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Spectral optical techniques are combined to characterise the distribution of large-molecule soot precursors, nanoparticles of organic carbon, and soot in two turbulent non-premixed ethylene flames with differing residence times. Laser-induced fluorescence, laser-induced incandescence and light scattering are used to define distributions across the particle size distribution. From the scattering and laser-induced emission measurements it appears that two classes of particles are formed. The first ones are preferentially formed in the fuel-rich region of the flame closer to the nozzle, have sizes of the order of few nanometers but are not fully solid particles, because the constituent molecules still maintain their individual identity exhibiting strong broadband fluorescence in the UV. The second class of particles constituted by solid particles, with sizes of the order of tens of nanometers are able to absorb a sufficient number of photons to be heated to incandescent temperatures. These larger particles are formed at larger residence times in the flame since they are the result of slow growth processes such as coagulation or carbonization. The flames are also modeled in order to produce mixture fraction maps. A new discovery is that nanoparticles of organic carbon concentration, unlike soot, does correlate well with mixture fraction, independent of position in the flame. This is likely to be a significant benefit to future modelling of soot inception processes in turbulent non-premixed flames.

A new optical diagnostic method has been developed based on the interaction of a pulsed UV laser source with combustion-generated aerosols. This method allows characterization of nanoparticles of organic carbon (NOC) and soot by point measurements. Fluorescence and incandescence measurements induced by the fifth harmonic of a Nd-YAG laser at 213 nm are used for the determination of the volume fractions of particulates in a laminar premixed flame and in a turbulent non-premixed flame of ethylene/air. The selected light source enhances the fluorescence of NOC, which exhibit a large absorption band between 200 and 250 nm and also heats up soot particles to give incandescent emission. Ultraviolet emission signals are correlated with NOC extinction coefficients, while LII signals are correlated with extinction coefficients in the visible region. Laser light scattering measurements are used to estimate the mean sizes of both classes of particles

In this study, we investigated the induction charging of water sprays and the effect of electric field on the breakup mechanism of liquid sprays. Two different kind of hollow cone hydraulic spray nozzles were used. Our investigation aimed to estimate the Droplet Charge to Mass Ratio (D-CMR) and the dependence of breakup length on electric potential. The experiments revealed that the D-CMR increased with the potential until to a maximum, then started to decrease. At the same time, the breakup length decreased more than 0.5 cm compared to the uncharged value, suggesting that the electric field actually influenced the jet break-up dynamics. For V

Phytoremediation technique is of growing interest in the restoration of trace elements contaminated soils. An integrated approach, combining land restoration and biomass post-processing, using a pyrolysis process for material and/or energy recovery, could allow for effective realization of such a process. The dependence of yields, chemical and structural characteristics of char on the biomass feedstock and pyrolysis thermal conditions are important features to be evaluated to explore the possible applications of such a product. In this framework, a comparative study of steam assisted slow pyrolysis of five biomasses has been carried at 873 K. Results demonstrate that for applications requiring high specific surface area Populus Nigra. On the contrary, if the goal is the maximization of the energy recovery in the char, Eucalyptus represents the best choice.