• Title/Summary/Keyword: Thermal NO

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Comparative Study on the Thermal Insulation of Membrane LNG CCS by Heat Transfer Analysis (열전달 해석을 이용한 멤브레인형 LNG 화물창의 단열구조 성능비교)

  • Hwang, Se-Yun;Lee, Jang-Hyun
    • Journal of the Computational Structural Engineering Institute of Korea
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    • v.29 no.1
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    • pp.53-60
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    • 2016
  • This study discusses the thermal insulation capacity of variant of NO96 LNG (liquefied natural gas) cargo containment insulation system. Changing the insulation materials and the insulation layers of conventional GTT NO96 containment system, The thermal resistance and BOR(boil off rate) caused by the heat transfer between cryogenic and environmental temperature is discussed. Therefore, thermal analysis of LNG CCS(cargo containment system) is carried out to determine the insulation capabilities. Also, BOR is evaluated in terms of the total amount of heat invaded into CCS(cargo containment system). Variant of NO96 CCS such as NO96, NO96GW and NO96L3 membrane type during laden voyage is selected for the comparative study. Finite element model for heat transfer analysis is conducted by employing the equivalent thermal resistance model to simplify the complex insulation layers. Finally the results for each variant model are relatively compared and discussed to minimize the BOR.

Detailed Analysis of NO Formation Routes with Strain Rate in H2/Air Nonpremixed Flames (H2/Air 비예혼합화염의 화염신장율에 따른 NO 생성경로의 상세해석)

  • Kim, Jong-Hyun;Hwang, Cheol-Hong;Lee, Chang-Eon
    • Transactions of the Korean Society of Mechanical Engineers B
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    • v.32 no.8
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    • pp.604-611
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    • 2008
  • Detailed analysis of NO formation routes and its contributions with strain rate in hydrogen/air flames were numerically investigated. LiG detailed reaction mechanism has been used for calculation, which is compared with experimental data in literature. It shows good agreement with experiment for both temperature and NO mole fraction. Three routes have been found important for NO formation in hydrogen flames. These are the Thermal route, NNH route and $N_2O$ route. Strain rate were varied to discuss the $EI_{NO}$ reduction trend in hydrogen nonpremixed flames, which are analyzed by each NO formation routes. As a result, as the strain rate increase, $EI_{NO}$ decrease sharply until strain rate $100s^{-1}$ and decrease slowly until strain rate $310s^{-1}$ again, after that $EI_{NO}$ keeps nearly constant. It can be identified that $EI_{NO}$ trend with the strain rate is well explained by a combination of variation of production rate of above Thermal, NNH and $N_2O$ route. Also result of Thermal-Mech. that includes only thermal NO reaction is compared with those of Full-Mech. As a result, It can be identified that there was difference between the two results of calculation. It is attributed to result that Thermal-mech did not consider contributions of NNH and $N_2O$ route. From these result, we can conclude that NOx emission characteristics of hydrogen nonpremixed flames should consider contributions of above three routes simultaneously.

NOx Reduction with Secondary Air and Fuel in a Catalytic Combustor (촉매연소기에서 2단 공급공기와 연료가 NOx 저감에 미치는 연구)

  • 정진도;이보영
    • Journal of Korean Society for Atmospheric Environment
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    • v.19 no.5
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    • pp.541-549
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    • 2003
  • A basic experimental study was conducted in order to find the optimum combustion control technology to decrease the thermal NO$_{x}$, by applying the catalytic combustion method with natural gas. NO$_{x}$ emission increased with increasing space velocity due to temperature rising in the furnace. In order to overcome the low resistance to high temperature, secondary air was supplied to the CST combustor. The following secondary fuel formed combustible mixture in part, which resulted in steep increase of the exiting temperature of the 2nd catalyst bed. It led to the more generator of NO$_{x}$, 30∼60% of the 1 st catalyst bed. It might be due to the potential increase of thermal NO$_{x}$.

