Consider a power plant operating on an ideal, air-standard Brayton cycle with intercooling and reheating. Dry air enters the low-pressure compressor with a volumetric flow rate of 5 m3 /s at 100 kPa and 300 K (State 1) and exits the compressor at 316.2 kPa (State 2). Air leaving the low-pressure compressor is cooled to 300 K (State 3) using an intercooler and is then compressed to 1000 kPa (State 4) in the high-pressure compressor. Air enters the high-pressure turbine at 1000 kPa and 1400 K (State 5) and exits at 316.2 kPa (State 6). Air leaving the highpressure turbine is reheated to 1400 K (State 7) and is then expanded to 100 kPa (State 8) in the low-pressure turbine.

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?