Heat is generated inside a very long hollow cylinder of length L due to radioactive decay. This heat flow per length of the cylinder, has a value of Q/L ˙ = 550W/m. The hollow cylinder is made of a...

Heat is generated inside a very long hollow cylinder of length L due to radioactive decay. This heat flow per length of the cylinder, has a value of Q/L ˙ = 550W/m. The hollow cylinder is made of a steel alloy (λ = 15W/K m), with inner diameter d_i
= 20 mm and wall thickness δ = 10 mm. Heat is only given up from its outer surface into space (T = 0 K) by radiation. The emissivity of the cylinder surface is ε = 0.17. Calculate the Celsius temperatures ϑ_i
of the inner and ϑ_o
of the outer surfaces. What is the value for the radiative heat transfer coefficient α_rad?