At equal mass velocities, the values of film co-efficients for gases as compared to that for liquids are generally ?

Related Mcqs:

1. Overall mass transfer co-efficient in case of absorption of __________ in water is based on the gas film co-efficient only, as the mass transfer process is gas film (phase) controlling ?

   A. CO2
   B. SO2
   C. NH3
   D. None of these

2. In a shell and tube heat exchanger, the overall heat transfer co-efficient is proportional to the tube side (volumetric flow rate)0.8. This is valid, only when the ratio of the tube side film resistance to the total resistance is almost equal to____________________?

   A. ∞
   B. 1
   C. 20.8
   D. 2

3. Multiple blade paddle agitator is used for mixing high viscosity liquids/paste in which the paddle diameter is commonly 0.8 times the tank diameter. However, the width of the blade is in the range of ______________ times the paddle diameter?

   A. 0.1 to 0.25
   B. 0.3 to 0.5
   C. 0.5 to 0.6
   D. 0.65 to 0.80

4. Cylindrical storage tanks used for the storage of volatile liquids (e.g., naphtha) have ______________ roofs?

   A. Conical
   B. Flat
   C. Floating
   D. Fixed

5. Angled baffles are preferred in the agitation tank to control the swirling action; if the viscosity of the liquid to be mixed is about 200 poise. However, the baffle may be completely eliminated for mixing liquids having viscosity above ____________________ poise?

   A. 300
   B. 600
   C. 1000
   D. 1500

6. A single pass air heater is connected to a two pass unit. For the air flow rate and other conditions remaining the same, the film heat transfer co-efficient for air will vary in the ratio of_________________?

   A. 2
   B. 20.8
   C. 20.2
   D. None of these

7. For identical situation, condensing film coefficient in case of a horizontal condenser is almost ______________ the value expected in case of vertical condenser?

   A. Half
   B. Twice
   C. Thrice
   D. Five times

8. In case of a shell and tube heat exchanger, the effect of L/D on inside film heat transfer coefficient (hi) vanishes after a Reynold number of_____________?

   A. 1000
   B. 3000
   C. 5000
   D. 10000

9. The practical representative values of HETP for a number of commercial operations lies within a range of ______________ metre?

   A. 0.1-0.2
   B. 0.2-0.5
   C. 0.4-0.9
   D. 1.2-1.5

10. Heat transfer co-efficient, hG(Kcal/hr.m2 .°C) and mass velocity of air, G (kg/hr.m2 ) for air flow parallel to the surface in case of constant drying rate in batch drying is related as hG = 0.0176G0.8. But when the flow of air perpendicular to the surface is encountered, this equation changes to ____________________?

    A. hG = 1.004G0.37
    B. 1.004G0.8
    C. hG = 0.0176G0.37
    D. 0.0176G1.37