?A typical vertical section of a $23-$cm$-$thick and $3-$m$-$high wall is shown in the figure below. The wall extends $6$ ?m into the page.

The wall consists of $15-$cm $\backslash$times $21-$cm bricks $($kB $=0\mathrm{.}81$ ?W$/$m$.$K$)$ ?separated vertically by $4-$cm$-$thick plaster layers $($kA $=0\mathrm{.}81$ ?W$/$m$.$K$).$ ?There are also $3-$cm$-$thick plaster layers on each side of the bricks $($t$1=3$ ?cm$),$ ?and a layer of $2-$cm$-$thick foam $($kC $=0\mathrm{.}03$ ?W$/$m$.$K$)$ ?on the right hand side of the wall.

The inside $($right$)$ ?surface of the wall is maintained at a uniform temperature of $25\backslash$deg C $($T$5=25\backslash$deg C$)$ ?and the convective heat transfer coefficient on the outside $($left$)$ ?surface is $15$ ?W$/$m$2.$K$.$

The outside $($left$)$ ?temperature is $37\backslash$deg C i$)$ ?Sketch the thermal resistance network for the wall, defining and labelling the resistances and the endpoint temperatures, T$\backslash$infty and T$5.$ ?If you have sketched this in your working solution, answer yes: Answer

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ii$)$ ?Write the equation for the total thermal resistance Rtotal in terms of the individual resistances. If you have written the equation in your working solution, answer yes: Answer

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iii$)$ ?Calculate the numerical value of each resistance, and hence the total thermal resistance. Answer

$º$C$/$W

iii$)$ ?Determine the total rate of heat transfer through the wall in W$.$ ?AnswerAssume one$-$dimensional steady heat transfer and disregard radiation.

Transcribed Image Text:

t1 t2 t3 2 cm Too A B C 21 cm 5 34 2 cm 12 Assume one-dimensional steady heat transfer and disregard radiation. t1 t2 t3 2 cm Too A B C 21 cm 5 34 2 cm 12 Assume one-dimensional steady heat transfer and disregard radiation.