• Title/Summary/Keyword: 유입공기온도

Search Result 162, Processing Time 0.032 seconds

A Study on the Treatment of Radioactive Liquid Wastes using Synthetic textile by Air Intake System (공기유입시스템에서의 섬유매체에 의한 방사성액체폐기물 처리에 관한 연구)

  • 김태국;이영희;안섬진;손종식;홍권표
    • Proceedings of the Korean Radioactive Waste Society Conference
    • /
    • 2003.11a
    • /
    • pp.101-104
    • /
    • 2003
  • In this study based on the mass transfer theory, experiments for the evaporation rates depending on various conditions were carried out through the operation of the existing Natural Evaporation Facility in KAERI. Evaporation media were made of the cotton and polyester. Air circulation in the facility was forced by exhausting fans. The evaporation rate and the decontamination factor were calculated by the result of experiment. The evaporation rate increased as the flow rate of air supply, the feed rate of liquid waste, and the temperature of supplied air increased. As for the humidity of supplied air, the evaporation rate was getting higher as the humidity was getting lower. As the result of this study, operation conditions of the Natural Evaporation Facility are optimized as follows : The air temperature above $8^{\circ}C$, the air humidity below 70%, the air flow rate 1.14-1.47 m/sec, and the liquid waste feed rate $4.6{\ell}/hr\cdotm^2$. The decontamination factor and the radioactivity are $5.1{\times}10^3$and $4.7{\times}10^{-13}{\mu}Ci/\textrm{m}{\ell}$ respectively, at the above mentioned optimum operation conditions. The air factor in the Dalton's equation for evaporation was determined from results of experiment on the temperature, the humidity, and the flow rate of supplied air as following : $[\textit{Eh}=(0.018 + 0.0141\textitv) {\delta}textitH]$

  • PDF

Combustion Characteristics of Pool Fire by Height of Fire Source (화점높이 변화에 따른 Pool Fire의 연소특성)

  • Park, Hyung-Ju;Cha, Jong-Ho
    • Journal of the Korea Academia-Industrial cooperation Society
    • /
    • v.11 no.11
    • /
    • pp.4671-4676
    • /
    • 2010
  • This study is intended to understand flame behavior of the pool fire by height of fire source. Liquid fuels were methanol and n-Heptane which are used in many studies of pool fire. Size of vessel was $100mm{\times}100mm{\times}50mm$ and the vessel was made by stainless steel. Combustion time, mass loss rate, flame temperature, flame height and air entrainment rate from the outside to flame were measured, and flame behavior was visualized with video camera. Based on the experiment, it was found that combustion characteristics of pool fire was decreased according to increase of height of fire source because entrainment volume of relative cold air was increased from the outside to flame.

Thermodynamic Energy Balance Analysis of Underground Lined Rock Caverns (LRC) for Compressed Air Energy Storage (CAES) (복공식 지하 압축공기에너지 저장공동의 열역학적 에너지수지 분석)

  • Kim, Hyung-Mok;Park, Do-Hyun;Ryu, Dong-Woo;Choi, Byung-Hee;Song, Won-Kyong
    • Tunnel and Underground Space
    • /
    • v.21 no.4
    • /
    • pp.297-306
    • /
    • 2011
  • In this paper, we performed thermodynamic energy balance analysis of the underground lined rock cavern for compressed air energy storage (CAES) using the results of multi-phase heat flow analysis to simulate complex groundwater-compressed air flow around the cavern as well as heat transfer to concrete linings and surrounding rock mass. Our energy balance analysis demonstrated that the energy loss for a daily compression and decompression cycle predominantly depends on the energy loss by heat conduction to the concrete linings and surrounding rock mass for a sufficiently air-tight system with low permeability of the concrete linings. Overall energy efficiency of the underground lined rock caverns for CAES was sensitive to air injection temperature, and the energy loss by heat conduction can be minimized by keeping the air injection temperature closer to the ambient temperature of the surroundings. In such a case, almost all the heat loss during compression phase was gained back in a subsequent decompression phase. Meanwhile, the influence of heat conductivity of the concrete linings to energy efficiency was negligible.

