• Title/Summary/Keyword: Thermal oxidizer

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The Effects of Carbon Dioxide as Additives on Soot Formatio in Jet Diffusion Flames (제트확산화염에서 이산화탄소의 첨가가 매연생성에 미치는 영향)

  • Ji, Jung-Hoon;Lee, Eui-Ju
    • Fire Science and Engineering
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    • v.24 no.6
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    • pp.170-175
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    • 2010
  • The effect of carbon dioxide addition on soot formation was investigated in jet diffusion flames in coflow. Flame temperature were measured with R-type thermocouple and the boundary temperature between blue and yellow flame was confirmed. Light-extinction method was introduced for the relative soot density (1-I/$I_0$) in the in-flame region. He-Ne laser with wave length at 632.8 nm was used for the light source, and the signal attenuated by absorption and scattering was detected directly. Oxidizer velocity effect on soot formation was studied to know that the thermal influence for soot formation. The results showed that the temperature of both blue and yellow flame were decreased according to the dilution of carbon dioxide but boundary temperature was nearly constant. The relative soot density was lower when carbon dioxide was added in oxidizer stream and oxidizer velocity increased. These were caused by the reduction of flame temperature and shorter residence time for soot growth. Also carbon dioxide addition enhanced the instability of jet flames like flickering, so the flame length was a little longer than pure ethylene/air flame.

A Study on Acceleration Aging Characteristics of B-KNO3 Igniter (B-KNO3 점화제의 가속 노화 특성 연구)

  • Paik, Jong Gyu;Ryu, Byung Tae;Kwon, Mira
    • Korean Chemical Engineering Research
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    • v.52 no.2
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    • pp.166-174
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    • 2014
  • This research investigated the aging properties of the $B-KNO_3$ system as the igniter. The $B-KNO_3$ system showed the degradation in ignition properties depending on the method and period of storage. It should be found out the cause of the degradation to predict the reliability of the igniters. The changes of the properties by the degradation after aging tests were analyzed by microstructure analysis, XRD analysis and thermal analysis using DSC. It was found out that the lattice parameters of the $KNO_3$ as the oxidizer in the ignition system was changed into the JCPDS values as the aging time increased. Conclusively, the changes of the crystal structure of oxidizer affected the activation energy increasing as aging time increased.

Preparations of PZT Ceramic by Solution Combustion Synthesis (용액연소합성방법에 의한 PZT세라믹의 제조)

  • 이상진;윤존도;권혁보;전병세
    • Journal of the Korean Ceramic Society
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    • v.39 no.1
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    • pp.74-78
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    • 2002
  • In this study, the solution combustion method was employed to synthesize perovskite PZT ceramics. Multicomponent oxides can be prepared by the solution combustion synthesis using redox exothermic reaction of precursor solutions. The results of DTA/TG showed exothermic peaks in 214$^{\circ}C$ and 350$^{\circ}C$. Those were caused by the differences of the thermal decomposition behavior of oxidizer and fuel. The combustion reaction was completed at 370$^{\circ}C$ during heating procedure, but the product was not transformed into perovskite. The thermal decomposition behavior of both oxidizer and fuel were considered during solution combustion process at 600$^{\circ}C$, which showed tetragonal single phase PZT ceramics with 50 nm crystalline size. The lattice constant a was 3.997 ${\pm}$ 0.001 ${\AA}$ and the lattice constant c was 4.147${\pm}$0.001 ${\AA}$.

A Study on the Influence Factors for Ablation Rate of Graphite Nozzle Throat Insert (흑연 노즐목 삽입재의 삭마율에 미치는 영향 인자 연구)

  • Hahm, Heecheol;Kang, Yoongoo;Seo, Sangkyu
    • Journal of the Korean Society of Propulsion Engineers
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    • v.21 no.4
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    • pp.12-20
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    • 2017
  • The ablation characteristics of graphite nozzle throat insert was analyzed for the use in solid rocket propulsion system. The propulsion system was composed of three types of conventional nozzles, such as De-Laval type, blast tube type, and submerged type. Various kinds of propellants were used in ten kinds of propulsion system that had different shapes with each other. Total forty eight tests were performed. From the results of the analysis, it was found that the ablation rate was increased for the higher average chamber pressure and the higher oxidizer mole fraction. A useful correlation for nozzle throat ablation rate was developed in terms of the chamber pressure, oxidizer mole fraction, and throat size. The calculated ablation rates from the correlation showed agreement within ${\pm}0.10mm/s$ with the experimentally determined values.

Preparation of Cu and Mn Bimetallic Catalyst Based on Co-Precipitation Method for Removal of Ethyl Acetate (아세트산 에틸 제거를 위한 공침법 기반의 Cu 및 Mn 이종금속 촉매의 제조)

  • Kim, Min Jae;Yoon, Jo Hee;Jeong, Jae-Min;Choi, Bong Gill
    • Applied Chemistry for Engineering
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    • v.33 no.5
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    • pp.466-470
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    • 2022
  • The catalytic thermal oxidizer process has recently attracted considerable attention for the oxidation and decomposition of volatile organic compounds at low temperatures (< 450 ℃) with high efficiency (> 95%). Although many noble metal catalytic materials are well established, they are expensive and hazardous. Herein, highly active and low-cost Cu-Mn bimetallic catalysts were prepared using a simple and facile synthesis method involving the co-precipitation of Cu and Mn precursors. The synthesis of the catalyst was optimized by controlling the composition ratio of Cu and Mn. The optimized catalyst exhibited a large surface area of 230.8 m2/g with a mesoporous structure. To demonstrate the catalytic performance, the Cu-Mn catalyst was tested for the oxidation reaction of ethyl acetate, showing a high conversion efficiency of 100% at a low temperature of 250 ℃.

Combustion characteristics of coaxial diffusion flame with high preheated and swirled air (고온 공기와 선회수에 의한 동축 분류 화염의 연소 특성)

  • Kim, Jin-Sik;Kwark, Ji-Hyun;Jeon, Chung-Hwan;Chang, Young-June
    • Proceedings of the KSME Conference
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    • 2001.11b
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    • pp.112-117
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    • 2001
  • An experiment using high preheated and swirled air in the coaxial diffusion flame burner was carried out in order to decrease NOx emission and improve the thermal efficiency. $N_2$ gas was used for diluent and propane was utilized for fuel. Combustion using high preheated air has two remarkable characteristics ; (1) low NOx emission with increasing dilution level, (2) high thermal efficiency in the furnace. Also, swirled air can mix fuel and oxidizer well in condition of diffusion flme and maintain the stable combustion. The color of flame changes from yellow to blue green according to increasing the dilution level of mixture gas. NO emission decreased with increasing dilution level and the swirl number.

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Preparation and Characterization of LiMn₂O₄ Powder by Combustion of Poly(ethylene glycol)-Metal Nitrate Precursor

  • 박휴범;홍영식;이지은;권호진;김시중
    • Bulletin of the Korean Chemical Society
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    • v.18 no.6
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    • pp.612-618
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    • 1997
  • $LiMn_2O_4$ powders were prepared by burning and subsequent calcination of PEG-metal nitrate precursor. After the burning stage of the precursor, some minor phases such as $Mn_2O_3$ (or $Mn_3O_4$), MnO, and carbonate were formed and single phases of $LiMn_2O_4$ were obtained by further calcinations above 400 ℃. From thermal analysis of the precursor, a violent thermal decomposition, which was indicated by a drastic weight loss accompanied by a sharp and strong exothermic peak, was observed and probably caused by an oxidation-reduction reaction between oxidizer and fuel. The formation of the minor phases could be explained in terms of the burning behavior of the precursor by employing valence concepts of propellant chemistry. The calcined powders were composed of submicron-sized but highly agglomerated particles and showed very broad particle size distribution.

