= The dark surface of a ceramic stove top may be approximated as a blackbody. The "burners", which are integral with the stove top, are heated from below by electric resistance heaters. Consider a burner of diameter D 200 mm operating at a uniform surface temperature of Ts = 250 C in ambient air at To = 25 C. Air properties: k = 34.36 10- W/m-K, Pr = 0.671, kinematic viscosity v = 27.37 x 10-6 m/s. The natural convection correlation equation for circular horizontal flat plate is NUL 0.54 Ral 1/4 where the characteristic length L is calculated by the area of the circle divided by the parameter of the circle. Assume air is an ideal gas. = " Quiescent air, T Burner, T Stove top o o o o o o o o o 00 Heater, P. elec a) Without a pot or pan on the burner, what are the rates of heat loss by radiation and convection from the burner? b) If the efficiency associated with the energy transfer from the heaters to the burners is 90%, what is the electric power requirement? D-