Question

Heat transfer from a transistor may be enhanced by

Answer 1

Answer:

Heat transfer from a transistor may be enhanced by

inserting it in an aluminium sleeve (k = 200 W/m −

K) having integrally machined longitudinal fins on its

outer surface. Transistor radius and height are r1 =

2 mm & H = 6 mm respectively, while the fins are of

length L = r3 − r2 = 10 mm of uniform thickness t =

0.7 mm. The thickness of the sleeve base is r2 − r1 =

1 mm. Contact resistance of the sleeve transistor

interface is Rt,c

′′ = 10−3 m2

.K/W. Air at T∞ = 20°C

flows over the fin surface providing uniform

convection with h = 25 W

m2−K

. Assume 1-D radial heat

transfer,

Explanation: