• Title/Summary/Keyword: Air circulation

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Evaluation of Thermal Performance in a Stadium with Air Circulation System (공기순환 시스템이 설치된 경기장 공간의 열성능 평가)

  • Kim, Kyung-Hwan;Im, Yoon-Chul;Lee, Jae-Heon;Oh, Myung-Do;Park, Myung-Sig;Lee, Dae-Woo;Park, Young-Woo
    • Proceedings of the KSME Conference
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    • 2001.06d
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    • pp.170-174
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    • 2001
  • In this paper, CFD technique has been used at design stage to predict space air distribution in a cycle stadium with air circulation system. An air circulation flow of 0.67 rev./min was observed at computed results in the stadium space with and without air circulation system. Comparing the thermal comfort of the two models with or without air circulation system showed that the thermal environment in the former was superior in the latter. Energy savings could be achieved for the model with air circulation due to its lower air inflow temperature.

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Effect of the Vertical Air Circulation on the Thermal "Environment in a Large Space (대공간 열환경 특성에 관한 수직순환기류의 영향)

  • 김경환;강석윤;최충현;조영진;이재헌;오명도
    • Korean Journal of Air-Conditioning and Refrigeration Engineering
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    • v.12 no.6
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    • pp.581-588
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    • 2000
  • This paper describes the effect of vertical air circulation on the thermal environment in an airport passenger terminal with induced flow by jet fans. In comparing the level of thermal comfort at the breathing line of 1.5 m in height, the results from the two models with or without the vertical air circulation, show that the average PPD is 8% in the former and 23% in the latter, respectively. It is thought that vertical air circulation lends to improved thermal comfort for human in respect of ventilation in a large space.

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Investigation into circulation of ground water by air sparging (Air sparging에 의한 지하수 순환에 관한 연구)

  • 이준희;강구영
    • Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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    • 1998.11a
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    • pp.232-235
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    • 1998
  • Air sparging system is a kind of in-situ bioremediation method in the contaminated ground water. When Air sparging, the both of water circulation and oxygen transfer happend in the same time. The hydraulic differential head is zero at the middle height of well, is negative below the height and is possitive above the height. Hydroraulic head gradient is proportioned to air superficial velocity in the well. But over 24m/min of the superficial velocity, the hydraulic head gradient increase little.

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A Non-Heating Small-Sclaed Experimental Study on the Two-Phase Natural Circulation Flow through an Annular Gap between Reactor Vessel and Insulation (소형 비가열 실험을 이용한 원자로용기 외벽냉각시 용기와 단열재 사이의 자연순환 이상유동에 관한 연구)

  • Ha, Kwang-Soon;Park, Rae-Joon;Cho, Young-Rho;Kim, Sang-Baik;Kim, Hee-Dong
    • Proceedings of the KSME Conference
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    • 2004.04a
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    • pp.1927-1932
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    • 2004
  • A 1/21.6 scaled non-heating experimental facility was prepared utilizing the results of a scaling analysis to simulate the APR1400 reactor and insulation system. The behaviors of the air bubble-induced two-phase natural circulation flow in the insulation gap were observed, and the liquid mass flow rates driven by natural circulation loop were measured by varying the injected air flow rate and distribution. As the injected air flow rates increased, the natural circulation flow rates also increased. Both the longitudinal and the latitudinal distributions of the injected air affected the natural circulation flow rates, especially, the longitudinal effect is more larger.

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One-Dimensional Analysis of Air-Water Two Phase Natural Circulation Flow (공기와 물의 이상 자연순환 유동의 1 차원 해석)

  • Park, Rae-Joon;Ha, Kwang-Soon;Kim, Jae-Cheol;Hong, Seong-Wan;Kim, Sang-Baik
    • Proceedings of the KSME Conference
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    • 2007.05b
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    • pp.2626-2631
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    • 2007
  • Air-water two phase natural circulation flow in the T-HERMES (Thermo-Hydraulic Evaluation of Reactor cooling Mechanism by External Self-induced flow)-1D experiment has been evaluated to verify and evaluate the experimental results by using the RELAP5/MOD3 computer code. The RELAP5 results have shown that an increase in the coolant inlet area leads to an increase in the water circulation mass flow rate. However, the water outlet area does not effective on the water circulation mass flow rate. As the coolant outlet moves to a lower position, the water circulation mass flow rate decreases. The water level is not effective on the water circulation mass flow rate. As the height increases in the air injection part, the void fraction increases. However, the void fraction in the upper part of the air injector maintains a constant value. An increase in the air injection mass flow rate leads to an increase in the local void fraction, but it is not effective on the local pressure.

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A Numerical Experiments on the Atmospheric Circulation over a Complex terrain around Coastal Area. Part I : A Verification of Proprietyh of Local Circulation Model Using the Linear Theory (연안부근 복잡지형의 대기유동장 수치실험 I -선형이론을 이용한 국지순환모형의 타당성 검토-)

  • 이화운;김유근;정우식
    • Journal of Environmental Science International
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    • v.8 no.5
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    • pp.555-558
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    • 1999
  • A sea/land breeze circulation system and a regional scale circulation system are formed at a region which has complex terrain around coastal area and affect to the dispersion and advection of air pollutants. Therefore, it is important that atmospheric circulation model should be well designed for the simulation of regional dispersion of air pollutants. For this, Local Circulation Model, LCM which has an ability of high resolution is used. To verify the propriety of a LCM, we compared the simulation result of LCM with an exact solution of a linear theory over a simple topography. Since they presented almost the same value and pattern of a vertical velocity at the level of 1 km, we had a reliance of a LCM. For the prediction of dispersion and advection of air pollutants, the wind filed should be calculated with high accuracy. A numerical simulation using LCM will provide more accurate results over a complex terrain around coastal area.

