For a fluid flowing in an annulus space, the wetted perimeter for heat transfer and pressure drop are__________________?

Related Mcqs:

1. If average heat transfer co-efficient is ha and the local coefficient at the end of the plate is hl then in case of heat transfer to a fluid flowing over a flat plate, heated over its entire length________________?

   A. ha = hl
   B. ha = 2hl
   C. ha = 0.5 hl
   D. ha = 0.75 hl

2. Extended heat transfer surface like fins are used to increase the heat transfer rate. Fin efficiency is defined as the ratio of heat transferred across the fin surface to the theoretical heat transfer across an equal area held at the________________?

   A. Surrounding temperature
   B. Average temperature of the fin
   C. Temperature of the fin end
   D. Constant temperature equal to that of the base

3. 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

4. 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

5. A 10 cm dia steam pipe, carrying steam at 180°C, is covered with an insulation (conductivity = 0.6 W/m.°C). It losses heat to the surroundings at 30°C. Assume a heat transfer co-efficient of 0.8 W/m2.°C for heat transfer from surface to the surroundings. Neglect wall resistance of the pipe and film resistance of steam. If the insulation thickness is 2 cms, the rate of heat loss from this insulated pipe will be__________________?

   A. Greater than that for un-insulated steam pipe
   B. Less than that of the un-insulated steam pipe
   C. Equal to that of the un-insulated steam pipe
   D. Less than the steam pipe with 5 cms insulation

6. 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

7. Mode of heat transfer in which the fluid moves under the influence of changes in fluid pressure produced by external work is called_______________?

   A. Radiation
   B. Natural convection
   C. Forced convection
   D. Conduction

8. 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

9. 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

10. Bulk of the convective heat transfer resistance from a hot tube surface to the fluid flowing in it, is __________________?

    A. In the central core of the fluid
    B. Uniformly distributed throughout the fluid
    C. Mainly confined to a thin film of fluid near the surface
    D. None of these