• 한국대기환경학회지
• /
• 제16권4호
• /
• pp.409-414
• /
• 2000

Catalytic combustion of acetaldehyde has been investigated as a representative of unpleasant odor by its reaction with metal-phthalocyanines(PC). The experiment was conducted at the reaction temperature of 200~41$0^{\circ}C$ and the concentratio of acetaldehyde in air at the range of 0.07~0.94 mole% The pretreated metal-PC has been characterized by UV-VIS and XRD analysis. According to this study catalytic activity of metal -PC was improved by air pretreatment at 45$0^{\circ}C$ for 1hr. Under this pretreatment condition Co-PC and Cu($\alpha$)-PC were destroyed and new metal oxides were formed such as Co3O4 and CuO respectively. However Zn-PC retained its basic structure even afte air pretreatment. The order of catalytic activity on acetaldehyde combustion was summarized as follows : Zn-PC$\alpha$)-PC. It was found that the complete combustin of acetaldehyde with Cu($\alpha$)-PC was accomplished at its concentrations below 0.2mole% (32$0^{\circ}C$) and 0.6 mole%(35$0^{\circ}C$) in air.

• 한국연소학회:학술대회논문집
• /
• 한국연소학회 2002년도 제24회 KOSCO SYMPOSIUM 논문집
• /
• pp.41-45
• /
• 2002

The zone-conditioned CMC equations are derived by taking an unconditional average of the generic conservation equations multiplied by delta and Heaviside functions in terms of mixture fraction and reaction progress variable. The resulting equations are essentially in the same form as the single zone CMC equations except for separate flow fields for burned and unburned gas. The zone-conditioned two-fluid equations are applied to a stagnating turbulent premixed flame brush of Cheng and Shepherd[5l. It is shown that the flame stretch factor is of crucial importance to accurately reproduce the measured mean reaction progress variable and conditional velocities. Further work is in progress for the relationship between surface and volume averages and extension to partially premixed combustion on the basis of a triple flame structure, e. g. in a lifted turbulent diffusion flame.

• 한국분말재료학회지
• /
• 제5권4호
• /
• pp.312-318
• /
• 1998

The effect of the mechanical alloying of elemental Mo and Si powders on the combustion densification behavior of MoSi$_2$ was investigated. The ignition temperature of the combustion reaction of the mechanically alloyed powder was measured to be significantly lower than that of the powder mixture prepared by the low energy ball milling process. The densification of the products after the combustion reaction under compressive pressure from the mechanically alloyed powders, however, was found to be poorer than that of the products from the ball milled powder.

• 한국연소학회:학술대회논문집
• /
• 한국연소학회 1999년도 제19회 KOSCO SYMPOSIUM 논문집
• /
• pp.155-163
• /
• 1999

A numerical study for simulating a swirling pulverized coal combustion in axisymmetric geometry is done here by applying the weighted sum of gray gases model (WSGGM) approach with the discrete ordinate method (DOM) to model the radiative heat transfer equation. In the radiative transfer equation, the same polynomial equation and coefficients for weighting factors as those for gas are adopted for the coal/char particles as a function of partial pressure and particle temperature. The Eulerian balance equations for mass, momentum, energy, and species mass fractions are adopted with the standard ${\kappa}-{\varepsilon}$ turbulence model, whereas the Lagrangian approach is used for the particulate phase for soot. The eddydissipation model is employed for the reaction rate for gaseous mixture, and the single-step first-order reaction model for the devolatilization process for coal. By comparing the numerical results with experimental ones, the models used here are confirmed and found to be one of good alternatives for simulating the combustion as well as radiative characteristics.

• 한국에너지공학회:학술대회논문집
• /
• 한국에너지공학회 2004년도 춘계 학술발표회 논문집
• /
• pp.197-200
• /
• 2004

Compared to conventional flame combustion, catalytic combustion had the advantage of oxidation of V.O.C. gas which was high voluminous, low caloric mixture flow. However, the temperature of mixture gas should be over the one of catalytic reaction start and the control of reaction on the catalytic surface tends to be vulnerable. To overcome these obstacles, composition of both catalytic combustor and heat exchanger was devised and named the sequential catalytic combustion system. In this system, only trigger unit needed preheating process for transient starting time. Once trigger unit was ignited, the next unit w3s supplied heat to ignite from that and same process was performed to the last one sequentially. When it come to steady state, whole mixture gas was oxidated at each unit simultaneously and preheating for trigger unit was not needed any more. System of 100 kcalh/hr capacity was devised and operated successfully.

