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Question 10.1: Estimate the Nusselt number for a flat plate with characteri...

Estimate the Nusselt number for a flat plate with characteristic dimension 50 mm exposed to a windspeed of 2.0 m s^{-1}. Assume now that a real leaf can be treated as a flat plate with the same characteristic dimension, but that its Nusselt number is twice the value calculated earlier (i.e. β = 2, pp. 160–161). Estimate the rate of convective heat transfer from the leaf at a windspeed of 2.0 m s^{-1} when the difference between leaf and air temperature is 1.5 °C.

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For the flat plate, Re= 2.0 \times 50\times 10^{-3} /15\times 10^{-6}  = 6.6\times 10^{3} .

Nu = 0.60 Re^{0.5} = 49. For the leaf, Nu = 2 × 49 = 98.

Then convective heat transfer is C = 98\times 26\times 10^{-3} \times 1.5/50\times 10^{-3} = 76\; W\; m^{-2} .

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