• Title/Summary/Keyword: Numerical ventilation

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A Numerical Study of Ventilation System Operation for Smoke Control in a Subway Station when a Train under Fire is Approaching (화재열차가 진입하여 정차하는 지하철 역사에서 제연을 위한 환기장치 운전에 대한 수치해석 연구)

  • Lee, Seung-Ho;Hur, Nahm-Keon;Cha, Chul-Hyun;Ryou, Hong-Sun;Kim, Dong-Hyeon;Jang, Yong-Jun
    • Proceedings of the SAREK Conference
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    • 2009.06a
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    • pp.136-141
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    • 2009
  • The platform screen door(PSD) is installed in the station of the Seoul Metro 9th line for passengers' safety and comfortable environment of the station. The track way exhaust system(TES) is also operated with PSD to exhaust heat released from train. TES can also be used for the purpose of the heat and smoke control in an emergency case of the carriage fire. When the fire is occurred, operation of TES is switched to the smoke exhaust mode form its normal ventilation mode. In the present study, a subway station of Seoul Metro 9th line is modeled, and a 3-D CFD simulation is performed to investigate effectiveness of designed TES in case of fire. A scenario that a train under fire is arriving the station is simulated for several possible operation modes of the TES using moving mesh technique. As a result, temperature and CO concentration distribution in the station is obtained for each operation modes of TES. The effectiveness of TES operation in case of fire is also discussed.

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Numerical Simulation on Smoke Movement in Multi-Compartment Enclosure Fires under Pressurized Air Supply Conditions (급기가압 조건에서 복합 구획 공간 화재의 연기 거동에 대한 수치해석 연구)

  • Ko, Gwon Hyun
    • Fire Science and Engineering
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    • v.32 no.6
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    • pp.15-21
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    • 2018
  • This study examined the flow characteristics of fire smoke under pressurized air ventilation conditions by carrying out fire simulations on multi-compartment enclosure, including room, ancillary room and stair case. Fire simulations were conducted for the air-leakage test facility, which was constructed to measure the effective leakage area and aimed to improve the understandings of fire and smoke movement by analyzing the overall behaviors of fire smoke flow and pressure distributions of each compartment. The simulation results showed that the heat release rate of the fires was controlled sensitively by the amount of air supplied by the ventilation system. An analysis of the velocity distributions between the room and ancillary room showed that fire smoke could be leaked to the ancillary room through the upper layer of the door, even under pressurized air supply conditions. From these results, it was confirmed that the fire size and spatial characteristics should be considered for the design and application of a smoke control system by a pressurized air supply.

Analysis of Ventilation Performance of PCVD Facility for Solar Cell Manufacturing (Explosion Prevention Aspect) (태양전지 제조용 PCVD설비의 환기 성능 분석(폭발 방지 측면))

  • Lee, Seoung-Sam;An, Hyeong-hwan
    • Journal of the Korean Institute of Gas
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    • v.26 no.5
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    • pp.35-40
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    • 2022
  • PCVD (Plasma Chemical Vapor Deposition), a solar cell manufacturing facility, is a facility that deposits plasma generated in a chamber (NH3, SIH4, O2 on a wafer. In the PCVD facility, gas movement and injection is performed in the gas cabinet, and there are many leak points inside because MFC, regulator, valve, pipe, etc. are intricately connected. In order to prevent explosion in case of leakage of NH3 with an upper explosive limit (UEL) of 33.6% and a lower explosive limit (LEL) of 15%, the dilution capacity must be capable of allowing the concentration of NH3 to be out of the explosive range. This study was analyzed using the CFD analysis technique, which can confirm the dilution ability in 3D and numerical values when NH3 gas leaks from the existing PCVD gas cabinet. As a result, it was concluded that it corresponds to medium dilution and that testicular ventilation is possible through facility improvement.

