The Simulation of Natural Ventilation of Buildings With Different Location of Windows/Openings

2015 ◽  
Author(s):  
A. Idris ◽  
B. P. Huynh ◽  
Z. Abdullah
Keyword(s):  
Air Quality ◽  
Flow Pattern ◽  
Turbulence Model ◽  
Natural Ventilation ◽  
Air Flow ◽  
Building Design ◽  
Building Envelope ◽  
Navier Stokes ◽  
Computational Domain ◽  
Numerical Predictions

Ventilation is a process of changing air in an enclosed space. Air should continuously be withdrawn and replaced by fresh air from a clean external source to maintain internal good air quality, which may referred to air quality within and around the building structures. In natural ventilation the air flow is due through cracks in the building envelope or purposely installed openings. Its can save significant amount of fossil fuel based energy by reducing the needs for mechanical ventilation and air conditioning. Numerical predictions of air velocities and the flow patterns inside the building are determined. To achieve optimum efficiency of natural ventilation, the building design should start from the climatic conditions and orography of the construction to ensure the building permeability to the outside airflow to absorb heat from indoors to reduce temperatures. Effective ventilation in a building will affects the occupant health and productivity. In this work, computational simulation is performed on a real-sized box-room with dimensions 5 m × 5 m × 5 m. Single-sided ventilation is considered whereby openings are located only on the same wall. Two opening of the total area 4 m2 are differently arranged, resulting in 16 configurations to be investigated. A logarithmic wind profile upwind of the building is employed. A commercial Computational Fluid Dynamics (CFD) software package CFD-ACE of ESI group is used. A Reynolds Average Navier Stokes (RANS) turbulence model & LES turbulence model are used to predict the air’s flow rate and air flow pattern. The governing equations for large eddy motion were obtained by filtering the Navier-Stokes and continuity equations. The computational domain was constructed had a height of 4H, width of 9H and length of 13H (H=5m), sufficiently large to avoid disturbance of air flow around the building. From the overall results, the lowest and the highest ventilation rates were obtained with windward opening and leeward opening respectively. The location and arrangement of opening affects ventilation and air flow pattern.

Effect of Inlet Location on Ventilation Flow Through a Room Fitted With Solar Chimney

2018 ◽  
Author(s):  
Kashif Nazir ◽  
B. P. Huynh
Keyword(s):  
Solar Radiation ◽  
Flow Pattern ◽  
Natural Ventilation ◽  
Air Flow ◽  
Ventilation Rate ◽  
Navier Stokes ◽  
Computational Domain ◽  
Solar Chimney ◽  
Flow Through ◽  
Inlet Opening

Solar chimney (thermal chimney) is a device which absorbs solar radiation to heat the air. The heated air, becoming buoyant, rises through the chimney’s passage and induces further air currents. When fitted to a building, solar chimney can thus induce fresh outside air to flow through the building for ventilation. Because only natural means (solar radiation here) are involved to cause the air flow, solar chimney is considered a natural-ventilation device. This work investigates computationally natural ventilation induced by a roof-mounted solar chimney through a real-sized 3-dimensional room, using a commercial CFD (Computational Fluid Dynamics) software package which employs the Finite Volume Method. Chien’s turbulence model of low-Reynolds-number K-ε is used in a Reynolds-Averaged Navier-Stokes (RANS) formulation. Computational domain that includes regions outside the room’s inlet opening and chimney’s exit allows for employing realistic boundary conditions for the computational model. Ventilation rate and air-flow pattern through the room are considered in terms of the location of the room’s inlet opening. It is found that while ventilation flow-rate through the room is higher with the room-inlet opening being located high on the wall opposite to the chimney’s entrance, a room-inlet opening being located near the ground results in better flow pattern with more flow through the living area in the lower part of the room.

Large Eddy Simulation of Single-Sided Ventilated Room With Different Location of Windows

2014 ◽  
Author(s):  
A. Idris ◽  
B. P. Huynh
Keyword(s):  
Large Eddy Simulation ◽  
Flow Pattern ◽  
Flow Rate ◽  
Natural Ventilation ◽  
Air Flow ◽  
Navier Stokes ◽  
Eddy Motion ◽  
Eddy Simulation ◽  
Continuity Equations ◽  
Large Eddy

The natural ventilation contributes the improvement of internal thermal comfort and internal air quality when applied properly. An investigation of single-sided double opening was performed to a 3-dimensional rectangular-box room using a commercial Computational Fluid Dynamics (CFD) software package of ESI group. Sixteen models with different location of double-openings were investigated. The large eddy simulation (LES) turbulence model was used to predict the air’s flow rate and air flow pattern. The governing equations for large eddy motion was obtained by filtering the Navier-Stokes and continuity equations. From the overall results, the lowest and the highest air flow rates were obtained to be 1.14 × 10−3 m3/s and 2.12 × 100 m3/s respectively. The location & arrangement of opening influences the air flow rate and air flow pattern.

