Question: Consider a concentric circular-tube annulus, with outer diameter 2.5 cm and inner diameter 1.25 cm, in which air is flowing under fully developed, constant-he at-rate conditions. Heat is supplied to the inner tube, and the outer tube is externally insulated. The radiation emissivity of both tube surfaces is 0.8. The mixed mean temperature of the air at a particular point in question is 260°C. The inner-tube surface temperature at this point is 300°C. What is total heat flux from the inner-tube surface at this point? What is the outer-tube surface temperature at this point? What percentage of the heat supplied to the inner tube is transferred directly to the air, and what percentage indirectly from the outer surface? The Reynolds number is sufficiently low that the flow is laminar. Assume. that the air is transparent to the thermal radiation. Make use of any of the material in the text as needed.