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

A 2-m-diameter and 4-m-long horizontal cylinder is maintained at a uniform temperature of 80°C. Water flows across the cylinder at 15°C with a velocity of 3.5 m/s. Determine the rate of heat transfer.

Assuming $k=50W/mK$ for the wire material,

$r_{o}=0.04m$

$\dot{Q}=h \pi D L(T_{s}-T_{\infty})$

(b) Convection:

Assuming $h=10W/m^{2}K$,

The Nusselt number can be calculated by:

$\dot{Q}=10 \times \pi \times 0.08 \times 5 \times (150-20)=3719W$

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