An object of irregular shape 1 m long maintained at a constant temperature of 100°C is suspended in an airstream having a free stream temperature of 0°C, a pressure of 1 atm, and a velocity of 120 m/s. The air temperature measured at a point near the object in the airstream is 80°C. A second object having the same shape is 2 m long and is suspended in an airstream in the same manner. The air free stream velocity is 60 m/s. Both the air and the object are at 50°C, and the total pressure is 1 atm. A plastic coating on the surface of the object is being dried by this process. The molecular weight of the vapor is 82, and the saturation pressure at 50°C for the plastic material is 0.0323 atm. The mass diffusivity for the vapor in air at 50°C is 2.60 × 10-5 m2 /s.
(a) For the second object, at a location corresponding to the point of measurement on the first object, determine the vapor concentration and partial pressure.
(b) If the average heat flux q" is 2000 W/m2 for the first object, determine the average mass flux n"A (kg/s· m2) for the second object.