scholarly journals How a Natural Ventilation Shaft Affects Smoke Layer Descent in Room Fires

2012 ◽  
Vol 11 (1) ◽  
pp. 199-204
Author(s):  
Jui-Lin Chen ◽  
Chi-ming Lai
Keyword(s):  
Natural Ventilation ◽  
Ventilation Shaft ◽  
Room Fires ◽  
Smoke Layer

scholarly journals AN ANALYTICAL MODEL ON STATIC SMOKE EXHAUST IN ATRIA

2010 ◽  
Vol 16 (3) ◽  
pp. 372-381 ◽  
Author(s):  
Cheuk Lun Chow ◽  
Junmei Li
Keyword(s):  
Fluid Dynamics ◽  
Driving Force ◽  
Natural Ventilation ◽  
Flow Model ◽  
Far East ◽  
Field Tests ◽  
The Far East ◽  
Smoke Layer ◽  
Simple Flow ◽  
Exhaust Systems

Static smoke exhaust systems with natural vents are starting to be installed in big shopping complexes, ware‐houses and cargo terminals in the Far East. These systems are used for natural ventilation as well as for letting out smoke. This paper responds to concerns over the performance of static smoke exhaust systems, which remain less popular than dynamic smoke exhaust systems with mechanical fans. We propose a modification of a simple flow model found in the literature, adapting this to study smoke layer interface height with natural vents opened. We compare and justify our results, as generated by both Computational Fluid Dynamics and zone models, alongside reports of historical field tests. The model of smoke exhaust is applied in an illustrative example of a large hall, leading to the suggestion that a flow model could be used for designing natural vents. As the key driving force in removing smoke through natural vents is smoke's own buoyancy, the system might only be effective for bigger fires. Santrauka Tolimuosiuose Rytuose statines dūmu šalinimo sistemos su natūralios ventiliacijos angomis pradedamos irengti dideliuose prekybos kompleksuose, sandeliuose ir kroviniu terminaluose. Tokios sistemos naudojamos ir natūraliai ventiliacijai, ir dūmams šalinti. Šis straipsnis parengtas susirūpinus, kad statines dūmu išmetimo sistemos yra ne tokios populiarios nei dinamines dūmu išmetimo sistemos su mechaniniais ventiliatoriais. Autoriai siūlo literatūroje aprašomo paprasto srauto modelio modifikacija, pritaikant ši modeli dūmu sluoksnio salyčio su natūralios ventiliacijos angomis aukščiui tirti. Straipsnyje palyginti ir pagristi rezultatai, gauti taikant tiek skaičiuojamosios skysčiu dinamikos, tiek zonavimo modelius kartu su eksperimentiniais tyrimais vietoveje. Pateiktas dūmu šalinimo modelio taikymo pavyzdys dideleje saleje ir padaryta išvada, kad srauto modelis galetu būti taikomas irengiant natūralia ventiliacija. Kadangi pagrindine varomoji jega šalinant dūmus per natūralias ventiliacijos angas yra dūmu plūdrumas, sistema gali būti veiksminga tik esant didesniems gaisrams.

scholarly journals Determination of the speed of air outflow from the ventilation shaft of the warm attic of a multi-storey residential building under different initial conditions

2021 ◽  
Vol 18 (5) ◽  
pp. 126-129
Author(s):  
E. A. Anshukova ◽  
Keyword(s):  
Mathematical Modeling ◽  
System Performance ◽  
Natural Ventilation ◽  
Initial Conditions ◽  
Ventilation System ◽  
Residential Building ◽  
Operating Conditions ◽  
Ventilation Shaft

The operating conditions of a warm attic as an element of natural ventilation of a multi-storey residential building have an impact on the efficiency of the entire ventilation system performance, as well as on the condition of the enclosing structures. The study of the distribution of microclimate parameters in its volume makes it possible to more fully assess the ongoing processes. The result of calculating the rate of air outflow from the ventilation shaft of a warm attic by mathematical modeling is provided.

Green Ventilation System Design for Underground Garage

2015 ◽  
Vol 763 ◽  
pp. 105-109
Author(s):  
Shih Ming Chen ◽  
Yu Ying Huang ◽  
Yeng Horng Perng
Keyword(s):  
Air Quality ◽  
Indoor Air ◽  
Natural Ventilation ◽  
Ventilation System ◽  
Branch Pipe ◽  
Cost Effective ◽  
Design System ◽  
Horizontal Branch ◽  
Ventilation Shaft ◽  
Indoor Spaces

In recent years, the issues of indoor air quality and thermal comfort in underground garages have attained considerable importance. The purpose of this study is to present a green natural ventilation system with a ventilation shaft connected to the outdoors through a horizontal branch pipe. The system combines with a diaphragm wall and steel cage frame for an underground garage or similar underground enclosed spaces. The design system reduces use of tradition fans and motors used in mechanical ventilation. It improves exhaust from indoor spaces and reduces energy consumption. The green design of the ventilation system in this study is cost effective, saves energy and improves the air quality in an underground garage.

