Thermal revision 2

Which of the following is NOT one of the methods to improve Rankine efficiency?

• Increasing condensor pressure

• Increasing Boiler pressure

• Lowering condensor pressure

• Super heating to higher temperature

Fixed blade in reaction turbine does NOT

• reduce pressure of steam

• Just change the direction and neither increase velocity nor decrease pressure

• reduce of enthalpy of steam

• reduce velocity of steam

Fixed blade in impulse turbine

• Just change the direction and neither increase velocity or decrease pressure

• reduce pressure of steam

• increase velocity of steam

• reduce of enthalpy of steam

Reason for compounding in impulse turbine

• To reduce cost

• To reduce efficiency

• To extract maximum of energy from steam

• To save space and noise

Reduction in steam velocity at outlet of nozzle is NOT due to

• inlet velocity of steam

• Friction between the steam and nozzle

• Friction between the steam particles

• Shock at nozzle

Blade coefficient

• ratio of outlet relative velocity to inlet relative velocity

• ratio of inlet relative velocity to outlet relative velocity

• ratio of outlet relative velocity to inlet absolute velocity

• ratio of outlet relative velocity to inlet flow velocity

The water (density = 1000 kg/m³) is pumped from 80 kPa to 3 MPa.Isentropic efficiency = 0.85, specific work (in kJ/kg)?

• 2.92

• 3.43

• 2.48

• 0.34

Rankine cycle turbine inlet= 2800 kJ/kg,outlet = 1800 kJ/kg, steam rate = 1 kg/s. Specific steam consumption in kg/kW-hr

• 0.01

• 0.06

• 0.36

• 3.6

Brake thermal eff = 70 %, indicate thermal eff = 80%, Find mechanical efficiency

• 87.5 %

• 56 %

• 70 %

• data insufficient

Brake thermal eff = 70 %, indicate thermal eff = 80%, IP = 10 kW, What is the BP in kW?

• 5.65

• 10

• 8.75

• data insufficient