Consider laminar, parallel flow past an isothermal flat plate of length /, providing an average heat transfer coefficient of . if the plate is divided into 1 smaller plates, each of length determine an expression for the ratio of the heat transfer coefficient averaged over the 1 plates to the heat transfer coefficient averaged over the single plate, . repeat problem 7.11 for the case when the boundary layer is tripped to a turbulent condition at its leading edge.

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.