A closed cycle gas turbine gives ________ efficiency as compared to an open cycle gas turbine.
Same
Lower
Higher
None of these
Correct Answer :
C. Higher
Related Questions
A rotary compressor is driven by an
Electric motor
Engine
Either (A) or (B)
None of these
Losses in a centrifugal compressor are due to
Inlet losses
Impeller channel losses
Diffuser losses
All of the above
Which of the following statement is correct?
The ratio of the discharge pressure to the inlet pressure of air is called compressor efficiency
The compression ratio for the compressor is always greater than unity
The compressor capacity is the ratio of workdone per cycle to the stroke volume
During isothermal compression of air, the workdone in a compressor is maximum
During base load operation, the best method of controlling compressor is
Start-stop motor
Constant speed unloader
Relief valve
Variable speed
After-cooler is used to
Cool the air
Decrease the delivery temperature for ease in handling
Cause moisture and oil vapour to drop out
Reduce volume
Open cycle gas turbine works on
Brayton or Atkinson cycle
Rankine cycle
Carnot cycle
Erricson cycle
The intercooler pressure, for minimum work required, for a two stage reciprocating air compressor, is given by (where p₁ = Intake pressure of air, p₂ = Intercooler pressure, and p₃ = Delivery pressure of air)
p₂ = p₁ × p₃
p₂ = p₁/p₃
p₂ = p₁ × p₂
p₂ = p₃/p₁
The volumetric efficiency of a compressor
Increases with decrease in compression ratio
Decreases with decrease in compression ratio
Increases with increase in compression ratio
Decreases with increase in compression ratio
In a single stage, single acting reciprocating air compressor, without clearance, the workdone on the air during isentropic compression is ________ the heat required to raise the temperature of air from T₁ to T₂ at a constant pressure.
Equal to
Less than
Greater than
None of these
The thermal efficiency of a gas turbine as compared to a diesel plant is
Same
More
Less
Depends on other factors
Maximum delivery pressure is a rotary air compressor is of the order of
6 kg/cm²
10 kg/cm²
16 kg/cm²
25 kg/cm²
A closed cycle gas turbine works on
Carnot cycle
Rankine cycle
Ericsson cycle
Joule cycle
More than one stage will be preferred for reciprocating compressor if the delivery pressure is more than
2 kg/cm²
6 kg/cm²
10 kg/cm²
14.7 kg/cm²
High air-fuel ratio in gas turbines
Increases power output
Improves thermal efficiency
Reduces exhaust temperature
Do not damage turbine blades
The type of rotary compressor used in aeroplanes, is of
Centrifugal type
Axial flow type
Radial flow type
None of these
The inlet pressure is always ________ the discharge pressure.
Equal to
Less than
More than
None of these
Which is false statement about advantages of multistage compressor in comparison to single stage compressor?
Less power requirement
Better mechanical balance
Less loss of air due to leakage past the cylinder
Lower volumetric efficiency
Actual compression curve is
Same as isothermal
Same as adiabatic
Better than isothermal and adiabatic
In between isothermal and adiabatic
If the clearance ratio for a reciprocating air compressor is 'K', then its volumetric efficiency is given by
1 - k + k (p₁/p₂)1/n
1 + k - k (p₂/p₁)1/n
1 - k + k (p₁/p₂) n- 1/n
1 + k - k (p₂/p₁) n-1/n
The compressor capacity is defined as the
Actual volume of the air delivered by the compressor when reduced to normal temperature and pressure conditions
Volume of air delivered by the compressor
Volume of air sucked by the compressor during its suction stroke
None of the above
Gas turbines use following type of air compressor
Centrifugal type
Reciprocating type
Lobe type
Axial flow type
The blades of gas turbine are made of
High nickel alloy
Stainless steel
Carbon steel
High alloy steel
The maximum combustion pressure in gas turbine as compared to I.C. engine is
More
Less
Same
Depends on other factors
The weight per horse power ratio for gas in Turbine as compared to I.C. engine and steam turbine is
Same
Higher
Lower
None of these
In axial flow compressor, exit flow angle deviation from the blade angle is a function of
Blade camber
Blade camber and incidence angle
Spacechord ratio
Blade camber and spacechord ratio
Cylinder clearance in a compressor should be
As large as possible
As small as possible
About 50% of swept volume
About 100% of swept volume
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)
D₁/D₂ = p₁ p₂
D₁/D₂ = p₁/p₂
D₁/D₂ = p₂/p₁
None of these
Fighter bombers use following type of engine
Turbojet
Turbo-propeller
Rocket
Ramjet
The working fluid in a turbine is
In two phases
In three phases
In a single phase
In the form of air and water mixture
In n₁ and n₂ are the indices of compression for the first and second stage of compression, then the ratio of workdone on the first and second stages (W₁/W₂) with perfect intercooling is given by
W₁/W₂ = n₂(n₁ - 1)/n₁(n₂ - 1)
W₁/W₂ = n₁(n₂ - 1)/n₂(n₁ - 1)
W₁/W₂ = n₁/n₂
W₁/W₂ = n₂/n₁