# Thermal Engineering 25

Objective Questions and Answer: Thermal Engineering 25

Subject: Thermal Engineering 25

Part 25: Objective questions and answers of Thermal Engineering

Q1. Maximum delivery pressure is a rotary air compressor is of the order of

a) 6 kg/cm^2

b) 10 kg/cm^2

c) 16 kg/cm^2

d) 25 kg/cm^2

Q2. Surging is the phenomenon of

a) Air stream blocking the passage

b) Motion of air at sonic velocity

c) Unsteady, periodic and reversed flow

Q3. Pick up wrong statement. Surging phenomenon in centrifugal compressor depends on

a) Mass flow rate

b) Pressure ratio

d) Stagnation pressure at the outlet

Q4. The ratio of the increase in pressure in rotor blades to total increase in pressure in the stage is called

a) Pressure ratio

b) Pressure coefficient

c) Degree of reaction

d) Slip factor

Q5. Axial flow compressor resembles

a) Centrifugal pump

b) Reciprocating pump

c) Turbine

d) Sliding vane compressor

Q6. Axial flow compressor has the following advantage over centrifugal compressor

a) Larger air handling ability per unit frontal area

b) Higher pressure ratio per stage

d) Higher average velocities

Q7. Actual compression curve is

a) Same as isothermal

c) Better than isothermal and adiabatic

d) In between isothermal and adiabatic

Q8. Atmospheric pressure is 1.03 kg/cm and vapors pressure is 0.03 kg/cm . The air pressure will be

a) 1.03 kg/cm^2

b) 1.06 kg/cm^2

c) 1.00 kg/cm^2

d) 0.53 kg/cm^2

Q9. The pressure ratio of an ideal vaned compressor with increase in mass flow rate

a) Increases

b) Decreases

c) Remains constant

d) First decreases and then increases

Q10. Rotary compressors are suitable for

a) Large discharge at high pressure

b) Low discharge at high pressure

c) Large discharge at low pressure

d) Low discharge at low pressure

Q11. The volumetric efficiency of compressor with increase in compression ratio will

a) Increase

b) Decrease

c) Remain same

d) May increase/decrease depending on clearance volume

Q12. Stalling of blades in axial flow compressor is the phenomenon of

a) Air stream blocking the passage

b) Motion of air at sonic velocity

c) Unsteady periodic and reversed flow

Q13. Pick up the wrong statement

a) Centrifugal compressors deliver practically constant pressure over a considerable range of capacities

b) Axial flow compressors have a sub-stantially constant delivery at variable pressures

c) Centrifugal compressors have a wider stable operating range than axial flow compressors

d) Axial flow compressors are bigger in diameter compared to centrifugal type

Q14. The work ratio of a gas turbine plant is defined as the ratio of

a) Net work output and heat supplied

b) Net work output and work done by turbine

c) Actual heat drop and isentropic heat drop

d) Net work output and isentropic heat drop

Q15. Gas turbine works on

a) Brayton or Atkinson cycle

b) Carnot cycle

c) Rankine cycle

d) Erricsson cycle

Q16. The work ratio of simple gas turbine cycle depends on

a) Pressure ratio

b) Maximum cycle temperature

c) Minimum cycle temperature

d) All of the above

Q17. The pressure ratio for an open cycle gas turbine compared to closed cycle gas turbine of same h.p. Is

a) Low

b) High

c) Same

d) Low/high depending on make and type

Q18. Open cycle gas turbine works on

a) Brayton or Atkinson cycle

b) Rankine cycle

c) Carnot cycle

d) Erricsson cycle

Q19. The fuel consumption in gas turbines is accounted for by

a) Lower heating value

b) Higher heating value

c) Heating value

d) Higher calorific value

Q20. Gas turbines for power generaion are normally used

a) To supply base load requirements

b) To supply peak load requirements

c) To enable start thermal power plant

d) In emergency

Part 25: Objective questions and answers of Thermal Engineering