Asimple brayton cycle is working under the following conditions: working fluid: air pressure ratio: 8 minimum and maximum temperatures of the cycle: 290k and 1500 k, respectively an engineer decides to double the pressure ratio and keep the maximum and minimum temperatures constant. evaluate the change in specific net work and thermal efficiency of the cycle as result of that modification. assume variable specific heat for the air.

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.