scholarly journals Analysis on the Exhaust Air Recirculation of the Ventilation System in Multi-Story Building

2021 ◽  
Vol 11 (10) ◽  
pp. 4441
Author(s):  
Seonghyun Park ◽  
Hyungyu Park ◽  
Janghoo Seo
Keyword(s):  
Mechanical Ventilation ◽  
South Korea ◽  
Indoor Air ◽  
Ventilation System ◽  
Ventilation Rate ◽  
Cfd Analysis ◽  
Recirculation Rate ◽  
Computational Fluid Dynamics Cfd ◽  
And Performance ◽  
Story Building

In South Korea, the installation of a mechanical ventilation system is mandatory for the management of indoor air quality, and various studies concerning the ventilation rate and performance of the ventilation system have been conducted. However, only a few studies have been conducted regarding the recirculation rate of the ventilation system. If the appropriate arrangement of intake and exhaust vents in the ventilation system is not considered, the pollutants emitted from the circulation movement may be recirculated into the indoor environment and cause the degradation of the performance of the ventilation system. Therefore, this study aimed to quantitatively analyze the recirculation rate of pollutants emitted from a kindergarten building with an installed mechanical ventilation system in Seoul, South Korea, using computational fluid dynamics (CFD) analysis, and analyze the effectiveness of the guide panel installed for the prevention of the pollutants’ recirculation. The number of cases for the CFD analysis was set to a total of ten based on the ventilation rate in a mechanical ventilation system, external wind direction, and the existence of the guide panel for preventing the recirculation of exhaust air. The maximum recirculation rate of exhaust air without the installation of a guide panel was shown to be 20.0%. The maximum recirculation rate in the case where the external wind speed, direction of wind, and the ventilation rate were assumed to be identical to the other case but the guide panel for preventing the recirculation of exhaust air was assumed to be installed was 7.7%, 12.3% lower compared with the case with maximum recirculation rate.

Numerical Evaluation of Ventilation Efficiency of Window Type Ventilation Systems

2019 ◽  
Vol 27 (03) ◽  
pp. 1950027
Author(s):  
Young Kwon Yang ◽  
Min Young Kim ◽  
Jin Woo Moon ◽  
Jin Chul Park
Keyword(s):  
Mechanical Ventilation ◽  
Indoor Air ◽  
Numerical Evaluation ◽  
Natural Ventilation ◽  
Ventilation System ◽  
Adverse Pressure Gradient ◽  
Building Energy ◽  
Window Opening ◽  
Ventilation Efficiency ◽  
Air Purifier

Ventilation in buildings is the simplest and most convenient way to purify indoor air. However, when the ventilation is not enough due to natural ventilation, it should be cleaned by mechanical ventilation or air purifier. This process requires building energy. Therefore, it is possible to save the energy of the building by merely increasing the natural ventilation efficiency. This study conducted airflow analysis simulations to investigate the effects of changes in the shape of ventilation openings and louvers on the ventilation efficiency of a window ventilation system. The streamlined window opening exhibited a greater increase in airflow (41.3%) than did the conventional window (24.3%) for the ventilation model with four openings. It was also observed that flow separation and wakes were generated by the adverse pressure gradient arising from the increased airflow speed when a louver was employed. Based on these results, it can be concluded that using a louver as a wind augmentation device is an obstacle to improving the airflow in a window ventilation system.

Numerical Simulation of the Flow Field for Rotor Ventilation System of Large-Scale Nuclear Power Turbo-Generator

2012 ◽  
Vol 152-154 ◽  
pp. 1498-1504 ◽  
Author(s):  
Xiao Hu Zhang ◽  
Lei Hu ◽  
Jian Hua Yuan ◽  
Yi Chao Yuan
Keyword(s):  
Flow Field ◽  
Nuclear Power ◽  
Large Scale ◽  
Ventilation System ◽  
Flow Distribution ◽  
Basic Unit ◽  
Turbo Generator ◽  
Key Issues ◽  
Computational Fluid Dynamics Cfd ◽  
And Performance

The nuclear power turbo-generator with large capacity is a basic unit of nuclear power plant, while the cooling technology becomes one of the key issues which affect its design and operation deeply. Axial-radial ventilation structure for rotor is commonly used in large nuclear power generator. In this article, according to the basic principles of computational fluid dynamics (CFD), ventilation’s structure and performance is analyzed, 3D flow model is also established. After the boundary conditions are determined, the numerical calculation and analysis is finished. And then, the rules of flow distribution is obtained, the flow field and the static pressure character of the gap is also computed, which could be very important to the ventilation system of the whole generator.

