Chips of width L = 15 mm on a side are mounted to a substrate that is installed in an enclosure whose walls and air are maintained at a temperature of Tsur = 25°C. The chips have an emissivity of s = 0.60 and a maxi- mum allowable temperature of Ts = 85°C. Exposed surface is h = 8 W/m2 · K, and the surface is characterized by an emissivity of ss = 0.9. The solid sili- con powder is at Tsi,i = 298 K, and the solid silicon sheet exits the chamber at Tsi,o = 420 K. Both the surroundings and ambient temperatures are T00 = Tsur = 298 K.