A solid teflon cylinder 0.05 m in diameter and 1 m in length initially at a uniform temperature of 100°C is cooled by blowing air at 20°C over it.

The Biot number is Bi = 2.0.

(a) Determine the time needed for the centerline of the cylinder to reach 40°C.

(b) Make a table and plot the temperature profile in the cylinder as a function of radial position from the center to its outer surface when the centerline temperature reaches 40°C. (c)

Based on the results in (b), determine the average temperature in the cylinder using the appropriate “cylindrical average” by integrating the tabulated values in part (b).

(d) Compare your result in

(c) with that obtained directly from Fig. 5.12 or item B in Table 5.3.

FIGURE 5.12:

Table 5.3.:

Transcribed Image Text:

Centerline Time Xx=0 To X =B Surface at T Ta Fluid at Ta