Compressors, Gas Turbines & Jet Engines Mcqs - Set 1

1)   Adiabatic compression is one in which___________________?

a. temperature during compression remains constant
b. no heat leaves or enters the compressor cylinder during cornpression
c. temperature rise follows a linear relationship
d. work done is maximum
e. entropy decreases
Answer  Explanation 

ANSWER: no heat leaves or enters the compressor cylinder during cornpression

Explanation:
No explanation is available for this question!


2)   The- most efficient method of compressing air is to compress it_________________?

a. isothermally
b. adiabatically
c. isentropically
d. isochronically
e. as per law pV
Answer  Explanation 

ANSWER: isothermally

Explanation:
No explanation is available for this question!


3)   Isothermal compression effeicency can be attained by running the compressor__________________?

a. at very high speed
b. at very slow speed
c. at average speed
d. at zero speed
e. isothermally
Answer  Explanation 

ANSWER: at very slow speed

Explanation:
No explanation is available for this question!


4)   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
Answer  Explanation 

ANSWER: both A. and B. above

Explanation:
No explanation is available for this question!


5)   The overall isothermal eiffciency of compressor is defined as the ratio of_______________?

a. isothermal h.p. to the BHP of motor
b. isothermal h.p. to adiabatic h.p.
c. power to drive compressor to isothermal h.p.
d. work to compress air isothermally to work for actual compression
e. isothermal work to ideal work
Answer  Explanation 

ANSWER: isothermal h.p. to the BHP of motor

Explanation:
No explanation is available for this question!


6)   1 m of air at atmospheric condition weighs approximately__________________?

a. 0.5 kg
b. 1.0 kg
c. 1.3 kg
d. 2.2 kg
e. 3.2 kg
Answer  Explanation 

ANSWER: 1.3 kg

Explanation:
No explanation is available for this question!


7)   Free air is the air at________________?

a. atmospheric conditions at any specific location
b. 20°C and 1 kg/cm2 and relative humidity of 36%
c. 0°C and standard atmospheric conditions
d. 15°C and 1 kg/cm2
e. 25°C, 1 kg/cm2 and relative humidity of 50%
Answer  Explanation 

ANSWER: atmospheric conditions at any specific location

Explanation:
No explanation is available for this question!


8)   The capacity of a compressor is 5 m /mih. 5 m /min refers to_______________?

a. standard air
b. free air
c. compressed air
d. compressed air at delivery pressure
e. air sucked
Answer  Explanation 

ANSWER: free air

Explanation:
No explanation is available for this question!


9)   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
Answer  Explanation 

ANSWER: adiabatic

Explanation:
No explanation is available for this question!


10)   Standard air is the air at_____________________?

a. atmospheric conditions at any specific location
b. 20°C and 1 kg/cm2 and relative humidity 36%
c. 0°C and standard atmospheric conditions
d. 15°C and 1 kg/cm2
e. 25°C, 1 kg/cm2 and RH of 60%.
Answer  Explanation 

ANSWER: 20°C and 1 kg/cm2 and relative humidity 36%

Explanation:
No explanation is available for this question!


11)   The compressor capacity with decrease in suction temperature_________________?

a. increases
b. decreases
c. remains unaffected
d. may increase or decrease depending on compressor capacity
e. increases upto certain limit and then decreases
Answer  Explanation 

ANSWER: increases

Explanation:
No explanation is available for this question!


12)   Inter cooling in compressors__________________?

a. cools the delivered air
b. results in saving of power in compressing a given volume to given pressure
c. is the standard practice for big compressors
d. enables compression in two stages
e. prevents compressor jacket running very hot
Answer  Explanation 

ANSWER: results in saving of power in compressing a given volume to given pressure

Explanation:
No explanation is available for this question!


13)   Isothermal compression though most efficient, but is not -practicable because_________________?

a. ityrequires very big cylinder
b. it does not increase pressure much
c. it is impossible in practice
d. compressor has to run at very slow speed to achieve it
e. it requires cylinder to be placed in water
Answer  Explanation 

ANSWER: compressor has to run at very slow speed to achieve it

Explanation:
No explanation is available for this question!


14)   What will be the volume of air at 327°C if its volume at 27°C is 1.5 m3/mt ?

a. 3 m3/mt
b. 1.5 m3/mt
c. 18 m3/mt
d. 6 m3/mt
e. 0.75 m3/mt
Answer  Explanation 

ANSWER: 3 m3/mt

Explanation:
No explanation is available for this question!


15)   An ideal air compressor cycle without clearance on p-v diagram can be represented by following processes________________?

a. one adiabatic, two isobaric, and one constant volume
b. two adiabatic and two isobaric
c. two adiabatic, one isobaric and one constant volume
d. one adiabatic, one isobaric and two constant volume
e. two isobaric, two adiabatic and one constant volume
Answer  Explanation 

ANSWER: one adiabatic, two isobaric, and one constant volume

Explanation:
No explanation is available for this question!


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

a. 1
b. 1.2
c. 1.3
d. 1.4
e. 1.5
Answer  Explanation 

ANSWER: 1

Explanation:
No explanation is available for this question!


17)   An ideal air compressor cycle with clearance on p-v diagram can be represented by following processes_______________?

a. one adiabatic, two isobaric, and one constant volume
b. two adiabatic and two isobaric
c. two adiabatic, one isobaric and one constant volume
d. one adiabatic, one isobaric and two constant volume
e. two isobaric, two adiabatic and one constant volume
Answer  Explanation 

ANSWER: two adiabatic and two isobaric

Explanation:
No explanation is available for this question!


18)   Compression efficiency is compared against_____________________?

a. ideal compression
b. adiabatic compression
c. botii isothermal and adiabatic compression
d. isentropic compression
e. isothermal compression
Answer  Explanation 

ANSWER: isothermal compression

Explanation:
No explanation is available for this question!


19)   Aeroplanes employ following type of compressor_______________?

a. radial flow
b. axial flow
c. centrifugal
d. combination of above
e. none of the above
Answer  Explanation 

ANSWER: axial flow

Explanation:
No explanation is available for this question!


20)   Ratio of indicated H.P. and brake H.P. is known as_________________?

a. mechanical efficiency
b. volumetric efficiency
c. isothermal efficiency
d. adiabatic efficiency
e. relative efficiency
Answer  Explanation 

ANSWER: mechanical efficiency

Explanation:
No explanation is available for this question!