Microsoft PowerPoint - INTRODUCTION TO HEAT Radiation

Microsoft PowerPoint - INTRODUCTION TO HEAT Radiation -...

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Unformatted text preview: INTRODUCTION TO HEAT Radiation Course By : Prof. Mohajer prepared by: S.M. rafigh 2011 Radiation Heat Transfer • e = emissive power • G = total irradiation • J = total radiosity ε = emissivity α=ε α=ε α=ε α=ε 1 = + + τ ρ α In general: Opaque material : 1 = + ρ α α = absorptivity ρ = reflectivity τ = transmissivity T 3 Energy Ideal Emitter Schematic T 3 > T 2 > T 1 λ e λ T 1 T 2 e Radiation Heat Transfer • Black Body – absorptivity = α=1 – emissivity = ε=1 4 T e b σ = 1 = = ε α – ideal emissive power = e b ( 29 λ α f ≠ ( 29 λ ε f ≠ 4 T e gray σ ε σ ε σ ε σ ε = b gray e e ε = • Gray Body – absorptivity < 1 – emissivity < 1 – emissive power<1 Black Body Energy black gray e e = ε ε α = ( 29 λ ε f ≠ Schematic λ e λ Gray Body Real Body Radiation Heat Transfer View Factor: F ij = fraction of radiation from surface i intercepted by surface j....
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This note was uploaded on 06/21/2011 for the course CHE 21345 taught by Professor Prof.mohajer during the Fall '10 term at Sharif University of Technology.

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Microsoft PowerPoint - INTRODUCTION TO HEAT Radiation -...

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