Abstract
The surface-averaged forced Convective Heat Transfer Coefficient (CHTCavg) at a windward building facade is influenced by the complex interaction between a wide range of parameters. Existing CHTC expressions, however, consider the impact of these parameters either incompletely or not at all. Earlier studies have shown that this shortcoming can lead to significant errors in Building Energy Simulations. In this paper, therefore, the combined impacts of wind speed (U10), building height (H) and width (W), and wind direction (θ) on the CHTCavg for the windward facade of buildings are systematically investigated. High-resolution CFD simulations of wind flow and forced convective heat transfer, validated with wind-tunnel measurements, are performed for 64 building geometries (10 m ≤ H and W ≤ 80 m), 8 wind directions (0° ≤ θ ≤ 78.75°) and 4 reference wind speeds (1 m/s ≤ U10 ≤ 4 m/s). The 3D steady RANS equations with the realizable k-ε turbulence model and the low-Re number Wolfshtein model are used. The results show that for a given building geometry and U10, the CHTCavg decreases as θ increases from 0° to 78.75°. The maximum reduction of about 42% occurs for the building with H = 8W = 80 m. In addition, for a given θ and U10, by increasing H, the CHTCavg increases, while increasing W has the opposite impact on the CHTCavg. Finally, a new generalized CHTC expression is presented as a function of U10, H, W and θ and its accuracy is confirmed by detailed in-sample and out-of-sample evaluations.
Original language | English |
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Pages (from-to) | 194-208 |
Number of pages | 15 |
Journal | Building and Environment |
Volume | 140 |
DOIs | |
Publication status | Published - 30 May 2018 |
Funding
The authors gratefully acknowledge the partnership with ANSYS CFD. This work was sponsored by NWO Exacte Wetenschappen (Physical Sciences) for the use of supercomputer facilities, with financial support from the Nederlandse Organisatie voor Wetenschappelijk Onderzoek (Netherlands Organization for Scientific Research, NWO). Hamid Montazeri is currently a postdoctoral fellow of the Research Foundation – Flanders (FWO) at KU Leuven and is grateful for its financial support (project FWO 12M5316N ).
Keywords
- Building aerodynamics
- Building energy
- Building Energy Simulation (BES)
- Computational Fluid Dynamics (CFD)
- Convective heat transfer coefficient