Home / Mechanical Engineering / Heat Transfer,Refrigeration and Air Conditioning :: Section 2

Mechanical Engineering :: Heat Transfer,Refrigeration and Air Conditioning

  1. For evaporators and condensers, for the given conditions, the logarithmic mean temperature difference (tm) for parallel flow is __________ that for counter flow.

  2. A.
    equal to
    B.
    less than
    C.
    greater than

    View Answer

    Workspace

    Discuss Discuss in Forum


  3. A vapour absorption refrigerator uses __________ as a refrigerant.

  4. A.
    water
    B.
    ammonia
    C.
    freon
    D.
    aqua-ammonia

    View Answer

    Workspace

    Discuss Discuss in Forum


  5. Thermal conductivity of air increases with rise in temperature.

  6. A.
    Correct
    B.
    Incorrect

    View Answer

    Workspace

    Discuss Discuss in Forum


  7. The material of pipe lines for a system using ammonia as a refrigerant should be copper.

  8. A.
    Yes
    B.
    No

    View Answer

    Workspace

    Discuss Discuss in Forum


  9. The wave length corresponding to the maximum energy is inversely proportional to the absolute temperature. This statement is called Planck's law.

  10. A.
    Yes
    B.
    No

    View Answer

    Workspace

    Discuss Discuss in Forum


  11. Which of the following refrigerant has the highest freezing point.

  12. A.
    Ammonia
    B.
    Carbon dioxide
    C.
    Sulphur dioxide
    D.
    R-12

    View Answer

    Workspace

    Discuss Discuss in Forum


  13. Air conditioning means

  14. A.
    cooling
    B.
    heating
    C.
    dehumidifying
    D.
    all of these

    View Answer

    Workspace

    Discuss Discuss in Forum


  15. Which of the following would lead to a reduction in thermal resistance?

  16. A.
    In conduction, reduction in the thickness of the material and an increase in thermal conductivity.
    B.
    In convection, stirring of the fluid and cleaning the heating surface.
    C.
    In radiation, increasing the temperature and reducing the emissivity.
    D.
    all of the above

    View Answer

    Workspace

    Discuss Discuss in Forum


  17. The ratio of the thickness of thermal boundary layer to the thickness of hydrodynamic boundary layer is equal to (Prandtl number)n, where n is equal to

  18. A.
    -1/3
    B.
    -2/3
    C.
    1
    D.
    -1

    View Answer

    Workspace

    Discuss Discuss in Forum


  19. Free convection flow depends on

  20. A.
    density
    B.
    coefficient of viscosity
    C.
    gravitational force
    D.
    all of these

    View Answer

    Workspace

    Discuss Discuss in Forum