This paper presents the numerical investigation of the effects of momentum, thermal and species boundary layers on the characteristics of polycrystalline silicon deposition by comparing the deposition rates in three c...This paper presents the numerical investigation of the effects of momentum, thermal and species boundary layers on the characteristics of polycrystalline silicon deposition by comparing the deposition rates in three chemical vapor deposition （CVD） reactors. A two-dimensional model for the gas flow, heat transfer, and mass transfer was coupled to the gas-phase reaction and surface reaction mechanism for the deposition of polycrystalline silicon from trichlorosilane （TCS）-hydrogen system. The model was verified by comparing the simulated growth rate with the experimental and numerical data in the open literature. Computed results in the reactors indicate that the deposition characteristics are closely related to the momentum, thermal and mass boundary layer thickness. To yield higher deposition rate, there should be higher concentration of TCS gas on the substrate, and there should also be thinner boundary layer of HCl gas so that HCl gas could be pushed away from the surface of the substrate immediately.展开更多
Chlorophenols are typical priority pollutants listed by USEPA (U.S. Environmental Protection Agency). The removal of chlorophenol could be carried out by a combination of electrochemical reduction and oxidation method...Chlorophenols are typical priority pollutants listed by USEPA (U.S. Environmental Protection Agency). The removal of chlorophenol could be carried out by a combination of electrochemical reduction and oxidation method. Results showed that it was feasible to degrade contaminants containing chlorine atoms by electrochemical reduction to form phenol, which was further degraded on the anode by electrochemical oxidation. Chlorophenol removal rate was more than 90% by the combined electro- chemical reduction and oxidation at current of 6 mA and pH 6. The hydrogen atom is a powerful reducing agent that reductively dechlorinates chlorophenols. The instantaneous current efficiency was calculated and the results indicated that cathodic reduction was the main contributor to the degradation of chlorophenol.展开更多
The chemism of the chlorination of copper （I） sulphide by calcium chloride in the presence of oxygen has been determined based on the thermodynamic analysis in the Cu2S-CaCl2-O2 system as well as characterization of...The chemism of the chlorination of copper （I） sulphide by calcium chloride in the presence of oxygen has been determined based on the thermodynamic analysis in the Cu2S-CaCl2-O2 system as well as characterization of used raw materials and obtained products. The influence of temperature （from 473 to 773 K）, time （from 2 to 120 min）, oxygen flow （from 20 to 100 L/h） and calcium chloride quantity （from 5 to 40%） on the chlorination degree has been investigated. Kinetic analysis and the activation energy values of 20.89 kJ/mol showed that the chlorination of copper （I） sulphide by calcium chloride in the presence of oxygen is diffusion controlled.展开更多
基金Supported by the Natural Science Foundation of Shandong Province of China （ZR2009BM011） the Doctor Foundation of Shandong Province of China （BS2010NJ005）
文摘This paper presents the numerical investigation of the effects of momentum, thermal and species boundary layers on the characteristics of polycrystalline silicon deposition by comparing the deposition rates in three chemical vapor deposition （CVD） reactors. A two-dimensional model for the gas flow, heat transfer, and mass transfer was coupled to the gas-phase reaction and surface reaction mechanism for the deposition of polycrystalline silicon from trichlorosilane （TCS）-hydrogen system. The model was verified by comparing the simulated growth rate with the experimental and numerical data in the open literature. Computed results in the reactors indicate that the deposition characteristics are closely related to the momentum, thermal and mass boundary layer thickness. To yield higher deposition rate, there should be higher concentration of TCS gas on the substrate, and there should also be thinner boundary layer of HCl gas so that HCl gas could be pushed away from the surface of the substrate immediately.
基金Project supported by the Foundation of Education Ministry of China(No. 98679) and the Natural Science Foundation of Zhejiang Province(No. 200043), China
文摘Chlorophenols are typical priority pollutants listed by USEPA (U.S. Environmental Protection Agency). The removal of chlorophenol could be carried out by a combination of electrochemical reduction and oxidation method. Results showed that it was feasible to degrade contaminants containing chlorine atoms by electrochemical reduction to form phenol, which was further degraded on the anode by electrochemical oxidation. Chlorophenol removal rate was more than 90% by the combined electro- chemical reduction and oxidation at current of 6 mA and pH 6. The hydrogen atom is a powerful reducing agent that reductively dechlorinates chlorophenols. The instantaneous current efficiency was calculated and the results indicated that cathodic reduction was the main contributor to the degradation of chlorophenol.
文摘The chemism of the chlorination of copper （I） sulphide by calcium chloride in the presence of oxygen has been determined based on the thermodynamic analysis in the Cu2S-CaCl2-O2 system as well as characterization of used raw materials and obtained products. The influence of temperature （from 473 to 773 K）, time （from 2 to 120 min）, oxygen flow （from 20 to 100 L/h） and calcium chloride quantity （from 5 to 40%） on the chlorination degree has been investigated. Kinetic analysis and the activation energy values of 20.89 kJ/mol showed that the chlorination of copper （I） sulphide by calcium chloride in the presence of oxygen is diffusion controlled.
