Acomputer terminal room contains 125 computers with a power consumption of 130w. the room is well-insulated so that only 25% of the energy generated by the computers and their operators is dissipated through the walls. the room is 15 x 40 m with a 2.5m high ceiling and the ventilation system changes 0.9m/s resulting in a net energy flow 20kj/m. calculate the temperature of the air in the room at 10am if all of the computers are used continuously by operators with a metabolic output 85w from 9am when the temperature was 18°c. assume the specific gas constant and specific heat capacity for air are 287 j/kg. k and 1.005 kj/kg. k respectively and that atmospheric pressure is 101bar.

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?