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Brayton Cycle Efficiency Equation:
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The Brayton cycle is a thermodynamic cycle that describes the workings of a constant-pressure heat engine, most commonly used in gas turbine engines and jet engines. It consists of adiabatic compression, constant-pressure heat addition, adiabatic expansion, and constant-pressure heat rejection.
The calculator uses the Brayton cycle efficiency equation:
Where:
Explanation: The equation shows that thermal efficiency increases with higher pressure ratios and is also affected by the specific heat ratio of the working fluid.
Details: Calculating thermal efficiency is crucial for evaluating the performance of gas turbine engines, optimizing energy conversion processes, and comparing different engine designs and configurations.
Tips: Enter the pressure ratio (r) and specific heat ratio (γ) as dimensionless values. Typical values for γ are 1.4 for air and 1.33 for combustion products.
Q1: What is a typical pressure ratio for gas turbines?
A: Modern gas turbines typically operate with pressure ratios between 15:1 and 40:1, with higher ratios generally leading to better efficiency.
Q2: Why does efficiency increase with pressure ratio?
A: Higher pressure ratios allow the turbine to extract more work from the expanding gases, converting more thermal energy to mechanical work.
Q3: What factors limit practical pressure ratios?
A: Material strength limits, compressor design challenges, and increasing temperatures that require advanced cooling technologies.
Q4: How does specific heat ratio affect efficiency?
A: Higher γ values result in higher efficiency for the same pressure ratio, which is why different working fluids have different ideal efficiencies.
Q5: Is this the actual efficiency of real gas turbines?
A: This represents the ideal air-standard Brayton cycle efficiency. Real engines have lower efficiency due to various losses including friction, heat loss, and component inefficiencies.