Dry air at 300 K temperature and 1 bar pressure flows parallel to a flat surface at a velocity of 1.5 m/s. The flat surface is everywhere at 300 K temperature. The surface is dry up to a distance of...

Dry air at 300 K temperature and 1 bar pressure flows parallel to a flat surface at a velocity of 1.5 m/s. The flat surface is everywhere at 300 K temperature. The surface is dry up to a distance of 12 cm downstream from the leading edge of the surface, but is maintained wet with water beyond that point. Calculate the evaporation rate at a distance of 18 cm from the leading edge, assuming that the surface temperature is maintained at 300 K everywhere. Also, calculate the rate and direction of heat transfer that is needed to maintain the surface at 300 KWater flows through a flat channel with a hydraulic diameter of 5 cm. At a location where the flow field is fully developed, the water mean temperature is 40°C. The tube wall surface temperature is T_s
= 70°C everywhere. The Reynolds number defined based on the hydraulic diameter is 2 × 10⁴
. Using the velocity and temperature laws-of-the-wall, calculate the mean (time average) velocity and temperature at y = 0.5 mm, where y is the normal distance from