Plant leaves possess small channels that connect the interior moist region of the leaf to the environment. The channels, called stomata, pose the primary resistance to moisture transport through the entire plant, and the diameter of an individual stoma is sensitive to the level of CO2 in the atmosphere.
Consider a leaf of corn (maize) whose top surface is exposed to solar irradiation of GS = 600 W/m2 and an effective sky A > 3 µ,m.
The inner surface is exposed to a working fluid (a pressurized liquid) for which T00,i = 700 K and hi = 1000 W/m2 · K. The outer surface is also exposed to surroundings for which Tsur = 300 K. If the wall is fabricated from a high-temperature material for which k = 15 W/m · K, what is the minimum thickness L needed to ensure that the outer surface temperature does not exceed Ts,o = 1000 K? What is the collection efficiency associated with this thickness?