# Conduction Toturial

Topics: Heat transfer, Heat, Heat transfer coefficient Pages: 2 (722 words) Published: March 24, 2013
Tutorial 1
(Conduction and Convection)
1. Consider a composite structure shown on below. Conductivities of the layer are: k1 = k3 = 10 W/mK, k2 = 16 W/mK, and k4 = 46 W/mK. The convection coefficient on the right side of the composite is 30 W/m2K. Calculate the total resistance and the heat flow through the composite. (0.46, 173.9 W)

2. Consider a 1.2-m high and 2-m-wide glass window whose thickness is 6 mm and thermal conductivity is k= 0.78W/m. 0C. Determine the steady rate of heat transfer through this glass window and the temperature of its inner surface for a day during which the room is maintained at 24 0C while the temperature of the outdoors is -5 0C. Take the convection heat transfer coefficients on the inner and outer surfaces of the window to be h1= 10 W/m2 .0C and h2 = 25 W/m2 .0C and disregard any heat transfer by radiation. (471W, 4.40C)

3. Consider a 1.2-m-high and 2-m-wide double-pane window consisting of two 3-mm-thick layers of glass (k=0.78 W/m .0C) separated by 12-mm-wide stagnant air space. Determine the steady rate of heat transfer through this double-pane window and the temperature of its inner surface for a day during which the room is maintained at 24 0C while the temperature of the outdoors is -50C. Take the convection heat transfer coefficients on the inner and outer surfaces of the window to be h1=10 W/ m2 .0C and h2 = 25 W/m2 .0C and disregard any heat transfer by radiation. Given also k air = 0.026 W/ m .0C (114W, 19.20C)

4. A cylindrical resistor element on a circuit board dissipates 0.15W of power in an environment at 400C. The resistor is 1.2 cm long, and has a diameter of 0.3cm. Assuming heat to be transferred uniformly from all surfaces, determine (a) the amount of heat this resistor dissipates during a 24-h period, (b) the heat flux on the surface of the resistor, in W/m2 and (c) the...