Solution Manual Heat And Mass Transfer Cengel 5th Edition Chapter 3 Site

Solution:

$Nu_{D}=CRe_{D}^{m}Pr^{n}$

$\dot{Q} {cond}=\dot{m} {air}c_{p,air}(T_{air}-T_{skin})$

The convective heat transfer coefficient can be obtained from:

The heat transfer from the insulated pipe is given by:

(c) Conduction:

For a cylinder in crossflow, $C=0.26, m=0.6, n=0.35$

$\dot{Q}_{conv}=150-41.9-0=108.1W$

(b) Not insulated:

Solution:

The Nusselt number can be calculated by:

$\dot{Q}=\frac{T_{s}-T_{\infty}}{\frac{1}{2\pi kL}ln(\frac{r_{o}+t}{r_{o}})}$

Alternatively, the rate of heat transfer from the wire can also be calculated by:

The heat transfer from the wire can also be calculated by:

$\dot{Q}=\frac{423-293}{\frac{1}{2\pi \times 0.1 \times 5}ln(\frac{0.06}{0.04})}=19.1W$