• Title, Summary, Keyword: Natural ventilation pressure

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A Study on Natural Ventilation Performance by Periodic Outdoor Pressure Fluctuations (주기적인 외부 압력변동에 의한 자연환기성능 연구)

  • Lee, Seung-Yeon;Yom, Chol-Min;Han, Hwa-Taek
    • Proceedings of the SAREK Conference
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    • pp.27-32
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    • 2005
  • This paper investigates the effects of outdoor pressure fluctuations on natural ventilation through openings of a building envelope. The ventilation airflow rate depends on the magnitude and the period of the pressure fluctuations, the size of the opening compared to the space volume, and the resistance characteristics of the opening. Non-dimensional parameters have been derived, which determine indoor pressure responses due to outdoor pressure fluctuations. The flow regions are categorized into synchronized region, opening resistance region, and transition region depending on the non-dimensional parameters.

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Analysis on Ventilation Performance of Natural Ventilation Systems in Multi-Family Housing Using Blower Door Test (Blower Door Test를 이용한 공동주택 자연환기시스템의 환기성능 분석)

  • Kim, Min Seok;Auh, Jin Sun;Hong, Goopyo;Kim, Byungseon Sean
    • KIEAE Journal
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    • v.16 no.6
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    • pp.129-134
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    • 2016
  • Today, natural ventilation systems are widely applied in multi-family housing. However, studies using the wind data trend line of the blower door test are insufficient. Purpose: Through this study, we will propose a computational method about ventilation performance of natural ventilation systems by conducting blower door test. Method: First, we sealed the gaps between the main systems including the natural ventilation system and conducted the blower door test. Next, the natural ventilation system was opened, the blower door test was conducted, and the difference in air flow rate between when closed and when opened was checked. Blower door test was carried out with a pressure difference of 50 Pa. Result: Therefore, the ventilation performance of the natural ventilation system was checked by drawing a trend line using the data to calculate the air flow rate at 2 Pa of the natural ventilation equipment standard pressure difference.

Modeling of Turbulent Ventilation through an Opening due to Outdoor Pressure Fluctuations (개구부를 통한 외부압력 변동에 의한 난류환기 모델링)

  • Han, Hwa-Taik;Yom, Chol-Min
    • Korean Journal of Air-Conditioning and Refrigeration Engineering
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    • v.20 no.2
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    • pp.121-127
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    • 2008
  • This paper investigates the effects of outdoor pressure fluctuations on natural ventilation through an opening on a building envelope. The ventilation airflow rate depends on the magnitude and the period of the pressure fluctuations, the size of the opening relative to the space volume, and the resistance characteristics of the opening. Non-dimensional parameters have been derived, which determine indoor pressure responses due to outdoor pressure fluctuations. The flow regions are categorized into (1) synchronized region, (2) opening resistance region, and (3) transition region depending on the non-dimensional parameter derived. Pressure fluctuations and flow characteristics are investigated numerically using the 4th order Runge-Kutta method.

A Study on Thermodynamic Natural Ventilation Analysis by the Field Survey of Underground Mines in Korea (현장실측을 통한 국내 일반광의 열역학적 자연통기력 연구)

  • Yu, Yeong-Seok;Roh, Jang-Hoon;Kim, Jin
    • Tunnel and Underground Space
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    • v.23 no.4
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    • pp.288-296
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    • 2013
  • In this study, a total of 13 mines were finally selected as study subjects and field measurements were conducted. Thereafter, calculations of thermodynamic natural ventilation were attempted using spread sheets and solutions for natural ventilation of mine types with multiple vertical shafts were obtained. Based on the results, natural ventilation of each mine was quantified. In addition, changes in natural ventilation energy (NVE) and natural ventilation pressure (NVP) were estimated assuming mine deepening and the resultant values were applied to mine conditions to observe changes in flow rates. Natural ventilation pressure in domestic mines is generally calculated to be in a range of 5 Pa~300 Pa. Although NVP increases as the depth increases, resistance also increases. Therefore, as the depth increases, flow rates show a tendency of converging on a certain value because of the relationship between NVP and mine resistance. Natural ventilation using shafts with depth differences is effective up to depths of 200~300 m. However, flow rate change rates resulting from NVP are small at depths deeper than approximately 200~300 m. Therefore, if a mine is deepened over 300 m, NVP will become insufficient and thus additional pressure obtained through mechanical ventilation will be necessary.

