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Brayton Cycle (Intercooling & Reheat) Efficiency Calculator

Advanced gas turbine engines and combined-cycle plants utilize multistage compression with intercooling and multistage expansion with reheating.

Total pressure ratio across the entire compression train.

Maximum cycle temperature entering HP turbine.

Ambient air temperature entering stage 1 compressor.

Heat exchanger effectiveness (typically 75-85%).

Specific heat ratio of air (default 1.4).

Calculated Result
65.0%

Thermal Efficiency (η_th)

Optimal Stage Pressure Ratio (r_p,stage)

4.00

Carnot Theoretical Limit

80.0%

Compressor Work Savings

32.7%

Calculation Breakdown

  1. Optimal Stage Ratio: r_p,stage = √(r_p,total)√16 = 4.00
  2. Carnot Limit: 1 - T_in / T_turb80.0%
  3. Cycle Thermal Efficiency65.0%

What Is the Brayton Cycle (Intercooling & Reheat) Efficiency Calculator?

The modified Brayton cycle employs intercooling to cool air between compressor stages and reheating to reheat gas between turbine stages.

When paired with a regenerator, it achieves thermal efficiencies far exceeding simple open-cycle turbines.

How Does the Brayton Cycle (Intercooling & Reheat) Efficiency Calculator Work?

Calculates the optimal stage pressure ratio equal to sqrt(overall pressure ratio).

Evaluates compressor work savings achieved by cold-air intercooling.

Determines cycle thermal efficiency and theoretical Carnot limit.

Brayton Cycle (Intercooling & Reheat) Efficiency Calculator Formula & Variables

The core mathematical equation utilized by this calculator is expressed as:

r_{p,stage} = \sqrt{r_{p,total}}, \quad w_{net} = (w_{t1} + w_{t2}) - (w_{c1} + w_{c2}), \quad \eta_{th} = \frac{w_{net}}{q_{in}}

Optimal geometric mean pressure split for two-stage intercooled and reheated Brayton cycle.

How to Use the Brayton Cycle (Intercooling & Reheat) Efficiency Calculator

  1. Enter overall cycle pressure ratio and turbine firing temperature.
  2. Specify compressor inlet ambient temperature and regenerator effectiveness.

Step-by-Step Example Calculation

Heavy-Duty Industrial Aeroderivative Gas Turbine

Input Values:

overallPressureRatio:16
turbineInletTempKelvin:1500
compressorInletTempKelvin:300
regeneratorEffectivenessPct:80
heatCapacityRatioGamma:1.4
Worked Steps: High-efficiency intercooled aeroderivative turbine (e.g. GE LMS100).

Understanding Your Result

Thermal efficiency typically reaches 45% to 55% with high-effectiveness regenerators.

Compressor work reduction indicates the drop in parasitic back-work ratio.

Factors That Affect the Result

  • Regeneration: Without a regenerator, intercooling and reheat actually DECREASE efficiency because more fuel heat must be added; regeneration is essential.
  • Pressure ratio: The optimal pressure ratio for regenerative cycles is lower than for simple cycles.

When Should You Use This Calculator?

  • Preliminary sizing and thermodynamic cycle optimization of gas turbines and marine propulsion plants.
  • Feasibility analysis of microturbines and supercritical CO2 Brayton loops.

Assumptions & Limitations

  • Assumes cold-air standard assumptions with constant specific heats.
  • Assumes intercooling returns air to initial compressor inlet temperature.

Frequently Asked Questions

Calculation Accuracy & Reference Note

Standard thermodynamic formulations aligned with ASME gas turbine cycle calculations.

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