Question

Consider a laminar fully developed fluid (k = 0.175 W/mK) flow inside a 6 mm inside diameter tube under uniform wall temperature boundary conditions. If the mean temperature difference between the wall and the fluid is ${50}^{\circ }C$ and the tube length is 8 m, then the heat transfer rate between the tube wall and the fluid will be

• A. 233.4 W
• B. 959 W
• C. 804.87 W
• D. 106.75 W

Answer 1

The correct option is C 804.87 W

For laminar fully developed fluid flow in a tube under constant surface temperature boundary condition, we know that,

$h=3.66\frac{k}{D}$

$=3.66\times \frac{0.175}{6\times {10}^{-3}}=106.75W/m^{2}K$

The required heat transfer rate,

$Q=hA\Delta T$

$=h\pi DL(T_s-T_m)$

$=106.75\times \pi \times 6\times {10}^{-3}\times 8\times 50$

$=804.87W$