• Fire Science and Engineering
• /
• v.22 no.4
• /
• pp.11-19
• /
• 2008

In order to show the most suitable ventilation conditions for the prevention of spontaneous combustion of small ship engine room, We have performed CFD simulation and analyzed flow and temperature fields. The flow patterns indicated differently according to the number and location of supply and exhaust opening. The case of locating the exhaust openings at the center of left and right side ceiling to the longitudinal symmetric line were more effective to eliminate the generated heat. When the number of supply and exhaust openings were increased, the case of increasing the number of exhaust opening showed more suitable ventilation conditions. The most suitable ventilation conditions in order to prevent the spontaneous combustion of small ship engine room was predicted that the supply opening located at the center of front and after side ceiling to across symmetric line, and the exhaust opening located at the center of both side walls.

• Journal of Navigation and Port Research
• /
• v.48 no.4
• /
• pp.274-283
• /
• 2024

Climate change is currently one of the most pressing environmental issues, primarily caused by carbon emissions from fossil fuel usage. As a result, alternative fuels that effectively reduce carbon emissions are garnering more attention. Among these alternatives, hydrogen has numerous advantages, such as its ability for large-scale storage and transport. However, it is crucial to prioritize safety measures, particularly in facilities that handle hydrogen, due to its highly flammable and fast-spreading nature. This study aims to compare and analyze the placement of supply and exhaust vents to efficiently release hydrogen in the event of a leak in an enclosed space. The experiments involved six different scenarios, each with various combinations of supply and exhaust vents. To ensure the experimental process's safety, helium, which shares similar physical properties with hydrogen, was used to analyze the internal oxygen concentration during ventilation system operations. The results revealed that among the six scenarios, Case 2, which employed a lower side supply vent and an upper side exhaust vent, exhibited the shortest ventilation time of 4 minutes and 30 seconds. Additionally, the decrease rate in oxygen concentration was examined in the upper, middle, and lower areas. Ventilation utilizing an upper surface supply vent and two exhaust vents on the upper surface and upper side (Case 6), showed lower oxygen concentration values in the upper area, while Case 2 yielded lower values in the middle and lower areas. Therefore, it is crucial to select an appropriate supply and exhaust vent configuration considering the space's characteristics and usage environment.

• Journal of the Korean Society of Marine Environment & Safety
• /
• v.28 no.2
• /
• pp.385-393
• /
• 2022

Hydrogen has reduced greenhouse gas (GHG) emissions, the main cause of global warming, and is emerging as an eco-friendly energy source for ships. Hydrogen is a substance with a lower flammability limit (LFL) of 4 to 75% and a high risk of explosion. To be used for ships, it must be sufficiently safe against leaks. In this study, we analyzed the effect of changes in the area of the air inlet / vent port on the ventilation performance when hydrogen leaks occur in the hydrogen tank storage room. The area of the air inlet / vent port is 1A = 740 mm × 740 mm, and the size and position can be easily changed on the surface of the storage chamber. Using ANSYS CFX ver 18.1, which is a CFD commercial software, the area of the air inlet / vent port was changed to 1A, 2A, 3A, and 5A, and the hydrogen mole fraction in the storage chamber when the area changed was analyzed. Consequently, the increase in the area of the air inlet port further reduced the concentration of the leaked hydrogen as compared with that of the vent port, and improved the ventilation performance of at least 2A or more from the single air inlet port. As the area of the air inlet port increased, hydrogen was uniformly stratified at the upper part of the storage chamber, but was out of the LFL range. However, simply increasing the area of the vent port inadequately affected the ventilation performance.

• Journal of the Korean Solar Energy Society
• /
• v.25 no.2
• /
• pp.71-79
• /
• 2005

In this study, the ventilation performance of mechanical ventilation system in apartment House was analyzed through model test according to characteristics of air-vent. Then adequate interval of air-vent was suggested using computer simulation which will create comfort environment through improvement of ventilation performance in apartment house. The result of experiment with separation plate to prevent mixture of contaminated exhaust air with fresh supply air, the ventilation efficiency improved about 10%. The result of simulation with horizontal location of exterior air-vent, contaminated exhaust air is mixed regardless of interval variation. Consequently, mixture of the exhaust air can be prevented through locating the supply air vent on the top side and exhaust air vent on the lower side.

