The design of a single 'pin fin' which is to be used in an array of identical pin fins on an electronics heat sink is shown in Figure 2.6. The fin is made from cast aluminium, k = 180 W / m K, the diameter is 3 mm and the length 15 mm. There is a heat transfer coefficient of 30 W / m2 K between the surface of the fin and surrounding air which is at 25C. 1. Use the expression for a fin with an adiabatic tip to calculate the heat flow through a single pin fin when the base has a temperature of 55C. 2. Calculate also the efficiency and the effectiveness of this fin design. 3. How long would this fin have to be to be considered "infinite"? Surrounding air, h = 30 W/m K, Tfluid = 25C L = 15 mm Figure 2-6 Pin Fin design d = 3 mm Base, T = 55C