Recent Progress in Air-Conditioning and Refrigeration Research : A Review of Papers Published in the Korean Journal of Air-Conditioning and Refrigeration Engineering in 2013 (설비공학 분야의 최근 연구 동향 : 2013년 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.26 no.12
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    • pp.605-619
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    • 2014
  • This article reviews the papers published in the Korean Journal of Air-Conditioning and Refrigeration Engineering during 2013. 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 fluid machinery, pipes and relative parts including orifices, dampers and ducts, fuel cells and power plants, cooling and air-conditioning, heat and mass transfer, two phase flow, and the flow around buildings and structures. Research issues dealing with home appliances, flows around buildings, nuclear power plant, and manufacturing processes are 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 general analytical model for desiccant wheels, the effects of water absorption on the thermal conductivity of insulation materials, thermal properties of Octadecane/xGnP shape-stabilized phase change materials and $CO_2$ and $CO_2$-Hydrate mixture, effect of ground source heat pump system, the heat flux meter location for the performance test of a refrigerator vacuum insulation panel, a parallel flow evaporator for a heat pump dryer, the condensation risk assessment of vacuum multi-layer glass and triple glass, optimization of a forced convection type PCM refrigeration module, surface temperature sensor using fluorescent nanoporous thin film. In the area of pool boiling and condensing heat transfer, researches on ammonia inside horizontal smooth small tube, R1234yf on various enhanced surfaces, HFC32/HFC152a on a plain surface, spray cooling up to critical heat flux on a low-fin enhanced surface were actively carried out. In the area of industrial heat exchangers, researches on a fin tube type adsorber, the mass-transfer kinetics of a fin-tube-type adsorption bed, fin-and-tube heat exchangers having sine wave fins and oval tubes, louvered fin heat exchanger were performed. (3) In the field of refrigeration, studies are categorized into three groups namely refrigeration cycle, refrigerant and modeling and control. In the category of refrigeration cycle, studies were focused on the enhancement or optimization of experimental or commercial systems including a R410a VRF(Various Refrigerant Flow) heat pump, a R134a 2-stage screw heat pump and a R134a double-heat source automotive air-conditioner system. In the category of refrigerant, studies were carried out for the application of alternative refrigerants or refrigeration technologies including $CO_2$ water heaters, a R1234yf automotive air-conditioner, a R436b water cooler and a thermoelectric refrigerator. In the category of modeling and control, theoretical and experimental studies were carried out to predict the performance of various thermal and control systems including the long-term energy analysis of a geo-thermal heat pump system coupled to cast-in-place energy piles, the dynamic simulation of a water heater-coupled hybrid heat pump and the numerical simulation of an integral optimum regulating controller for a system heat pump. (4) In building mechanical system research fields, twenty one studies were conducted to achieve effective design of the mechanical systems, and also to maximize the energy efficiency of buildings. The topics of the studies included heating and cooling, HVAC system, ventilation, and renewable energies in the buildings. Proposed designs, 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 is mostly focused on indoor environment and building energy. The main researches of indoor environment are related to infiltration, ventilation, leak flow and airtightness performance in residential building. The subjects of building energy are worked on energy saving, operation method and optimum operation of building energy systems. The remained studies are related to the special facility such as cleanroom, internet data center and biosafety laboratory. water supply and drain system, defining standard input variables of BIM (Building Information Modeling) for facility management system, estimating capability and providing operation guidelines of subway station as shelter for refuge and evaluation of pollutant emissions from furniture-like products.

A Numerical Study of Automotive Indoor Thermal Comfort Model According to Boarding Conditions and Parameters Related to HVAC (HVAC 관련 매개변수 및 탑승조건에 따른 자동차 실내의 온열쾌적성 평가모델에 관한 수치해석적 연구)

  • Yoon, Seong Hyun;Park, Jun Yong;Son, Deok Young;Choi, Yunho;Park, Kyungseok
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.38 no.9
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    • pp.979-988
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    • 2014
  • Recently, the interest in the thermal comfort is ever increasing as the time people stay in the automobile is gradually increasing. So far, however, the cooling performance of the HVAC(heating and ventilation air conditioning) system is evaluated by thermal environment criteria such as indoor air velocity and temperature, not by a thermal comfort index. Furthermore, the precise criteria has not been established yet when the thermal comfort for the automobile is evaluated using numerical analysis. In this study, the numerical analysis of automobile indoor thermal comfort according to various parameters such as HVAC operating mode, airflow, passenger boarding conditions is performed during the HVAC system's initial operating time(20 minutes). The solar ray tracing model and S2S radiation model are used and validated to simulate an external heat source. Based on this study, an evaluation model which can predict the thermal comfort index for the combination of the above parameters is presented.