• Land and Housing Review
• /
• v.14 no.4
• /
• pp.111-120
• /
• 2023

Indoor air quality has become increasingly important with the increase in time spent in residential environments, impact of external fine dust, yellow dust, and the post-COVID 19 pandemic. Residential mechanical ventilation plays a key role in addressing indoor air quality. The legal standard for residential air changes per hour in Korea is 0.5 ACH. However, there are no standards for the location of supply and return vents. This study atempts to analyze the impact of ventilation performance based on the location of supply and return vents. An experiment was conducted using the CO₂ tracer gas concentration decay method in a mock-up house set inside a large chamber to minimize external influences. The experimental results indicated that the commonly used combination of 2 supply and 2 return vents in living room spaces had a lower mean age of air than the combination of 1 supply and 2 return vents. Using multiple supply and return vents had lower mean age of air than using just 1 supply and 1 return vent.

• Proceedings of the Korea Water Resources Association Conference
• /
• 2017.05a
• /
• pp.323-323
• /
• 2017

본 연구 대상인 주암댐-주암조절지댐간 도수터널은 저수지 간 연계운영을 통하여 서 남해안 일대의 용수 공급하기 위하여 건설되어 운영되었으나, 터널의 구조적 불안정성이 제기됨에 따라 향후 발생 가능성이 있는 용수공급 중단을 방지하기 위하여 신규 도수터널이 제안되었다. 계획된 신규 도수 터널의 주요 시설물은 크게 양방향 운영이 가능한 터널(D=3.3 m, L=11.23 km), 각 저수지 상황별 운영을 위한 취수문비 2개소, 도수가 이루어지는 상황에서 수문 돌발 폐쇄시 수충격을 감쇄하기 위한 배기구(air vents) 2개소가 계획되었다. 이에 따라 본 연구에서는 주암댐에서 주암조절지댐으로 최대 유량이 통수되는 상태에서, 수문폐쇄에 따른 수충격을 정량적으로 분석하고자 Joukowsky 공식에 적용하여 완폐쇄와 급폐쇄시 도수터널의 안정성을 검토하였으며, 수문 폐쇄로 인한 천이적인 흐름상태 등 수충격 모의가 가능한 1차원 ITM 모형을 적용하여, 수리분석과 수치모형과 결과 비교하고, 계획된 배기구의 유무에 따른 효과를 알아보고자 하였다. 분석 결과, 계획된 0.3 m/min으로 수문을 폐쇄할 경우, 도수터널의 안정성에는 문제가 없을 것으로 분석되었으나, 수문을 급 폐쇄 할 경우, 압력수두가 크게 증가하여 도수터널에 위험이 있을 것으로 분석되었으며 배기구 유무에 따른 수충격 검토 결과 도수터널 내의 수압상승을 적절히 조절하는 조압수조의 역할을 만족스럽게 수행할 것으로 분석되었다.

• Proceedings of the SAREK Conference
• /
• 2006.11a
• /
• pp.53-53
• /
• 2006

• Korean Journal of Air-Conditioning and Refrigeration Engineering
• /
• v.21 no.3
• /
• pp.193-200
• /
• 2009

The ventilation system of apartments can be divided by supply and exhaust fan, supply fan and exhaust free and supply free and exhaust fan. Recently, the individual ventilation system and central ventilation system which is combined cooling system with duct system are applied to apartment ventilation system. The airflow pattern is affected by location of supply unit and exhaust unit in indoor. This study is to investigate the proper distance between supply unit and exhaust unit using CFD. As a result of this study, the proper distance between supply unit and exhaust unit could be suggested at the interval of 3 m in supply and exhaust fan system and 2.5 m in supply fan and exhaust free.

• Journal of Korean Tunnelling and Underground Space Association
• /
• v.21 no.1
• /
• pp.177-188
• /
• 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.

• 한국전산유체공학회:학술대회논문집
• /
• 2011.05a
• /
• pp.240-242
• /
• 2011

Wind power system is generally divided into the onshore wind turbine and the offshore wind turbine according to site locations. The offshore wind turbine is manufactured as a closed nacelle cooling system including a heat exchanger to prevent corrosion, but the onshore wind turbine is manufactured as open nacelle cooling system dependent on only the outdoor air without a heat exchanger. The indoor of a nacelle which is composed of a generator, foil power converters and a gearbox with a lot of heat is very narrow and airtight. This aim of the study is to demonstrate the temperature effect depending on positions of air-supply and exhaust ports. And this study discusses the flow field and removal efficiency of heat caused by components.