Air in a rigid box is heated from 250 k to 273 k. match the premises on the left with the most adequate response on the right. 1. pressure 2. specific volume 3. work choices: a. is zero b. is negative c. remains constant d. decreases e. increases

The inner surface of a 0.25m thick brick wall of a furnace is kept at 810ºc, when the outside surrounding air is at 22ºc. the convective heat transfer coefficient of the outer surface is 12 w/m2k and the thermal conductivity of the brick is 0.865 w/mk.neglect the convective resistance for the inner side of the furnace and assume that the problem is steady state and thermal radiation is neglected. (a)-sketch the system and calculate the rate of heat loss per unit wall area. (b)-calculate the temperature of the outer wall surface.