A Review on Major Foreign Research Trend of Monomethylhydrazine Reaction for Space Propulsion Part I : Thermal Decomposition Reaction of Monomethylhydrazine (우주추진용 모노메틸하이드라진 반응에 대한 주요 해외연구 동향 조사 Part I : 모노메틸하이드라진의 열분해 반응)

  • Jang, Yohan;Lee, Kyun Ho
    • Journal of Aerospace System Engineering
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    • v.10 no.1
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    • pp.66-73
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    • 2016
  • Space propulsion system produces required thrust for satellites and space launch vehicles by using chemical reactions of a liquid fuel and a liquid oxidizer typically. For example, monomethylhydrazine-dinitrogen tetroxide, liquid hydrogen-liquid oxygen and RP-1-liquid oxygen are conventional combinations of liquid propellants used for the liquid propulsion system. Among several liquid propellants, the monomethylhydrazine is expecially preferred for a satellite fuel due to its better storability in liquid phase during a relatively long mission period under a space environment. Thus, a development importance of a bipropellant system using the monomethylhydrazine fuel is recognized recently as the national space program proceeds on a large scale. The objective of the present study is to review a foreign research trend of a thermal decomposition reaction of monomethyhydrazine to understand a fundamental basis of its chemical reaction to prepare for domestic development in future.

Investigation of Thermal/hygrothermal Aging Effects on the Ignition Characteristics of Ti Metal-based Pyrotechnics and Construction of the Aging Models (열/수분노화로 인한 Ti 금속 기반의 파이로 물질의 점화 성능 변화와 노화 모델 제시)

  • Oh, Juyoung;Yoh, Jai-ick
    • Journal of the Korean Society of Propulsion Engineers
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    • v.25 no.3
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    • pp.26-41
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    • 2021
  • Titanium hydride potassium perchlorate (THPP) has played an important role as initiators of the propulsion system. However, the 'aging' may cause performance degradation and even give rise to a failure in the total system. In this study, various hygrothermal aging conditions were considered and the aging effects on thermodynamic and ignition characteristics of THPP are provided via thermal analysis and ignition measurements. Also, physical-chemical changes were identified by morphological analysis. In conclusion, thermal aging led to Eα decrease-high reactivity due to oxidizer decomposition whereas hygrothermal aging gave rise to an opposite tendency by fuel oxidation.

Oscillating Boundary Layer Flow and Low Frequency Instability in Hybrid Rocket Combustion (하이브리드 로켓 연소에서의 경계층 진동 변화와 저주파수 연소불안정)

  • Kim, Jina;Lee, Changjin
    • Journal of the Korean Society for Aeronautical & Space Sciences
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    • v.47 no.10
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    • pp.720-727
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    • 2019
  • Resonating thermal lags of solid fuel with heat transfer oscillations generated by boundary layer oscillation is the primary mechanism of the occurrence of the LFI (Low Frequency Combustion Instability) in hybrid rocket combustion. This study was experimentally attempted to confirm that how the boundary layer was perturbed and led to the LFI. Special attention was also made on oxidizer swirl injection to investigate the contribution to combustion stabilization. Also the overall behavior of fluctuating boundary layer flow and the occurrence of the LFI was monitored as swirl intensity increased. Fluctuating boundary layer was successfully monitored by the captured image and POD (Proper Orthogonal Decomposition) analysis. In the results, oscillating boundary layer became stabilized as the swirl intensity increases. And the coupling strength between high frequency p', q' diminished and periodical amplification of RI (Rayleigh Index) with similar frequency band of thermal lag was also decreased. Thus, results confirmed that oscillating axial boundary layer triggered by periodic coupling of high frequency p', q' is the primary mechanism to excite thermal resonance with thermal lag characteristics of solid fuel.