A thin aluminum sheet with an emissivity of 0.15 on both sides is placed between two very...

A thin aluminum sheet with an emissivity of 0.15 on both sides is placed between two very large parallel plates, which are maintained at uniform temperatures T1 = 900 K and T2= 650 K and have emissivities ε1 = 0.5 and ε2 = 0.8, respectively. Determine the net rate of radiation heat transfer between the two plates per unit surface area of the plates and compare the result with that without the shield.