Convection ovens operate on the principle of inducing forced convection inside the oven chamber with a fan. A small cake is to be baked in an oven when the convection feature is disabled. For this situation, the free convection coefficient associated with the cake and its pan is h_fr = 3 W/m² · K. The oven air and wall are at temperatures T_∞ T_sur = 180°C. Determine the heat flux delivered to the cake pan and cake batter when they are initially inserted into the oven and are at a temperature of T_i =
24°C. If the convection feature is activated, the forced convection heat transfer coefficient is h_fo = 27 W/m² · K. What is the heat flux at the batter or pan surface when the oven is operated in the convection mode? Assume a value of 0.97 for the emissivity of the cake batter and pan.