Mechanical Engineering - Compressors, Gas Dynamics and Gas Turbines

Exercise :: Compressors, Gas Dynamics and Gas Turbines - Section 1

41. 

An aftercooler is used to

A. remove impurities from air
B. reduce volume of air
C. cause moisture and oil vapour to drop out
D. cool the air

Answer: Option C

Explanation:

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42. 

High air-fuel ratio in gas turbines

A. increases power output
B. improves thermal efficiency
C. reduces exhaust temperature
D. do not damage turbine blades

Answer: Option C

Explanation:

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43. 

The ratio of the volume of free air delivery per stroke to the swept volume of the piston, is known as

A. compressor efficiency
B. volumetric efficiency
C. isothermal efficiency
D. mechanical efficiency

Answer: Option B

Explanation:

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44. 

If p1, is the pressure of air entering the L.P. cylinder and p2 is the pressure of air leaving the L.P. cylinder (or intercooler pressure), then the ratio of cylinder diameters for a single acting, two stage reciprocating air compressor with complete intercooling is given by (where D1 = Dia. of L.P. cylinder, and D2 = Dia. of H.P. cylinder)

A. D1/D2 = p1p2
B. D1/D2 = p1/p2
C. D1/D2 = p2/p1
D. none of these

Answer: Option C

Explanation:

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45. 

The ratio of the indicated power to the shaft power or brake power of the motor or engine required to drive the compressor, is called

A. compressor efficiency
B. volumetric efficiency
C. isothermal efficiency
D. mechanical efficiency

Answer: Option D

Explanation:

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