A rigid compressed- air tank is to be repressurized to 40 bar by being connected to a high-pressure line containing air at 50 bar and 20°C. The repressurization of the tank occurs fast enough that the process can be assumed to be adiabatic. Assume that the gas can be modeled as ideal and that the specific hear ratio is k = 1.4.
1. If the tank initially contains air at 1 bar and 25°C determine what will be the temperature of the air in the tank at the end of the filling process?

A3-mm-thick panel of aluminum alloy (k 177 w/m-k, c 875 j/kg-k and ? = 2770 kg/m) is finished on both sides with an epoxy coating that must be cured at or above t,-150°c for at least 5 min. the production line for the curing operation involves two steps: (1) heating in a large oven with air at ts,0-175°c and a convection coefficient of h, 40 w/m2. k, and (2) cooling in a large chamber with air at 25°c and a con- vection coefficient of he 10 w/m2.k. the heating portion of the process is conducted over a time interval te which exceeds the ime required to reach 150°c by 5 min (h = r + 300 s). the coating has an emissivity of ? = 0.8, and the temperatures of the oven and chamber walls are 175 and 25°c, respectively. if the panel is placed in the oven at an initial temperature of 25°c and removed from the chamber at a safe-to-touch tempera ture of 37°c, what is the total elapsed time for the two-step curing operation?