• Title/Summary/Keyword: 가스냉각

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An Analysis on the Temperature Safety of a Boiler Desuperheater (보일러 과열증기 냉각기의 온도 안전성에 관한 연구)

  • Ha, Ji-Soo;Kim, Tae-Kwon;Chang, Hyuk-Sang
    • Journal of the Korean Institute of Gas
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    • v.16 no.2
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    • pp.9-13
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    • 2012
  • The present study has been carried out to diagnose the temperature safety of a boiler desuperheater which decreases abnormally higher temperature of superheated steam in a reheater of a power plant. The liquid water in the desuperheater stays in a closed space. It becomes heated by the high temperature superheated steam and boiling could occur. Boiling might increase internal pressure and it could destroy the desuperheater if the internal pressure exceeds the allowable pressure of the desuperheater. The present study modeled reasonably the desuperheater and four cases of heat transfer analysis are executed with the consideration of insulator and natural convective fluid flow of the inside cooling water. For the case excluded the natural convective fluid flow, the temperature exceeds the allowable temperature and pressure. On the other hand, for the real case included natural convective fluid flow and insulator, the active heat transfer from higher temperature region to lower temperature region occurs and it makes the temperature in the cooling water below the allowable temperature and pressure. From this fact, it could be thought that the desuperheater in the reheater is safe from destroy or back flow.

액체로켓엔진 단일추진제 가스발생기 설계에 관한 고찰

  • 김명철;윤덕진;김승우
    • Proceedings of the Korean Society of Propulsion Engineers Conference
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    • 2000.04a
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    • pp.30-30
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    • 2000
  • 액체로켓엔진의 단일추진제 가스발생기는 연료공급 시스템의 터보펌프를 구동시키기 위한 작동가스 생성을 목적으로 사용된다. 고체추진제 가스발생기와 비교할 경우 작동시간이 보다 길고 연소생성물에 의한 터빈 블레이드의 삭마가 없으며 제어가 용이하므로 초기 액체로켓엔진 개발시부터 사용되어 왔다. 80년대 이후 개발된 액체로켓엔진은 이원추진제 가스발생기 또는 연소가스 FEEDBACK 시스템을 채용하고 있지만 단일추진제 가스발생기는 과산화수소수 또는 하이드라진과 같은 별도의 추진제 공급 시스템을 필요로 하는 단점에도 불구하고 상대적으로 낮은 온도의 무연 작동 가스를 발생하므로 가스발생기 자체를 위한 냉각시스템을 제거 또는 최소화 시켜 간단한 구조로 전체 시스템 설계를 가능하게 하므로 중소형 액체로켓엔진에 사용되고 있다.

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Research Activities of Transpiration Cooling for High-Performance Flight Engines (고성능 비행체 엔진을 위한 분출냉각의 연구동향)

  • Hwang, Ki-Young;Kim, You-Il
    • Journal of the Korean Society for Aeronautical & Space Sciences
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    • v.39 no.10
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    • pp.966-978
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    • 2011
  • Transpiration cooling is the most effective cooling technique for the high-performance liquid rockets and air-breathing engines operating in aggressive environments with higher pressures and temperatures. When applying transpiration cooling, combustor liners and turbine blades/vanes are cooled by the coolant(air or fuel) passing through their porous walls and also the exit coolant acting as an insulating film. Practical implementation of the cooling technique has been hampered by the limitations of available porous materials. But advances in metal-joining techniques have led to the development of multi-laminate porous structures such as Lamilloy$^{(R)}$ fabricated from several diffusion-bonded, etched metal thin sheets. And also with the availability of lightweight, ceramic matrix composites(CMC), transpiration cooling now seems to be a promising technique for high-performance engine cooling. This paper reviews recent research activities of transpiration cooling and its applications to gas turbines, liquid rockets, and the engines for hypersonic vehicles.

