Power Plant Questions and Answers – Thermodynamics of Brayton-Rankine Combined Plant – I

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This set of Power Plant Engineering Multiple Choice Questions & Answers (MCQs) focuses on “Thermodynamics of Brayton-Rankine Combined Plant – I”.

1. If p and q are the efficiencies of a Brayton & Rankine cycles respectively in a Brayton-Rankine combined plant, the efficiency n of a combined plant is?
a) n = p/q
b) n = p+q-pq
c) n = pq
d) n = (1 – pq)
View Answer

Answer: b
Explanation: The efficiency of a Brayton-Rankine combined plant when p and q are the efficiencies of a Brayton & Rankine cycles respectively is given as,
n = p + q – pq.
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2. Which of these is a working fluid in the topping plant of a Brayton-Rankine combined plant?
a) Hydrogen
b) Helium
c) Nitrogen
d) All of the mentioned
View Answer

Answer: b
Explanation: The low molecular mass of Helium makes it the most suitable working fluid in the topping plant.

3. Which of these is a working fluid in the bottoming plant of a Brayton-Rankine combined plant?
a) Mercury
b) Steam
c) Water
d) Air
View Answer

Answer: c
Explanation: Water is the bottoming fluid due to its high specific heat capacity.

4. What would be the temperature of the gas in the combustion chamber?
a) 500 °C
b) 1600 °C
c) 1200 °C
d) 650 °C
View Answer

Answer: b
Explanation: The gas in the combustion chamber is at a temperature of 1600 °C.
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5. The efficiency of the open cycle gas plant is quite low. Why?
a) Gas gets cooled before reaching the turbine wheels
b) A lot of mechanical energy is used up by the compressor
c) Due to the presence of regenerator and absence of air pre heater
d) Both (a) and (b)
View Answer

Answer: d
Explanation: The efficiency of the open cycle gas plant is quite low. This is because of mainly two reasons,
Gas gets cooled before reaching the turbine wheels and a lot of mechanical energy is used up by the turbine wheels.

6. To improve the efficiency of the gas turbines, which among these are used?
a) Regenerator
b) Inter cooling
c) Reheating
d) All of the mentioned
View Answer

Answer: d
Explanation: All of the methods- Reheating, Regeneration and Intercooling are used to improve the efficiency of gas turbines.

7. What is regeneration?
a) Removal of heat from compressed air between stages of compression
b) Transfer of heat energy from exhaust gases to the compressed air flowing between compressor and the combustion chamber
c) To increase the temperature of partially expanded gases by burning more fuel
d) Both (b) & (c)
View Answer

Answer: b
Explanation: Transfer of heat energy from exhaust gases to the compressed air flowing between compressor and the combustion chamber is called the process of Regeneration.
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8. What is meant by inter cooling?
a) Removal of heat from compressed air between stages of compression
b) Transfer of heat energy from exhaust gases to the compressed air flowing between compressor and the combustion chamber
c) To increase the temperature of partially expanded gases by burning more fuel
d) None of the mentioned
View Answer

Answer: a
Explanation: Removal of heat from compressed air between various stages of compression is called Inter cooling.

9. Which material is used for the manufacture of the turbine blades?
a) Stainless steel
b) Carbon steel
c) High nickel alloy
d) High alloy steel
View Answer

Answer: c
Explanation: High nickel alloy is the most sufficient material for the manufacture of Turbine Blades.

Sanfoundry Global Education & Learning Series – Power Plant Engineering.

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Manish Bhojasia, a technology veteran with 20+ years @ Cisco & Wipro, is Founder and CTO at Sanfoundry. He is Linux Kernel Developer & SAN Architect and is passionate about competency developments in these areas. He lives in Bangalore and delivers focused training sessions to IT professionals in Linux Kernel, Linux Debugging, Linux Device Drivers, Linux Networking, Linux Storage, Advanced C Programming, SAN Storage Technologies, SCSI Internals & Storage Protocols such as iSCSI & Fiber Channel. Stay connected with him @ LinkedIn