Natural-Ventilation Flow in a 3-D Room Fitted With Solar Chimney

2012 ◽  
Author(s):  
B. P. Huynh
Keyword(s):  
Heat Flux ◽  
Flow Pattern ◽  
Natural Ventilation ◽  
Air Flow ◽  
Ventilation Rate ◽  
High Heat Flux ◽  
Solar Chimney ◽  
Solar Heat ◽  
Solar Heat Flux ◽  
Inlet Opening

Natural-ventilation flow induced in a real-sized rectangular-box room fitted with a solar chimney on its roof is investigated numerically, using a commercial CFD (Computational Fluid Dynamics) software package. The chimney in turn is in the form of a parallel channel with one plate being subjected to uniform solar heat flux. Ventilation rate and air-flow pattern through the room are considered in terms of the heat flux for two different locations of the room’s inlet opening. Chien’s turbulence model of low-Reynolds-number K-ε is used in a Reynolds-Averaged Navier-Stokes (RANS) formulation. It is found that ventilation flow rate increases quickly with solar heat flux when this flux is low, but more gradually at higher flux. At low heat flux, ventilation rate is not significantly affected by location of the inlet opening to the room. On the other hand, at high heat flux, ventilation rate varies substantially with the opening’s location. Location of the inlet opening to the room also affects strongly the air-flow pattern. In any case, ample ventilation rate is readily induced by the chimney.

scholarly journals Indoor Air Quality (IAQ): Accuracy of Natural Ventilation for Temperature, Air Flow Rate and Relative Humidity (RH) in School Building Classrooms

2018 ◽  
Vol 7 (3.9) ◽  
pp. 42
Author(s):  
Norsafiah Norazman ◽  
Adi Irfan Che Ani ◽  
Nor Haslina Ja’afar ◽  
Muhamad Azry Khoiry
Keyword(s):  
Air Quality ◽  
Relative Humidity ◽  
Indoor Air Quality ◽  
Indoor Air ◽  
Natural Ventilation ◽  
Air Flow ◽  
Weather Conditions ◽  
Potential Health ◽  
The Hours ◽  
Hot Weather

Indoor Air Quality (IAQ) is an essential matter in achieving students’ satisfaction for the learning process. Building’s orientation is a factor that may encourage sufficient natural ventilation for the classroom occupants. Inadequate ventilation is an issue for most existing classrooms. The purpose of this paper is to analyze the accuracy of natural ventilation in classrooms. Therefore, experimental on 20 classrooms has been conducted by using Multipurpose Meter at secondary school buildings in Malaysia. The findings indicated that the accuracy of natural ventilation testing was below the permissible limits throughout the hours monitored, thus this may cause potential health hazards to the students. Temperature and air flow rates were lower than 23 °C and 0.15 m/s respectively, it fulfilled the basic requirements as a standard learning environment. However, measurements taken showed the overall relative humidity (RH) in the classrooms can be categorized as acceptable with 40% to 70% range. On the basis of these findings, it is evident that naturally ventilated classrooms are important especially due to energy efficiency, whereas mechanical ventilation should only be installed as an alternative under extremely hot weather conditions.   

Tall building influence on city wind pattern

2018 ◽  
Vol 29 (10) ◽  
pp. 1850086
Author(s):  
M. S. Almeida ◽  
A. D. Araújo ◽  
M. P. Almeida
Keyword(s):  
Population Growth ◽  
Numerical Simulations ◽  
Turbulence Model ◽  
Natural Ventilation ◽  
Tall Buildings ◽  
Navier Stokes ◽  
Urban Centers ◽  
Wind Pattern ◽  
Rans Equations ◽  
Weak Wind

The population growth in big urban centers generates the necessity for tall buildings. This phenomenon happens also in tourist regions where it is necessary to host many people. However, locations with high buildings interfere with the flow of the wind and can affect the comfort and safety of pedestrians at street level. Tall buildings barrier reduces the natural ventilation in regions far from the beach. This work presents the results concerning the effects created by tall buildings on Mucuripe beach, Fortaleza, Brazil. We performed numerical simulations to verify the wind interference with buildings in an area of [Formula: see text][Formula: see text]m2, using the OpenFOAM toolbox, to solve the Reynolds Averaged Navier–Stokes (RANS) equations with the [Formula: see text]–[Formula: see text] turbulence model. The results showed how the obstacles alter the airflow. From them, one can identify the regions with reduced safety and pedestrian comfort, and also the weak wind zone created by the downstream of the constructions for the different wind directions that are locally observed.

