Numerical modelling of forced convective heat transfer from the inclined windward roof of an isolated low-rise building with application to photovoltaic/thermal systems
Karava, P., Jubayer, C. M. and Savory, E.
2011
Applied Thermal Engineering, 31(11-12): 1950-1963
Keywords: Photovoltaic¨Cthermal systems; Building, convective heat transfer coefficient; Computational fluid dynamics; RANS; Atmospheric boundary layer
Karava, P., Jubayer, C. M. and Savory, E., (2011), "Numerical modelling of forced convective heat transfer from the inclined windward roof of an isolated low-rise building with application to photovoltaic/thermal systems", Applied Thermal Engineering, 31(11-12): 1950-1963.
| Abstract: |
| The present work evaluates forced convective heat transfer from the inclined windward roof of an isolated low-rise building, with application to building-integrated Photovoltaic/Thermal (PV/T) systems. High resolution, 3-D, steady, Reynolds-Averaged Navier¨CStokes (RANS) Computational Fluid Dynamics (CFD) simulations of the wind flow field near the roof of a building with plan dimensions of 4.2 m by 6 m, a 3 m eaves height and a 30¡ã roof slope, are conducted, with the results validated by experimental data from a 1:50 scale model tested in a boundary layer wind tunnel. The heat transfer model is validated using the boundary layer correlation for an isothermal horizontal flat plate in uniform flow. Full-scale simulations, with the same building geometry and numerical model, for Reynolds numbers (Re) from 2.2 ¡Á 105 to 7.7 ¡Á 105 based on wind speed at eaves height and sloped roof length, are also carried out, for four roughness length (z0) values representing open and suburban terrain. From these, dimensionless correlations for the exterior convective heat transfer coefficient (CHTC), expressed as Nusselt number (Nu), for the windward roof are developed which include the Re and the incident turbulence intensity at eaves height. The windward roof average CHTC is dependent upon the presence and extent of the leading edge separated flow region. This region reduces in size as both Re and eaves height turbulence intensity are increased, such that at high turbulence levels it disappears and the value of the exponent on the Re term in the Nu correlation approaches that for a flat plate turbulent boundary layer. |
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