Predictive accuracy of Boussinesq approximation in opposed mixed convection with a high-temperature heat source inside a building

Zhou, Yu; Wang, Mengying; Wang, Manning; Wang, Yi

doi:10.1016/j.buildenv.2018.08.043

Cited by 38 publications

(5 citation statements)

References 35 publications

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“…The realizable k-ε model was selected for all sets of simulations in this study for better simulation results under high-temperature buoyant effects conditions [45]. The air is treated as incompressible, with density variation effects addressed through the Boussinesq approximation [46]. Consideration radiation effects, the air was assumed to be transparent to radiation [47].…”

Section: Governing Equationsmentioning

confidence: 99%

“…A constant wall temperature was applied to the top and side surfaces of the heating plants. Heat transfer due to radiation was accounted for using a constant emissivity value of 0.85 [46,52,53]. Initially, the outdoor air temperature was set at 25 • C and the heating plant temperature at 80 • C. For modelling the buoyancy-driven flow within the corridor, all inlet and outlet openings were designated as pressure inlet and outlet [54], respectively, with their values set at 0 Pa.…”

Section: Computational Grids and Boundary Conditionsmentioning

confidence: 99%

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Investigation on the Natural Convection Inside Thermal Corridors of Industrial Buildings

Pu,

Zhu,

et al. 2024

Buildings

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The installation of successional heating devices in industrial buildings will result in thermal corridors. To improve the thermal environment in and around these corridors, buoyancy-driven ventilation is commonly utilized to dissipate heat, which is based on the natural convection design for buildings. However, the flow and heat exchange patterns of natural convection related to thermal corridors have not been clearly clarified, and no relevant correlations have been established to quantify them. The conducted numerical study aimed to analyze the flow and heat transfer characteristics of natural convection within thermal corridors in industrial buildings. Experimental data were utilized to validate a computational fluid dynamics (CFD) model developed for this purpose. The study considered the influence of various parameters on the results obtained. In the side corridor, the prevalence of reverse flow dominates much of the channel, while in the middle corridor, reverse flow near the bottom corner is observed. The ambient air temperature significantly impacts the temperature distribution in both corridors. Increasing the ambient air temperature at the inlet from 22 to 28 °C results in a substantial temperature rise within the corridor, by approximately 6–7 °C. When the outlet size is constant and the inlet size drops by 30%, the air temperature in the corridor increases by 3 °C. Finally, correlations were established based on the simulation data to predict the surface-averaged Nu¯ of the heated wall and the induced mass flow rate, m˙, of the natural convection. The correlations have relative errors of less than 16% when compared to the simulation data.

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Section: Governing Equationsmentioning

confidence: 99%

Section: Computational Grids and Boundary Conditionsmentioning

confidence: 99%

Investigation on the Natural Convection Inside Thermal Corridors of Industrial Buildings

Pu,

Zhu,

et al. 2024

Buildings

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“…Çalışmanın amacı yüzeyler arası ışınım ve kaldırma kuvvetinin eğik plakanın genel ısı transfer performansına etkilerini incelemek olduğundan dolayı taşınımla ısı transferine ek olarak yüzeyler arası ışınımla ısı transferi (S2S) ışınım modeli kullanılarak hesaplanmıştır. Kaldırma kuvvetinin akış ve ısı transferine etkisi ele alınırken havanın yoğunluğundaki değişim sıkıştırılamaz ideal gaz modeli kullanılarak modellenmiştir [32]. SIMPLE algoritması hız-basınç çiftinin çözümü amacıyla kullanılırken, momentum ve enerji denklemleri 2. dereceden akış yönlü fark şeması ile ayrıklaştırılmış, basınç interpolasyonu ise kaldırma kuvveti etkisindeki akışlar için önerilen PRESTO algoritması ile gerçekleştirilmiştir [33].…”

Section: B Sayisal Metot Ve Sinir Koşullariunclassified

“…Yukarıda belirtildiği gibi, akışkanın yoğunluğundaki değişim sıkıştırılamaz ideal gaz modeli kullanılarak modellenmiştir [32,33]:…”

