Thermal Engineering 23

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Objective Questions and Answer: Thermal Engineering 23

Subject: Thermal Engineering 23

Part 23: Objective questions and answers of Thermal Engineering

 

Q1. Rotary compressor is best suited for

a) Large quantity of air at high pressure

b) Small quantity of air at high pressure

c) Small quantity of air at low pressure

d) Large quantity of air at low pressure

 

Q2. The capacity of compressor will be highest when its intake temperature is

a) Lowest

b) Highest

c) Anything.

d) Atmospheric

 

Q3. After-cooler is used to

a) Cool the air

b) Decrease the delivery temperature for ease in handling

c) Cause moisture and oil vapor to drop out

d) Reduce volume

 

Q4. To avoid moisture troubles, the compressed air main line should

a) Rise gradually towards the point of use

b) Drop gradually towards the point of use

c) Be laid vertically

d) Be laid exactly horizontally

 

Q5. Separators in compressor installations are located

a) Before intercooler

b) After intercooler

c) After receiver

d) Between after-cooler and air receiver

 

Q6. The area of actual indicator diagram on an air compressor as compared to area of ideal indicator diagram is

a) Less

b) More

c) Same

d) More/less depending on compressor capacity

 

Q7. An air compressor may be controlled by

a) Throttle control

b) Clearance control

c) Blow-off control

d) Any one of the above

 

Q8. The compressor efficiency is the

a) Isothermal H.P/indicated H.R

b) Isothermal H.P./shaft H.R

c) Total output/air input

d) Compression work/motor input

 

Q9. To avoid moisture troubles, the branch connections from compressed air lines should be taken from

a) Top side of main

b) Bottom side of main

c) Left side of main

d) Right side of main

 

Q10. The thrust on the rotor in a centrifugal compressor is produced by

a) Radial component

b) Axial component

c) Tangential component

d) Resultant component

 

Q11. The compressor performance at higher altitude compared to sea level will be

a) Same

b) Higher

c) Lower

d) Dependent on other factors

 

Q12. A compressor at high altitude will draw

a) More power

b) Less power

c) Same power

d) More/less power depending on other factors

 

Q13. During peak load periods, the best method of controlling compressors is

a) Start-stop motor

b) Constant speed unloader

c) Relief valve

d) Variable speed

 

Q14. A centrifugal compressor works on the principle of

a) Conversion of pressure energy into kinetic energy

b) Conversion of kinetic energy into pressure energy

c) Centripetal action

d) Generating pressure directly

 

Q15. 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

 

Q16. In a compressor, free air delivered is the actual volume delivered at the stated pressure reduced to

a) N.T.P. conditions

b) Intake temperature and pressure conditions

c) 0°C and 1 kg/cm^2

d) 20°C and 1 kg/cm^2

 

Q17. The volumetric efficiency of a compressor is calculated on the basis of

a) Volume of air inhaled at working conditions

b) Volume of air inhaled at N.T.P. conditions

c) Volume at 0°C and 1 kg/cm^2

d) Volume at 20°C and 1 kg/cm^2

 

Q18. The volumetric efficiency of a compressor falls roughly as follows for every 100 m increase in elevation

a) 0.10%

b) 0.50%

c) 1.00%

d) 5%

 

Q19. For slow-speed large capacity compressor, following type of valve will be best suited

a) Poppet valve

b) Mechanical valve of the Corliss, sleeve, rotary or semirotary type

c) Disc or feather type

d) Any of the above

 

Q20. During base load operation, the best method of controlling compressor is

a) Start-stop motor

b) Constant speed unloader

c) Relief valve

d) Variable speed

 

Part 23: Objective questions and answers of Thermal Engineering

 

Q1. Answer: b

Q2. Answer: d

Q3. Answer: c

Q4. Answer: b

Q5. Answer: d

Q6. Answer: b

Q7. Answer: d

Q8. Answer: a

Q9. Answer: a

Q10. Answer: b

Q11. Answer: c

Q12. Answer: b

Q13. Answer: b

Q14. Answer: b

Q15. Answer: b

Q16. Answer: b

Q17. Answer: b

Q18. Answer: a

Q19. Answer: c

Q20. Answer: a

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