A rectangular cavity consists of two parallel, 0.5-m- square plates separated by a distance of 50 mm, with the lateral boundaries insulated. The heated plate is maintained at 325 K and the cooled plate at 275 K. Esti- mate the heat flux between the surfaces for three orien- tations of the cavity using the notation of Figure 9.6: vertical with T = 90°, horizontal with T = 0°, and hori- zontal with T = 180°.