Experimental, variable properties natural convection from a large, vertical, flat surface

Natural-convection heat transfer (NCHT) to air at room temperature and atmospheric pressure from a vertical 3.02 x 2.95-m panel heated to 60-520 C is investigated experimentally in the 4.3-m-high 1.2-m-wide 4.3-m-long test section of an open-return draw-through wind tunnel. Heat-transfer coefficients at 105 locations and boundary-layer temperature profiles are obtained, and the results are presented in tables and graphs and characterized. An empirical expression relating the Nusselt number to the Grashof number and the wall/ambient temperature ratio is derived for turbulent NCHT but the variation in temperature is found to have little effect on laminar NCHT. Also determined are the decrease in transition Grashof number with increasing temperature and a quasi-universal boundary-layer mean temperature profile for turbulent natural convection.