RRB/SSC JE Mech: POWER PLANT Quiz 3

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Question 1

Blade erosion in steam turbines takes place

• ADue to high temperature steam
• BDue to droplets in steam
• CDue to high rotational speed
• DDue to high flow rate

Question 2

Consider a simple gas turbine (Brayton) cycle and a gas turbine cycle with perfect regeneration. In both the cycles, the pressure ratio is 6 and the ratio of the specific heats of the working medium is 1.4. The ratio of minimum to maximum temperatures is 0.3 (with temperatures expressed in K) in the regenerative cycle. The ratio of the thermal efficiency of the simple cycle to that of the regenerative cycle is ____ .

• A0.7022
• B0.8021
• C0.6521
• D0.5321

Question 3

In a Brayton cycle, what is the value of optimum pressure ratio for maximum net work done between temperatures and where is the maximum temperature and is the minimum temperature?

• A
• B
• C
• D

Question 4

The specific power output of a gas turbine is 336.5 kW/Kg and the exhaust gases leave the turbine at 700 K. If the value of C_P and C_V are 1 kJ/kg-K and 0.717 kJ/kg-K respectively, the turbine pressure ratio is

• A3.5
• B4.5
• C4
• D5

Question 5

A refrigerant compressor of 50 mm bore and 40 mm stroke operates at a speed of 1460 rpm between condensing and evaporating pressure limits of 1.219 MPa and 0.151 MPa. The clearance ratio is 5%, polytropic index of expansion in compressor is 1.18, specific volume of refrigerant at suction is 0.11 m3/kg. The mass flow rate of refrigerant will be

• A0.01057 kg/s
• B0.01327 kg/s
• C0.01585 kg/
• D0.02035 kg/s

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