Practice Test: Question Set - 17
1. Isothermal compression efficiency, even when running at high speed, can be approached by using
- (A) Multistage
compression
- (B) Cold water spray
- (C) Both (A) and (B)
above
- (D) Fully insulating the
cylinder
2. In a four stage compressor, if the pressure at the first and third stage is 1 bar and 16 bar, then the delivery pressure at the fourth stage will be
- (A) 1 bar
- (B) 16 bar
- (C) 64 bar
- (D) 256 bar
3. 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
4. The stagnation pressure rise in a centrifugal compressor takes place
- (A) In the
diffuser only
- (B) In the
impeller only
- (C) In the
diffuser and impeller
- (D) In the inlet
guide vanes only
5. 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.
6. A 3 m³/min compressor means that it
- (A) Compresses 3
m³/min of standard air
- (B) Compresses 3
m³/ min of free air
- (C) Delivers 3
m³/ min of compressed air
- (D) Delivers 3
m³/ min of compressed air at delivery pressure
7. Euler's equation is applicable for
- (A) Centrifugal compressor
- (B) Axial compressor
- (C) Pumps
- (D) All of the above
8. In a high pressure compressor, the delivery pressure is
- (A) 1 to 5 bar
- (B) 5 to 8 bar
- (C) 8 to 10 bar
- (D) 10 to 15 bar
9. Which is false statement about air receivers?
- (A) These are used to dampen pulsations
- (B) These act as
reservoir to take care of sudden demands
- (C) These increase
compressor efficiency
- (D) These knock out some
oil and moisture
10. A rocket engine uses __________ for the combustion of its fuel.
- (A) Surrounding
air
- (B) Compressed
atmospheric air
- (C) Its own
oxygen
- (D) None
of these
11. The volumetric efficiency of a compressor falls roughly as follows for every 100 m increase in elevation
- (A) 0.1%
- (B) 0.5%
- (C) 1.0%
- (D) 5%
12. For a two stage reciprocating compressor, compression from p₁ to p₃ is with perfect intercooling and no pressure losses. If compression in both the cylinders follows the same polytropic process and the atmospheric pressure is pa, then the intermediate pressure p₂ is given by
- (A) p₂ =
(p₁ + p₃)/2
- (B) p₂ = p₁.
p₃
- (C) P₂ = Pa
× p₃/p₁
- (D) p₂ = Pa
p₃/p₁
13. 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 semi rotary type
- (C) Disc or feather type
- (D) Any of the above
14. The type of rotary compressor used in gas turbines, is of
- (A) Centrifugal
type
- (B) Axial flow
type
- (C) Radial flow
type
- (D) None of
these
15. 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
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