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

Solution:

The heat transfer due to conduction through inhaled air is given by:

The heat transfer due to radiation is given by:

The outer radius of the insulation is:

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

$Re_{D}=\frac{\rho V D}{\mu}=\frac{999.1 \times 3.5 \times 2}{1.138 \times 10^{-3}}=6.14 \times 10^{6}$

Solution:

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

(b) Not insulated:

$\dot{Q}_{cond}=0.0006 \times 1005 \times (20-32)=-1.806W$

(b) Convection:

Assuming $Nu_{D}=10$ for a cylinder in crossflow, Solution: $\dot{Q} {cond}=\dot{m} {air}c_{p

The heat transfer from the not insulated pipe is given by: