In order to heat oil (cp = 1.8 kj/kg. k), a shell-and-tube heat exchanger with 1-shell pass and 6-tube passes is used. the oil enters the tube side at a rate of 10 kg/s at 22°c and exits at 48°c. heat is supplied by hot water (cp = 4.18 kj/kg. k) that enters the shell side at 80 °c at a rate of 5.1 kg/s. the overall heat transfer coefficient is estimated to be 975 w/m2 . k. determine the heat transfer surface area of the heat exchanger using lmtd method.

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.

Arigid tank contains 10 kg of air at 137 kpa (abs) and 21°c. more air is added to the tank until the pressure and temperature rise to 242 kpa (abs) and 32°c, respectively. determine the amount of air added to the tank. [r-0.287 kj/kg k]

Apure substance is a)-mixture of various chemical elements or compounds b)-substance that has a fixed chemical composition throughout c)-mixture that is homogeneous (such as air) d)-all the answers