If a steady-state heat transfer rate of 3 kW is conducted through a section of insulating material 1.0 m2 in cross section and 2.5 cm thick and the thermal conductivity may be taken as 0.2 W/m K, what is the temperature difference across the material?

Respuesta :

Answer:

[tex] \Delta T = \frac{3000 W *0.025 m}{1 m^2 (0.2 \frac{W}{mK})}= 375 K[/tex]

So then the difference of temperature across the material would be [tex] \Delta T = 375 K[/tex]

Explanation:

For this case we can use the Fourier Law of heat conduction given by the following equation:

[tex] Q = -kA \frac{\Delta T}{\Delta x}[/tex]   (1)

Where k = thermal conductivity = 0.2 W/ mK

A= 1m^2 represent the cross sectional area

Q= 3KW represent the rate of heat transfer

[tex] \Delta T[/tex] is the temperature of difference that we want to find

[tex] \Delta x=2.5 cm =0.025 m[/tex] represent the thickness of the material

If we solve [tex]\Delta T[/tex] in absolute value from the equation (1) we got:

[tex] \Delta T =\frac{Q \Delta x}{Ak}[/tex]

First we convert 3KW to W and we got:

[tex] Q= 3 KW* \frac{1000W}{1 Kw}= 3000 W[/tex]

And we have everything to replace and we got:

[tex] \Delta T = \frac{3000 W *0.025 m}{1 m^2 (0.2 \frac{W}{mK})}= 375 K[/tex]

So then the difference of temperature across the material would be [tex] \Delta T = 375 K[/tex]

This question involves the concepts of Fourier's Law of Heat Conduction and thermal conuctivity.

The temperature difference across the material is "375°C".

According to Fourier's Law of Heat Conduction:

[tex]Q=KA\frac{\Delta T}{\Delta x}\\\\\Delta T=\frac{Q\Delta x}{KA}[/tex]

where,

ΔT = temperature difference = ?

Q = heat transfer rate = 3 KW = 3000 W

Δx = thickness = 2.5 cm = 0.025 m

A = cross-sectional area = 1 m²

K = thermal conductivity = 0.2 W/mK

Therefore,

[tex]\Delta T =\frac{(3000\ W)(0.025\ m)}{(0.2\ W/mK)(1\ m^2)}\\\\[/tex]

ΔT = 375°C

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