When raised to very high temperatures, many conventional liquid fuels dissociate into hydrogen and other components. Thus the advantage of a solid oxide fuel cell is that such a device can internally reformreadily available liquid fuels into hydrogen that can then be used to produce electrical power in a manner similar to Example 1.5. Consider a portable solid oxide fuel cell, operating at a temperature of Tfc = 800°C. The fuel cell aerogel (k = 0.006 W/m · K). The temperatures of the surroundings and the ambient are Tsur = 300 K andToo = 298 K, respectively. The outer surface is characterized by a convective heat transfer coeffi- cient of h = 12 W/m2 · K.

(b) Calculate the outer surface temperature of the can- ister for the four cases (high and low thermal con- ductivity; high and low surface emissivity).

(c) Calculate the heat loss from the cylindrical walls of the canister for the four cases.