Two very long concentric cylinders of diameters d1 = 0.42 m and d2 = 0.5 m are maintained at uniform temperatures of t1 = 950 k and t2 = 500 k and have emissivities ε1 = 1 and ε2 = 0.55, respectively. determine the net rate of radiation heat transfer between the two cylinders per unit length of the cylinders. (use σ = 5.67 × 10-8)

Q=33.34 KW/m

Explanation:

Given that

D₁=0.42 m

A₁= π D₁ L

For unit length

A₁= π D₁ = 0.42 π m²

D₂=0.5 m

A₂= 0.5 π m²

ε₁= 1 ,ε₂= 0.55

T₁=950 K  ,T₂ = 500 K

F₁₁+F₁₂= 1

F₁₁= 0

So, F₁₂= 1

Q=33.34 KW/m

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