=+14-4.

A tube has circular fins as shown in Fig. 14-26; R is 1.0 in, whereas r is 0.5 in. The fin thick-

ness y is 0.008 in ., and the fin pitch is 10 fins/in. The average heat-transfer coefficient for the fin and tube is 10 Btu/(hr-ft2-F), whereas the thermal conductivity k of the fin and tube mate-

rial is 90 (Bru-ft)/(ft2-hr-F). Determine

(a) the fin efficiency n using Fig. 14-4,

(b) the fin effi-

ciency using Eq. 14-17, and

(c) compare

(a) and (b).