Firooz Rasouli

Characterizing biomatrix materials using pyrolysis molecular beam mass spectrometer and pattern recognition

Abstract Fingerprinting techniques have been applied to pyrolysis molecular beam mass spectra of a complex biomatix material such as tobacco. Pyrolysis products of three major tobaccos (burley, bright and oriental) and their blends were scanned from m/z 25 to 500 by a molecular beam mass spectrometer (MBMS) in high vacuum and soft ionization (25 eV). The resultant complex mass spectra were further analyzed using multivariate data analysis (pattern recognition) to discover the underlying chemical differences that may not be obvious by comparison of such complex mass spectra. Using the MBMS and pattern recognition techniques, we were able to statistically distinguish among different major tobaccos and their blends and show their characteristic components by only looking at their primary pyrolysis products. Burley was signified by its nitrogen containing products, oriental by its abundant carbohydrate-derived products and bright by its intermediate behavior. Blended tobacco samples of burley and oriental with a ratio of 66:34 resulted in similar product composition to that of bright. Classes of pyrolysis products of a tobacco sample at different reaction conditions were also extracted by using the same analysis. These results indicate that this approach could be used to rapidly predict biomass pyrolysis product distribution.

Heat Transfer Coefficient for a Packed Bed of Shredded Materials at Low Peclet Numbers

The application of the Nusselt number (Nu) correlation of a packed bed of spherical particles overestimates the rate of heat transfer in the packed beds of shredded materials. This is due to the dependence of flow distribution on the particle geometry. This discrepancy is even more pronounced due to a channeling effect at low Peclet numbers (Pe). In this study, the heat transfer coefficient for a packed bed of shredded materials was derived at low Peclet numbers. In deriving the correlation, both numerical simulation and experimental work were employed. The experimental work was carried out in a packed bed of combustible materials for the flow rates of 15 × 10− 6 to 50 × 10− 6 m 3/s and a temperature range of 30 to 60°C. Using the results of experimental work along with numerical modeling and applying a power law formulation, the best-fit Nusselt number for the packed bed of shredded materials for Pe < 25 was derived to be Nu = 0.015 0.11 + Pe 0.73 . The Nusselt number calculated from this correlation is in good agreement with the experimental data.

Heat Transfer Coefficient for a Packed Bed of Shredded Materials

Heat transfer coefficient of packed beds of shredded materials such as biomass fuels at low Peclet numbers is of interest. Due to the dependence of flow distribution on particle shape, the application of the Nusselt number correlation of packed bed of spherical particles overestimates the rate of heat transfer. This discrepancy is even more pronounced due to channeling effect at low Peclet numbers. Here, based on applying a pore submodel and combining the numerical simulation and experimental results of a cylindrical packed bed, a new correlation is derived for apparent Nusselt number of the packed bed of shredded materials. The correlation is approximated by a power law formulation for Pecelt < 25. The Nusselt number calculated from this correlation is in a good agreement with other experimental data.Copyright