Effect of interior venetian blinds on natural convective heat exchange at a full-scale window glazing

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• The setting of the louver enhances the convection heat transfer from the window. • The space of the louver from the window has a great influence on the heat transfer. • Differences in louver angles result in up to 45% difference in heat transfer. • Differences in flow types will result in a deviation of 70% in the heat transfer. • Correlations are proposed for the convective heat transfer from the louvered surface. The indoor venetian blinds are commonly used to block the solar radiation, which will also have an impact on the convective heat transfer from windows. The existing research on this phenomenon is almost based on reduced-scale experiments or simulations, which do not reflect the natural convection of actual windows. In this work, the natural convection near a full-scale window when louver close to the window ( n ≤ 10 mm) is firstly investigated by CFD simulation. Research indicates that the convective heat transfer from the full-scale window will be enhanced when the louver is closer to the window. The cause for the increased heat transfer is not only related to the thermal bridge effect of the aluminum louvers, but also to the type of flow near the window. Three different flow types will be generated along the window surface with venetian blinds during our simulation, which are named as Duct-directed flow (DDF), Transition flow (TF) and Louver-directed flow (LDF). The difference between the flow types will result in a discrepancy of approximately 70% in the convective heat transfer from the window. In addition, the influence of the slat angle φ , space from slats to window n and temperature difference between air and window Δ T on flow development and convective heat transfer has been investigated in this study. The correlation obtained from this work allows to accurately calculate the convective heat transfer from the full-scale window covered with venetian blinds, and the average error of the correlation is within 8.2%.