Gas Turbine ELEMENTS

Brayton cycle has

• two isentropic and two constant volume processes

• two isentropic and two constant pressure processes

• one constant pressure, one constant volume, and two adiabatic processes

• two isothermals, one constant volume and a constant pressure process

Brayton cycle cannot be used in reciprocating engines even for same adiabatic compression ratio and work output because

• Otto cycle is highly efficient

• Brayton cycle is less efficient

• Brayton cycle is for slow speed engines only

• large volume of low pressure air cannot be efficiently handled in reciprocating engines

which cycle is generally used for gas turbine?

• Otto cycle

• Dual cycle

• Carnot cycle

• Brayton cycle

When r is the compression ratio, the efficiency of Brayton cycle is given by

• 1 - 1/r^(k-1)/k

• 1 - 1/r^k-1

• 1 - 1/r^k

• 1 - 1/r

A regenerator in a gas turbine

• reduces heat loss during exhaust

• allows use of higher compression ratio

• improves thermal efficiency

• allows use of fuels of inferior quality

Which of the following compressors is generally used for gas turbines?

• lobe type

• centrifugal type

• axial flow type

• reciprocating type

The constant pressure gas turbine works on the principle of

• Carnot cycle

• Bell - Coleman cycle

• Rankine cycle

• Brayton cycle

What type of gas turbine is used in an aircraft?

• Open cycle type

• Closed cycle type with reheating

• Closed type with reheating and regeneration

• Open cycle type with reheating, regeneration and intercooling

In a gas turbine combined cycle plant, a waste heat boiler is used to

• heat air from intercooler

• gases from regenerator

• recover heat from exhaust gases

• none of the above

Overall efficiency of a gas turbine is

• equal to Carnot cycle efficiency

• equal to Rankine cycle efficiency

• less than Diesel cycle efficiency

• more than Otto or Diesel cycle efficiency