For _______________ Prandtl number values, the heat conduction will be negligible in the buffer zone?

Related Mcqs:

1. Conduction occurs in the buffer zone for a fluid flowing through a heated pipe, only when Prandtl number is________________?

   A. 0.1
   B. > 1
   C. < 1
   D. 1

2. Heat transfer by conduction in the turbulent core of a fluid flowing through a heated pipe is negligible, if the value of Prandtl number is_______________?

   A. 0.2
   B. 0.4
   C. 0.6
   D. 0.8

3. At what value of Prandtl number, conduction is negligible in the turbulent core of a fluid flowing through a heated pipe ?

   A. 0.5
   B. < 0.5
   C. > 0.6
   D. < 0.1

4. Heat transfer by conduction results due to the transfer of free electrons, kinetic energy & vibrational energy from one molecule to another. Conduction heat transfer cannot take place____________________?

   A. Between two bodies in physical contact with each other
   B. Between two bodies not in physical contact with each other
   C. From one part of a body to the another part of the same body
   D. Both B & C

5. 1000 Kg of liquid at 30°C in a well stirred vessel has to be heated to 120°C, using immersed coils carrying condensing steam at 150°C. The area of the steam coils is 1.2 m2 and the overall heat transfer co-efficient to the liquid is 1500 W/m2.°C. Assuming negligible heat loss to the surrounding and specific heat capacity of the liquid to be 4 kJ/kg.°C, the time taken for the liquid to reach desired temperature will be__________________?

   A. 15 min
   B. 22 min
   C. 44 min
   D. 51 min

6. Prandtl and Reynold’s analogies are identical for Prandtl number value of__________________?

   A. 0
   B. 0.5
   C. 1
   D. 5

7. Prandtl and Reynolds analogy are same, when Prandtl number is____________________?

   A. 0.5
   B. 1
   C. > 2
   D. 1.5

8. Resistance to heat flow by conduction is proportional to (where, t & ρ are thickness & density of the material respectively and A = area normal to the direction of heat flow.) ?

   A. t
   B. 1/ρ
   C. 1/A
   D. All A., B. & C.

9. In case of heat transfer by conduction in a hollow cylinder, ______________ mean area is used to calculate the heat transfer rate?

   A. Geometric
   B. Arithmetic
   C. Logarithmic
   D. Either A., B. or C.

10. Arithmetic mean area can be used in heat transfer problem to calculate the heat flow by conduction through a cylinder which is ____________________?

    A. Thin walled having the value of Ao Ai/< 2
    B. Thick walled
    C. Having the value of Ao/Ai > 2
    D. Both B. and C.