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Mechanical Engineering :: Thermodynamics

  1. Otto cycle efficiency is higher than Diesel cycle efficiency for the same compression ratio and heat input because in Otto cycle

  2. A.

     Heat rejection is lower

    B.

     Expansion and compression are isentropic

    C.

     Combustion is at constant volume

    D.

     Maximum temperature is higher


  3. Which of the following processes is irreversible process?

  4. A.

     Isothermal

    B.

     Adiabatic

    C.

     Throttling

    D.

     All of the above


  5. The amount of heat required to raise the temperature of the unit mass of gas through one degree at constant volume, is called

  6. A.

     Kilo Joule

    B.

     Specific heat at constant volume

    C.

     Specific heat at constant pressure

    D.

     None of these


  7. A diathermic wall is one which

  8. A.

     Prevents thermal interaction

    B.

     Permits thermal interaction

    C.

     Encourages thermal interaction

    D.

     Discourages thermal interaction


  9. An adiabatic wall is one which

  10. A.

     Prevents thermal interaction

    B.

     Permits thermal interaction

    C.

     Encourages thermal interaction

    D.

     Discourages thermal interaction


  11. The polytropic index (n) is given by

  12. A.

     log (p1p2)/log (v1v2)

    B.

     log (p2/ p1)/log (v1/ v2)

    C.

     log (v1/ v2)/ log (p1/p2)

    D.

     log [(p1v1)/(p2v2)]


  13. Minimum work in compressor is possible when the value of adiabatic index ‘n’ is equal to

  14. A.

     0.75

    B.

     1

    C.

     1.27

    D.

     1.35


  15. Which of the following cycles has maximum efficiency?

  16. A.

     Rankine

    B.

     Stirling

    C.

     Carnot

    D.

     Brayton


  17. No liquid can exist as liquid at

  18. A.

     273°K

    B.

     Vacuum

    C.

     Zero pressure

    D.

     Centre of earth


  19. In a free expansion process,

  20. A.

     W1 - 2 = 0

    B.

     Q1 - 2 = 0

    C.

     dU = 0

    D.

     All of these