Enhancement of natural ventilation rate and attic heat gain reduction of roof solar collector using radiant barrier

2007 ◽  
Vol 42 (6) ◽  
pp. 2218-2226 ◽  
Author(s):  
W. Puangsombut ◽  
J. Hirunlabh ◽  
J. Khedari ◽  
B. Zeghmati ◽  
M.M. Win
Keyword(s):  
Solar Collector ◽  
Natural Ventilation ◽  
Ventilation Rate ◽  
Heat Gain ◽  
Gain Reduction

Heat gain reduction by means of thermoelectric roof solar collector

Solar Energy ◽  
2005 ◽  
Vol 78 (4) ◽  
pp. 495-503 ◽  
Author(s):  
S. Maneewan ◽  
J. Hirunlabh ◽  
J. Khedari ◽  
B. Zeghmati ◽  
S. Teekasap
Keyword(s):  
Solar Collector ◽  
Heat Gain ◽  
Gain Reduction

Reducing Roof Solar Heat Gain by Using Double-Skin Ventilated Roofs

2020 ◽  
Vol 38 (3A) ◽  
pp. 402-411
Author(s):  
Mohannad R. Ghanim ◽  
Sabah T. Ahmed
Keyword(s):  
Inclination Angle ◽  
Convection Heat Transfer ◽  
Ventilation Rate ◽  
Channel Length ◽  
Air Gap ◽  
Galvanized Steel ◽  
Heat Gain ◽  
Solar Heat ◽  
Double Skin ◽  
Solar Heat Gain

Double skin ventilated roof is one of the important passive cooling techniques to reduce solar heat gain through roofs. In this research, an experimental study was performed to investigate the thermal behaviour of a double skin roof model. The model was made of two parallel galvanized steel plates. Galvanized steel has been used in the roof construction of industrial buildings and storehouses in Iraq. The effect of inclination angle (ϴ) from the horizontal and the spacing (S) between the plates was investigated at different radiation intensities. It is found that using a double skin roof arrangement with a sufficient air gap (S) can reduce the heat gain significantly. The higher the inclination angle (ϴ) the higher the ventilation rate, the lower the heat gain through the roof. In this study, increasing the air gap from 2 cm to 4 cm reduced the heat gain significantly but when the gap was further increased to 6 cm, the reduction in the heat flux was insignificant. A dimensionless correlation was also reduced between Nusselt number () and the single parameter  where L is the channel length. This correlation can be handily utilized for designing of engineering applications dealing with high temperature difference natural convection heat transfer.

scholarly journals Proposing Alternative Solutions to Enhance Natural Ventilation Rates in Residential Buildings in the Cfa Climate Zone of Rasht

2021 ◽  
Vol 13 (2) ◽  
pp. 679
Author(s):  
Roya Aeinehvand ◽  
Amiraslan Darvish ◽  
Abdollah Baghaei Daemei ◽  
Shima Barati ◽  
Asma Jamali ◽  
...  
Keyword(s):  
Natural Ventilation ◽  
Residential Buildings ◽  
Residential Building ◽  
Ventilation Rate ◽  
Humid Climate ◽  
The Sustainable Development ◽  
Passive Strategies ◽  
Development Goals ◽  
Ventilation Rates ◽  
Ventilation Systems

Today, renewable resources and the crucial role of passive strategies in energy efficiency in the building sector toward the sustainable development goals are more indispensable than ever. Natural ventilation has traditionally been considered as one of the most fundamental techniques to decrease energy usage by building dwellers and designers. The main purpose of the present study is to enhance the natural ventilation rates in an existing six-story residential building situated in the humid climate of Rasht during the summertime. On this basis, two types of ventilation systems, the Double-Skin Facade Twin Face System (DSF-TFS) and Single-Sided Wind Tower (SSWT), were simulated through DesignBuilder version 4.5. Then, two types of additional ventilation systems were proposed in order to accelerate the airflow, including four-sided as well as multi-opening wind towers. The wind foldable directions were at about 45 degrees (northwest to southeast). The simulation results show that SSWT could have a better performance than the aforementioned systems by about 38%. Therefore, the multi-opening system was able to enhance the ventilation rate by approximately 10% during the summertime.

