CFD Analysis of Convective Heat Transfer Coefficient on External Surfaces of Buildings

Vollaro, Andrea de Lieto; Galli, G.; Vallati, Andrea

doi:10.3390/su7079088

Cited by 42 publications

(7 citation statements)

References 32 publications

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“…A review concluded that the urban microclimate can have a net positive effect on the building energy demand on a yearly basis [15]. Existing studies typically have considered one influential variable isolated from the other influential variables, for example, CHTCs [16][17][18], wind speed [19,20], wind direction [20,21], thermal parameters [22], neighborhood densities [23], urban geometrical parameters [24,25], and solar radiation [26][27][28]. However, there are limited quantitative studies to comprehensively understand understand the impacts of the outdoor built environment on building energy consumption patterns.…”

Section: Introductionmentioning

confidence: 99%

Quantifying Impacts of Urban Microclimate on a Building Energy Consumption—A Case Study

et al. 2019

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This paper considered an actual neighborhood to quantify impacts of the local urban microclimate on energy consumption for an academic building in College Park, USA. Specifically, this study accounted for solar irradiances on building and ground surfaces to evaluate impacts of the local convective heat transfer coefficient (CHTC), infiltration rate, and coefficient of performance (COP) on building cooling systems. Using computational fluid dynamics (CFD) allowed for the calculation of local temperature and velocity values and implementation of the local variables in the building energy simulation (BES) model. The discrepancies among the cases with different CHTCs showed slight influence of CHTCs on sensible load, in which the maximum variations existed 1.95% for sensible cooling load and 3.82% for sensible heating load. The COP analyses indicated windward wall and upstream roof are the best locations for the installation of these cooling systems. This study used adjusted infiltration rate values that take into account the local temperature and velocity. The results indicated the annual cooling and heating energy increased by 2.67% and decreased by 2.18%, respectively.

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Section: Introductionmentioning

confidence: 99%

Quantifying Impacts of Urban Microclimate on a Building Energy Consumption—A Case Study

et al. 2019

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“…The standard k-epsilon (k-e) turbulence model which is frequently used for incompressible flows, was used to define the turbulence kinetic energy and flow dissipation rate within the model [29]. The use of the standard k-e transport model on building configurations has been found accurate in previous works on natural ventilation studies [2][3][4][5][30][31][32][33][34]. The governing equations for the mass conservation, momentum conservation, energy conservation, turbulence kinetic energy and dissipation rate are not included here but fully available in the FLUENT user guide [35].…”

Section: Computational Modellingmentioning

confidence: 99%

Computational Analysis of Natural Ventilation Flows in Geodesic Dome Building in Hot Climates

2016

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For centuries, dome roofs were used in traditional houses in hot regions such as the Middle East and Mediterranean basin due to its thermal advantages, structural benefits and availability of construction materials. This article presents the computational modelling of the wind-and buoyancy-induced ventilation in a geodesic dome building in a hot climate. The airflow and temperature distributions and ventilation flow rates were predicted using Computational Fluid Dynamics (CFD). The three-dimensional Reynolds-Averaged Navier-Stokes (RANS) equations were solved using the CFD tool ANSYS FLUENT15. The standard k-epsilon was used as turbulence model. The modelling was verified using grid sensitivity and flux balance analysis. In order to validate the modelling method used in the current study, additional simulation of a similar domed-roof building was conducted for comparison. For wind-induced ventilation, the dome building was modelled with upper roof vents. For buoyancy-induced ventilation, the geometry was modelled with roof vents and also with two windows open in the lower level. The results showed that using the upper roof openings as a natural ventilation strategy during winter periods is advantageous and could reduce the indoor temperature and also introduce fresh air. The results also revealed that natural ventilation using roof vents cannot satisfy thermal requirements during hot summer periods and complementary cooling solutions should be considered. The analysis showed that buoyancy-induced ventilation model can still generate air movement inside the building during periods with no or very low wind.

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“…One important limitation of BES models is their approach to model the convective heat transfer in sheltered building conditions as they do not take into account the influence of neighboring buildings on the local microclimate. The profiles of convective heat transfer coefficient (CHTC) are dynamic and inhomogeneous from a surface to another one throughout the domains; however, this is not considered in BES models (Vollaro et al, 2015; Zhang et al, 2013). Although there were efforts to include CHTC in dynamic CFD-BES coupling studies, most of them were mainly focused on the interior surfaces (Beausoleil-Morrison, 2002; Djunaedy et al, 2003; Negrão, 1998; Zhai and Chen, 2003).…”

Section: Introductionmentioning

confidence: 99%

CFD-CFD coupling: A novel method to develop a fast urban microclimate model

Zhang

Mirzaei

2020

Journal of Building Physics

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Computational fluid dynamics (CFD) technique is well-known for its powerful capability of modelling the cross-ventilation. CFD is broadly coupled with energy simulation programmes, such as EnergyPlus, to expand its application in building energy calculation. During the coupling process, iterative calculation is required to improve the accuracy of the coupling method, which means the scale of the model should be designed with extra care so that the simulation can be practical in terms of computational cost. A coarse-resolution mesh (here denoted as CFDc) cannot properly represent the required local environment to study the underlying physics. However, a fine-resolution CFD microclimate model (here denoted as CFDf), which includes both indoor and outdoor spaces, always requires a large number of cells to capture the complexities of environment; this makes the coupling procedure a challenging problem. This study aims to propose an innovative, high-resolution and computationally cost-effective CFDf-CFDc model to overcome this gap. The full-scale CFDf works in an off-line manner at the preliminary simulation stage and generates detailed flow parameters at the interfaces for CFDc. At the dynamic stage of the simulation, CFDc participates in the coupling procedure with the other tools, for example, building energy simulation (BES) tool (e.g. EnergyPlus). The coupling of CFDf-CFDc-BES is about 200 times faster than an ordinary coupled CFDf-BES method with a significantly quicker and more stable achievement in the convergence.

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CFD Analysis of Convective Heat Transfer Coefficient on External Surfaces of Buildings

Cited by 42 publications

References 32 publications

Quantifying Impacts of Urban Microclimate on a Building Energy Consumption—A Case Study

Quantifying Impacts of Urban Microclimate on a Building Energy Consumption—A Case Study

Computational Analysis of Natural Ventilation Flows in Geodesic Dome Building in Hot Climates

CFD-CFD coupling: A novel method to develop a fast urban microclimate model

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