Question

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

Answer 1

22.474 KW

Step-by-step explanation:

We have given casting surface
`a=6.5m^2`

Surface temperature
`T_1=400^(\circ)C=400+237=673K`

Foundry temperature
`T_2=30^(\circ)C=273+30=303K`

Emissivity of grey = 0.31 given

Now the rate heat of heat radiated from the casting is

`Q_(radiated)=\epsilon A\sigma \left ( T_1^4-T_2^4 \right )`

Here
`\sigma =5.67* 10^(-8)`

So
`Q_(radiated)=0.31* 6.5* 5.67* 10^(-8)\left ( 673^4 \right-303^4 )=22474.846\ W=22.474KW`