Consider the conducting rod of Example 15.3 under steady-state conditions. As suggested in Comment 3, the temperature of the rod may be controlled by varying the speed of air flow over the rod, which, in turn, alters the convection heat transfer coefficient. To consider the effect of the convection coefficient, generate plots of T versus I for values of h = 50, 100, and 250 W/m2 . K. Would variations in the surface emissivity have a significant effect on the rod temperature?
Example 15.3:
A long conducting rod of diameter D and electrical resistance per unit length is initially in thermal equilibrium with the ambient air and its surroundings. This equilibrium condition is disturbed when an electrical current I is passed through the rod. Develop an equation that could be used to compute the variation of the rod temperature with time during passage of the current.