contestada

A heat rate of 3 kW is conducted through a section of an insulating materials of cross-sectional area 10 m^2 and thickness 2.5 cm. If the inner (hot) surface temperature is 415°C and the thermal conductivity of the material is 0.2 W/m*k , what is the outer surface temperature?

Respuesta :

Answer: The outer surface temperature is [tex]377.5^{o}C[/tex].

Explanation:

Given: Heat = 3 kW (1 kW = 1000 W) = 3000 W

Area = 10 [tex]m^{2}[/tex]

Length = 2.5 cm (1 cm = 0.01 m) = 0.025 m

Thermal conductivity = 0.2 W/m K

Temperature (inner) = [tex]415^{o}C[/tex]

Formula used is as follows.

[tex]q = KA \frac{(t_{in} - t_{out})}{L}[/tex]

where,

K = thermal conductivity

A = area

L = length

[tex]t_{in}[/tex] = inner surface temperature

[tex]t_{out}[/tex] = outer surface temperature

Substitute the values into above formula as follows.

[tex]q = KA \frac{(t_{in} - t_{out})}{L}\\3000 W = 0.2 \times 10 \times \frac{415 - t_{out}}{0.025 m}\\t_{out} = 377.5^{o}C[/tex]

Thus, we can conclude that the outer surface temperature is [tex]377.5^{o}C[/tex].