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RISS 인기검색어
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- 저자 : Dekui Shen (검색결과 3 건)
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Dekui Shen,Qian Liu,Rui Xiao,Huiyan Zhang,Mengxiang Fang 한국화학공학회 2013 Korean Journal of Chemical Engineering Vol.30 No.3
A mathematical model of thermal decomposition together with the flammability limit is proposed to describe the pyrolysis and spontaneous ignition of wood slab subjected to the radiation from a truncated-cone heater. The prominent physical and chemical phenomena were considered in the model, involving heat transfer in a solid, heat consumed by thermal decomposition reactions, the evaporation of moisture, re-radiation from pore surfaces inside a solid and so on. The numerical solution allows the prediction of in-depth temperature profiles, evolution of volatiles,variation of thermal conductivity, apparent mass loss (solid conversion) and ignition time. The different densities for wood species and effect of moisture content and grain orientation on thermal conductivity are also considered in the model, producing a good prediction of surface temperatures. This gives birth to the reasonable prediction on ignition time of wood by employing fixed surface temperature (400 oC) as ignition criterion. However, the analysis of constituent fractions for the species associated with the multi-components kinetic scheme should be included in the mathematical model to give a more precise prediction on the apparent mass loss of solid.
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Thermal-balanced integral model for pyrolysis and ignition of wood
Rui Xiao,Dekui Shen,Mengxiang Fang,Wanki Chow 한국화학공학회 2013 Korean Journal of Chemical Engineering Vol.30 No.1
The pyrolysis and ignition of wood is of great importance to understand the initial stage of combustion,helping control the occurrence and spread of unwanted building and forestry fires. The development of a thermal-balanced model is introduced for examining the analytical relationship between the ignition time and external heat flux. The critical heat flux, one of the important fire-retardant characteristics of combustible solid, is determined from a correlation study between the ignition time and external heat flux. One of the thermal-balanced integral models, considering the effect of surface heat losses, average absorptivity and moisture content, is employed to give the prediction of surface temperature rise, ignition time and ignition temperature of the Aspen. The results show that the model readily and satisfactorily predicts ignition temperature and ignition time of wood with different moisture contents.
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Xiaoxiang Jiang,Dekui Shen 한국화학공학회 2017 Korean Journal of Chemical Engineering Vol.34 No.10
Biomass-based activated carbonaceous fiber (ACF) was modified by nitric-acid oxidation under microwave heating (ACF-O) and then further treated by thioglycolic acid (ACF-S) to prepare carbon materials with high capability for the removal of Pb(II) ions. The physico-chemical properties of the original and modified ACF samples were characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), Zeta potential, Boehm titration, BET, Raman spectrum and X-ray photoelectron spectroscopy (XPS). It was found that modification treatments damage the pore and graphite crystalline structure of ACF, while the micropore structure is protected and extra oxygen-containing surface functional groups are grafted on its surface. The adsorption performance of the original and the modified ACF samples affected by adsorption conditions regarding to Pb(II) ion strength (10mg/L- 105mg/L), contact time (10min-120 min), pH value (2.5-6.5), and solvent temperature (15 oC-45 oC) was investigated through batch experiments. Compared to the maximum Pb(II) ion adsorption capacity of 75.24mg/g by ACF sample, the value was substantially improved by the integrated modification method (193.42mg/g for ACF-O and 209.21mg/g for ACF-S sample). The Biot number determined from the homogeneous surface diffusion model (HSDM) was between 1 and 100 for the original and modified ACF samples, suggesting that the adsorption process of Pb(II) ions is limited by both the surface diffusion and film mass transfer.
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