Similitude modeling of natural convection heat transfer through an aperture in passive solar heated buildings

An experimental study of natural convection heat transfer through a doorway in a two room passive solar heated building is described. Similitude modeling was the method used to measure natural convection heat transfer coefficients in a model geometrically scaled down by a factor of five. Freon gas was used as the working fluid to obtain dynamic similarity within the model. A temperature difference was maintained between the two rooms by a heated vertical wall which simulated a thermal storage wall in the other room. Heat transfer through the doorway was measured as a function of a characteristics temperature differential and the geometry of the doorway. A comparison of the results of this work with previous full scale studies and with the theory shows good correlation. Deviation of the Grashof number dependence from the theoretical predictions were caused by errors in assumptions of the relationship between the characteristic temperature differential and the temperature differences in the doorway. Velocity and temperature profiles measured in the doorway allowed a critical examination of these assumptions.