Discuss the following in detail:
Q: Evaporation of liquid fuel droplets is often studied in the laboratory by using a porous sphere technique in which the fuel is supplied at a rate just sufficient to maintain a completely wetted surface on the sphere.
Consider the use of kerosene at 300 K with a porous sphere of I-mm diameter. At this temperature the kerosene has a saturated vapor density of 0.015 kg/m3 and a latent heat of vaporization of 300kJ/kg. The mass diffusivity for the vapor-air mixture is 10-5 m2/s. If dry, atmospheric air at V = 15 m/s and T8 = 300 K flows over the sphere, what is the minimum mass rate at which kerosene must be supplied to maintain a wetted surface? For this condition, by how much must T8 actually exceed Ts to maintain the wetted surface at 300 K?