Experimental and Simulation Validation Methods of Local Exhaust Ventilation (LEV) in Training Facilities Building

2013 ◽  
Vol 315 ◽  
pp. 997-1001 ◽  
Author(s):  
Ng Chee Seng ◽  
Abdul Mutalib Leman ◽  
Azmahani Sadikin
Keyword(s):  
Indoor Air ◽  
Ventilation System ◽  
Percentage Error ◽  
Local Exhaust Ventilation ◽  
Geometry Model ◽  
Exhaust Ventilation ◽  
Simulation Validation ◽  
Air Ventilation ◽  
Computational Fluid Dynamics Cfd ◽  
Real Flow

LEV is a ventilation system that collects and sucks out particles such as dusts, mists, gases, vapors or fumes out of work station, so that they can’t be breathed in by occupants. There is a lot of LEV allocated and installed in order to help protecting occupants’ health but it doesn’t work properly. To overcome this issue, computational fluid dynamics (CFD) will be implemented. Past studies CFD techniques represent a very significant improvement of air ventilation systems. However, CFD is just a tool in prediction model, which can lead to inaccuracy of predicting airflow due to problems with pre-processing, solver and post-processing with parameter from actual experimental results. As of yet, it is not possible to 100% accurately simulate airflow around a body. These codes are simply models which are close to that of a real flow, but not an exact match. All of these require validation to help minimizing percentage error in CFD methodology. Several strategies are needed to boost effectiveness of LEV in terms of predicting airflow in a geometry model. The outcome of this research can be used as a benchmark or guideline for industries to help improving indoor air quality (IAQ).

scholarly journals Exposure Assessment in Nail Salons: An Indoor Air Approach

2012 ◽  
Vol 2012 ◽  
pp. 1-7 ◽  
Author(s):  
Cora Roelofs ◽  
Tuan Do
Keyword(s):  
Carbon Dioxide ◽  
Exposure Assessment ◽  
Indoor Air ◽  
Ventilation System ◽  
Ventilation Rate ◽  
Self Report ◽  
Adequate Ventilation ◽  
The Common ◽  
Traditional Approaches ◽  
Nail Salons

Due to the complexity of the nail salon work environment, traditional approaches to exposure assessment in this context tend to mischaracterize potential hazards as nuisances. For this investigation, a workable “indoor air” approach was devised to characterize potential hazards and ventilation in Boston, Massachusetts area nail salons which are primarily owned and staffed by Vietnamese immigrants. A community-university partnership project recruited salons to participate in a short audit which included carbon dioxide measurements and evaluation of other air quality metrics. Twenty-two salons participated. Seventy-three percent of the salons had spot carbon dioxide measurements in excess of 700 ppm, the level corresponding to a ventilation rate recommended for beauty salons. Fourteen salons (64%) did not have a mechanical ventilation system to provide fresh air and/or exhaust contaminated air. The lack of adequate ventilation is of significant concern because of the presence of potentially hazardous chemicals in salon products and the common self-report of symptoms among nail technicians. Community and worker health may be improved through adoption of recommended ventilation guidelines and reduction in the hazard potential of nail products.

scholarly journals Advancement of Turbine Aerodynamic Design Techniques

1993 ◽  
Author(s):  
Lisa W. Griffin ◽  
Frank W. Huber
Keyword(s):  
Fluid Dynamics ◽  
State Of The Art ◽  
Cfd Analysis ◽  
Aerodynamic Design ◽  
Turbine Efficiency ◽  
Component Design ◽  
Pump Stage ◽  
Computational Fluid Dynamics Cfd ◽  
The Government ◽  
And Performance

The Consortium for Computational Fluid Dynamics (CFD) Application in Propulsion Technology has been created at NASA/MSFC. Its purpose is to advance the state-of-the-art of CFD technology, to validate CFD codes and models, and to demonstrate the benefits attainable through the application of CFD in component design. Three teams are currently active within the Consortium: (1) the Turbine Technology Team, (2) the Pump Stage Technology Team, and (3) the Combustion Devices Technology Team. The goals, dynamics, and activities of the Turbine Team are the subjects of this paper. The Consortium is managed by NASA. The Turbine Team is co-coordinated by a NASA representative from the CFD area and an industry (Pratt & Whitney) representative from the area of turbine aerodynamic design. Membership of the Turbine Team includes experts in design, analysis, and testing from the government, industry, and academia. Each member brings a unique perspective, expertise, and experience to bear on the team’s goals of improving turbine efficiency and robustness while reducing the amount of developmental testing. To this end, an advanced turbine concept has been developed within the team using CFD as an integral part of the design process. This concept employs unconventionally high turning blades and is predicted to provide cost and performance benefits over traditional designs. This concept will be tested in the MSFC Turbine Airflow Facility to verify the design and to provide a unique set of data for CFD code validation. Currently, the team is developing and analyzing methods to reduce secondary and tip losses to further enhance turbine efficiency. The team has also targeted volute development as an area that could benefit from detailed CFD analysis.

