• Title/Summary/Keyword: duct design

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Evaluation Study of a Double Blind Light Pipe Daylighting System Efficiency and an Illumination Energy Reduction (이중 블라인드 광파이프 주광 조명시스템 효율 및 조명에너지 절감량 평가 연구)

  • Kang, Eun-Chul;Yoo, Seong-Yeon;Lee, Euy-Joon
    • Journal of the Korean Solar Energy Society
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    • v.33 no.1
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    • pp.89-95
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    • 2013
  • A DBLP(Double blind light pipe) daylight system can be installed at a building exterior wall or roof to replace artificial light during the day time. This system was consisted of a double blind light collector, a mirror duct type light transformer and a prism light pipe distributor. The double blinds were used to track the sun's altitude and azimuth movements to collect the sunlight throughout the day. The sunlight collected by the light collector was reflected on the first mirror and the second mirror and sent to the light pipe through the light transformer. The transformer was designed to deliver the sunlight into the light pipe efficiently. The light distributor plays a role in diffusing the sunlight coming in through the light collector to be used for indoor lighting. In this paper, a DBLP system has been designed, installed and tested at a KIER daylighting twin test cell. The DBLP daylighting system was applied to the experimental test cell which has an indoor area of 2.0 m wide ${\times}$ 2.4 m height ${\times}$ 3.8 m length. The experiment was conducted from January 30 to February 27, 2012, under clear skies and partially cloudy skies. Data was collected from 10:00 am to 16:00 pm every 2 minute and the average was calculated for every 30 minute of the data collection to obtain the system efficiency. The results indicated that the DBLP system efficiency was evaluated as 11.67%. The DBLP system indoor illumination energy reduction was predicted as 0.822 kWh/day. This could replace 4 sets of a 32W fluorescent lamp operating 6.4 hours per a day.

Pressure Recovery in a supersonic ejector of a high altitude testing chamber (초음속 이젝터의 압력회복에 관한 연구)

  • Omollo, Owino George;Kong, Chang-Duk
    • Proceedings of the Korean Society of Propulsion Engineers Conference
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    • 2010.11a
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    • pp.833-837
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    • 2010
  • This study aims at finding an optimal exhaust diffuser design of a high altitude testing chamber for a low bypass turbofan engine (F404-402) with thrust pound force of 17,700 and air mass flow rate of 66kg/s ejecting at a speed of Mach 1.66. The final proposed ejector size has better pressure recovery characteristics and targets to reduce operational cost at engine performance testing. Conventional high altitude test chamber layout was adopted and first drawn in two dimensions using Autocad software so as to determine the gas path, the ejector frontal size was then determined from gas dynamics equations considering traditional gas ejection method where both the engine exhaust and cell cooling air are exhausted via the ejector. Modification to a smaller ejector with an alternative secondary cell cooling exhaust port was then performed and modelled in 3D using Solid Works software.

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Assessment of the Counter-Flow Thrust Vector Control in a Three-Dimensional Rectangular Nozzle (3차원 직사각형 노즐에서 역유동 추력벡터 제어 평가)

  • Wu, Kexin;Kim, Tae Ho;Kochupulickal, James Jintu;Kim, Heuy Dong
    • Journal of the Korean Society of Propulsion Engineers
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    • v.24 no.1
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    • pp.34-46
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    • 2020
  • Computational assessment of gas-dynamic characteristics is explored for a three-dimensional counter-flow thrust vector control system in a rectangular supersonic nozzle. This convergent-divergent nozzle is designed by Method of Characteristics and its design Mach number is specially set as 2.5. Performance variations of the counter-flow vector system are illustrated by varying the gap height of the secondary flow duct. Key parameters are quantitatively analyzed, such as static pressure distribution along the centerline of the upper suction collar, deflection angle, secondary mass flow ratio, and resultant thrust coefficient. Additionally, the streamline on the symmetry plane, three-dimensional iso-Mach number surface contour, and three-dimensional turbulent kinetic energy contour are presented to reveal overall flow-field characteristics in detail.