Development of a Natural Ventilation Model in a Single Zone Building with Large Openings (큰 개구부를 가진 단일구획 빌딩에서의 자연환기 모델의 개발)

  • Cho, Seok-Ho
    • Journal of Environmental Science International
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    • v.27 no.6
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    • pp.359-369
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    • 2018
  • A model has been developed to predict natural ventilation in a single zone building with large openings. This study first presents pressure-based equations on natural ventilation, that include the combined effect of wind and thermal buoyancy. Moreover, the concept of neutral pressure level(NPL) is introduced to consider the two-way flow through a large opening. The total pressure differences across the opening and the NPL are calculated, and nonlinear equations are solved to find the zonal pressure to satisfy mass conservation. For this analysis, an iterative technique of successively approximating the zonal pressure is used. The results of applying this study model to several simple cases are as follows. When there is no wind and only the stack effect is caused, a one-way flow occurs in both the top and bottom openings in the case of two openings of equal-area, and a one-way flow occurs in the top opening; however, a two-way flow occurs in the bottom opening in the case of two openings of unequal-area. When there is a wind effect, regardless of whether the outside air temperature is lower or higher than the indoor air temperature, air flows into the room through the bottom opening and out of the room through the top opening. As the wind velocity increases, the wind effect appears to be more influential than the stack effect owing to the temperature difference.

The Analysis on the Variation of the Ventilation Rates by Wind Pressure and Temperature Difference between Indoor and Outdoor in the Multi-Story Type Double Skin Facade applied to the Office Building (오피스 건물에 적용된 다층형 이중외피의 풍압과 실내·외 온도차에 의한 환기량 변화 분석)

  • Song, Chi-Ho;Kim, Teayeon;Leigh, Seung-Bok
    • KIEAE Journal
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    • v.15 no.2
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    • pp.123-131
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    • 2015
  • Purpose : Improvement of indoor thermal comfort and reduction of the energy consumption in building can be obtained by applying a double skin facade system. In order to achieve effectively this purpose, design team would have to perform easy and appropriate performance analysis for making better design decision during the design process. Method : This paper focus on the natural ventilation performance of a multi-story type double skin facade with main causes which are pressure difference according to the wind and temperature difference between indoor and outdoor (Buoyancy Effect). Using this main causes, the natural ventilation ratio of wind effect-to-buoyancy effect in cavity of multi-story type double skin facade were analyzed through the performance analysis results of CFD (Computational Fluid Dynamics) simulation. Result : When the wind velocity was 2m/s, the ventilation rate in the cavity was highest. If wind velocity was slower than 2m/s wind velocity, buoyancy effect has more influence on the ventilation rate in the cavity, and if wind velocity was faster than 2m/s wind velocity, wind effect has more influence on the ventilation rate in the cavity.

A Study on the Site Planning of an Apartment Complex for Improving the Outdoor and Indoor Air Quality (아파트의 실내외 공기질 향상을 위한 주동 배치 계획 연구)

  • Shin, Jee-Woong;Kim, Tae-Yeon;Lee, Kyung-Hoi
    • KIEAE Journal
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    • v.4 no.3
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    • pp.195-202
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    • 2004
  • This study focuses on the impacts of apartment building arrangements on the outdoor and indoor air quality - the efficiency of natural ventilation in the outside/inside area of an apartment with consideration to the characteristics of an air flow in outside area depending on the types of the arrangements, the main direction of the wind, and the outside wind pressure on the building facade. As indices to evaluate the efficiency of natural ventilation, the concepts of "Age of Air" and "Purging Flow Rate(PFR)" were used in this study. As indices to classify the efficiency of indoor natural ventilation, the mean values of the wind pressure differences between the front and the back elevations of an apartment building were used. The research showed that the PFR of each apartment building arrangement ranges from 0.867 to 3.253. The "minus-shaped" arrangement showed the highest PFR, 2.306; the "zigzag-shaped" arrangement measured 1.889; the "angle-shaped" arrangement measured 1.465, and the "square-shaped" arrangement measured 1.241. Depending on the direction of the wind, the pressure differences range extremely, with variations from 170% to 2300%. Thus, the indoor natural ventilation efficiency can be changed by the pressure differences of the wind, which are sensitive to the main direction of the wind even though the structure and planning of the apartment complexes are the same. Despite the same direction of the wind, even the efficiency can be diverse. This study showed how to predict the most beneficial apartment building arrangement for the profitable natural ventilation efficiency in each direction of the wind.

