Two streams of dry air come together and mix in an insulated mixing box. One of the air flows enters the mixing box at 60°F with a volumetric flow rate of 400 cfm.
The second stream enters the mixing box at 130°F at 600 cfm. The mixed air leaves the mixing box at a rate sufficient to maintain a steady state. The pressure throughout the system is atmospheric (1 atm). Determine the,

a. Temperature of the mixed air stream leaving the mixing box (°F)

b. Entropy generation rate associated with the mixing process (Btu/min-°R)

c. Exergy destruction rate for the mixing box assuming that the dead state conditions are atmospheric; 70°F, 1 atm (Btu/min)