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Gaseous unburned hydrocarbons (UHC) are investigated in an atmospheric pressure combustor with premixing and prevaporization. The rectangular combustion chamber is equipped with silica quartz windows allowing laser-based investigations in the UV regime. A new double shell concept is employed to atomize the fuel (n-heptane) and to stabilize the flame. For the detection of UHC, a tuneable ArF (λ ≈ 193 nm) or KrF (λ ≈ 248 nm) excimer laser is used. The results show that this imaging technique is feasible in an atmospheric pressure, liquid fuelled combustor. Liquid and gaseous fuel is detected inside the vortices induced by the double shell, where the main combustion processes occur. Furthermore, droplets and UHC can be found along the symmetry line of the double shell. Comparing the two approaches used for the visualization of UHC, it turns out that the application of a KrF laser seems to be more suitable.

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Carbon nanotube (CNT) sampling using an open-faced 25 mm cassette fiber sampling method and a newly developed direct sampling device was evaluated for the size fractioned analysis of collected airborne CNT fibers to improve the sampling and analytical methods. The open-faced 25 mm cassette fiber sampling method primarily collected large agglomerates, with the majority of collected particles being larger than two micrometer in size. Most of CNT structures collected by the new direct sampling device were individual fibers and clusters smaller than one micrometer with a high particle number concentration discrepancy compared to the open-faced 25 mm cassette method raising the concern of this sampling method to representatively characterize the respirable size fraction of CNT aerosols. This work demonstrates that a specialized technique is needed for collecting small fibers to provide a more representative estimate of exposure. It is recommended that an additional sampler be used to directly collect and analyze small fibers in addition to the widely accepted sampling method which utilizes an open-faced 25 mm cassette.