| OCR Text |
Show 1 Numerical Simulation of Soot Aggregates Shapes by Benzene Pyrolysis ) Yutaka Hisaeda, Shinji Hayashi, Yuusuke Asakuma, Hideyuki Aoki and Takatoshi Miura Department of Chemical Engineering, Tohoku University Aoba 07, Aramaki, Aoba-ku, Sendai 980-8579 Japan Abstract Experiments and numerical simulations were carried out to analyze the soot aggregate formation behavior by benzene pyrolysis. Soot was formed by the pyrolysis of 1mol% benzene (in 99mol% nitrogen) in an alumina tube, which was kept at 1573K, with variations of residence time (0.05 to LOOsec). The classification, i.e. spherical, ellipsoidal, linear and branched shape, was carried out in order to provide an overall characterization of the soot formation process. A numerical model, which was based on the work of Ivie et al. [1], assumed the particle growth and coagulation. In the present model, the shape of soot aggregate was furthermore considered by applying the specific fractal dimension (D) to the coagulation rate equation. In particular, the numerical model well predicted the soot yields, which are in good agreement with measured values in any residence time. Introduction Carbon black (CB) has been produced as a soot by incomplete combustion of heavy oils and mainly applied to tires of automobiles. The aggregate shape of CB is essential to the development of high-performance tires, because the fuel efficiency of tires is influenced by an energy loss generated at the interface between rubber and CB. On the other hand, soot formed by the incomplete combustion of hydrocarbon fuel in a combustor causes air pollution, while indispensable for accelerating radiative heat transfer in the combustor. From these points of view, it is important to clarify the process of the soot formation involving gas phase reaction, nucleation, particle growth and coagulation. However, to our knowledge, there are many unsolved parts in this process. Simulations applied to the soot formation are roughly divided in two kinds of models, taking phenomenon and kinetics into consideration. Tesners model [2, 3] and |
