12 mol/s O2 at 2 atm and 400K is first compressed adiabatically to 15 atm with a compressor operating at 75% isentropic efficiency, then intercooled to 500K before being sent to a second adiabatic compressor
operating at 80% isentropic efficiency which compresses the gas to 40 atm. Calculate the temperature at
the end of each compression stage, as well as the entropy generated in each stage and the amount of heat
that must be removed in the intercooling stage

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?