Development of Decompressed Dryer for Mushroom (버섯의 감압건조기 개발)

  • 김영민;김유호;조영길;최희석;조광환
    • Proceedings of the Korean Society for Agricultural Machinery Conference
    • /
    • 2003.07a
    • /
    • pp.267-272
    • /
    • 2003
  • 본 연구에서는 버섯의 건조시간을 줄여 건조 후 버섯의 품질을 향상시키기 위하여 버섯의 감압건조기를 개발하였으며 연구 결과는 다음과 같다. 가. 버섯의 감압건조기의 시작기를 제작하였고, 시작기의 구조는 건조실, 감압블로워, 흡ㆍ배기구 솔레노이드 밸브, 제습장치, 송풍기, 전기히터로 구성되어 있으며, 건조실의 내부 압력이 표준대기압-900hPa, 열풍온도는 상온에서 5$0^{\circ}C$까지 조절할 수 있도록 제작하였다. 나. 시작기를 이용하여 표고버섯을 대상으로 건조특성시험을 실시한 결과, 열풍온도 5$0^{\circ}C$, 건조실 내부압력 900-940hPa에서 건조시간은 11.5h으로 대기압과 비교하여 6.5h 단축되는 것으로 나타났다. 또한, 건조 전ㆍ후의 색차, 수축률, 복원률의 품위가 우수한 것으로 나타났으며 F-test 유의성 검증 결과, 5%의 유의수준에서 갓주름의 색차, 갓직경의 수축률, 복원률에서 유의차가 있는 것으로 나타났다. 다. 열풍온도 5$0^{\circ}C$, 건조실 내부압력 900-940hPa로 표고버섯과 아가리쿠스에 대하여 건조성능시험을 실시한 결과, 표고버섯의 경우 건조시간은 13h으로 열풍식 농산물 건조기와 비교하여 건조시간이 4.5h 단축되는 것으로 나타났으며, 아가리쿠스의 경우 건조시간이 17.5h로 나타났다. 라. 성능시험 결과, 시작기가 열풍식 농산물건조기와 비교하여 건감률, 색택, 수축률, 복원률 등의 품위가 전반적으로 우수한 것으로 나타났다. 마. 시작기의 건조비용을 분석한 결과, 건조시간은 단축되었지만 시설투자비가 높아 건조비용이 표고버섯의 경우 2,461원/kg으로 열풍식 농산물건조기 보다 13% 높은 것으로 나타났지만, 추후 고품질 건조버섯 생산을 위한 기초자료로 활용이 가능할 것으로 판단된다.라갈수록 낮은 온도분포를 나타내고 있는 것은 상부에는 외부공기가 유입되면서 온도가 떨어지는 반면 하부에는 외부공기 유입이 적기 때문으로 사료된다. 또한 열풍실의 길이방향 위치별 온도 분포에서도 같은 현상으로 나타났고, 버너쪽과 송풍기쪽의 온도편차는 나타나지 않아 균일 건조를 기대할 수 있다. 마. 열풍온도를 45$^{\circ}C$로 설정하고 조사거리와 방사체 길이를 각각 119, 1,470mm로 하여 벼의 건조성능시험을 열풍건조기(대비구)와 비교시험 결과 시험구에서 건감률, 건조소요에너지가 각각 0.58%(w.b.), 470kcal/kg - water로 대비구보다 각각 건감율은 23% 높았고, 건조소요에너지는 2%의 절감되었다. 바. 건조기에서 발생되는 소음은 버너쪽 근처에서는 대비구 94.12㏈의 87%에 불과하였으나, 거리가 멀어질수록 차이는 크지 않았다. 이것은 버너에서 멀어질수록 외부적인 요인이 소음에 영향을 미쳤기 때문인 것으로 생각된다. 사. 시작기와 대비구간의 경제성에서 시작기의 구입가격이 20% 비싸기 때문에 시간당 고정비가 높았으나, 건조성능이 우수하여 건조비용이 69,350원/톤으로 대비구보다 14% 절감되는 것으로 나타났다.작용하는 것으로 사료된다.된다.정량 분석한 결과이다. 시편의 조성은 33.6 at% U, 66.4 at% O의 결과를 얻었다. 산화물 핵연료의 표면 관찰 및 정량 분석 시험시 시편 표면을 전도성 물질로 증착시키지 않고, Silver Paint 에 시편을 접착하는 방법으로도 만족한 시험 결과를 얻을 수 있었다.째, 회복기 중에 일어나는 입자들의 유입은 자기폭풍의 지속시간을 연장시키는 경향을 보이며 큰 자기폭풍일수록 현저했다. 주상에서 관측된 이러한 특성은 서브스톰 확장기 활동이 자기폭풍의 발달과 밀접한 관계가 있음을 시사한다.se that were all

  • PDF

A Study on the Heat Flow Characteristics and High Efficiency Thermal Storage of Inflowing Warm Air in the Room (실내유입온기의 열유동특성과 고효율 축열에 관한 연구)

