A packed column is used to reduce the levels of a pollu- tant in a gas stream from a mole fraction of 0.025 to a mole fraction of 0.00015. The gas stream lows at a rate of 10.0 m3/min while pure water enters the top of the column at a rate of 15.0 kg/min. The 2.25 m diameter tower will be packed with 19 mm ceramic Raschig rings, providing an interfacial surface area-to-volume ratio of 262 m2/m3. The overall mass-transfer coefficient based on the gas-phase driving force is 69.4 mol/m2 h. The system operates at 40°C and atmospheric pressure. The pollutant follows the Henry's law relation with the Ben- ry's law constant equal to 1.75 x 105 Pa. Probiem 27 The total height of packing required to achieve the de- sired separation is most nearly (A) 1.61 ㎡ (B) 5.81 m (C) 20.3 r (D) 53.5 m

Which of the following is an easy way to remember the modified “x” tire rotation? a. nondrive wheels straight, cross the drive wheels b. drive wheels straight, cross the nondrive wheels c. drive wheels crossed, nondrive wheels straight d. drive wheels crossed, nondrive wheels crossed

Most leaks in reciprocating air compressors can be detected and minimized by: (clo4) a)-detecting leakage areas using ultrasonic acoustic detector. b)-tightening joints and connections c)-replacing faulty equipment d)-all of the given options

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?