Experimental Study on Underwater Docking of a Visual Servoing Autonomous Underwater Vehicle (비쥬얼 서보 자율무인잠수정의 수중 도킹에 관한 실험적 연구)

  • Lee, Pan-Mook;Jeon, Bong-Hwan;Lee, Ji-Hong;Kim, Sea-Moon;Hong, Young-Hwan
    • Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
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    • 2003.05a
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    • pp.89-93
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    • 2003
  • The Korea Research Institute of Ships and Ocean Engineering (KRISO), the ocean engineering branch of KORDI, has designed and manufactured a model of an autonomous underwater vehicle (AUV) to test underwater docking. This paper introduces the AUV model, ASUM, equipped with a visual servo control system to dock into an underwater station with a camera and motion sensors. To make a visual servoing AUV, this paper implemented the visual servo control system designed with an augmented state equation, which was composed of the optical flow model of a camera and the equation of the AUV's motion. The system design and the hardware configuration of ASUM are presented in this paper. A small long baseline acoustic positioning system was developed to monitor and record the AUV's position for the experiment in the Ocean Engineering Basin of KRISO, KORDI. ASUM recognizes the target position by processing the captured image for the lights, which are installed around the end of the cone-type entrance of the duct. Unfortunately, experiments are not yet conducted when we write this article. The authors will present the results for the docking test of the AUV in near future.

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Thermodynamic simulation and structural optimization of the collimator in the drift duct of EAST-NBI

  • Ning Tang;Chun-dong Hu;Yuan-lai Xie;Jiang-long Wei;Zhi-Wei Cui;Jun-Wei Xie;Zhuo Pan;Yao Jiang
    • Nuclear Engineering and Technology
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    • v.54 no.11
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    • pp.4134-4145
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    • 2022
  • The collimator is one of the high-heat-flux components used to avoid a series of vacuum and thermal problems. In this paper, the heat load distribution throughout the collimator is first calculated through experimental data, and a transient thermodynamic simulation analysis of the original model is carried out. The error of the pipe outlet temperature between the simulated and experimental values is 1.632%, indicating that the simulation result is reliable. Second, the model is optimized to improve the heat transfer performance of the collimator, including the contact mode between the pipe and the flange, the pipe material and the addition of a twisted tape in the pipe. It is concluded that the convective heat transfer coefficient of the optimized model is increased by 15.381% and the maximum wall temperature is reduced by 16.415%; thus, the heat transfer capacity of the optimized model is effectively improved. Third, to adapt the long-pulse steady-state operation of the experimental advanced superconducting Tokamak (EAST) in the future, steady-state simulations of the original and optimized collimators are carried out. The results show that the maximum temperature of the optimized model is reduced by 37.864% compared with that of the original model. The optimized model was changed as little as possible to obtain a better heat exchange structure on the premise of ensuring the consumption of the same mass flow rate of water so that the collimator can adapt to operational environments with higher heat fluxes and long pulses in the future. These research methods also provide a reference for the future design of components under high-energy and long-pulse operational conditions.

Recent Progress in Air-Conditioning and Refrigeration Research: A Review of Papers Published in the Korean Journal of Air-Conditioning and Refrigeration Engineering in 2014 (설비공학 분야의 최근 연구 동향: 2014년 학회지 논문에 대한 종합적 고찰)

