• 제목/요약/키워드: Supply air velocity

검색결과 124건 처리시간 0.024초

부상된 수소난류확산화염에서 동축공기의 음향가진에 의한 NOx 저감 (NOx Reduction by Acoustic Excitation on Coaxial Air Stream in Lifted Turbulent Hydrogen Non-Premixed Flame)

  • 허필원;오정석;윤영빈
    • 한국연소학회지
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    • 제14권1호
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    • pp.31-38
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    • 2009
  • The effects of acoustic excitation of coaxial air on mixing enhancement and reduction of nitrogen oxides (NOx) emission were investigated. A compression driver was attached to the coaxial air supply tube to impose excitation. Measurements of NOx emission with frequency sweeping were performed to observe the trend of NOx emission according to the fuel and air flow conditions and to inquire about the effective excitation frequency for reducing NOx. Then, Schlieren photographs were taken to visualize the flow field and to study the effect of excitation. In addition, phase-locked particle image velocimetry (PIV) was performed to acquire velocity field for each case and to investigate the effect of vortices more clearly. Direct photographs and OH chemiluminescence photographs were taken to study the variation of flame length and reaction zone. It was found that acoustic forcing frequencies close to the resonance frequencies of coaxial air supply tube could reduce NOx emission. This NOx reduction was influenced by mixing enhancement due to large-scale vortices formed by fluctuation of coaxial air jet velocity.

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분배계통에 따른 지하주차장 환기설비 성능의 예측

  • 김경환;이재헌;오명도;김종필
    • 설비공학논문집
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    • 제13권10호
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    • pp.982-992
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    • 2001
  • In this paper, the performance of ventilation equipments in enclosed parking garages were investigated for several air distribution systems by numerical method. Air change effectiveness of the non-mixing system was 0.42. It meant that more supply air as much as the design supply air was needed to maintain good indoor air quality. In the high speed nozzle ventilating system which is most expensive one, air change effectiveness was 0.54. Therefore this system satisfied to ventilation design. In the jet fan ventilating systems, air change effectiveness for jet fan ventilating system-A with 18 jet fans and jet fan ventilating system-B with 6 jet fans in circulation mixing arrangement were 0.565 and 0.42 respectively. Jet fan ventilating system-C with 6 jet fans in transport mixing arrangement was 0.535. Jet fan ventilating system-A and jet fan ventilating system-C met the ventilation design. But velocity in jet fan ventilating system-A was over 2.0m/s which is inappropriate in human comfort. Therefore this system is not proper to ventilation. Jet fan ventilating system-C was the optimum one for enclosed parking garages among 5 systems examined in this paper.

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200 t/d급 MHI 석탄 가스화기의 석탄 및 공기 배분에 따른 가스화 특성 평가 (Influence of coal and air flow rate distribution on gasification characteristics in 200 t/d scale MHI coal gasifier)

  • 도윤영;예인수;김봉근;류창국
    • 한국연소학회:학술대회논문집
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    • 한국연소학회 2015년도 제51회 KOSCO SYMPOSIUM 초록집
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    • pp.93-96
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    • 2015
  • Commercial coal gasifiers typically use entrained flow type reactors, but have unique features in terms of reactor shape, gasifying agent, coal feeding type, ash/slag discharge, and reaction stages. The MHI gasifier is characterized as air-blow dry-feed entrained reactor, which incorporates a short combustion stage at the bottom and a tall gasification stage above. This study investigates the flow and reaction characteristics inside a MHI gasifier by using computational fluid dynamics (CFD) in order to understand its design and operation features. For its pilot-scale system at 200 ton/day capacity, the distribution of coal and air supply between the two reaction stages was varied. It was found that the syngas composition and carbon conversion rate were not significantly influenced by the changes in the distribution of coal and air supply. However, the temperature, velocity and flow pattern changed sensitively to the changes in the distribution of coal and air supply. The results suggest that one key factor to determine the operational ranges of coal and air supply would be the temperature and flow pattern along the narrower wall between the two reaction stages.

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쉘앤튜브형 열교환기의 단일 쉘 내 고온공기 열유동 특성 해석 (Analysis on Characteristics of Thermal Flow of Hot Air in Single Shell of Shell and Tube-type Heat Exchanger)

  • 양영준
    • 한국산업융합학회 논문집
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    • 제26권2_2호
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    • pp.255-263
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    • 2023
  • The shell and tube-type heat exchangers have been frequently used in many industrial field because of its simple structure and wide operation conditions and so on. The purpose of this study is to investigate the flow characteristics in single shell of shell and tube-type heat exchanger according to velocity and temperature of hot air released from heat exchanger simulator through numerical analysis. As the results, the temperature was decreased in almost quadratic curve from top to bottom in single shell of the shell and tube-type heat exchanger. Further the changes of pressure and velocity in outlet according to change of inlet temperature were not observed. The cost for operating the shell and tube-type heat exchanger should be compared the supply cost of hot air with that of velocity in order to make a economic decision.

공기실이 설치된 건축물 급수관로의 과도압력 특성 (Characteristics of the Transient Pressure in a Building Water Supply System with an Air Chamber)

  • 황희성;임기원;이광복;조병선;차동진
    • 설비공학논문집
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    • 제12권8호
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    • pp.782-790
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    • 2000
  • A numerical study has been conducted to characterize the transient pressure in a building water supply system with an air chamber by utilizing a commercial code that employs the method of characteristics. Some results produced for the purpose of verification in the study agree quite well with the previously reported. Several parameters are then varied. Among them are the valve closure time, the wave speed, the static pressure, the polytropic exponent, the air chamber volume, the inner diameter and the shape of orifice in the air chamber, etc, while the water temperature and velocity are kept constant at $20^P{circ}C $,/TEX> and 0.8 m/s, respectively, Results reported in this parametric study may be useful to understand the unsteady behavior of the system.

