Question

A vertical tube has an outer diameter of 150 mm. The pipe is 4 m long and the outdoor temperature is 60 C. The room temperature is 20 oC. The heat transfer coefficient, $\alpha$ ,for the air is 6 $\frac{W}{m^{2 ^\circ} C}$ Calculate heat transfer / heat flow / heat output W from pipe to air.

A vertical tube has an outer diameter of 150 mm. The pipe is 4 m long and the outdoor temperature is 60 oC. The room temperature is 20 oC. The heat transfer coefficient for the air is 6 W m-2 oC Calculate 1: heat transfer

2: heat flow

3: heat output W from pipe to air.

Explain all steps taken!

Answer 1

Heat transfer

Q = 2 $\prod$ k L ( T_i-T_o)/ log (r2/r1)

Where,

k = heat transfer coefficient = 6

$\prod$ = pi= 3.14159

L = length of pipe = 4 m

Ti = inside temperature of the pipe = 20

To= outside temperature of the pipe = 60

r1 = inner radius = 0.1 m ( assume)

r2 = outer radius = 0.15m

So, Q = 2 * 3.14 * 6 * 4 (60-20)/ log (0.15/0.1)

= 34254.54 W

= 0.342 * 10⁵ W