The Reynolds number of the liquid was increased 100 fold for a laminar falling film used for gas-liquid contacting. Assuming penetrating theory is applicable, the fold increase in the mass transfer co-efficient (Kc) for the same system is_______________________?

Related Mcqs:

1. In a vapor-liquid contacting equipment, the overall gas phase mass transfer co-efficient (M.T.C), KG is related to individual co-efficients (KG and KL) as ___________________ ?

   A. KG = 1/KG + m/KL
   B. 1/KG = 1/KG + m/KL
   C. 1/KG = 1/KL + m/KG
   D. KG = 1/KL + m/KG

2. Experiments were conducted to determine the flux of a species A in a stagnant medium across a gas-liquid interface. The overall mass transfer co-efficient based on the liquid side for dilute systems for the above was estimated to be 4 × 10-3 kg mole/m2.s. The equilibrium data for the system is given as y = 2x. The flux across the interface (in kg mole/m2 .s) for bulk concentrations of A in gas phase and liquid phase as y = 0.4 and x = 0.01 respectively is _________________________?

   A. 5.6 × 10-4
   B. 8.5 × 10-4
   C. 5.6 × 10-3
   D. 8.5 × 10-3

3. For the gas absorption, the height of a transfer unit, based on the gas phase is given by (G: superficial molar gas velocity, L: superficial molar liquid velocity, FG: mass transfer co-efficient, moles/m2, a: interfacial area per unit volume of tower) ?

   A. G/(FG . a)
   B. FG/(G . a)
   C. (G . a)/FG
   D. L/(FG . G)

4. According to the film theory of mass transfer, the mass transfer co-efficient is proportional to (where, D = molecular diffusivity) ?

   A. D
   B. D2
   C. D0.5
   D. 1/D

5. JD factor for mass transfer is a function of Reynolds number. Mass transfer by molecular diffusion from a single drop to surrounding still air is given by___________________?

   A. Nsh = 2
   B. Nst = 2
   C. Nsc = 2
   D. None of these

6. H2S is being absorbed in a gas absorber unit. The height of the transfer unit based on the overall mass transfer coefficient on the gas side is 0.4 m. The equilibrium data is given by, y = 1.5 x. The bulk concentration of H2S has to be reduced from 0.05 to 0.001 mole fraction in the gas side. The height of the tower (in meters) corresponding to an operating line given by, y = 5x + 0.001 is ______________________?

   A. 2.0
   B. 1.56
   C. 1.0
   D. 0.56

7. Out of the following gas-liquid contacting devices, for a given set of operating conditions, gas pressure drop is the least in ______________ tower?

   A. Wetted wall
   B. Bubble cap
   C. Perforated tray
   D. Packed

8. For experimental determination of mass transfer co-efficient by wetted wall tower, the mass transfer area is___________________?

   A. Calculated
   B. Unknown
   C. Known
   D. Not required

9. Mass transfer co-efficient (K) and diffusivity D. are related according to film theory as______________________?

   A. K ∝ D
   B. K ∝√D
   C. K ∝ D1.5
   D. K ∝ D2

10. With increase in the liquid flow rate at a fixed gas velocity in a randomly packed counter current gas-liquid absorption column, the gas pressure drop___________________?

    A. Decreases
    B. Remains unchanged
    C. Increases
    D. Decreases exponentially