• 한국연소학회:학술대회논문집
• /
• 2006.10a
• /
• pp.196-201
• /
• 2006

Silica(SiO2) nanoparticles are used as additives in plastics and rubbers to improve mechanical, electrical, magnetic properties and optical material. Silica nanoparticles were synthesized by the gas phase thermal oxidation of several kinds of precursors in many types of reactor. Diffusion flame reactor has some advantages compared with other types of reactors. In this study, we investigated the generation of silica nanoparticles on the effect of residence time by tetraethylothosilicate(TEOS) in a turbulent diffusion flame reactor controlled by providing reactant flowrate and reactor geometry affect particle morphology, particle size and particle size distribution. To determine the flame residence time, flame length should be determined which was examined by ICCD image. Particle size, distribution and morphology were performed with TEM.

• Journal of Industrial Technology
• /
• v.22 no.A
• /
• pp.255-260
• /
• 2002

We prepared the nano-sized $TiO_2$ particles by the diffusion flame reactor and investigated the effects of several process variables on the generation and transport properties of $TiO_2$ particle. As the length from the tip of diffusion flame reactor increases, the size of $TiO_2$ particle increases by the coagulation between particles. The structure of $TiO_2$ particles prepared is almost found to be anatase. It was found that the $TiO_2$ particle size depends more largely on the change of reactor temperature than on the change of inlet $TiCl_4$ concentration.

• Journal of Industrial Technology
• /
• v.22 no.B
• /
• pp.117-124
• /
• 2002

We prepared the nano-sized $TiO_2$ particles by the diffusion flame reactor and investigated the effects of several process variables on the generation and transport properties of $TiO_2$ particle. As the length from the tip of diffusion flame reactor increases, the size of $TiO_2$ particle increases by the coagulation between particles. The structure of $TiO_2$ particles prepared is almost found to be anatase. It was found that the $TiO_2$ particle size depends more largely on the change of reactor temperature than on the change of inlet $TiCl_4$ concentration. By the photo-degradation experiment of phenol and toluene with the prepared $TiO_2$ particles, we found that the photo-degradation efficiencies of phenol and toluene change, depending on the process variables such as size of $TiO_2$ photocatlysts, concentration of phenol or toluene. Degradation efficiencies of phenol and toluene was above 90% in our experiments in 60 minutes.

• Journal of the Korean Society of Safety
• /
• v.24 no.1
• /
• pp.21-25
• /
• 2009

Extinguishing limits of laminar ethylene/oxygen flames in both normal and inverse co-flow jet burner have been determined experimentally and computationally. An inert gas($N_2$, Ar, $CO_2$) was added into the oxidizer to find the critical concentration and the effectiveness of the agents on flame extinction. The experimental results showed that the physical aspect of inert gases was main mechanism for flame blow-out as same as cup burner test, but the flow effect should be considered to determine the extinction concentration. The numerical prediction was performed with modified WSR model and the result was in good agreement with the measurements. The experimental and numerical methods could be used for the assessment of various flame suppression agents such as minimum extinguishing concentration.

• Journal of Industrial Technology
• /
• v.24 no.B
• /
• pp.133-138
• /
• 2004

The photodegradation of phenol and toluene with the $TiO_2$-coated polyethylene (PE) particles were investigated in the slurry type photocatalytic reactor, changing the $TiO_2$ particle sizes, initial phenol and toluene concentrations, and the oxygen flow rate. The nano-sized $TiO_2$ photocatalyst particles were prepared by the diffusion flame reactor and they were coated onto PE particles by using the hybridization system for the efficient recollection of $TiO_2$-coated particles after photodegradation experiments. The degradation efficiencies of phenol and toluene with the $TiO_2$-coated PE particles were more than 90% after photodegradation of 80 minutes for most cases. The efficiencies of photodegradation with the $TiO_2$-coated PE particles were found to be lower than those by the pure $TiO_2$ particles by 50%, because of the decrease in specific surface area of $TiO_2$ particles in PE particles.

• Journal of Industrial Technology
• /
• v.17
• /
• pp.241-247
• /
• 1997

A numerical model has been proposed for a diffusion flame reactor to manufacture ultrafine $TiO_2$ powders. The model equations such as mass balance equation, the 0th, 1st, and 2nd moment equations of aerosols were considered. The phenomena such as $TiCl_4$ reaction rate, $TiO_2$ nucleation rate and the coagulation of $TiO_2$ powders were included in the aerosol dynamic equation. It is found that the $TiO_2$ particle concentration becomes higher, as the inlet $TiCl_4$ concentration and the total gas flow rate increase, and also as the flame temperature decreases. The $TiO_2$ particle size increases, as the flame temperature and the inlet $TiCl_4$ concentration increase and the total gas flow rate decreases.

• Journal of Industrial Technology
• /
• v.21 no.A
• /
• pp.273-278
• /
• 2001

In this study, we prepared nano-sized $TiO_2$ particles for various process variables by the diffusion flame reactor and we collected $TiO_2$ particles by thermophoresis. It is found that the size of $TiO_2$ particles increases, as the flame temperature or the inlet $TiCl_4$ concentration increase or the total gas flow rate decreases. We investigated the photo-degradation of phenol wish the prepared $TiO_2$ particles. We found the optimum amounts of $TiO_2$ photocatalysts for our experimental apparatus and investigated the photo-degradation efficiencies of phenol, changing the process variables such as size of $TiO_2$ photocatlysts, phase ratio of rutile/anatase, concentration of phenol, input ratio of $O_2$. Degradation efficiencies of phenol were almost 95% in 15 minutes for the standard conditions of our experiments.

• Transactions of the Korean Society of Mechanical Engineers B
• /
• v.24 no.7
• /
• pp.1002-1009
• /
• 2000

Among the various types of diesel after-treatment device, the corona discharge reactor may be considered as a powerful process for trapping submicron particles. But after precipitation on the electrodes occurs, the reentrainment of particles is severe and often causes low or negative precipitation efficiency. Experiments were performed to investigate the effect of an applied voltage on the reentrainment of soot particles from the electrodes. A co-annular laminar diffusion flame burner was used as the soot generator. When a highly negative voltage was applied, exfoliation of the deposited soot particles and an increase in concentration of particles smaller than approximately 150 nm were observed. Turbulence induced from the negative tuft corona and sputtering caused particle reentrainment from the corona wire and from plates as well. Under soot laden combustion gas, a streamer corona often occurred in the wire-cylinder reactor. Because of its transient nature, streamer corona violently increased the concentration of reentrained particles and CO gas.

• 한국지구물리탐사학회:학술대회논문집
• /
• 2003.11a
• /
• pp.569-572
• /
• 2003

Titanium dioxide ($TiO_2$) nanoparticles were prepared by the oxidation of titanium tetrachloride ($TiCl_4$) in a diffusion flame reactor. The average diameter of particles was 15 to 30 nm and mass fraction of anatase ranged from $40\;to\;80\%$. Effects of particle size and phase composition of those $TiO_2$ nanoparticles on photocatalytic properties such as decomposition of methylene blue and bacteria gas were investigated. The degree of decomposition of methylene blue by the $TiO_2$ nanoparticles under the illumination of the black light was directly proportional to the anantase mass fraction, but inversely to the particle size. The decomposition of bacteria by the $TiO_2$ nanoparticles under the illumination of the fluorescent light showed the same trend as in the case of the methylene blue.