Jawaharlal Nehru Technological University Hyderabad B.Tech II POWER SYSTEMS-I Previous Question Paper (July/August - 2021 - R13)

A gas power station operates on the Brayton cycle. The process begins with an air compressor that draws in atmospheric air and compresses it to a high pressure. This compressed air is then directed into a combustion chamber where fuel, typically natural gas or distillate oil, is injected and ignited. The resulting high-temperature, high-pressure combustion gases expand through a gas turbine, causing it to rotate. The turbine is coupled to an alternator, which converts the mechanical energy into electrical energy. Finally, the exhaust gases are released into the atmosphere or passed through a heat recovery steam generator in combined-cycle plants.

The sequence of components in the line diagram is: Air Intake -> Compressor -> Combustion Chamber (with fuel input) -> Gas Turbine -> Alternator -> Exhaust.

Nuclear reactors are primarily classified based on the moderator and coolant used:

• Pressurized Water Reactor (PWR): Uses ordinary water as both moderator and coolant under high pressure to prevent boiling. The primary loop transfers heat to a secondary loop through a steam generator to drive the turbine.
• Boiling Water Reactor (BWR): Water acts as both moderator and coolant, but it is allowed to boil directly within the reactor core. The resulting steam is piped directly to the turbine.
• Pressurized Heavy Water Reactor (PHWR): Uses heavy water (D2O) as the moderator and coolant. It is efficient because heavy water has a lower neutron absorption cross-section, allowing the use of natural uranium as fuel.
• Gas-Cooled Reactor (GCR): Uses a gas like carbon dioxide as the coolant and graphite as the moderator. These reactors operate at higher temperatures, improving thermal efficiency.
• Fast Breeder Reactor (FBR): Operates without a moderator to sustain a chain reaction using fast neutrons. It uses liquid metal (like sodium) as a coolant and produces more fissile material than it consumes.