A Numerical Study on the Fire Behavior Phenomena in a Special Fire Protection Compartment (특수 방호공간에서 가상화재의 발생으로 인한 화재거동에 관한 수치적 연구)

  • Kim, Tae-Kuk;Son, Bong-Sei
    • Journal of the Korean Society of Hazard Mitigation
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    • v.1 no.1 s.1
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    • pp.157-163
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    • 2001
  • The objective of the present study is to predict the characteristics of the fire and smoke propagations in a clean room. Numerical calculations have been performed by using the finite volume method to obtain temperature and velocity distributions in the clean room. In odor to account for the turbulent flow characteristics, the standard $k-{\varepsilon}$ model is used. From this study, it was found that the fire propagation could be fully developed only after 150 seconds when the ventilation system in the clean room was off. And the smoke mass fraction showed a similar distribution as the gas temperature. Since the simulated fire was proceeded up to $20{\sim}30%$ of the room within 60 seconds. it could be recommended that the occupants should be evacuated from the room within 30 seconds.

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Scaled model tests for improvement and applicability of the transverse smoke control system on tunnels (횡류식 제·배연 시스템의 개선 및 적용성 분석을 위한 모형실험 연구)

  • Kim, Hyo-Gyu;Baek, Doo-San;Kim, Jae-Hyun;Lee, Seong-Won;Yoo, Ji-Oh
    • Journal of Korean Tunnelling and Underground Space Association
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    • v.22 no.5
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    • pp.563-574
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    • 2020
  • Currently, road tunnels and railroad tunnels are building smoke control systems to emit toxic gases and smoke from fires. Among the various smoke control systems, the transverse smoke control system has the disadvantage that air supply or exhaust is performed on only half of the cross-section, rather than air supply or exhaust on the entire cross-section of the tunnel as air is supplied or exhausted by partitioning the wind path. Therefore, this study analyzed the effect of exhaustion through numerical analysis and scaled model tests on the zoning smoke control system, which improved the limitations of the transverse smoke control system. As a result of the scaled model test, the transverse ventilation system exhibited a 25.6% smoke control rate based on the state where no smoke was controled, and zoning smoke control system showed a smoke control rate of 40.8%. In addition, as a result of numerical analysis, it was found that transverse ventilation system did not control fire smoke spreading from the tunnel and continued to spread. On the other hand, zoning smoke control system was found to be smoke controled within a certain section due to the air curtain effect and the flue gas effect.

Recent Progress in Air-Conditioning and Refrigeration Research: A Review of Papers Published in the Korean Journal of Air-Conditioning and Refrigeration Engineering in 2008 (설비공학 분야의 최근 연구 동향: 2008년 학회지 논문에 대한 종합적 고찰)

