The work done per unit mass of air in compression will’be least when n is equal to______________?

Related Mcqs:

1. For a compressor, least work will be done if the compression is________________ ?

   A. isentropic
   B. isothermal
   C. polytropic
   D. somewhere in between isentropic and isothermal
   E. none of the above

2. Maximum work is done in compressing air when the compression is_________________?

   A. isothermal
   B. adiabatic
   C. polytropic
   D. any one of the above
   E. none of the above

3. The indicated work per unit mass of air delivered is___________________?

   A. directly proportional to clearance volume
   B. greatly affected by clearance volume
   C. not affected by clearance volume
   D. inversely proportional to clearance volume

4. For minimum work in multistage compression, assuming same index of compression in all stages_________________?

   A. work done in first stage should be more
   B. work done in subsequent stages should increase
   C. work done in subsequent stages should decrease
   D. work done in all stages should be equal
   E. work done in any stage is no criterion for minimum work but depends on other factors

5. Isothermal compression efficiency, even when running at high speed, can be approached by using A. multi-stage compression B. cold water spray C. both A. and B. above D. fully insulating the cylinder E. high stroke_________________?

   Isothermal compression efficiency, even when running at high speed, can be approached by using
   A. multi-stage compression
   B. cold water spray
   C. both A. and B. above
   D. fully insulating the cylinder
   E. high stroke

6. The advantage of multistage compression over single stage compression is ________________?

   A. lower power consumption per unit of air delivered
   B. higher volumetric efficiency
   C. decreased discharge temperature
   D. moisture free air
   E. all of the above

7. For a two stage compressor* if index of compression for higher stage is greater than index of compression for lower stage, then the optimum pressure as compared to ideal case will___________________?

   A. increase
   B. decrease
   C. remain unaffected
   D. other factors control it
   E. unpredictable

8. What is the weight (in lbf) of one gallon of air at 1 atm and 25˚C? The molecular mass of air is 28.97 g/mole = 0.02897 kg/mole

   A. 90 lbf
   B. 65.78 lbf
   C. 0.00989 lbf
   D. 3.00989 lbf

   Submitted by: Faheem Zaman Dhaunroo

9. Surface energy per unit area of a surface is numerically equal to _____________________?

   A. atmospheric pressure
   B. surface tension
   C. force of adhesion
   D. force of cohesion
   E. viscosity

10. In an experiment to determine dryness fraction of steam, the mass of water separated was 1.2 kg in 15 mts and the mass of steam passed out in same time was 4.8 kg. Dryness fraction is__________________?

    A. 40%
    B. 25%
    C. 50%
    D. 80%
    E. 90%