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Development of Bubble Detector for Extracorporeal Circulation Support System (체외 순환 보조 장치 위한 공기방울 감지 장치 개발)

  • Lee, Hyuk-Soo
    • Journal of the Institute of Convergence Signal Processing
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    • v.11 no.4
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    • pp.298-302
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    • 2010
  • Extracorporeal circulation support system is a device for repiratory and heart failure treatment, and there have been many trials for development and clinical application in the world. These devices need to be careful while using is air embolism. Air embolism can be a lethal complication of surgical procedures during which venous pressure at the site of surgery is sub-atmospheric or air is forced under pressure into a body cavity or using extracorporeal circulation support system. To solve the problem, we developed the air detector using relative dielectric constant change. In experiments with a mock circulation system, the proposed system showed a signal difference depending on the amount of air in the tube.

Analysis of Air Circulation in Oyster Mushroom Farm

  • Jeong, Won-Geun;Lim, Hack-Kyu;Kim, Tae-Han
    • Journal of Biosystems Engineering
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    • v.37 no.2
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    • pp.75-81
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    • 2012
  • Oyster mushroom farm which could not meet optimum temperature range yields non-uniform sized, low quality products. Thus, this study, utilizing STAR CCM+, one of the computational fluid dynamics (CFD) programs, analyzed the impact of air circulation and temperature distribution. Methods: After we visited numerous mushroom farms, we measured the temperature at the discharge ports of heaters, fan capacity, and the locations of the air circulators in the farms. According to the data, most mushroom growers installed the heaters near the entrance and discharge ports of the heaters at the third growing bed on the same height as the heaters in the entrance. The temperature at the discharge port of heater was $1,26^{\circ}C$, and the fan capacity was 4,500 $m^3$/hr. The air circulator was placed in the center of the mushroom farm 50cm above the ground, and its capacity of inlet port was 1,100 $m^3$/hr and discharge port 1,600 $m^3$/hr. The mushroom farm was insulated. Results: According to the analysis of the temperature distribution in the vertical plane of the entrance side, no air circulation causes the high temperature zone of 296~299K at the discharge port of the heater to take up 34% of area while the operation of air circulators causes it to occupy only 9%. This means that not using air circulators leads to a concentration of high temperature at the discharge port near the entrance. In addition, with the results of the analysis of the temperature distribution in the vertical planes of the center, no air circulation causes the temperature zone of 295~298K at the discharge port of the heater to take up 48% of area while the operation of air circulators causes it to occupy 80%. This shows that the high outlet port temperature disseminated to the center. Conclusions: After ninety minute operation of both heater and air circulator, the interior temperature became stabilized in the mushroom farm. Air circulation made the high temperature at the discharge port disseminate to the center and exit in the farm and equalize the temperature distribution.

Numerical Analysis of Wind Driven Current and Mesoscale Air Flow in Coastal Region with Land Topography (육상지형을 고려한 연안해역에서의 중규모 기상장과 취송류에 관한 수치해석)

  • Lee, Seong-Dae
    • Journal of Ocean Engineering and Technology
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    • v.20 no.5 s.72
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    • pp.23-29
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    • 2006
  • A quasi depth-varying mathematical model for wind-generated circulation in coastal areas, expressed in terms of the depth-averaged horizontal velocity components and free surface elevation was validated and used to understand the diurnal circulation process. The wind velocity is considered as a dominant factor for driving the current. In this paper, three-dimensional numerical experiments that included the land topography were used to investigate the mesoscale air flaw over the coastal regions. The surface temperature of the inland area was determined through a surface heat budget consideration with the inclusion of a layer of vegetation.A series of numerical experiments were then carried out to investigate the diurnal response of the air flaw and wind-generated circulation to various types of surface inhomogeneities.

Development of CFD model for analyzing the air flow and temperature distribution in greenhouse with air-circulation fans (유동팬이 설치된 온실 내 기류 및 기온분포 해석을 위한 CFD 모델 개발)

  • Yu, In-Ho;Yun, Nam-Kyu;Cho, Myeong-Whan;Ryu, Hee-Ryong;Moon, Doo-Gyung
    • Korean Journal of Agricultural Science
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    • v.41 no.4
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    • pp.461-472
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    • 2014
  • This study was conducted to build the CFD simulation model which can quantify the distribution of the meteorological factors in air-heated greenhouse for chrysanthemum according to the location and capacity of air-circulation fan. The CFD model was also verified by experiment. It was judged that SST model was the most appropriate turbulence model which can properly describe the airflow by the air-circulation fan. According to the simulation results, the differences between the measured and predicted temperatures from 18 points at each height in the greenhouse were $0.2{\sim}0.4^{\circ}C$ in average. This showed a good agreement between the predicted data and the measured ones. The developed CFD model can be a useful tool to evaluate and design the air-circulation systems in the greenhouse with various configurations.