Air contained in an upright piston/cylinder arrangement is compressed from an initial pressure of 10 atm. and volume of 0.42m^3 to a final pressure of 25 atm. if the atmospheric pressure is 1.013 bar and the cylinder contains 5kg of air, find the final temperature, the work done and the heat transfer if the expansion occurs: isothermally, polytropically with an index of expansion of 1.3, isentropically with γ = 1.4.

Along 8-cm diameter steam pipe whose external surface temperature is 900c connects two buildings. the pipe is exposed to ambient air at 70c with a wind speed of 50 km/hr blowing across the pipe. determine the heat loss from the pipe per unit length. (b) air at 500c enters a section of a rectangular duct (15 cm x 20 cm) at an average velocity of 7 m/s. if the walls of the duct are maintained at 100c. a) the length of the tube for an exit temperature of the air to be 40 0c. b)the rate of heat transfer from the air. c) the fan power needed to overcome the pressure drop in this section of the duct.