To augment heat transfer between two flowing fluids, it is proposed to insert a 100-mm- long, 5-mm-diameter 2024 aluminum pin fin through the wall separating the two fluids, as seen in fig.1. the pin is inserted to a depth of d into fluid 1. fluid 1 is air with a mean temperature of 10°c and nearly uniform velocity of 10 m/s. fluid 2 is air with a mean temperature of 40°c and mean velocity of 3 m/s.

a) determine the rate of heat transfer from the warm air to the cool air through the pin fin for d=50 mm

b) plot the variation of the heat transfer rate with the insertion distance,

d. does an optimal insertion distance exist? t = 10°c, v = 10 m/s d-5 mm l = 100 mm 7.-40°c, v = 3 m/s