Variability and impact of internal surfaces convective heat transfer coefficients in the thermal evaluation of office buildings

Obyn, Sophie; Moeseke, Geoffrey Van

doi:10.1016/j.applthermaleng.2015.05.030

Cited by 50 publications

(28 citation statements)

References 34 publications

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“…This may be because any kind of empirical model is based on specific test geometries with various kinds of focuses and limitations. For the targeted experiments [32], it was mentioned that the cavity walls were constructed of insulation board with polished aluminium on their internal faces, so the heat transfer coefficient of the two hot surfaces was assumed as 15 W/m 2 •K, see also [34,35].…”

Section: Experiments For the Validationmentioning

confidence: 99%

An empirical model to predict the performance of typical solar chimneys considering both room and cavity configurations

Shi

Zhang

2016

Building and Environment

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The solar chimney is a reliable passive ventilation system that can largely reduce the energy requirements with both low costs and maintenance for buildings to overcome the current energy crisis. To optimize its design, an empirical model is developed to predict the performance of typical solar chimneys considering both room and chimney cavity configurations using easily acquired inputs. Fire Dynamics Simulator (FDS) as an excellent and open-source tool to solve heating, ventilation and air conditioning problems is selected for this study. The numerical modelling of FDS was first validated by previous experimental data, and then used to develop the empirical model. In this model, a coefficient describing room and chimney configuration (e.g., room opening, inlet and outlet of cavity) is proposed.

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Section: Experiments For the Validationmentioning

confidence: 99%

An empirical model to predict the performance of typical solar chimneys considering both room and cavity configurations

Shi

Zhang

2016

Building and Environment

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“…Recent work shows that research is continuing on these issues, as presented by Altaç and Uğurlubilek (2016) with regard to three-dimensional effect and various turbulence models. Another recent study carried out by Obyn and Van Moeseke (2015) focuses on the impact of convection heat transfer coefficient (CHTC) expressions used for the calculation of heating and cooling loads of buildings.…”

Section: Introductionmentioning

confidence: 99%

New natural convection heat transfer correlations in enclosures for building performance simulation

Rincón-Casado

Flor

Vera

et al. 2017

Engineering Applications of Computational Fluid Mechanics

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This paper presents new correlations to calculate natural convection heat transfer coefficients (CHTC) in enclosures for building performance simulation. Current work related to the development of correlations is not oriented to building enclosures, and the influence of high numbers of Rayleigh (Ra) and aspect ratio on the CHTC has not been studied in detail. In this work, two new correlations have been developed for a vertical wall, one in laminar regime (Ra < 10 7) and another one in turbulent regime (10 7 < Ra < 10 11). Moreover, two new correlations have been developed for floor and ceiling, one in laminar regime (Ra < 10 6) and another one in turbulent regime (Ra > 10 6). All correlations have been developed as function of the aspect ratio (H/L) and Ra numbers calculated from the enclosure average air temperature and wall surface temperature. By contrast, in previous works the Ra numbers have been calculated from the temperature difference of opposite walls. Computer Fluid Dynamics (CFD) simulations for different aspect ratios (H/L = 0.5-1-2) and Ra numbers (10 3-10 11) have been carried out in order to obtain these correlations. The SIMPLE algorithm has been used for the solution of the Navier-Stokes equations and the realizable turbulence k-ε model with an enhanced wall-function treatment has been used. The correlations developed follow the expected trend for the low number of Ra in comparison with the expressions developed by other authors. For a high number of Ra, our correlations improve the previous correlations, because it is a function of the aspect ratio of the enclosure and the average air temperature of the enclosure. This approach is simple to implement in the construction of thermal simulation programs with low computational cost.

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“…Recent work of Altac and Ugurlubilek [1] shows that research is continuing on these issues, with regard to three-dimensional effect and various turbulence models. In this line another recent study carried out by Obyn and Van Moeseke [2] with the focus on the impact of convective heat transfer coefficient. They used their computations to calculate the heating and cooling loads of buildings.…”

Section: Introductionmentioning

confidence: 92%

Analysis of Aspect Ratio Effects of Left Heated 2D Cavity Using Energy Streamlines and Field Synergy Principle

Rani¹,

Narayana²,

Rameshwar³

2019

MMEP

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In the present study natural convective flow of air in a two dimensional cavity with three different aspect ratios (AR) are analyzed using direct numerical simulation. Established open source CFD package OpenFOAM, has been utilized to run the simulation. In this problem, the vertical walls are assumed to be maintained at an isothermal temperature with left vertical wall has high temperature than the right wall and the other walls are assumed to be thermally insulated. The governing equations of this problem are expressed in dimensionless form and are solved by using the finite volume method. For spatial derivatives, the second order upwind linearization technique was used. The CGS method was employed as an effective acceleration means. The divergent and Laplacian terms in the governing equations are discretized by the QUICK and Gauss linear schemes, respectively. The computations are conducted for Rayleigh number until 10 6. An attempt has been made to gather the visualization techniques such as streamlines, isotherms, energy streamlines and field synergy principle to analyse the flow behavior. When Ra is small, vertical energy streamlines appeared, as Ra further increases, free energy streamlines at the boundary are observed whereas trapped energy streamlines at the centre appeared in the horizontal direction. For a fixed Ra, as AR increases, average synergy angle () increases. This result implies that synergy between temperature field and velocity gets worse, which leads to the mild growth rate of ̅̅̅̅. The field synergy principle shows that the improving synergy between the temperature gradient and velocity vector, the heat transfer can be enhanced with less increased flow resistance.

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Variability and impact of internal surfaces convective heat transfer coefficients in the thermal evaluation of office buildings

Cited by 50 publications

References 34 publications

An empirical model to predict the performance of typical solar chimneys considering both room and cavity configurations

An empirical model to predict the performance of typical solar chimneys considering both room and cavity configurations

New natural convection heat transfer correlations in enclosures for building performance simulation

Analysis of Aspect Ratio Effects of Left Heated 2D Cavity Using Energy Streamlines and Field Synergy Principle

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