Prediction of Combustion Characteristics in a 3D Model Combustor with Swirling Flow (스월이 있는 3차원 모델 연소기 내의 연소특성)

  • Kim, Man-Young
    • Transactions of the Korean Society of Mechanical Engineers B
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    • v.27 no.1
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    • pp.95-104
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    • 2003
  • The objective of this work is to investigate the turbulent reacting flow in a three dimensional combustor with emphasis on thermal NO emission through a numerical simulation. Flow field is analyzed using the SIMPLE method which is known as stable as well as accurate in the combustion modeling, and the finite volume method is adopted in solving the radiative transfer equation. In this work, the thermal characteristics and NO emission in a three dimensional combustor by changing parameters such as equivalence ratio and inlet swirl angle have investigated. As the equivalence ratio increases, which means that more fuel is supplied due to a larger inlet fuel velocity, the flame temperature increases and the location of maximum temperature and thermal NO has moved towards downstream. In the mean while, the existence of inlet swirl velocity makes the fuel and combustion air more completely mixed and burnt in short distance. Therefore, the locations of the maximum reaction rate, temperature and thermal NO were shifted to forward direction compared with the case of no swirl.

Effect of Thermal Contact Resistance on Transient Thermoelastic Contact for an Elastic Foundation (탄성기반에서 과도 열탄성 접촉에 대한 열 접촉 저항의 영향)

  • Jang Yong-Hoon;Lee Seung-Wook
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.30 no.7 s.250
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    • pp.833-840
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    • 2006
  • The paper presents a numerical solution to the problem of a hot rigid indenter sliding over a thermoelastic Winkler foundation with a thermal contact resistance at constant speed. It is shown analytically that no steady-state solution can exist for sufficiently high temperature or sufficiently small normal load or speed, regardless of the thermal contact resistance. However the steady state solution may exist in the same situation if the thermal contact resistance is considered. This means that the effect of the large values of temperature difference and small value of force or velocity which occur at no steady state can be lessened due to the thermal contact resistance. When there is no steady state, the predicted transient behavior involves regions of transient stationary contact interspersed with regions of separation regardless of the thermal contact resistance. Initially, the system typically exhibits a small number of relatively large contact and separation regions, but after the initial transient, the trailing edge of the contact area is only established and the leading edge loses contact, reducing the total extent of contact considerably. As time progresses, larger and larger numbers of small contact areas are established, unlit eventually the accuracy of the algorithm is limited by the discretization used.

Effects of Thermal Contact Resistance on Transient Thermoelastic Contacts for an Elastic Foundation (시간에 따른 탄성지지 열탄성 접촉에 대한 열접촉저항의 영향)

  • Jang, Yong-Hoon
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2005.05a
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    • pp.330-333
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    • 2005
  • The paper presents a numerical solution to the problem of a hot rigid indenter siding over a thermoelastic Winkler foundation with a thermal contact resistance at constant speed. It is shown analytically that no steady-state solution can exist for sufficiently high temperature or sufficiently small normal load or speed regardless of the thermal contact resistance. However, the steady state solution may exist in the same situation if the thermal contact resistance is considered. This means that the effect of the large values of temperature difference and small value of force or velocity which occur at no steady state can be lessened due to the thermal contact resistance. When there is no steady-state the predicted transient behavior involves regions of transient stationary contact interspersed with regions of separation regardless of the thermal contact resistance. Initially, the system typically exhibits a small number of relatively large contact and separation regions, but after the initial transient the trailing edge of the contact area is only established and the leading edge loses contact, reducing the total extent of contact considerably. As time progresses, larger and larger number of small contact areas are established, until eventually the accuracy of the algorithm is limited by the discretization used.

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Study for thermal stability of Liquid Crystal Device (액정 소자의 열적 안전성에 관한 연구)

  • Lee, Sang-Keuk;Hwang, Jeoung-Yeon;Seo, Dae-Shik;Lee, Joon-Ung
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 2004.04a
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    • pp.9-12
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    • 2004
  • In this study, we investigated about electrooptics characteristic of three kind of TN cell on the polyimide surface. Monodomain alignments of thermal stressed TN cell over temperature of liquid crystal isotropic phase were almost same that of no thermal stressed TN cells. However, the thermal stressed TN cell have many defects. Also, threshold voltage and response time of thermal stressed TN cells show same performances of no thermal stressed TN cells. There were little changes of value in these TN cells. However, transmittances of TN cells on the polyimide surface decrease with increasing thermal stress time. Finally, the residual DC voltage of the thermal stressed TN cell on the polyimide surface show decrease of characteristics as increasing thermal stress time. Therefore, thermal stability of TN cell was decreased by high thermal stress for the long times.