scholarly journals Sustainable Smoke Extraction System for Atrium: A Numerical Study

2021 ◽  
Vol 13 (13) ◽  
pp. 7406
Author(s):  
Martin Lyubomirov Ivanov ◽  
Wei Peng ◽  
Qi Wang ◽  
Wan Ki Chow
Keyword(s):  
Mechanical Ventilation ◽  
Natural Ventilation ◽  
Numerical Study ◽  
Ventilation System ◽  
High Heat ◽  
Fire Dynamics ◽  
Sustainable Environment ◽  
Design Fire ◽  
Smoke Layer ◽  
Computational Fluid Dynamics Cfd

Smoke extraction systems, either static with natural ventilation, or dynamic with mechanical ventilation are required to keep smoke layer at high levels in many tall atria. It is observed that a design fire with high heat release rate (HRR) is commonly used for designing natural vents, but a low HRR is used for mechanical ventilation system. This will not produce a sustainable environment. There are no internationally agreed on design guides to determine the HRR in the design fire for different extraction systems and scenarios. This issue will be studied using a Computational Fluid Dynamics (CFD)-based software, the Fire Dynamics Simulator (FDS) version 6.7.1. Simulations on natural smoke filling, static and dynamic smoke extractions were carried out in a big example atrium. CFD-FDS predictions were compared with previous full-scale burning tests. Results confirmed that static smoke extraction is a good option for big fires, and a dynamic system is best for small fires. A sustainable new hybrid design combining the advantages of static and dynamic systems is proposed, which could result in a lower smoke temperature and higher smoke layer interface height, indicating a better extraction design.

Study on the Shaft Height of Natural Ventilation Using Smoking Shaft in Urban Tunnel

2011 ◽  
Vol 90-93 ◽  
pp. 2297-2300
Author(s):  
Wei Zhong ◽  
Jian Peng Yang ◽  
Bao An Pei ◽  
Wei Zhang
Keyword(s):  
Natural Ventilation ◽  
Inertia Force ◽  
Flow State ◽  
Critical Height ◽  
Large Eddy Simulation Model ◽  
Eddy Simulation ◽  
Ventilation Shaft ◽  
Structure Of Flow ◽  
Large Eddy ◽  
Height Increase

The characteristics of smoke flow in natural ventilation shaft are studied in this paper, Using the computational fluid dynamics software FDS5.0 to build a 3D model of an urban tunnel with a smoking shaft, Large Eddy Simulation model was used to obtain the structure of flow field and the mass flow rate of natural ventilation at different shaft height, The results show that when the shaft height is low, the driving force of exhaust is weak and the exhaust capacity reduces rapidly, the flow state in shaft is controlled by horizontal inertia force; when the shaft height increase to a critical height, the exhaust effect enhance significantly, the flow state in shaft will change to stack effect control.

Investigation of the natural ventilation of wind catchers with different geometries in arid region houses

2020 ◽  
Vol 14 (3) ◽  
pp. 7109-7124
Author(s):  
Nasreddine Sakhri ◽  
Younes Menni ◽  
Houari Ameur ◽  
Ali J. Chamkha ◽  
Noureddine Kaid ◽  
...  
Keyword(s):  
Arid Region ◽  
Natural Ventilation ◽  
Reduction Rate ◽  
Internal Flow ◽  
Climatic Conditions ◽  
Maximum Pressure ◽  
Ventilation Technique ◽  
Window Position ◽  
The One ◽  
Flow Velocities

The wind catcher or wind tower is a natural ventilation technique that has been employed in the Middle East region and still until nowadays. The present paper aims to study the effect of the one-sided position of a wind catcher device against the ventilated space or building geometry and its natural ventilation performance. Four models based on the traditional design of a one-sided wind catcher are studied and compared. The study is achieved under the climatic conditions of the South-west of Algeria (arid region). The obtained results showed that the front and Takhtabush’s models were able to create the maximum pressure difference (ΔP) between the windward and leeward of the tower-house system. Internal airflow velocities increased with the increase of wind speed in all studied models. For example, at Vwind = 2 m/s, the internal flow velocities were 1.7, 1.8, 1.3, and 2.5 m/s for model 1, 2, 3, and 4, respectively. However, at Vwind = 6 m/s, the internal flow velocities were 5.6, 5.5, 2.5, and 7 m/s for model 1, 2, 3, and 4, respectively. The higher internal airflow velocities are given by Takhtabush, traditional, front and middle tower models, respectively, with a reduction rate between the tower outlet and occupied space by 72, 42, 36, and 33% for the middle tower, Takhtabush, traditional tower, and the front model tower, respectively. This reduction is due to the due to internal flow resistance. The third part of the study investigates the effect of window (exist opening) position on the opposite wall. The upper, middle and lower window positions are studied and compared. The air stagnation or recirculation zone inside the ventilated space reduced from 55% with the lower window to 46% for the middle window and reached 35% for the upper window position. The Front and Takhtabush models for the one-sided wind catcher with an upper window position are highly recommended for the wind-driven natural ventilation in residential houses that are located in arid regions.

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