Reconsider Prob. 21–101. Using an appropriate software, investigate the effects of the temperature and the emissivity of the hot plate on the net rate of radiation heat transfer between the plates. Let the temperature vary from 500 K to 1000 K and the emissivity from 0.1 to 0.9. Plot the net rate of radiation heat transfer as functions of temperature and emissivity and discuss the results.

Reconsider Prob. 21–101.

Two very large parallel plates are maintained at uniform temperatures of T₁ = 600 K and T₂ = 400 K and have emissivities ε₁ = 0.5 and ε₂ = 0.9, respectively. Determine the net rate of radiation heat transfer between the two surfaces per unit area of the plates.