During air cooling of oranges, grapefruit, and tangelos, the heat transfer coefficient for combined convection, radiation, and evaporation for air velocities of 0.11 < V < 0.33 m/s is determined experimentally and is expressed as h = 5.05 k_airRe^1/3/D, where the diameter D is the characteristic length. Oranges are cooled by refrigerated air at 5°C and 1 atm at a velocity of 0.3 m/s. Determine

(a) The initial rate of heat transfer from a 7-cm-diameter orange initially at 15°C with a thermal conductivity of 0.50 W/m·K,

(b) The value of the initial temperature gradient inside the orange at the surface,

(c) The value of the Nusselt number.

Transcribed Image Text:

Air 5°C 1 atm Orange