laserinduzierten Glühtechnik (laser-induced incandescence, LII) steht ein nicht-invasives laseroptisches Online-Verfahren zur Verfügung, das neben einer hochempfindlichen Konzentrationsbestimmung auch dazu in der Lage ist, die spezifische Oberfläche bzw. die Primärteilchengröße der Partikel zu bestimmen.

Zeitaufgelöste selektive Partikelcharakterisierung zur Bewertung von Fahrzeugen mit Minimalemission

Die zeitaufgeloste selektive Partikelcharakterisierung von Fahrzeugen mit Minimalemission ist entscheidend fur die Bewertung von Abgasnachbehandlungssystemen und gezielter Motorenoptimierung. Im Rahmen eines Verbundprojektes, an dem unter anderem der Lehrstuhl fur Technische Thermodynamik (LTT) der Universitat Erlangen-Nurnberg und die RWTUV Fahrzeug GmbH in Essen involviert waren, wurde ein laserbasierter Sensor (LI2SA) zur Online-Rusbestimmung im Abgas an den unterschiedlichsten Versuchstragern eingesetzt.