Measurement of the Film Cooling Effectiveness on a Flat Plate using Pressure Sensitive Paint (압력감응 페인트를 이용한 평판에서의 막냉각 계수 측정)

  • Park, Seoung-Duck;Lee, Ki-Seon;Cho, Young-Shin;Kim, Hark-Bong;Kwak, Jae-Su;Kim, Jae-Hwan
    • Proceedings of the Korean Society of Propulsion Engineers Conference
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    • 2007.11a
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    • pp.329-334
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    • 2007
  • Various cooling techniques have been applied to the gas turbine blade in order to reduce heat load to the blade. On the blade surface, film cooling method is used and the accurate information of film cooling effectiveness should be evaluated in order to predict the exact temperature distribution in the blade. In this study, pressure sensitive paint (PSP) was used to measure the film cooling effectiveness on a flat plate. Results showed that PSP technique successfully evaluated the distribution of film cooling effectiveness. Three blowing ratios of 0.5, 1, and 2 were tested and the film cooling effectiveness near holes decreased as the blowing ratio increased, however, increased far downstream from the holes.

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Numerical Analysis on the Effect of Hole Arrangement on the Film Cooling Effectiveness on the Vane Endwall (터빈 1단 베인 엔드월에서 막냉각 홀 배열에 따른 막냉각 특성 변화)

  • Kim, TaeWoo;Kim, JeongJu;Park, Hee Seung;Ju, Won-Gu;Im, Ju Hyun;Cho, Hyung Hee
    • Journal of the Korean Society of Propulsion Engineers
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    • v.24 no.1
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    • pp.47-57
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    • 2020
  • The present study investigates to improve the film cooling performance on the vane endwall. Numerical simulation was conducted to analyze film cooling characteristics on the vane endwall. Six different hole arrangements were designed considering flow characteristics on the endwall. The results showed that the film cooling effectiveness was low on the pressure side and nozzle throat in the base case, because coolant was deflected from the pressure side to the suction side. On the other hand, when the holes were installed near the pressure side, the film cooling effectiveness was enhanced on the pressure side and nozzle throat, because the coolant was less affected by cross flow. Therefore, the film cooling effectiveness increases about 16% compared to the base hole arrangement.

Performance Analysis of Hybrid SOFC/Uncooled GT System for Marine Power Applications (선박동력용 SOFC/GT(무냉각) 하이브리드시스템의 성능 평가)

  • Kim, Myoung-Hwan;Kil, Byung-Lea
    • Journal of Advanced Marine Engineering and Technology
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    • v.36 no.8
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    • pp.1050-1060
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    • 2012
  • As an approach to high-efficiency of SOFC system, SOFC/GT Hybrid system is effective. However, if the output size of the system belongs to the marine class of dozens MWs, the introduction of the cooling system of GT system, which is used as sub-system, makes its related devices complicated and also makes its control difficult. Accordingly, for the marine use, SOFC/GT (non-cooling)Hybrid system looks more suitable than SOFC/GT(cooling)Hybrid system. This study established the SOFC/GT (non-cooling)Hybrid system, and examined the operating temperature & current density of the stack for the system, pressure ratio of the gas turbine, the influence of TIT(Turbine Inlet Temperature) on system performance, etc. through the simulation process. Through this research process, this study was able to confirm that electrical efficiency rises in spite of the increase in the required power for the air compressor, and there exists a limited range of temperatures for operation in TIT.

Thermo-fluid Dynamic and Missile-motion Performance Analysis of Gas-Steam Launch System Utilizing Multiphase Flow Model and Dynamic Grid System (다상 유동모델과 동적 격자계를 활용한 가스-스팀 발사체계의 열유동과 탄의 운동성능 해석)

  • Kim, Hyun Muk;Bae, Seong Hun;Park, Cheol Hyeon;Jeon, Hyeok Soo;Kim, Jeong Soo
    • Journal of the Korean Society of Propulsion Engineers
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    • v.21 no.2
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    • pp.48-59
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    • 2017
  • In this study, an analysis of the thermo-fluid dynamic and missile-motion performance was carried out through a numerical simulation inside the missile canister. Calculation was made in an analytical volume using dynamic grid and evaporated water was used as a coolant. To analyze the interaction among the hot gas, coolant, and mixture flow, Realizable $k-{\varepsilon}$ turbulence and VOF (Volume Of Fluid) model were chosen and a parametric study was performed with the change of coolant flow rate. As a result of the analysis, pressure of the canister showed a large difference depending on the presence or absence of the coolant, and also showed a dependancy on the amount of coolant. Velocity and acceleration were dependent on the canister pressure.