  • Pak, Ee-Tong;Jeong, Un-Chul;Lee, Do-Young
    • Solar Energy
    • /
    • v.17 no.2
    • /
    • pp.13-22
    • /
    • 1997
  • A study on the distribution characteristics of inflowed warm air is important to analyze warm air storage in a room. Also, in point of energy saving during heating, warm air flow characteristics occurred by circulation and distribution of inflowed warm air should be analyzed, and the storage efficiency should be considered in order to increase efficiency of heating system. For this study, in the real-sized model room, the temperature differences between inflowing warm air and inner room air are 10, 20, $30^{\circ}C$(3steps), and the flow rates of inflowing warm air are 0.5, 1, 2, 3m/s(4steps) respectively as dynamic parameters. Also, anemos and vane diffuser are used as inlet geometric condition. Consequently, on geometric conditions, high thermal storage efficiency can be obtained with the vane diffuser, and heat flow characteristics depend on the inflowing velocity more than reference temperature difference.

  • PDF

A Study on Water Balance in Stationary Load Proton Exchange Membrane(PEM) Fuel Cell Power Generator (고정 부하를 갖는 PEM 연료전지 발전기에 있어서의 수분 평형에 관한 연구)

  • Bakhtiar, Agung;Oh, Hoo-Kyu;Yoon, Jung-In;Kim, Young-Bok;Choi, Kwang-Hwan
    • Journal of the Korean Solar Energy Society
    • /
    • v.31 no.4
    • /
    • pp.128-135
    • /
    • 2011
  • 일반적으로 PEM 연료전지에서는 수분 균형이 시스템의 효율에 결정적으로 영향을 미치기 때문에, 이에 대한 균형(balance)을 잡는 것이 매우 중요하다. 특히, 촉매 층에서 물이 넘치는 익수현상(flooding)이나 건조현상(drying)이 발생하게 되면 연료전지의 효율이 급격하게 저하하므로, 항상 수분의 균형이 잡히도록 시스템을 제어하는 것이 일반적이다. 이 때,수분의 익수현상이나 건조현상은 PEM 연료전지의 용량과 주위의 환경, 즉 온도와 습도에 많은 영향을 받게 된다. 금번 논문에서는 가정용 규모인 3kW급에서 10kW급까지의 PEM 연료전지를 설치하였을 때, 주위의 환경(온도와 습도)이 수분 이동에 어떠한 영향을 미치는 지를 시간에 따라서 시뮬레이션(simulation)한 결과를 보여주고 있다. 결과에서 유입공기의 온도가 $50^{\circ}C$ 이하일 경우, 고정부하가 5kW급 이하이면 대부분이 건조현상이 발생하였으나, 고정부하가 6kW급 이상이 되면 익수현상이 운전시간이 20분 이내에서 발생하였다. 또한 고정부하를 최고 10kW급까지 올린 경우, 유입공기의 온도가 $50^{\circ}C$까지는 익수현상이 발생하였으나 $60^{\circ}C$ 이상인 경우에는 거의 건조현상이 발생함을 알 수 있었다.

CFD Analysis for Microclimate of Venlo Type Glasshouse with the Screen Height and Air-inflow Quantity (스크린설치높이·공기유입량 차이에 따른 벤로형 유리온실 미기상 CFD 유동해석)

  • Yang, Won Mo
    • Journal of Bio-Environment Control
    • /
    • v.29 no.1
    • /
    • pp.52-61
    • /
    • 2020
  • The natural change of winter night temperature from 00:00 to 04:30 O'clock with the different height of thermal screen in a venlo type glasshouse (W59×L68×H5.9 m) was studied using computational fluid dynamics (CFD). At the early stage of CFD analysis, the room temperature decrease of glasshouse with the 5.9 m height of thermal screen were faster than it with the 4.1m height of thermal screen, but at 2 hr after analysis it was slower than in it with the 4,1m, the temperature difference was 0.6℃ after 4 hr. If we consider that turn on the heater when the temperature were decrease below 13℃ at 1hr after CFD analysis, it is good for energy saving in the glasshouse with the 4.1 m height of thermal screen rather than in it with the 5.9 m height, because of the temperature decrease were slow during 2 hrs after analysis. The airflow at the height of 2 m which were grown tomato were fast and wide in the glasshouse with the 5.9 m height thermal screen rather than in it with the 4.1 m, the speed difference was 0.034m·s-1 at 1hr after CFD analysis. The effect of temperature decrease in summer season were compared with the different height of shading screen from 12:00 to 14:30 O'clock. The height of shading screen were 5.7, 3.9 m, the gap of it were 30%. The air-inflow quantity by the fan with duct at lower part of venlo glasshouse was 0.67 ㎥·s-1 until 1hr and to increase 3 times of it from 1hr after analysis. The roof window were open 100%. Until 1hr of CFD analysis, the temperature in the 30% open of shading screen was 0.9℃ higher than in the none shading screen. From 13:00 O'clock when the air-inlet quantity to increase 3 times, the temperature in case 30% gap of shading screen were decreased compare with the none shading screen, the temperature difference was 0.5℃ at 14:30 O'clock. The temperature on the floor surface in case 30% gap of shading screen were lower with it's height increase, the temperature difference was 8℃ compare with none shading screen. The relative humidity difference were insignificant by the height and gap of shading screen.