Section: B Sayisal Metot Ve Sinir Koşullariunclassified

Kaldırma Kuvveti ve Yüzey Işınımının Eğik Bir Plakanın Çarpan Jet ile Soğutulmasına Etkilerinin Sayısal Olarak İncelenmesi

SARPER

2024

Düzce Üniversitesi Bilim Ve Teknoloji Dergisi

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Bu çalışmada tek bir slot jet ile soğutulan eğik bir plakadan taşınımla ısı transferine kaldırma kuvveti ve yüzeyler arası ışınımın etkileri sayısal olarak incelenmiştir. Çalışma jet Reynolds sayısının (Re_j) 100 ile 1000 değerleri arasında gerçekleştirilmiş olup Richardson sayısı (Ri) ise 0.1 ile 10 arasında değişmektedir. Yüzeyler arası ışınımla ısı transferinin genel ısı transfer performansına etkileri hedef plaka ve sınırlandırıcı yüzeylerin üç farklı yayıcılık (ε=0.05-0.5-0.95) değeri ve üç farklı eğim açısı (α=0°-5°-10°) için analiz edilmiştir. Boyutsuz hedef plaka-nozül çapı mesafesi (H/D_j) 4’e eşit olup havanın (Pr=0.71) ışınım açısından katılımcı olmadığı kabulüyle hesaplamalar gerçekleştirilmiştir. Çalışma sonucunda, yüksek Richardson sayılarında kaldırma kuvvetinin akış ve ısı transfer karakteristiklerinin üzerindeki etkisinin ihmal edilemeyecek düzeyde olduğu, yüzey yayıcılığının artışının ise genel ısı transfer performansını iyileştirdiği ve plaka eğiminin ısı transferini önemli ölçüde etkilediği belirlenmiştir.

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“…Therefore, the full buoyancy-effects option may be selected to consider the effect of buoyancy on the turbulent dissipation rate (ε), since it is not well understood [148]. The predictive accuracy of the two models above is evaluated in mixed ventilation except in the case of a high-temperature heat source [150].…”

Section: Heat Exchange Between Human Body and Microenvironmentmentioning

confidence: 99%

A Review of CFD Analysis Methods for Personalized Ventilation (PV) in Indoor Built Environments

et al. 2019

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Computational fluid dynamics (CFD) is an effective analysis method of personalized ventilation (PV) in indoor built environments. As an increasingly important supplement to experimental and theoretical methods, the quality of CFD simulations must be maintained through an adequately controlled numerical modeling process. CFD numerical data can explain PV performance in terms of inhaled air quality, occupants’ thermal comfort, and building energy savings. Therefore, this paper presents state-of-the-art CFD analyses of PV systems in indoor built environments. The results emphasize the importance of accurate thermal boundary conditions for computational thermal manikins (CTMs) to properly analyze the heat exchange between human body and the microenvironment, including both convective and radiative heat exchange. CFD modeling performance is examined in terms of effectiveness of computational grids, convergence criteria, and validation methods. Additionally, indices of PV performance are suggested as system-performance evaluation criteria. A specific utilization of realistic PV air supply diffuser configurations remains a challenging task for further study. Overall, the adaptable airflow characteristics of a PV air supply provide an opportunity to achieve better thermal comfort with lower energy use based on CFD numerical analyses.

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Predictive accuracy of Boussinesq approximation in opposed mixed convection with a high-temperature heat source inside a building

Cited by 38 publications

References 35 publications

Investigation on the Natural Convection Inside Thermal Corridors of Industrial Buildings

Investigation on the Natural Convection Inside Thermal Corridors of Industrial Buildings

Kaldırma Kuvveti ve Yüzey Işınımının Eğik Bir Plakanın Çarpan Jet ile Soğutulmasına Etkilerinin Sayısal Olarak İncelenmesi

A Review of CFD Analysis Methods for Personalized Ventilation (PV) in Indoor Built Environments

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