Rib-Dimple Compound Cooling Techniques in a Gas Turbine Blade Cooling Channels with an Aspect ratio (4:1) (4:1 종횡비를 갖는 가스터빈 블레이드 냉각 유로에서의 립-딤플 복합 냉각 특성 연구)

  • Choi, Yong-Duck;Kim, Seok-Beom;Lee, Yong-Jin;Kim, Jin-Kon;Kwak, Jae-Su
    • Proceedings of the Korean Society of Propulsion Engineers Conference
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    • 2010.05a
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    • pp.304-310
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    • 2010
  • Heat transfer coefficients in a dimpled channel, a ribbed channel, and a rip-dimple compound channel were measured by the transient liquid crystal technique. The channel aspect ratio, the rib height, the rip pitch, and the rib angle were 4:1, 6 mm, 60 mm and $60^{\circ}$, respectively. The dimple diameter and the center-to-center distance were 6mm and 7.2 mm, respectively, and the Reynolds number range was 30,000-50,000. Results showed that the heat transfer coefficients were increased by the angled rib. For the dimple-rib compound cooling cases, the heat transfer coefficients were further augmented and the thermal performance factor for the case was the highest.

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Rib-Dimple Compound Cooling Techniques in a Gas Turbine Blade Cooling Channels with an Aspect ratio (4:1) (4:1 종횡비를 갖는 가스터빈 블레이드 냉각 유로에서의 립-딤플 복합 냉각 특성 연구)

  • Choi, Yong-Duck;Kim, Seok-Beom;Lee, Yong-Jin;Kim, Jin-Kon;Kwak, Jae-Su
    • Journal of the Korean Society of Propulsion Engineers
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    • v.14 no.4
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    • pp.32-38
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    • 2010
  • Heat transfer coefficients in a dimpled channel, a ribbed channel, and a rip-dimple compound channel were measured by the transient liquid crystal technique. The channel aspect ratio, the rib height, the rip pitch, and the rib angle were 4:1, 6 mm, 60 mm and $60^{\circ}$, respectively. The dimple diameter and the center-to-center distance were 6mm and 7.2 mm, respectively, and the Reynolds number range was 30,000-50,000. Results showed that the heat transfer coefficients were increased by the angled rib. For the dimple-rib compound cooling cases, the heat transfer coefficients were further augmented and the thermal performance factor for the case was the highest.

Analysis of atmospheric $CO_2$ in Korean Peninsula using Flask Sampling System (플라스크 시료 채취 시스템을 이용한 한반도 대기중 이산화탄소의 분석)

  • 박기준;최재천;방소영;최병철;이진복;문동민;김진석
    • Proceedings of the Korea Air Pollution Research Association Conference
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    • 2003.05b
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    • pp.419-420
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    • 2003
  • 산업화가 진행되면서 야기된 지구온난화와 프레온 가스등의 증가로 인한 오존층 파괴 그리고 화석연료의 사용으로 인한 산성비 발생 등은 지구 환경문제로서 전 세계적인 관심이 되고 있다. 특히, 산업혁명 이후부터 꾸준히 증가하고 있는 온실가스는 기후변화에 있어서 양의 복사강제력(radiative forcing)으로 작용하고 있으며, 지표면의 온도를 높임으로서 기후의 다른 변화를 일으키는 매개체로도 작용하고 있다. 대기중에 온실가스 농도가 증가하게 되면 지구가 에너지를 우주로 방출하게 되면서 냉각되는 효과를 감소시키게 된다. (중략)

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