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EMP 방호시설의 덕트 및 배관 최적 설계 방안 (Design Optimization for Air Ducts and Fluid Pipes at Electromagnetic Pulse(EMP) Shield in Highly Secured Facilities)

  • 방승기;김재훈
    • 한국지열·수열에너지학회논문집
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    • 제10권4호
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    • pp.15-24
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    • 2014
  • This study conducted a computational fluid dynamics(CFD) analysis to find an appropriate diameter or sectional area of air ducts and fluid pipes which have an electromagnetic pulse(EMP) shied to protect indoor electronic devices in special buildings like military fortifications. The result shows that the optimized outdoor air intake size can be defined with either the ratio of the maximum air velocity in the supply duct to the air intake size, or the shape ratio of indoor supply diffuser to the outdoor air intake. In the case of water channel, the fluid velocity at EMP shield with the identical size of the pipe, decreases by 25% in average due to the resistance of the shield. The enlargement of diameter at the shield, 2 step, improves the fluid flow. It illustrated that the diameter of downstream pipe size is 1step larger than the upstream for providing the design flow rate. The shield increases friction and resistance, in the case of oil pipe, so the average flow velocity at the middle of the shield increase by 50% in average. In consideration of the fluid viscosity, the oil pipe should be enlarged 4 or 5 step from the typical design configuration. Therefore, the fluid channel size for air, water, and oil, should be reconsidered by the engineering approach when EMP shield is placed in the middle of channel.

전산실의 환기성능 최적화를 위한 연구 (A Study for Optimization the Ventilation Performance of the Computer Room)

  • 권용일
    • 설비공학논문집
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    • 제27권2호
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    • pp.57-62
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    • 2015
  • The objective of the present study is to identify the ventilation problems and to suggest the optimal ventilation system to save energy and to improve IAQ in the computer rooms, which annually performs the cooling operation by the server with the highly thermal load. Numerical results on the temperature and local mean age are presented along with some of the discharge velocities. Results show many interesting aspects of airflow patterns affecting the ventilation performances, according to the discharge velocity of the supply diffuser installed in the bottom surfaces between the servers. As the results, 2.5 m/s of the optimal discharge velocity is needed in order to improve the ventilation performance.

Nonlinear Adaptive Velocity Controller Design for an Air-breathing Supersonic Engine

  • Park, Jung-Woo;Park, Ik-Soo;Tahk, Min-Jea
    • International Journal of Aeronautical and Space Sciences
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    • 제13권3호
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    • pp.361-368
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    • 2012
  • This paper presents an approach on the design of a nonlinear controller to track a reference velocity for an air-breathing supersonic vehicle. The nonlinear control scheme involves an adaptation of propulsive and aerodynamic characteristics in the equations of motion. In this paper, the coefficients of given thrust and drag functions are estimated and they are used to approximate the equations of motion under varying flight conditions. The form of the function of propulsive thrust is extracted from a thrust database which is given by preliminary engine input/output performance analysis. The aerodynamic drag is approximated as a function of angle of attack and fin deflection. The nonlinear controller, designed by using the approximated nonlinear control model equations, provides engine fuel supply command to follow the desired velocity varying with time. On the other hand, the stabilization of altitude, separated from the velocity control scheme, is done by a classical altitude hold autopilot design. Finally, several simulations are performed in order to demonstrate the relevance of the controller design regarding the vehicle.

가변체적내의 압축공기 충진 및 방출특성연구 (A Study on Chargin and Discharging Characteristics of Variable Volume with Compressed Air)

  • 김동수;김형의;박재범;강보식;성백주
    • 한국정밀공학회지
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    • 제12권11호
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    • pp.125-131
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    • 1995
  • Pneumatic System has been mainly used as main equipment for actuation and control of fluid force in manufacturing industry. For velocity control of piston, meter-out restriction method is used in many cases. In this systems, meter-out restriction method is adopted for analysing the Dynamic Charging and Discharging Process which is Variable Volume Chamber. Experiments has been conducted for different supply pressure condition. As a experimental result, charge side chamber pressure rises to supply pressure rapidily and discharge side chamber pressure decreases. Also, when the air in the cylinder is discharged, tempdrature of air decreases steeply. Restriction of the Cylinder sometimes freeze and it dose not function. The result will be useful for the analysis of pneumatic system.

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급수용 급속공기밸브의 성능특성에 관한 실험적 연구 (Experimental Study on Performance Characteristics of High Speed Air Valve for Water Works)

  • 이선곤;강세호;양철수;우창기
    • 한국안전학회지
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    • 제29권5호
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    • pp.1-6
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    • 2014
  • When the fluid energy convert into kinetic energy due to water hammer, the propagation velocity of pressure wave appear. The propagation velocity of pressure wave(1050 m/s) of very fast could be damage to the pipeline system. If the occurrence of water hammer is due to down-pressure, the faster the air exhaust or supply device is needed. it is high Speed Air Valve. In this paper, Each 3.12, 3.13, 3.72, $3.74kg/cm^2$ pipeline pressure were setting, and then executed pressure rapid drop for obtaining a high Speed Air Valve Operating time and pressure change data. the result was that pipe line pressure stabilization time were each 0.98, 1, 1.22, 1.25 sec. In other words, that pressure drop experimental results pipe line pressure was equal to atmospheric pressure without negative pressure After about one second. The study result would be useful to pipe line system stability design because this data could be foresee pressure stabilization time.