Application and Analysis Chilling Ceiling Combined with Displacement Ventilation System in Office Buildings

2010 ◽  
Vol 160-162 ◽  
pp. 294-300
Author(s):  
Ling Wang ◽  
Wei Yang Qi ◽  
Ri Chao Liu ◽  
Shun Jun He
Keyword(s):  
Indoor Air ◽  
Thermal Stratification ◽  
Ventilation System ◽  
Displacement Ventilation ◽  
Airflow Velocity ◽  
Indoor Airflow ◽  
Air Supply ◽  
Computational Fluid Dynamics Cfd ◽  
Save Energy ◽  
Lower Temperature

Using the method of computational fluid dynamics (CFD), numerically simulates office building with chilling ceiling /displacement ventilation (CC/DV) and analyzes indoor airflow velocity field, temperature field and thermal stratification height of the building. Consider that the CC/DV system can improve indoor air quality and save energy. And the CC/DV system could solve many constraints of displacement ventilation system. when the cooling load is large, due to the limit of air supply and temperature supply the displacement ventilation system can not be used, but the CC/DV system could well satisfied the requirement of body. The CC/DV system also has the problem of lower thermal stratification height because the chilling ceiling has a lower temperature.

Research on Demand Controlled Ventilation Strategy for Laboratory Ventilation System

2013 ◽  
Vol 805-806 ◽  
pp. 1558-1561
Author(s):  
Zhen Hua Bao
Keyword(s):  
Indoor Air ◽  
Energy Use ◽  
Ventilation System ◽  
Substantial Reduction ◽  
Ventilation Rate ◽  
Outdoor Air ◽  
Air Exchange Rate ◽  
Controlled Ventilation ◽  
Demand Controlled Ventilation ◽  
Rate Requirement

Reducing the amount of outdoor air entering a space has distinct advantages for ventilation system. However, it often brings the consequence of depressing indoor air quality (IAQ). For laboratories, on average, the laboratory IAQ conditions of low TVOCs and low particulates permitted the substantial reduction of minimum air change rates. With many modern laboratories operating with fewer fume hoods and more energy-efficient equipment and lighting, the labs minimum air exchange rate requirement is often the dominant energy use driver. Current codes or specifications for laboratories ventilation system are the most straight forward approaches. They do not optimize a laboratory's ventilation rate, or verify whether the intended levels of safety and comfort have been achieved by the labs design. Demand controlled ventilation (DCV) can also avoid over-ventilation by providing outdoor air rates based on actual occupancy rather than on design occupancy or full occupancy.

scholarly journals Room HVAC Influences on the Removal of Airborne Particulate Matter: Implications for School Reopening during the COVID-19 Pandemic

Energies ◽  
2021 ◽  
Vol 14 (22) ◽  
pp. 7463
Author(s):  
Ali Mohammadi Nafchi ◽  
Vincent Blouin ◽  
Nigel Kaye ◽  
Andrew Metcalf ◽  
Katie Van Valkinburgh ◽  
...  
Keyword(s):  
Higher Education ◽  
Indoor Air ◽  
Complex Function ◽  
Airborne Particulate Matter ◽  
Ventilation Rate ◽  
Air Distribution ◽  
Internal Source ◽  
Hvac System ◽  
Airborne Particulate ◽  
And Performance

(1) Background: Many schools and higher education settings have confronted the issue of reopening their facilities after the COVID-19 pandemic. In response, several airflow strategies spanning from adding portable air purifiers to major mechanical overhauls have been suggested to equip classrooms with what is necessary to provide a safe and reliable environment. Yet, there are many unknowns about specific contributions of the building system and its design and performance on indoor air quality (IAQ) improvements. (2) Methods: this study examined the combined effect of ventilation type, airflow rates, and filtration on IAQ in five different classrooms. Experiments were conducted by releasing inert surrogate particles into the classrooms and measuring the concentrations in various locations of the room. (3) Results: we showed that while the distribution of particles in the space is a complex function of space geometry and air distribution configurations, the average decay rate of contaminants is proportional to the number of air changes per hour in the room. (4) Conclusions: rooms with a central HVAC system responded quicker to an internal source of contamination than rooms with only fan coil units. Furthermore, increasing the ventilation rate without improved filtration is an inefficient use of energy.

scholarly journals Influence of Building Envelope Type on the Minimum Mechanical Ventilation Rate to Achieve a Positive Indoor Air Pressure

2020 ◽  
Vol 172 ◽  
pp. 05002
Author(s):  
Yuchen Shi ◽  
Xiaofeng Li ◽  
Seyedehelham Sadatiseyedmahalleh
Keyword(s):  
Mechanical Ventilation ◽  
Indoor Air ◽  
Ventilation Rate ◽  
Building Envelope ◽  
Air Pressure ◽  
Large Space ◽  
Industrial Plants ◽  
Window Width ◽  
Open Plan ◽  
Vertical Spacing

In order to limit the infiltration of outdoor air pollutants, a positive indoor air pressure should be maintained. This study aims to investigate the minimum mechanical ventilation rate to achieve a positive indoor air pressure for large space buildings with different kinds of envelopes. The types of building envelope include envelope with multilayer windows (which generally appears in shopping malls and open-plan office buildings), envelope with entrances on the first floor and multilayer windows, and envelope with openings at bottom and top levels (which generally appears in industrial plants). It is concluded that the minimum ratio between mechanical ventilation and initial infiltration rates to achieve a positive indoor air pressure depends on the window width-height ratio, the vertical spacing between windows, and the number of window layers. More regulations are summarized and analysed to guide the ventilation design.

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