379. If main steam pressure and back pressure are maintained constant, then the rankine cycle efficiency with increase in main steam temperature will
A.Increase
B.Decrease
C.Remain unaffected
D.Unpredictable
380. Inspite of obtaining high rankine cycle efficiency with increase in temperature, the main steam temperature is fixed at 5400 because
A.It is not possible to produce higher temperature than this
B.Cycle efficiency actually drops above this temperature
C.This is most commonly used temperature throughout the world
D.Of metallurgical limitations
381. The difference between supersaturation temperature and the saturation temperature at the corresponding pressrue is known as
A.Degree of supersaturation
B.Degree of undercooling
C.Degree of supeheat
D.Degree of saturation
382. Rankine cycle efficiency for fixed steam temperature of any value upto critical temperature will be maximum for steam pressure of
A.160 kg/cm2
B.Critical pressure
C.250 kg/cm2
D.400 kg/cm2
383. Generator in thermal power plants is cooled by
A.Hydrogen
B.Water
C.CO2
D.(a) air
384. For modem power plant using reheating and regenerative cycles, the cycle efficiency can be equal to cannot cycle
A.Yes
B.No
C.If super-critical pressure is used
D.If working substance is suitably chosen
385. Reheat cycle in steam power plant is used to
A.Prevent .excess of 10-12% moisture content in last stages of turbine
B.Utilise heat of the flue gases
C.Increase plant efficiency
D.Enable two or more cylinders of turnine
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