Find the heat transfer Q through a 12 thick concrete wall wi

Find the heat transfer. Q. through a 12\" thick concrete wall with a hot face temperature of 120F and a cold face temperature of 70F. The transfer surface is 8\' by 10\'. Use an online resource to find thermal conductivity of the concrete. The barrier shown consists of a steel section and a ceramic section. Knowing that the heat flux that passes through each section is equal, calculate the temperature at the right side of the barrier.

Solution

1.)

the conductivity of the concrete is 0.8 W/mk   = 0.00154077 Btu in / s ft^2 F

Q=A*k*T/x = A= (8*10)*0.00154077¨*(120-70)/12 = 0.51 Btu/ s

2)

The first part has the heat of

Q=k*T/x = 3*(400-100)/(3/1000) = 300,000 W / m^2

so the same heat is for the second part, so

300,000=17*(100-t)/(9/1000)

t= -58.82°C