• 한국전기전자재료학회:학술대회논문집
• /
• 한국전기전자재료학회 2001년도 추계학술대회 논문집
• /
• pp.81-84
• /
• 2001

The effect of silver oxide (14 wt.%) addition to YBCO compounds and electrophoretic deposition of composite particles prepared by solid phase reaction have been investigated. The results were compared with those for as-processed samples with YBCO films on Ag wire substrate. Our experiments show that the adhesion, microstructure changes, superconducting properties of these films is sensitive to the silver content and sintering conditions. Adding a small amount of PEG tends to remove cracks in the YBCO and (YBCO + Ag) films, which develop during the heating process. An attempt has been made to explain the experimental observations regarding variation of critical current density with the YBCO and (YBCO + Ag) films.

• 한국가스학회지
• /
• 제15권3호
• /
• pp.39-46
• /
• 2011

본 연구에서는 DME와 n-Butane 연료를 사용하여 혼합연료 및 성층화효과가 HCCI 연소 특성에 미치는 영향을 화학반응수치계산을 통해서 알아보고자 한다. 우선, 기존에 완성된 DME와 n-Butane 반응스킴을 이용하여 새로운 화학 반응 모델을 만들고 기존의 DME 화학 반응 모델과 n-Butane 화학 반응 모델과 비교하여 유효성을 확보한다. 나아가, 자발화 특성이 다른 DME와 n-Butane 두 연료의 혼합비 변화에 따른 HCCI 연소 특성을 파악한다. 마지막으로, 혼합 연료를 각각 성층급기 했을 경우에 압력상승률 저감 효과를 파악 한다.

• 한국추진공학회:학술대회논문집
• /
• 한국추진공학회 2008년도 제30회 춘계학술대회논문집
• /
• pp.187-192
• /
• 2008

A simplified model for an isolated aluminum particle burning in air is presented. Burning process consists of two stages, ignition and quasi-steady combustion (QSC). In ignition stage, aluminum which is inside of oxide film melts owing to the self heating called heterogeneous surface reaction (HSR) as well as the convective and radiative heat transfer from ambient air until the particle temperature reaches melting point of oxide film. In combustion stage, gas phase reaction occurs, and quasi-steady diffusion flame is assumed. For simplicity, 1-dimesional spherical symmetric condition and flame sheet assumption are also used. Extended conserved scalar formulations and modified Shvab-Zeldovich functions are used that account for the deposition of metal oxide on the surface of the molten aluminum. Using developed model, time variation of particle temperature, masses of molten aluminum and deposited oxide are predicted. Burning rate, flame radius and temperature are also calculated, and compared with some experimental data.

• 대한기계학회논문집B
• /
• 제33권5호
• /
• pp.343-348
• /
• 2009

The present study has experimentally investigated the effects of $CO_2$ diluted oxygen on the structure of swirl-stabilized flame in a lab-scale combustor. The methane fuel and oxidant mixture gas ($CO_2$ and $O_2$) were mixed in a pre-mixer and introduced to the combustor through different degrees of swirl vanes. The flame characteristics were examined for various amount of carbon dioxide addition to the methane fuel and various swirl strengths. The effects of carbon dioxide addition and swirl intensity on the combustion characteristics of pre-mixed methane flames were examined using chemiluminescence techniques to provide information about flow field. The results show that the hot combustion zone increases at the upstream reaction zone because of an increase in the recirculation flow for an increase in swirl intensity. The hot combustion zone is also increased at the downstream zone by recirculation flow because of an increase in swirl intensity which results in higher centrifugal force. The OH and CH radical intensities of reaction zone decrease with carbon dioxide addition because the carbon dioxide plays a role of diluted gas in the reaction zone.

• 한국세라믹학회지
• /
• 제42권9호
• /
• pp.607-612
• /
• 2005

The effect of MgO diluents in combustion synthesis of $TiB_2$ nano particles was investigated. The reaction $TiO_2\;+\;B_2O_3\;+\;xMg\;{\rightarrow}\;TiB_2\;+\;5MgO$ was used to synthesize $TiB_2$ nano particles. The combustion velocity was measured to examine the relation between the reaction temperature and the morphologies of particles. The diluent MgO did not react with the reactants and played a role to decrease combustion temperature. As the MgO diluents contents increased, the particles with the smaller size and the narrower size distribution were synthesized. At the condition of 6 mole of MgO, the combustion wave velocity was about 5 cm/see and the synthesized particles showed the size of 60 nm with narrow size distribution.