scholarly journals Effect of Cross-Ventilation and Solar Irradiation on IAQ as a function of Roof Angle

2019 ◽  
Vol 111 ◽  
pp. 01038
Author(s):  
Anil B. Atalar ◽  
Murat Cakan
Keyword(s):  
Solar Radiation ◽  
Natural Ventilation ◽  
Reference Model ◽  
Computational Cost ◽  
Reference Line ◽  
Solar Irradiation ◽  
Discrete Ordinates ◽  
Computational Domain ◽  
Numerical Predictions ◽  
The Impact

Natural ventilation is the most conventional and one of the significant alternative applications for energy efficiency. Cross-ventilation is commonly used in hospitals, shopping centres or greenhouses. In this study, cross-ventilation for a greenhouse was investigated. The greenhouse buildings may differ in design depending on the region and climate. Therefore, when natural ventilation methodology is carried out in these buildings, the effect of solar radiation should also be taken into consideration. There have been many studies on natural ventilation in the literature, but while these studies have been conducted, the impact of solar irradiation has never been combined. In the present study computational geometry was created according to 4 different roof inclinations: 0°, 15°, 30°, and 45° - provided that the inlet and outlet opening positions are fixed. Moreover, each inclination was simulated at the following hours of the day: 10:00, 13:00 and 16:00 in June. The hex-dominant grid was created for a computational domain using Cut-cell method and Renormalization-group (RNG) k-ε turbulence model provides the best results and efficient computational cost. In addition to this, Discrete Ordinates (DO) radiation model with SIMPLE algorithm was implemented for solar radiation effect. In order to decrease the temperature of the reference line, the evaporating cooling methodology was performed and a new PVC cover material was applied. Numerical predictions show that solar irradiance combined with roof inclination and outlet opening position has a significant effect on velocity and temperature distribution inside the building space. The air mass flow rate which aspirates from outlet increases considerably when the inclination angle is increased, also flow character changes according to configurations. Evaporative cooling creates a decrease in temperatures on the reference line up to 2 – 2.5°C when compared with the reference model.

scholarly journals On The Effect Of The Shape Of Buildings And Chimneystacks On Ventilation And Pollutant Dispersion

2019 ◽  
Vol 213 ◽  
pp. 02017 ◽  
Author(s):  
Simone Ferrari ◽  
Maria Grazia Badas ◽  
Michela Garau ◽  
Luca Salvadori ◽  
Alessandro Seoni ◽  
...  
Keyword(s):  
Air Quality ◽  
Natural Ventilation ◽  
Water Channel ◽  
Pollutant Dispersion ◽  
Building Design ◽  
Outer Flow ◽  
Air Exchange Rate ◽  
Roof Shape ◽  
Analysis Technique ◽  
Heat Dispersion

The purpose of this work is to investigate the modifications induced by the change of the roof shape in the flow field, inside and above the buildings, with an attention to their capability to modify the air quality and the dispersion of pollutants released from chimneystacks. We have carried out laboratory experiments on arrays of identical buildings, with symmetrical dual-pitched or flat roofs, and chimneystacks of different heights and positions. The experiments have been carried out in a close-loop water-channel, where two non-intrusive and quasi-continuous in space Digital Image Analysis technique have been implied to measure the velocity fields (Feature Tracking Velocimetry) and the concentration fields (Laser Induced Visualization). Results have highlight the meaningful role of gabled roofs in modifying turbulence, which increases the air exchange rate between the street canyon and the outer flow, but, in some conditions, they increase the dragging of pollutant inside the canyon. These results can have an immediate practical impact on the building design and on planning strategies, as the roof shape can be a useful tool to enhance natural ventilation and pollutant, humidity and/or heat dispersion, i.e. the air quality in urban and industrial areas.

Numerical Simulation of Gas Flow Pattern in Cyclone Spray Scrubber

2011 ◽  
Vol 233-235 ◽  
pp. 701-706
Author(s):  
Bing Tao Zhao ◽  
Yi Xin Zhang ◽  
Kai Bin Xiong
Keyword(s):  
Numerical Simulation ◽  
Fluid Flow ◽  
Flow Pattern ◽  
Gas Flow ◽  
Stokes Equations ◽  
Tangential Velocity ◽  
Navier Stokes ◽  
Computational Domain ◽  
Spray Scrubber ◽  
Cfd Method

The numerical simulation of the fluid flow is presented by CFD technique to characterize the flow pattern of cyclone spray scrubber. In this process, the Reynolds-averaged Navier-Stokes equations with the Reynolds stress turbulence model (RSM) for fluid flow are solved by use of the finite volume method based on the SIMPLE pressure correction algorithm in the fluid computational domain. According to the computational results, the tangential velocity, axial velocity and turbulence intensity of the gas flow are addressed in the different flowrate. The results indicate that the CFD method can effectively reveal the mechanism of gas flow in the cyclone spray scrubber.

Research on the Effect of Natural Ventilation on Buses in Summer Based on CFD Numerical Simulation Method

2011 ◽  
Vol 361-363 ◽  
pp. 1056-1060 ◽  
Author(s):  
Bao Lin ◽  
Xue Ting Wang ◽  
Xiao Hu
Keyword(s):  
Numerical Simulation ◽  
Thermal Comfort ◽  
Natural Ventilation ◽  
Thermal Environment ◽  
Air Flow ◽  
Cost Effective ◽  
Simulation Method ◽  
Computational Domain ◽  
Cfd Numerical Simulation ◽  
Different Parts

Because of the relatively narrow space and high density distribution of the passengers, the bus interior environment deteriorates in summer. Natural ventilating introduces a fresh natural freeze, provides the bus interior with appropriate distribution of air supply temperature and velocity field. Making good use of natural ventilation is an operating strategy ideal for improving passengers’ satisfaction, which is considered as an environmental friendly and cost effective approach. Based on CFD numerical simulation, with a whole-domain approach, this paper predicts air flow and thermal comfort in naturally ventilated bus. The outside and inside airflow is modelled simultaneously and within the same computational domain. The thermal environment in different parts of the bus interior is compared. Different vehicle velocities and conditions of windows are taken into account, analysis are made regarding to the effect of both of them on the interior thermal comfort. The result shows, air disturbance at the bus rear parts are intenser than the other parts with better thermal satisfaction; the quality of air flow in different parts makes the temperature difference in bus achieve as high as 3°C; the use of roof openings distributes the temperature more evenly.

scholarly journals Optimalisasi Penghawaan Alami melalui Tata Ruang di Rumah Susun Bertingkat Rendah

Jurnal IPTEK ◽  
2018 ◽  
Vol 2 (1) ◽  
pp. 150-160
Author(s):  
Fuad Rizal
Keyword(s):  
Air Quality ◽  
Indoor Air Quality ◽  
Public Housing ◽  
Wind Velocity ◽  
Indoor Air ◽  
Natural Ventilation ◽  
Electricity Consumption ◽  
Building Design ◽  
Maintenance Cost ◽  
Housing Design

ABSTRACT Quality of natural ventilation in low rise public housing in Jakarta tends to be low. Situation mentioned above presumably caused by several case, among other form and unadequate opening placement, unadequate furniture placement, form and orientation of public housing mass and minimum building protection from sun radiation. Whereas natural ventilation have an importent role in increasing indoor air quality, increasing occupant healthy and help increasing electricity consumption eficiency. The objective of this research is attempt solving natural ventilation problems in low rise public housing architecturally through designs that could used for occupant activity precisely and presenting good natural ventilation simultaneously so it can support occupant activity in public housing as efficiently, comfortable, healthy and secure. Research begins with conduct an observation towards existing public housing in Jakarta through interview, documentation of existing public housing condition and studying public housing designs through working documents and related standards. Collecting climate data especially wind velocity conducted to get illustration of condition that take place in definite period. Those data then analyzed to produce a model formula of public housing building that tested later with computer. The result of research show that the problems of natural ventilation in low rise public housing can be solved by accurately building design that can adapt with surrounding nature. Quite significant positive change occurs after modification does to the existing unit. Hopefully government through certain official can produce public housing design which more optimal, especially in natural ventilation. People also could knowing the caused of natural ventilation problems inside the room also could solving it by simply, efficiently and accurately through the result of this research. Some advantages occupant could gained are good and prevalent airflow inside the room, reducing air conditioning equipment utilization frequency, less maintenance cost and can it can works all the time.  Keywords: natural ventilation, sun radiation, electricity consumption efficiency, indoor air quality, low rise public housing, wind velocity

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