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Study on Thermal Stability of Liquid Crystal Display for Projection TV Application (프로젝션 TV 적용을 위한 액정 디스플레이의 열적 안전성에 관한 연구)

  • Kang, Hee-Jin;Hwang, Jeoung-Yeon;Kang, Hyung-Ku;Bae, Yu-Han;Lee, Whee-Won;Kim, Young-Hwan;Seo, Dae-Shik
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 2005.05a
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    • pp.177-180
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    • 2005
  • We have investigated electro-optical characteristics in three kinds of TN cells on the polyimide surface. Transmittance of no thermal stressed TN cells were better than that of thermal stressed TN cells. Also. the threshold voltage and the response time of thermal stressed TN cells were same that of no thermal stressed TN cells. There were little change of value in these TN cells. On the other hand. transmittances of TN cells on the polyimide surface decreased by increasing thermal stress time. Moreover. the residual DC of the thermal stressed TN cells on the polyimide surface showed the characteristics of thermal stressed TN cells were weakened as increasing thermal stress temperature and time. Therefore. thermal stability of TN cells were decreased gradually by giving high thermal stress for a long time.

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Mechanical and Thermal Conductivity Properties of Yttrium Nitrate Added AlN Sintering Body (Y(NO3)3·6H2O 첨가된 AlN 소결체의 기계적 및 열전도도 특성)

  • Chung, J.K.;Lee, J.H.;Ha, T.K.
    • Transactions of Materials Processing
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    • v.27 no.1
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    • pp.48-53
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    • 2018
  • Aluminum nitride (AlN) is used by the semiconductor industry that has requirements for high thermal conductivity. The theoretical thermal conductivity of single crystal AlN is 320W/mK. Whereas, the values measured for polycrystalline AlN ceramics range from 20 W/mK to 280 W/mK. The variability is strongly dependent upon the purity of the starting materials and non-uniform dispersibility of the sintering additive. The conventional AlN sintering additive used yttria ($Y_2O_3$), but the dispersibility of the powder in the mixing process was important. In this study, we investigated the mechanical and thermal conductivity of yttrium nitrate ($Y(NO_3)_3{\cdot}6H_2O$), as a sintering additive in order to improve the dispersibility of $Y_2O_3$. The sintering additives content was in the range of 2 to 4.5wt.%. The density of AlN gradually increased with increasing contents of sintering additive and the flexural strength gradually increased as well. The flexural strength of the sintered body containing 4 wt% of $Y_2O_3$ and $Y(NO_3)_3{\cdot}6H_2O$ was 334.1 MPa and 378.2 MPa, respectively. The thermal conductivities were 189.7W/mK and 209.4W/mK, respectively. In the case of hardness, there was only a slight difference and the average value was about 10 GPa. Therefore, densification, density and strength values were found to be proportional to its content. It was confirmed that AlN using $Y(NO_3)_3{\cdot}6H_2O$ displayed relatively higher thermal conductivity and mechanical properties than the $Y_2O_3$.

Numerical Investigation of Low-pollution Combustion with applying Flue Gas Recirculation in Counterflow Flames: Part II. Analysis of NOx formation mechanism (대향류 화염에서 FGR이 적용된 저공해 연소의 수치적 해석: Part II. NOx 생성기구 분석)

  • Cho, Seo-Hee;Kim, Gyeong-Mo;Lee, Kee-Man
    • Journal of the Korean Institute of Gas
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    • v.24 no.4
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    • pp.39-47
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    • 2020
  • Flue gas recirculation(FGR) is an effective combustion technique for reducing nitrogen oxides(NOx) and is applied in various fields of low-pollution combustion. Continuing the previous study, a numerical analysis was conducted to identify changes of flame characteristics and NOx formation mechanism with applying FGR technique in CH4/air premixed counterflow flames. NOx emitted was divided into four main reaction paths(thermal NO, prompt NO, N2H and N2O), showing relatively the production rate of NO with the recirculation ratio. As a result, thermal NO contributed greatly to the overall NO whereas the effect of N2H was minimal. In addition, emission index of NO was compared as the recirculation ratio increased by modifying the UC San Diego mechanism to examine the contribution of thermal NO.