Skip to main content
CalcStack

Turbomachinery Isentropic Efficiency Calculator (Compressor & Turbine)

Isentropic efficiency measures the departure of actual turbomachinery from reversible adiabatic (constant entropy) compression or expansion.

Select compression or expansion process.

Fluid inlet temperature in °C.

Inlet static pressure in bar.

Outlet discharge pressure in bar.

Machine isentropic efficiency rating (typical industrial compressors ≈ 75 - 85%).

Isentropic gas exponent (Air = 1.40, Methane = 1.31, Steam = 1.30).

Calculated Result
310.1 °C

Actual Discharge Temperature

Actual Discharge Temperature

310.1°C

Ideal Isentropic Temperature

257.9°C

Pressure Ratio (P₂ / P₁)

8:1

Specific Shaft Work

291.54 kJ/kg

Isentropic Efficiency

82%

Calculation Breakdown

  1. 1. Ideal Isentropic Temperature RatioT₂s / T₁ = (P₂ / P₁)^((k-1)/k) = (8)^(0.40 / 1.4) = 1.811. T₂s = 257.9°C
  2. 2. Isentropic Efficiency CorrectionT₂_act = T₁ + (T₂s - T₁) / η = 20°C + (237.89999999999998) / 0.82 = 310.1°C
  3. 3. Specific Work CalculationW = cp · |T₂_act - T₁| = 1.005 kJ/(kg·K) · 290.1 K = 291.54 kJ/kg

Temperature and Work Profile

Interactive visualization based on your current inputs

Value
0.078156233311Inlet Temp (°C)Ideal T2s (°C)Actual T2 (°C)Work (kJ/kg)MetricValue

What Is the Turbomachinery Isentropic Efficiency Calculator (Compressor & Turbine)?

Isentropic efficiency quantifies the real-world performance of compressors and turbines relative to an ideal reversible adiabatic process.

How Does the Turbomachinery Isentropic Efficiency Calculator (Compressor & Turbine) Work?

In a Mollier h-s diagram, ideal compression follows a vertical isentropic path; real irreversible processes veer right toward higher entropy.

Turbomachinery Isentropic Efficiency Calculator (Compressor & Turbine) Formula & Variables

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

T_{2s} = T_1 \left(\frac{P_2}{P_1}\right)^{\frac{k-1}{k}}, \quad T_{2,act} = T_1 + \frac{T_{2s} - T_1}{\eta_c}, \quad W = c_p (T_{2,act} - T_1)

Ideal isentropic discharge temperature follows the pressure ratio power law. Actual temperature accounts for efficiency losses, scaling specific work.

How to Use the Turbomachinery Isentropic Efficiency Calculator (Compressor & Turbine)

  1. Select compressor or turbine mode.
  2. Enter inlet temperature, inlet pressure, and discharge pressure.
  3. Supply isentropic efficiency percentage.

Step-by-Step Example Calculation

8:1 Pressure Ratio Air Compressor (20°C Inlet, 82% Efficiency)

Input Values:

machineType:compressor
inletTempC:20
inletPressureBar:1.0
dischargePressureBar:8.0
isentropicEfficiencyPercent:82
specificHeatRatioK:1.40
Worked Steps: Ideal isentropic temperature is 258.4°C. With 82% efficiency, actual discharge temperature rises to 311.1°C requiring 292.56 kJ/kg shaft work.

Understanding Your Result

Actual Discharge Temp: Real expected gas exit temperature.

Isentropic Temp: Minimum theoretical temperature of ideal compression.

Specific Shaft Work: Mechanical kilowatt-hours needed per kilogram fluid throughput.

Factors That Affect the Result

  • Higher pressure ratio amplifies temperature rise; lower efficiency requires proportionally higher compressor shaft power.

When Should You Use This Calculator?

  • Gas turbine power plants, turbocharger sizing, industrial air compressors, and jet engine Brayton cycle analysis.

Assumptions & Limitations

  • Assumes ideal gas behavior with constant specific heat cp over the compression temperature interval.

Frequently Asked Questions

Calculation Accuracy & Reference Note

Standard ASME PTC-10 turbomachinery thermodynamic relations.

Related Calculators

Explore more tools and calculators in Education Calculators

Chilled Water Cooling Coil Capacity & Flow Calculator

Calculates total cooling capacity (kW and Tons TR), sensible heat ratio (SHR), and required hydronic water flow rate (L/s and GPM) for AHU cooling coils.

Cooling Tower Evaporation & Blowdown Makeup Water Calculator

Calculates evaporative losses, chemical blowdown purge, drift rate, and total makeup water requirements based on cycles of concentration (CoC).

Heat Pipe Two-Phase Thermal Resistance & Conductivity Calculator

Calculates envelope radial wall conduction resistance, sintered wick resistance, total thermal impedance (°C/W), and effective thermal conductivity for copper-water heat pipes.

Hydronic Expansion Tank & Air Separator Sizing Calculator

Calculates water thermal expansion volume (V_e), acceptance volume, and diaphragm expansion tank sizing for closed hydronic heating and cooling systems.

Refrigeration Compressor Isentropic COP & Compression Ratio Calculator

Calculates compression ratio, Carnot ideal limit, actual isentropic Coefficient of Performance (COP), electrical power input, and condenser heat rejection.

Circular to Rectangular Duct Equivalent Hydraulic Diameter Calculator

Calculates the Huebscher equivalent circular duct diameter (equal friction and airflow), hydraulic diameter (4A/P), and air velocity for rectangular HVAC ducts.