Wind tunnel experiments were carried out to determine forced convection heat transfer coefficients for the leeward face of a roof-like structure. The experiments encompassed a variety of surface configurations, including: (a) a leeward face which transfers heat to the airflow over its entire surface, (b) a leeward face on which a thermally active zone is flanked by an adiabatic frame, and (c) eaves positioned along the lateral edges of the windward and leeward faces. Heat transfer coefficients were also measured on the windward face. It was found that in the operating range of flat plate collectors, the leeward-face heat transfer coefficients exceed those for the windward face. For a leeward face where adiabatic framing surfaces are situated along the lateral edges of a thermally active zone, the heat transfer coefficients are higher than those for the unframed case. On the other hand, framing adjacent to either the upper or lower edge of the face has little effect. Eaves situated along the lateral edges of the windward and leeward faces bring about only a slight increase in the leeward-face transfer coefficients. A flow visualization study revealed that the flow pattern adjacent to the leeward face is shaped by fluid which wells up from the sides of the roof-like structure.
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Acknowledgment--This research was sponsored, in part, by the American Society of Heating, Refrigeratinga nd Air-Conditioning Engineers.