1. Determine the thermal conductivity of the carbon nan- otube of Example 3.4 when the heating island tempera- ture is measured to be Th = 332.6 K, without evaluating the thermal resistances of the supports. The conditions are the same as in the example.
2. A thermopane window consists of two pieces of glass 7 mm thick that enclose an air space 7 mm thick. The window separates room air at 20°C from outside ambi- ent air at -10°C. The convection coefficient associated with the inner (room-side) surface is 10 W/m2 · K.
(a) If the convection coefficient associated with the outer (ambient) air is ho = 80 W/m2 · K, what is the heat loss through a window that is 0.8 m long by 0.5 m wide? Neglect radiation, and assume the air enclosed between the panes to be stagnant.
(b) Compute and plot the effect of ho on the heat loss for 10 ho 100 W/m2 · K. Repeat this calculation for a Lp Lb Ls
(a) Determine a symbolic expression for the total thermal resistance of the wall, including inside and outside convection effects for the prescribed conditions.
(b) Determine the total heat loss through the wall.
(c) If the wind were blowing violently, raising ho to 300 W/m2 · K, determine the percentage increase in the heat loss.
(d) What is the controlling resistance that determines the amount of heat flow through the wall?