A cylinder of 30-mm diameter and 150-mm length is heated in a large furnace having walls at 1000 K, while air at 400 K is circulating at 3 m/s. Estimate the steady-state cylinder temperature under the  following specified conditions.

  (a) The cylinder is in cross flow, and its surface is diffuse and gray with an emissivity of 0.5.

  (b) The cylinder is in cross flow, but its surface is spectrally selective with α_λ = 0.1 for as 3 μm and α_λ = 0.5 for λ > 3 μm.

  (c) The cylinder surface is positioned such that the airflow is longitudinal and its surface is diffuse and gray.

  (d) For the conditions of part (a), compute and plot the cylinder temperature as a function of the air velocity for 1 < V < 20 m/s.