This set of Mass Transfer Interview Questions & Answers focuses on “Material Balance Concepts-Counter Current”.
Explanation: There are parallel operating lines so the slope will be same.
2. Only small equipments are required for co-current process.
Explanation: Only for the counter current process, the mean driving force is large so small equipment is needed.
Explanation: The operating line is a curve, so the representation must be in mole or mass fraction.
4. Find the slope of the operating line from the figure below.
If, Ls,Gs- non diffusing solvent
X,Y- Concentrations in mole ratio
x,y- concentration in mole fraction
Explanation: Gs(Y1)+Ls(X2)= Gs(Y2)+ls(X1)
So the slope of the operating line is Ls/Gs.
Explanation: Here, the operating line touches the equilibrium line the mass transfer rates becomes zero. So the driving force will be zero at the point P.
6. The driving force line between the operating line and the equilibrium line depends on
a) Relative diffusion resistance
b) Relative mass resistance
c) Cumulative resistance
d) None of the mentioned
Explanation: As the driving force changes continuously at every point in a counter current process, the relative diffusion resistance is taken into consideration.
7. Removal of ammonia from the air with water is an example of a counter-current process.
Explanation: Here, the ammonia + air is sent through one side and water is sent through other end.
8. For Air-Water system Lewis Number equals to
a) Approx 1
d) 0 to 1
Explanation: For the air-water system the simultaneous heat and mass transfer takes place. Therefore the Schmidt number (Sc) and Prandtl number (Pr) become equal. Lewis number= (Sc/Pr) equals to 1.
Sanfoundry Global Education & Learning Series – Mass Transfer.
To practice all areas of Mass Transfer for interviews, here is complete set of 1000+ Multiple Choice Questions and Answers