Discuss the following:
Q: A small disk of diameter D1 = 50 mm and emissivity e1 = 0.6 is maintained at a temperature of T1 = 900 K. The disk is covered with a hemispherical radiation shield of the same diameter and an emissivity of e2 = 0.02 (both sides). The disk and cap are located at the bottom of a large evacuated refractory container (e4 = 0.85), facing another disk of diameter D3 = D1, emissivity e3 = 0.4, and temperature T3 = 400 K. The view factor F23 of the shield with respect to the upper disk is 0.3.
(a) Construct an equivalent thermal circuit for the above system. Label all nodes, resistances, and currents.
(b) Find the net rate of heat transfer between the hot disk and the rest of the system.
