An observation cabin is located in a hot-strip mill directly over the line, as shown in the schematic. The cabin floor is exposed to a portion of the hot strip that is at a temperature of T _ss = 920?C and has an emissivity of ? _ss = 0.85, as well as to surroundings within the mill (not shown) at a temperature of Tsur = 80?C. To protect the operating personnel in the cabin, the floor must be maintained at T_? = 50?C. Determine the coolant system heat removal rate required to maintain the cabin floor at 50?C for the following conditions:

(a) When the floor, with an emissivity of 8f = 0.6, is directly exposed to the strip; and

(b) When a radiation shield of emissivity 8, = 0.1 is installed between the floor and the strip.

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Observation cabin Cabin fioor maintained at Ty = 50°C 20 m 2.5 m 1.5 m lal Without shieid Ty. Ey= 0.6 Shield, e, = 0.10 rion of steel strip en by cabin floor (b) With shield Steel strip T= 920°C, e - 0.85