  • Lee, Dae-Young;Kim, Sa Ryang;Kim, Hyun-Jung;Kim, Dong-Seon;Park, Jun-Seok;Ihm, Pyeong Chan
    • Korean Journal of Air-Conditioning and Refrigeration Engineering
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    • v.27 no.7
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    • pp.380-394
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    • 2015
  • This article reviews the papers published in the Korean Journal of Air-Conditioning and Refrigeration Engineering during 2014. It is intended to understand the status of current research in the areas of heating, cooling, ventilation, sanitation, and indoor environments of buildings and plant facilities. Conclusions are as follows. (1) The research works on the thermal and fluid engineering have been reviewed as groups of heat and mass transfer, cooling and heating, and air-conditioning, the flow inside building rooms, and smoke control on fire. Research issues dealing with duct and pipe were reduced, but flows inside building rooms, and smoke controls were newly added in thermal and fluid engineering research area. (2) Research works on heat transfer area have been reviewed in the categories of heat transfer characteristics, pool boiling and condensing heat transfer and industrial heat exchangers. Researches on heat transfer characteristics included the results for thermal contact resistance measurement of metal interface, a fan coil with an oval-type heat exchanger, fouling characteristics of plate heat exchangers, effect of rib pitch in a two wall divergent channel, semi-empirical analysis in vertical mesoscale tubes, an integrated drying machine, microscale surface wrinkles, brazed plate heat exchangers, numerical analysis in printed circuit heat exchanger. In the area of pool boiling and condensing, non-uniform air flow, PCM applied thermal storage wall system, a new wavy cylindrical shape capsule, and HFC32/HFC152a mixtures on enhanced tubes, were actively studied. In the area of industrial heat exchangers, researches on solar water storage tank, effective design on the inserting part of refrigerator door gasket, impact of different boundary conditions in generating g-function, various construction of SCW type ground heat exchanger and a heat pump for closed cooling water heat recovery were performed. (3) In the field of refrigeration, various studies were carried out in the categories of refrigeration cycle, alternative refrigeration and modelling and controls including energy recoveries from industrial boilers and vehicles, improvement of dehumidification systems, novel defrost systems, fault diagnosis and optimum controls for heat pump systems. It is particularly notable that a substantial number of studies were dedicated for the development of air-conditioning and power recovery systems for electric vehicles in this year. (4) In building mechanical system research fields, seventeen studies were reported for achieving effective design of the mechanical systems, and also for maximizing the energy efficiency of buildings. The topics of the studies included energy performance, HVAC system, ventilation, and renewable energies, piping in the buildings. Proposed designs, performance performance tests using numerical methods and experiments provide useful information and key data which can improve the energy efficiency of the buildings. (5) The field of architectural environment was mostly focused on indoor environment and building energy. The main researches of indoor environment were related to the evaluation of work noise in tunnel construction and the simulation and development of a light-shelf system. The subjects of building energy were worked on the energy saving of office building applied with window blind and phase change material(PCM), a method of existing building energy simulation using energy audit data, the estimation of thermal consumption unit of apartment building and its case studies, dynamic window performance, a writing method of energy consumption report and energy estimation of apartment building using district heating system. The remained studies were related to the improvement of architectural engineering education system for plant engineering industry, estimating cooling and heating degree days for variable base temperature, a prediction method of underground temperature, the comfort control algorithm of car air conditioner, the smoke control performance evaluation of high-rise building, evaluation of thermal energy systems of bio safety laboratory and a development of measuring device of solar heat gain coefficient of fenestration system.

A study on the program development for area optimizing of damper ports in road tunnels with transverse ventilation system (횡류식 도로터널의 급, 배기구 포트 개구면적 최적화 프로그램 개발 연구)

  • Jo, Hyeong-Je;Chun, Kyu-Myung;Min, Dea-Kee;Kim, Jong-Won;Beak, Jong-Hoon
    • Journal of Korean Tunnelling and Underground Space Association
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    • v.21 no.1
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    • pp.177-188
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    • 2019
  • The purpose of the optimization of the installation of supply/exhaust ports for tunnels with transverse ventilation system is to supply fresh air from outside to inside of tunnels uniformly and exhaust pollutant from tunnels properly for creating safe and clean environment for tunnel users. For this purpose, a ventilation port area optimization program was developed to obtain a uniform supply or exhaust air volume inside a great depth double deck tunnel with transverse ventilation system. In order to area optimize the developed port sizing program, the wind velocity was measured in the duct of the currently operated tunnel with semi-transverse ventilation. Also 3D cfd was performed on the same tunnel and cfd results were compared to the measured value. As a result, the error rate between the predicted value from the program and measured value was 6.72%, while the error rate between the predicted value from the program and 3D cfd analysis value was 4.86%. Both of comparison results show less than 10% of error rate. Thus It is expected that supply/exhaust port optimization design of transverse ventilation tunnel can be possible with using this large exhaust port area optimization program.

A Study on Regulation Improvement of Local Ventilation System (국소배기장치의 규제개선에 관한 연구)

  • kim, Nam Suk;Kim, Young Suk;Woo, In Sung
    • Journal of the Korean Institute of Gas
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    • v.22 no.3
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    • pp.74-83
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    • 2018
  • Anyone who wants to install local ventilation system must obtain a permission from the Ministry of Employment and Labor even if he has permission from the Ministry of Environment. This is because not only the Atmospheric Environmental Protection Act, but also the manufacturing industry's hazardous risk prevention plan under Article 48 Clause 2 of the Industrial Safety and Health Act is to be submitted by 15 days before the construction. Under the current Environmental Protection Act, the Ministry of Environment regulates only the emission of pollutants from local exhaust ventilation systems into the atmosphere and the contents of workers' safety and health within industrial sites are managed by the Ministry of Employment and Labor. Even with the approval of the Ministry of Environment, the number of unsuccessful cases by the Ministry of Employment and Labor has increased, causing a growing discontent among the sites due to production delays and additional costs of improvement. In addition, local exhaust systems that are at greater risk of fire explosion have increased the risk of severe industrial accidents due to fire explosion. This is due to insufficient design of air volume, control speed, return speed, duct size, and risk of fire explosion. This is because the criteria and procedures for approval of local exhaust ventilation systems are similar, but the Industrial Safety and Health Act adds additional screening items for safety and safety of workers and fire and explosion. In this study, the Environment Ministry and the Employment and Labor Ministry seek to find a reasonable way to operate the system by comparing local exhaust ventilation system installation approval standards.

