What is the Brayton Cycle Process in Thermodynamics?

Isentropic compression air is compressed, increasing its pressure and temperature. Constant Pressure Heat Addition Fuel is burned, adding heat to the compressed air at constant pressure. Isentropic Expansion: The hot gases expand, producing work and decreasing pressure and temperature. Constant Pressure Heat Rejection Heat is rejected at constant pressure, returning the system to its initial state.

Brayton Cycle | PV and TS Diagram, Process, Work and Efficiency

Q: What is Brayton Cycle Principle Used in Gas Turbines?

Brayton cycle is the basis of the gas turbine . It is a thermodynamic cycle that describes the operation of a gas turbine engine. It is a type of heat engine that generates power by using a combination of compression, heat addition and expansion. The Brayton cycle is used in gas turbine engine.

Brayton Cycle | Definition, PV & TS Diagram, Work & Efficiency

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Brayton Cycle

The Brayton cycle, also known as the Joule Cycle. It is a thermodynamic cycle that describes the operation of a gas turbine engine. It is a type of heat engine that generates power by using a combination of compression, heat addition and expansion. The brayton cycle is used in gas turbine engine.

PV and TS Diagram of Brayton Cycle

The ideal Brayton cycle has four processes. PV and TS diagram shown below:

First is PV Diagram,

Second is TS Diagram,

Processes of Brayton Cycle

There are four process of ideal bryton cycle:

Process 1 → 2 Isentropic Compression

Compression of air, increasing pressure and temperature. Pressure is compressed from pressure P₁ to P₂. Volume reduces from V₁ to V₂ . Temperature increases from T₁ to T₂. Entropy (S) has remained constant, S₁ = S₂.

Process 2 → 3 Heat Addition

Heat addition at constant pressure, increasing volume and temperature. Fuel burns at constant pressure, P₂ = P₃. Temperature rises from T₂ to T₃, volume expands from V₂ to V₃ and entropy increases from S₂ to S₃.

Process 3 → 4 Isentropic Expansion

Expansion of hot gases, decreasing pressure and temperature. Pressure decreases from P₃ to P₄, temperature decreases from T₃ to T₄ and volume increases from V₃ to V₄.

Process 4 → 1 Heat Rejection

Heat rejection at constant pressure, decreasing volume and temperature. Isobaric heat rejection in this process pressure is constant, P₄ = P₁. Volume decreases from V₄ to V₁. Gas temperature decreases from T₄ to T₁ and entropy decreases from S₄ to S₁.

Work Output and Thermal Efficiency of Brayton Cycle

Here we find the work done, the heat absorbed and the thermal efficiency of the Brayton cycle. Firstly we take the cycle from a -b -c -d and back to a. According to the first law of thermodynamics,

Here change in μ is zero because μ is a state of function. The net work done is,

For a constant pressure, quasi-static process the heat exchange per unit mass is

First law in terms of enthalpy or by remembering the definition of c_p .

For the heat addition from the combustor,

Heat rejection is, similarly above equation,

Net work per unit mass is given by

The thermal efficiency of the brayton cycle,

$\displaystyle \eta = \frac{\textrm{Net work}}{\textrm{Heat in}} = \frac{c_p[(T_... ... = 1 - \frac{(T_d-T_a)}{(T_c-T_b)} = 1 - \frac{T_a(T_d/T_a-1)}{T_b(T_c/T_b-1)}.$

Constant pressure process points are a, b and c and P_a = P_b= P_c . The cycle are adiabatic and reversible,

the thermal efficiency of a Brayton cycle:

$\displaystyle \textrm{Ideal Brayton cycle efficiency: } \eta_B = 1-\frac{T_a}{T_b}=1-\frac{T_{\textrm{atmospheric}}}{T_{\textrm{compressor exit}}}.$

The temperature ratio, T_b /T_a = TR. This relation using for an adiabatic reversible process we can write the efficiency in terms of the pressure ratio,

$\displaystyle \eta_B=1-\frac{1}{TR}=1-\frac{1}{PR^{(\gamma-1)/\gamma}}.$

Frequently Asked Questions (FAQs)

What is the Brayton Cycle Process in Thermodynamics?

Isentropic compression air is compressed, increasing its pressure and temperature. Constant Pressure Heat Addition Fuel is burned, adding heat to the compressed air at constant pressure. Isentropic Expansion: The hot gases expand, producing work and decreasing pressure and temperature. Constant Pressure Heat Rejection Heat is rejected at constant pressure, returning the system to its initial state.
What is Brayton Cycle Principle Used in Gas Turbines?

Brayton cycle is the basis of the gas turbine. It is a thermodynamic cycle that describes the operation of a gas turbine engine. It is a type of heat engine that generates power by using a combination of compression, heat addition and expansion. The Brayton cycle is used in gas turbine engine.