Heating of air in a tube, a horizontal tube of 20 ft length is heated by means of an electrical heating element wrapped uniformly around it, Dry air enters at 5°F and 40 psia at a velocity 75 ft/s and 185 lb_m/hr the heating elements provides heat at a rate of 800 Btu/hr per foot of tube. At what temperature will the air leave the tube, if the exit pressure is 15 psia? Assume turbulent flow and ideal gas behavior. For air in the range of interest the heat capacity at constant pressure in Btu/lb-mole. F is C_p = 6.39 + (9.8 x 10^-4) T – (8.18 x 10^-8) T² where T is expressed in degrees Rankine.