Numerical computation of buoyant airflows confined to attic spaces under opposing hot and cold wall conditions

Ridouane, El Hassan; Campo, Antônio; McGarry, Matthew

doi:10.1016/j.ijthermalsci.2005.03.008

Cited by 50 publications

(28 citation statements)

References 12 publications

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“…In the first category, sealed attic configuration is considered, and the problem is usually represented by natural convection in triangular enclosures. As reviewed by Kamiyo et al [5] and by Saha and Khan [6], a considerable number of experimental and numerical studies in this category (e.g., [7][8][9][10][11][12][13][14][15][16]) have been devoted to the analysis of flow and heat transfer under laminar conditions, while only a few studies (e.g., [17,18]) investigated turbulent flow and heat transfer, although the air flow in real residential attics is almost always turbulent.…”

Section: Introductionmentioning

confidence: 99%

Impacts of Ventilation Ratio and Vent Balance on Cooling Load and Air Flow of Naturally Ventilated Attics

Wang

Shen

2012

Energies

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Abstract:The impacts of ventilation ratio and vent balance on cooling load and air flow of naturally ventilated attics are studied in this paper using an unsteady computational fluid dynamics (CFD) model. Buoyancy-driven turbulent ventilations in attics of gable-roof residential buildings are simulated for typical summer conditions. Ventilation ratios from 1/400 to 1/25 combined with both balanced and unbalanced vent configurations are investigated. The modeling results show that the air flows in the attics are steady and exhibit a general streamline pattern that is qualitatively insensitive to the variations in ventilation ratio and vent configuration. The predicted temperature fields are characterized by thermal stratification, except for the soffit regions. It is demonstrated that an increase in ventilation ratio will reduce attic cooling load. Compared with unbalanced vent configurations, balanced attic ventilation is shown to be the optimal solution in both maximizing ventilating flow rate and minimizing cooling load for attics with ventilation ratio lower than 1/100. For attics with ventilation ratios greater than 1/67, a configuration of large ridge vent with small soffit vent favors ventilating air flow enhancement, while a configuration of small ridge vent with large soffit vent results in the lowest cooling energy consumption.

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Section: Introductionmentioning

confidence: 99%

Impacts of Ventilation Ratio and Vent Balance on Cooling Load and Air Flow of Naturally Ventilated Attics

Wang

Shen

2012

Energies

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“…A comparison study is performed by Ridouane et al (2005) where the authors compare their numerical results produced for two different boundary conditions, (a) cold base and hot inclined walls (b) hot base and cold inclined walls with the experimental results obtained by Flack (1980;1979). A good agreement has been obtained between the numerical predictions and the experimental measurements of Nusselt number.…”

Section: Introductionmentioning

confidence: 89%

Periodically Forced Natural Convection Through the Roof of an Attic-Shaped Building

Saha¹

2011

Convection and Conduction Heat Transfer

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“…Subject to the Boussinesq approximation, they are written The validity of the Boussinesq approximation in the present context is corroborated by Gray and Giorgini [9], since they reported that the results would deviate of at most 3% from the corresponding non-Boussinesq solution. Also, in the process of validating their code, Ridouane et al [10] reexamined the benchmark numerical study of natural convection of air in a square enclosure carried out by de Vahl Davis [11]. Results obtained without enforcing the Boussinesq approximation were just 2% different from the benchmark solution.…”

Section: Computational Detailsmentioning

confidence: 99%

Natural convection in asymmetric triangular enclosures heated from below

Kamiyo

Angeli

Barozzi

et al. 2014

J. Phys.: Conf. Ser.

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. Among a number of scientific topics he cultivated in his brilliant academic career, convection heat transfer was the first and the most beloved.Abstract. Triangular enclosures are typical configurations of attic spaces found in residential as well as industrial pitched-roof buildings. Natural convection in triangular rooftops has received considerable attention over the years, mainly on right-angled and isosceles enclosures. In this paper, a finite volume CFD package is employed to study the laminar air flow and temperature distribution in asymmetric rooftop-shaped triangular enclosures when heated isothermally from the base wall, for aspect ratios (AR) 0.2 ≤ AR ≤ 1.0, and Rayleigh number (Ra) values 8 × 10 5 ≤ Ra ≤ 5 × 10 7 . The effects of Rayleigh number and pitch angle on the flow structure and temperature distributions within the enclosure are analysed. Results indicate that, at low pitch angle, the heat transfer between the cold inclined and the hot base walls is very high, resulting in a multi-cellular flow structure. As the pitch angle increases, however, the number of cells reduces, and the total heat transfer rate progressively reduces, even if the Rayleigh number, being based on the enclosure height, rapidly increases. Physical reasons for the above effect are inspected.

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Numerical computation of buoyant airflows confined to attic spaces under opposing hot and cold wall conditions

Cited by 50 publications

References 12 publications

Impacts of Ventilation Ratio and Vent Balance on Cooling Load and Air Flow of Naturally Ventilated Attics

Impacts of Ventilation Ratio and Vent Balance on Cooling Load and Air Flow of Naturally Ventilated Attics

Periodically Forced Natural Convection Through the Roof of an Attic-Shaped Building

Natural convection in asymmetric triangular enclosures heated from below

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