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A grey iron casting has a surface area of 6.5m². It is stripped from the mould when the surface temperature is 400°C. Determine the rate at which heat is radiated from the casting if the temperature in the foundry is 30°C and emissivity of the grey cast iron is 0.31

Respuesta :

Answer:

22.474 KW

Explanation:

We have given casting surface [tex]a=6.5m^2[/tex]

Surface temperature [tex]T_1=400^{\circ}C=400+237=673K[/tex]

Foundry temperature [tex]T_2=30^{\circ}C=273+30=303K[/tex]

Emissivity of grey = 0.31 given

Now the rate heat of heat radiated from the casting is

[tex]Q_{radiated}=\epsilon A\sigma \left ( T_1^4-T_2^4 \right )[/tex]

Here [tex]\sigma =5.67\times 10^{-8}[/tex]

So [tex]Q_{radiated}=0.31\times 6.5\times 5.67\times 10^{-8}\left ( 673^4 \right-303^4 )=22474.846\ W=22.474KW[/tex]

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