Asymptotic conditions is reached, when for a fluid flowing in laminar flow through a long tube___________________?

Related Mcqs:

1. A fluid is flowing inside the inner tube of a double pipe heat exchanger with diameter ‘d’. For a fixed mass flow rate, the tube side heat transfer co-efficient for turbulent flow conditions is proportional to_____________________?

   A. d0.8
   B. d-0.2
   C. d-1
   D. d-1.8

2. Heat exchangers operating, when the asymptotic range is reached, ?

   A. Provide very large heat transfer co-efficient
   B. Results in making part of the heating surface inactive
   C. Results in abruptly increased velocity
   D. None of these

3. The characteristic dimensionless groups for heat transfer to a fluid flowing through a pipe in laminar flow are_______________?

   A. Re.Gz
   B. Nu, Pr
   C. Nu, Pr, Re
   D. Nu, Gz

4. For a laminar flow of fluid in a circular tube, ‘h1’ is the convective heat transfer co-efficient at velocity ‘V1’. If the velocity is reduced by half and assuming the fluid properties are constant, the new convective heat transfer co-efficient is________________?

   A. 1.26 h1
   B. 0.794 h1
   C. 0.574 h1
   D. 1.741 h1

5. For a liquid in laminar flow through a very long tube, when the exit fluid temperature approaches the wall temperature, the equation to be used is______________?

   A. Nu = 0.023 Re0.8. Pr0.4
   B. Nu = (π/2) Gz
   C. Nu = (2/π) Gz
   D. Nu = 2Gz0.5

6. Convective heat transfer co-efficient in case of fluid flowing in tubes is not affected by the tube length/diameter ratio, if the flow is in the _____________ zone?

   A. Laminar
   B. Transition
   C. Both A & B
   D. Highly turbulent

7. LMTD for evaporators & condensers for a given terminal parameters & set of conditions for counter-flow is equal to that for parallel flow. In such heat exchangers, with one of the fluids condensing or evaporating, the surface area required is the least in the ______________ flow?

   A. Parallel
   B. Mixed
   C. Counter flow
   D. Same in either A , B. or C.

8. Heat transfer in the laminar sub-layer in case of a liquid flowing through a pipe, is mostly by__________________?

   A. Eddies current
   B. Conduction
   C. Convection
   D. None of these

9. In case of parallel flow heat exchanger, the lowest temperature theoretically attainable by the hot fluid is _____________ the outlet temperature of the cold fluid?

   A. Equal to
   B. More than
   C. Less than
   D. Either more or less than (depending upon the fluid)

10. 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