Analysis of the efficiency of natural ventilation in a multi-span greenhouse using CFD simulation (CFD 시뮬레이션을 이용한 연동형 온실 내 자연환기의 효율성 분석)

  • Short, Ted H.
    • Journal of Bio-Environment Control
    • /
    • v.8 no.1
    • /
    • pp.9-18
    • /
    • 1999
  • Natural ventilation in a four and one-half span, double polyethylene commercial greenhouse was investigated with actual data collected at Quailcrest Farm near Wooster, Ohio. Moreover, a computational fluid dynamics (CFD) numerical technique, FLUENT V4.3, was used to predict natural ventilation rates, thermal conditions, and airflow distributions in the greenhouse. The collected climate data showed that the multi-span greenhouse was well ventilated by the natural ventilation system during the typical summer weather conditions. The maximum recorded air temperature difference between inside and outside the greenhouse was 3.5$^{\circ}C$ during the hottest (34.7$^{\circ}C$) recorded sunny day; the air temperatures in the greenhouse were very uniform with the maximum temperature difference between six widely dispersed locations being only 1.7$^{\circ}C$. The CFD models predicted that air exchange rates were as high as 0.9 volume per minute (A.C. .min$^{-1}$ ) with 2.5m.s$^{-1}$ winds from the west as designed.

  • PDF

A study on flame bifurcation due to inlet mixture temperature and swirl strength in a swirl turbulent combustor (스월 난류연소기의 흡입공기온도, 스월세기에 따른 연소불안정 발생 메커니즘에 대한 연구)

  • Kim, Jong-Chan;Sung, Hong-Gye;Ryu, Hyeok
    • Proceedings of the Korean Society of Propulsion Engineers Conference
    • /
    • 2007.11a
    • /
    • pp.377-380
    • /
    • 2007
  • Large Eddy Simulation has been conducted to investigate both stable and unstable flame structures in a swirl turbulent combustor. While a flame is stabilized with periodic dynamic structure at 600K, a slight increase in the flame temperature of inlet mixture, 660K, lead to bifurcation of flame at swirl angle 45 degrees. It was observed that both swirl number and mixture temperature affect a flame bifurcation and the former is a major parameter. One major mechanism contributing to the unstable flame is that the local flame speed overshadows the local flow velocity near the wall of the combustor.

  • PDF

Study on the In-Furnace Desulfurization for Oxy-Fuel Combustion Flue Gases Using Drop Tube Furnace (Drop Tube Furnace를 이용한 순산소연소 배가스 로내탈황에 관한 연구)

  • An, Young-Mo;Jo, Hang-Dae;Choi, Won-kil;Park, Yeong-Sung;Keel, Sang-In;Lee, Hyung-Keun
    • Korean Chemical Engineering Research
    • /
    • v.47 no.4
    • /
    • pp.512-517
    • /
    • 2009
  • $SO_2$ concentrations in oxy-fuel combustion flue gases increases about three times as high as that of conventional air combustion system owing to the flue gas recirculation for the control of combustion temperature. So the desulfurization reaction is different from that of the conventional air combustion system due to exceptionally high $CO_2$ and $SO_2$ concentration. In this study, drop tube furnace(DTF) system was used to investigate the desulfurization characteristics of limestone in oxy-fuel combustion furnace. The experiments were performed under $O_2/CO_2$ atmosphere to examine the effect of operating variables such as reaction temperatures, Ca/S ratios and inlet $SO_2$ concentrations on the $SO_2$ removal efficiencies. $SO_2$ removal efficiency increased with reaction temperature, Ca/S ratio and inlet $SO_2$ concentration. And the addition of water vapor resulted in about 4~6% of increase in $SO_2$ removal efficiency.