Question

Use the worked example above to help you solve this problem. Find the energy transferred in 1 h by conduction through a concrete wall 1.6 m high, 4.00 m long, and 0.20 m thick if one side of the wall is held at 20°C and the other side is at 5°C.

Answer 1

Answer:

The energy transferred is 2.93 MJ.

Explanation:

Given that,

Time = 1 h = 3600 s

Area$A = 1.6\times4.00$

Width $\Delta x=0.20 m$

Temperature $T_{1}=20^{\circ}\ C$

$T_{2}=5^{\circ}\ C$

For concrete wall,

The thermal conductivity

k = 1.7 W/mK

Using Fourier's law

$Q=kA\dfrac{dt}{\Delta x}$

Where, A = area

$\Delta x$ = width

$\Delta t$ = change in temperature

k = thermal conductivity

Put the value into the formula

$Q=1.7\times 1.6\times 4.00\times\dfrac{15}{0.20}$

$Q=816\ W$

The energy transferred in 1 hour

$E = Q\times t$

$E=816\times3600$

$E=2937600$

$E = 2.93\times10^{6}\ J$

$E = 2.93\ MJ$

Hence, The energy transferred is 2.93 MJ.