Experimental study of convective heat transfer from windows with Venetian blinds

To provide for more detailed and accurate load calculations and energy simulation of buildings, the effect of blinds on convection heat transfer at interior window surfaces was analyzed. Based on full-scale experiments in an office-size chamber for various diffuser locations, window geometry, and blind angles, the study provides convective heat transfer models for natural convection, forced convection due to a ceiling slot diffuser, and forced convection due to a floor register. Results are given in the form of correlations which relate either supply volumetric flow rate or room-surface temperature difference to convection heat transfer at both window and exterior wall surfaces. Results show that heat transfer is dependent on supply flow rate, blind angle, diffuser location and window configuration. Results are compared against previously reported data and show that convection in cases with blinds follows the same form as often arises in turbulent forced convection situations, but differs appreciably in magnitude from previously given models for bare windows. These results should allow for more accurate simulation of energy use in buildings and contribute to the construction of more energy efficient buildings.