Development of Vehicle Tunnel Ventilation System (도로터널 환기시스템 개발연구)

  • Lee, Chang-Woo
    • Proceedings of the SAREK Conference
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    • pp.71-74
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    • 2008
  • This paper aims at studying the key design elements for the optimal ventilation system design, developing the design models and suggesting the design guidelines. The key elements include the basic exhaust emission rate, wall friction coefficient, vehicle drag coefficient and slip streaming effect, jet fan operating efficiency, natural ventilation force and installation scheme for jet fans and ventilation monitors in tunnel. The design models developed in this study are one-dimensional ventilation simulator to analyze the air flow, pressure profile and pollutant dispersion inside and outside tunnel, expert model to choose the optimal ventilation method, and the ventilation characteristic chart to evaluate the preliminary ventilation system. The study results are reflected in the design guideline for road tunnel ventilation system.

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A Study on Natural Ventilation by the Caloric Values of HLW in the Deep Geological Repository (지하처분장내 고준위 방사성 폐기물 발열량에 따른 자연환기력 연구)

  • Roh, Jang-Hoon;Choi, Heui-Joo;Yu, Yeong-Seok;Yoon, Chan-Hoon;Kim, Jin
    • Tunnel and Underground Space
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    • v.21 no.6
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    • pp.518-525
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    • 2011
  • In this study, the natural ventilation pressure resulting from the large altitude difference which is a characteristic of high radioactive waste repository and the caloric value of the heat emitted by wastes was calculated and based on the results, natural ventilation quantities were calculated. A high radioactive waste repository can be considered as being operated through closed cycle thermodynamic processes similar to those of thermal engines. The heat produced by the heating of high radioactive wastes in the underground repository is added to the surrounding air, and the air goes up through the upcast vertical shaft due to the added heat while working on its surroundings. Part of the heat added by the work done by the air can be temporarily changed into mechanical energy to promote the air flow. Therefore, if a sustained and powerful heat source exists in the repository, the heat source will naturally enable continued cyclic flows of air. Based on this assumption, the quantity of natural ventilation made during the disposal of high radioactive wastes in a deep geological layer was mathematically calculated and based on the results, natural ventilation pressure of $74{\sim}183$Pa made by the stack effect was identified along with the resultant natural ventilation quantity of $92.5{\sim}147.7m^3/s$. The result of an analysis by CFD was $82{\sim}143m^3/s$ which was very similar to the results obtained by the mathematical method.

An Application Study on a Strategy to Promote Natural Ventilation at an Atrium Building (아트리움을 이용한 자연환기 활성화 방안에 관한 사례 연구)

  • Shin, Seon-Joon;Lee, Seung-Yeon;Jo, Jin-Kyun;Han, Soo-Gon;Hong, Min-Ho
    • Proceedings of the SAREK Conference
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    • pp.540-545
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    • 2008
  • An atrium has great potential in natural ventilation aided by buoyance effect. Architectural design of an atrium is very critical to maximize the effect. However, it is not easy of an atrium to have optimum shape for natural ventilation, from the aesthetic and economic point of view. Admitting this condition, we suggested a strategy to promote natural ventilation, which can be adopted only with small design change. At first, we installed BIPV on the top of an atrium to strengthen buoyancy effect, and combine forced ventilation by low pressure fan. To evaluate the performance of the measure, CFD simulation and Energy-Airflow analysis were achieved.

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