For annular flow of a fluid, the ratio of the equivalent diameter for pressure drop calculation to the equivalent diameter for heat transfer calculation is_________________?

Related Mcqs:

1. For turbulent flow (NRe > 2100) of low viscosity fluid (μ > 20cp) in steel pipes, the optimum inside pipe diameter is given by(where, Q = fluid flow rate, ft3/sec, ρ = fluid density, lb/ft3 μ = fluid viscosity, centipoise Di = optimum inside pipe diameter, inches) ?

   A. Di, opt = 3.9 Q0.45 ρ0.13
   B. Di, opt = 3.9 Q0.45. μ0.95
   C. Di, opt = 4.7 Q0.36. μ3.2ρ0.13
   D. Di, opt = 3 Q0.36. μ0.88

2. The equivalent diameter for pressure drop is _______________ that for heat transfer?

   A. Smaller than
   B. Greater than
   C. Equal to
   D. Not related with

3. Equivalent diameter for heat transfer calculation for a duct of square cross-section having each side as ‘d’ will be__________________?

   A. d
   B. √d
   C. √(2πd)
   D. √(2d)

4. In a shell and tube heat exchanger for a given heat transfer surface area, smaller diameter tubes are favoured as compared to larger diameter ones; because the smaller diameter tubes ______________?

   A. Are easier to clean
   B. Are less prone to fouling
   C. Can be fitted into a smaller shell diameter hence the cost of the heat exchanger would be less
   D. None of these

5. Tube side pressure drop in a 1-2 heat exchanger (for turbulent flow of fluids through the tubes) is about __________ times, that in a 1-1 heat exchanger having the same size & number of tubes and operated at the same liquid flow rate ?

   A. 2
   B. ½
   C. 4
   D. 8

6. The equivalent diameter for fluid flow through a channel of constant non-circular cross section of area ‘A’ is given by (where, P = perimeter of the channel in contact with the fluid) ?

   A. 4 A/P
   B. A/P
   C. 4 P/A
   D. √A

7. Pressure drop due to pipe fittings can be estimated by the equation, ΔP/ρ = 4f, (Le/D) (V2/2gc) where, Le = equivalent length of straight pipeline which will incur the same frictional loss as the fitting and D = diameter of the fitting. The value of (Le/D) (dimensionless) for 45° elbow and 180° close return bends would be respectively around______________________?

   A. 5 and 10
   B. 45 and 75
   C. 180 and 300
   D. 300 and 500

8. In a shell and tube heat exchanger having square pitch, the shell side equivalent diameter is given by (where, P = pitch, d = outside diameter of the tube) ?

   A. 4(P2 – πd2/4)/πd
   B. (P2 – rd2/4)/rd
   C. 4P2/πd
   D. πd/4P2

9. 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

10. The difficulty of liquid distribution in packed towers is accentuated, when the ratio of tower diameter to packing diameter is_________________?

    A. < 30
    B. < 7
    C. > 7 20 < 50