Design & Performance of the Solar Energy Research & Test Center (태양에너지 연구 시험센타 설계 및 효율에 관한 연구)

  • Auh, Paul Chung-Moo;Lee, Jong-Ho;Choi, Byung-Owan;Cho, Yil-Sik
    • Solar Energy
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    • v.2 no.2
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    • pp.29-36
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    • 1982
  • The Solar Energy R&D Department of KIER under the auspice of the Korean government is pushing hard on the development of the passive solar technology with high priority for the expeditious widespread use of solar energy in Korea, since the past few years of experiences told us that the active solar technology is not yet ready for massive commercialization in Korea. KIER has completed the construction of the Solar Energy Research & Test Center in Seoul, which houses the major facilities for its all solar test programs. The Center was designed as a passive solar building with great emphasis on the energy conserving ideas. The Center is not only the largest passive building in Korea, but also the exhibit center for the effective demonstration of the passive heating and cooling technology to the Korean public. The Center was designed to satisfy the requirements based on the technical and economical criteria set by the KIER. Careful considerations, therefore, were given in depth in the following areas to meet the requirements. 1) Passive Heating Concepts The Center employed the combination of direct and indirect gain system. The shape of the Center is Balcomb House style, and it included a large built-in sunspace in front. A partition, consists of transparent and translucent glazings, separates the sunspace and the living space. Since most activities in the Center occur during the day time, direct utilization of the solar energy by the living spaces was emphasized with the limited energy storage capacity. 2) Passive Cooling Concepts(for Summer) Natural ventilation concept was utilized throughout the building. In the direct gain portion of the system, the front glazing can be openable during the cooling season. Natural convection scheme was also applied to the front sunspace for the Summer cooling. Reflective surfaces and curtains were utilized wherever needed. 3) Auxiliary Heat ing and Cooling System As an auxiliary cooling system, mechanical means(forced convection system) were adopted. Therefore forced air heating system was also used to match the duct work requirements of the auxiliary cool ing system. 4) Effect ive Insulation & Others These included the double glazed windows, the double entry doors, the night glazing insulation, the front glazing-frame insulation as well as the building skin insulation. All locally available construction materials were used, and natural lightings were provided as much as possible. The expected annual energy savings (compared to the non-insulated conventional building)of the Center was estimated to be about 80%, which accounts for both the energy conservation and the solar energy source. The Center is being instumented for the actual performance tests. The experimental results of the simplified tests are discussed in this paper.

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Numerical Study for Flow Uniformity in Selective Catalytic Reduction(SCR) Process (SCR 공정에서 반응기 내부의 유동 균일화를 위한 수치적 연구)

  • Jung, Yu-Jin;Hong, Sung-Gil;Kim, Min-Choul;Lee, Jae-Jeong;Lee, Gang-Woo;Shon, Byung-Hyun
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.12 no.10
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    • pp.4666-4672
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    • 2011
  • Performance of NOx removal in SCR(Selective Catalytic Reduction) process depends on such various factors as catalyst factors (catalyst composition, catalyst form, space velocity, etc.), temperature of exhaust gas, and velocity distribution of exhaust gas. Especially the flow uniformity of gas stream flowing into the catalyst layer is believed to be the most important factor to influence the performance. In this research, the flow characteristics of a SCR process at design stage was simulated, using 3-dimensional numerical analysis method, to confirm the uniformity of the gas stream. In addition, the effects of guide vanes, baffles, and perforated plates on the flow uniformity for the inside and catalyst layer of the reactor were studied in order to optimize the flow uniformity inside the SCR reactor. It was found that the installation of a guide vane at the inlet duct L-tube part and the installation of a baffle at the upper part is very effective in avoiding chaneling inside the reactor. It was also found that additional installation of a perforated plate at the lower part of the potential catalyst layer buffers once more the flow for very uniform distribution of the gas stream.