Gas Turbine Cycle(Brayton cycle/Joule Cycle)

Gas Turbine Cycle

Brayton Cycle

The Brayton cycle (Joule Cycle) is the ideal cycle for gas-turbine engines. It’s also known as a Constant Pressure Cycle. Today, it is used for gas turbines and air-craft engine.

Types of Brayton Cycle

Brayton cycle are two types
•Open Cycle
•Closed Cycle

Schematic diagram of open cycle gas turbine

Schematic diagram of closed cycle gas turbine

During the open gas turbine cycle, a combustion process takes place, and exhaust gases are thrown out, in other words the exhaust gases cannot be recirculated, while the closed gas turbine cycle, the combustion process is replaced by a heat-addition process, the exhaust gases are also utilized so as to increase the temperature of the air which enters the compressor.

Simple Brayton Cycle

Schematic Diagram

Process:
1-2: Isentropic compression( in a compressor)
2-3: Constant Pressure Heat Addition
3-4: Isentropic Expansion( in a turbine)
4-1: Constant Pressure Heat Rejection

P-V and T-S Diagram of Simple Brayton Cycle:

P-V and T-S Diagram of Simple Brayton Cycle

Thermal Efficiency: 

Brayton Cycle With Regeneration (Heat exchanger)

Brayton Cycle With Regeneration

Brayton Cycle With Reheat

Brayton Cycle With Reheat

q_s=q_in=q_comb+q_reheat

    =c_p(T₃-T₂)+ c_p(T₅-T₄)

W_net=W_T1+ W_T2- W_c

₌ c_p(T₃-T₄)+ c_p(T₅-T₆)- c_p(T₂-T₁)

Brayton Cycle With Inter-Cooling

Brayton Cycle With Intercooling, Reheating and Regeneration

Schematic Diagram:Gas Turbine with two stage compression with intercooling, two stage expansion with reheating and regeneration

Reference:
Thermodynamics an Engineering Approach By Cengel
Image courtesy: Google

Rankine Cycle: https://learnedutech.blogspot.com/2019/09/blog-post_29.html

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Saddam Hossain
DUET, ME-12

Executive Trainee(Mechanical)
Nuclear Power Company Bangladesh Ltd.(NPCBL)
Rooppur, Ishwardi, Pabna

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