Define mass transfer, mass diffusion coefficient. Explain the mechanism of mass transfer.
Define Lewis number, Sherwood number, and Schemidt number. Explain the physical significance of these.
Draw NTU versus ϵ\epsilon for counter and parallel flow. Is there any limit for effective design of exchanger based on NTU versus ϵ\epsilon? Explain.
State 5 types of diffusion process.
Determine the mole fraction of the water vapor at the surface of a lake whose temperature is 15°C. Compare the mole fraction of water in the lake having atmospheric pressure of 92 kPa.
Dry air at 15°C and 92 kPa flows over a 2m long wet surface with a free stream velocity of 4 m/s. Determine the average mass transfer coefficient.
Define Fick's law of mass transfer. What is the mechanism of mass transfer? Describe in brief.
Write short notes on:
Determine the mole fraction of air dissolved in water at the surface of a lake whose temperature is 17°C. Take the atmospheric pressure at lake level to be 92 kPa.
How does mass transfer differ from bulk fluid flow? Can mass transfer occur in a homogeneous medium?
Define Lewis number and Schmidt number. What are the significances of these numbers?
An open pan 20 cm in diameter and 10 cm deep contains water at 25 °C and is exposed to atmospheric air at 25 °C. Calculate the evaporation rate of water. Diffusion coefficient of water vapor in air at 25 °C and 1 atm is 0.256 cm²/s.
Write the expression for Fick's law of diffusion. Why does mass transfer occur?
Write short notes on (Any three) : i) Sherwood number ii) Mass transfer coefficient iii) Schemidt number iv) Lewis number v) Stanton number
A mixture of head N₂ gas is contained in a pipe at 298 K and 1 atm, total pressure of which is constant throughout. At one end of the pipe at point 1, the partial pressure PA1 Of He is .6 atm and at the other end 0.2 m distance is PA2 = 0.2 atm. Calculate the flux of He at steady state if DAB Of He-N₂ mixture is 0.687 × 10⁻⁴ m²/s.