Question

Assume a steel pipe of inner radius r1= 20 mm and outer radius r2= 25 mm, which is exposed to natural convection at h = 50 W/m2.K with the surrounding ambient temperature of 30oC. If the outer wall temperature the pipe is 100oC, determine the amount of heat loss from the pipe per unit length

Answer 1

Answer:

98,614.82 W/m²

Explanation:

$Q = 2\pi hL(\frac{T_2-T_1}{Ln\frac{r_2}{r_1}})$

Where;

Q = the amount of heat loss from the pipe

h =  the heat transfer coefficient of the pipe = 50 W/m².K

T₁ = the ambient temperature of the pipe = 30⁰C

T₂  = the outside temperature of the pipe = 100⁰C

L= the length of pipe

r₁ = inner radius of the pipe = 20mm

r₂ = outer radius of the pipe = 25mm

To determine the amount of heat loss from the pipe per unit length

From the equation above

$\frac{Q}{L} = 2\pi h(\frac{T_2-T_1}{Ln\frac{r_2}{r_1}})$

$\frac{Q}{L} = 2\pi* 50(\frac{100-30}{Ln\frac{25}{20}})$

$\frac{Q}{L} = 314.159(\frac{70}{0.223})$

$\frac{Q}{L} = 314.159(313.901)$ = 98,614.82 W/m²