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 The Role of Ab-Anbars in the Vernacular Architecture of Iran with Emphasis on the Performance of Wind-Catchers in Hot and Dry Climates

Heritage ◽  
2021 ◽  
Vol 4 (4) ◽  
pp. 3987-4000
Author(s):  
Fazeleh Yousefi ◽  
Francesco Nocera
Keyword(s):  
Natural Ventilation ◽  
Vernacular Architecture ◽  
Ventilation Rate ◽  
The People ◽  
Desert Areas ◽  
Dry Climates ◽  
Yazd City ◽  
Cooling Loads ◽  
Contemporary Architecture

Vernacular and traditional Iranian architecture has always acted rationally, harmoniously, and climate-friendly to meet the needs of the people in dealing with the environment. In addition, without harming the environment, they have achieved the best initiatives with the least facilities. For example, we can mention that the Ab-Anbars in arid and desert areas of Iran, which are used to store water in seasons with precipitation for use in the rest of the year, has been an optimal way to use natural resources and provide climate comfort. The Ab-Anbars are realized with ventilated cisterns through openings on their roof or wind-catchers to keep the water cool and provide comfortable conditions for the occupants. In order to study the essential role of natural ventilation and cooling in the Ab-Anbars, thermal analysis with CFD software was carried out to assess the effectiveness of a typical wind-catcher according to different wind directions in Yazd city. The results showed that Ab-Anbars have played an important role in reducing cooling loads and supply the necessary ventilation rate of buildings and can be used in the future for application in contemporary architecture and urban planning.

On the thermal buffering of naturally ventilated buildings through internal thermal mass

2007 ◽  
Vol 580 ◽  
pp. 3-29 ◽  
Author(s):  
J. M. HOLFORD ◽  
A. W. WOODS
Keyword(s):  
Heat Exchange ◽  
Air Temperature ◽  
Natural Ventilation ◽  
Ventilation Rate ◽  
Temperature Cycle ◽  
Thermal Mass ◽  
Thermal Equilibration ◽  
Environment Temperature ◽  
Naturally Ventilated Buildings ◽  
Diurnal Fluctuations

In this paper we examine the role of thermal mass in buffering the interior temperature of a naturally ventilated building from the diurnal fluctuations in the environment. First, we show that the effective thermal mass which is in good thermal contact with the air is limited by the diffusion distance into the thermal mass over one diurnal temperature cycle. We also show that this effective thermal mass may be modelled as an isothermal mass. Temperature fluctuations in the effective thermal mass are attenuated and phase-shifted from those of the interior air, and therefore heat is exchanged with the interior air. The evolution of the interior air temperature is then controlled by the relative magnitudes of (i) the time for the heat exchange between the effective thermal mass and the air; (ii) the time for the natural ventilation to replace the air in the space with air from the environment; and (iii) the period of the diurnal oscillations of the environment. Through analysis and numerical solution of the governing equations, we characterize a number of different limiting cases. If the ventilation rate is very small, then the thermal mass buffers the interior air temperature from fluctuations in the environment, creating a near-isothermal interior. If the ventilation rate increases, so that there are many air changes over the course of a day, but if there is little heat exchange between the thermal mass and interior air, then the interior air temperature locks on to the environment temperature. If there is rapid thermal equilibration of the thermal mass and interior air, and a high ventilation rate, then both the thermal mass and the interior air temperatures lock on to the environment temperature. However, in many buildings, the more usual case is that in which the time for thermal equilibration is comparable to the period of diurnal fluctuations, and in which ventilation rates are moderate. In this case, the fluctuations of the temperature of the thermal mass lag those of the interior air, which in turn lag those of the environment. We consider the implications of these results for the use of thermal mass in naturally ventilated buildings.

Expertmental study of a Roof Solar Collector towards the natural ventilation of new habitations

1996 ◽  
Vol 8 (1-4) ◽  
pp. 335-338 ◽  
Author(s):  
J. Khedari ◽  
J. Hirunlabh ◽  
T. Bunnag
Keyword(s):  
Solar Collector ◽  
Natural Ventilation

Measurement of Natural Ventilation Rate in a Japanese Residential Building

2008 ◽  
Vol 7 (1) ◽  
pp. 37-47 ◽  
Author(s):  
Shigeki Nishizawa ◽  
Takao Sawachi ◽  
Hiromi Habara ◽  
Hironao Seto
Keyword(s):  
Natural Ventilation ◽  
Residential Building ◽  
Ventilation Rate

Wind Tunnel Study on the Pressure Coefficient Performance of Different Venturi Shaped Roof Configurations for Wind Induced Natural Ventilation

2014 ◽  
Vol 564 ◽  
pp. 287-291
Author(s):  
M.M. Boroojerdian ◽  
Nor Maria Adam ◽  
Azmin Shakrine Mohd Rafie
Keyword(s):  
Wind Tunnel ◽  
Negative Pressure ◽  
Natural Ventilation ◽  
Pressure Coefficient ◽  
Ventilation Rate ◽  
Wind Tunnel Study

Wind catchers are structures used for natural ventilation using wind induced into buildings. Recently this has attracted attention for green buolding features There is limited studies on the different venturi shapes and their effects on inducing wind into buildingss.. This study considered three configurations ie. the shallow ellipse, the ellipse and the hemisphere in a wind tunnel with different speeds ranging from 8 m/s to 20 m/s. The negative pressure coefficient at the lower center of the roof is considered as the criteria for higher ventilation rate. The shallow ellipse performed the best but due to construction limitations other alternatives are recommended.

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