Determination of convective heat transfer for fenestration with between-the-glass louvered shades

Abstract

In previous work, a two-dimensional steady laminar natural convection model of a window cavity with between-panes louvers (i.e., slats) was developed by approximating the system as a vertical cavity with isothermal walls at different temperatures, and with rotatable baffles located midway between the walls. The baffles were set to a third temperature so that night-time and day-time conditions, and the effects of low emissivity coatings (low-e), could be considered. It was found that the system is suited to a traditional one-dimensional analysis. A novel approach that allows the use of standard vertical cavity convection correlations and a modified cavity half-width is described, and a cavity modification factor, n∗, is presented. Finally, the n∗ factor and vertical cavity convection correlation are joined with a longwave radiant model, and the results are compared to experimental results. The models show good agreement with experiments.