  • Han, Hwa-Taik;Choi, Chang-Ho;Lee, Dae-Young;Kim, Seo-Young;Kwon, Yong-Il;Choi, Jong-Min
    • Korean Journal of Air-Conditioning and Refrigeration Engineering
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    • v.21 no.12
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    • pp.715-732
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    • 2009
  • This article reviews the papers published in the Korean Journal of Air-Conditioning and Refrigeration Engineering during 2008. 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) Research trends in thermal and fluid engineering have been surveyed in the categories of general fluid flow, fluid machinery and piping, new and renewable energy, and fire. Well-developed CFD technologies were widely applied in developing facilities and their systems. New research topics include fire, fuel cell, and solar energy. Research was mainly focused on flow distribution and optimization in the fields of fluid machinery and piping. Topics related to the development of fans and compressors had been popular, but were no longer investigated widely. Research papers on micro heat exchangers using nanofluids and micro pumps were also not presented during this period. There were some studies on thermal reliability and performance in the fields of new and renewable energy. Numerical simulations of smoke ventilation and the spread of fire were the main topics in the field of fire. (2) Research works on heat transfer presented in 2008 have been reviewed in the categories of heat transfer characteristics, industrial heat exchangers, and ground heat exchangers. Research on heat transfer characteristics included thermal transport in cryogenic vessels, dish solar collectors, radiative thermal reflectors, variable conductance heat pipes, and flow condensation and evaporation of refrigerants. In the area of industrial heat exchangers, examined are research on micro-channel plate heat exchangers, liquid cooled cold plates, fin-tube heat exchangers, and frost behavior of heat exchanger fins. Measurements on ground thermal conductivity and on the thermal diffusion characteristics of ground heat exchangers were reported. (3) In the field of refrigeration, many studies were presented on simultaneous heating and cooling heat pump systems. Switching between various operation modes and optimizing the refrigerant charge were considered in this research. Studies of heat pump systems using unutilized energy sources such as sewage water and river water were reported. Evaporative cooling was studied both theoretically and experimentally as a potential alternative to the conventional methods. (4) Research papers on building facilities have been reviewed and divided into studies on heat and cold sources, air conditioning and air cleaning, ventilation, automatic control of heat sources with piping systems, and sound reduction in hydraulic turbine dynamo rooms. In particular, considered were efficient and effective uses of energy resulting in reduced environmental pollution and operating costs. (5) In the field of building environments, many studies focused on health and comfort. Ventilation. system performance was considered to be important in improving indoor air conditions. Due to high oil prices, various tests were planned to examine building energy consumption and to cut life cycle costs.

A Study on Simulator for Environment Control of Agricultural Production Facility - Construction of Basic System with Numerical Model - (농업생산시설의 환경조절용 시뮬레이터에 관한 연구 - 수치모델에 의한 기본시스템 구축 -)

  • 손정익;최규홍
    • Journal of Bio-Environment Control
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    • v.5 no.2
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    • pp.111-119
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    • 1996
  • The purpose of this study is to construct the main system of simulator for the environment control of agricultural production facilities. The model describing the system was based on the energy and mass balance in an unsteady - state situation. The model consist of the three major parts : the main model, the light model, and the environmental control model, and each part was separated to be developed individually. The main model which is the core of this system includes the thermal model, the soil model, the ventilation model, the cultivation model, and the carbon dioxide model. And also the environmental control model includes the thermal curtain model, the heater/cooler model and the underground heat exchanger model. The equations used in this model were written in analog programming methods using PCSMP The simulator was evaluated through comparison between simulated and measured temperatures controlled during daytime and night. The results showed good agreements between the predicted and measured temperatures.

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Numerical Investigation of Smoke Behavior in Rescue Station for Tunnel Fire (철도터널 화재 시 구난역 내의 연기거동에 대한 수치해석 연구)

  • Hong, Sa-Hoon;Ro, Kyung-Chul;Ryou, Hong-Sun;Lee, Seong-Hyuk
    • Journal of the Korean Society for Railway
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    • v.12 no.1
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    • pp.25-30
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    • 2009
  • The present study deals with numerical investigation for smoke behavior in rescue station by using the commercial CFD code (FLUENT Ver 6.3). With the use of the MVHS(Modify Volumetric Heat Source) model modified from the original VHS(Volumetric Heat Source) model, a 10 MW mode was adopted for simulation and the MVHS model can describe the generation of product and the oxygen consumption at the stoichiometric state. In addition, the present simulation includes the species conservation equations for the materialization of heat source and the estimation of smoke movement. From the results, the smoke flows are moving along the ceiling because of thermal buoyancy force and as time goes, the smoke gradually moves downward at the vicinity of the entrance. Moreover, without using ventilation, it is found that the smoke flows no longer spread across the cross-passages because the pressure in the non-accident tunnel is higher than that in the accident tunnel.