Compressor Efficiency Factor Calculator

Enter Compressor Data

Compressor Type

Inlet Pressure (kPa abs)

Outlet Pressure (kPa abs)

Inlet Temperature (°C)

Mass Flow Rate (kg/s)

Actual Input Power (kW)

Specific Heat Ratio, k

Gas Constant, R (J/kg·K)

Compressibility Factor, Z

Motor Efficiency (%)

Mechanical Efficiency (%)

Load Factor (%)

Compression Stages

Example Data Table

Compressor Type	Inlet Pressure	Outlet Pressure	Inlet Temp	Mass Flow	Input Power	Efficiency Factor
Centrifugal	100 kPa abs	700 kPa abs	25 °C	1.20 kg/s	320 kW	75.17%
Screw	101 kPa abs	450 kPa abs	30 °C	0.85 kg/s	150 kW	68.42%
Reciprocating	95 kPa abs	900 kPa abs	20 °C	0.60 kg/s	210 kW	73.88%

Formula Used

Pressure Ratio: PR = P₂ / P₁

This shows how much the compressor raises absolute pressure.

Isentropic Outlet Temperature:

T_2s = T₁ × PR^(k−1)/k

Ideal Specific Work:

w_s = [k/(k−1)] × Z × R × T₁ × [PR^(k−1)/k − 1]

Actual Gas Power:

P_gas = P_input × η_motor × η_mechanical

Actual Gas Specific Work:

w_actual = P_gas / ṁ

Isentropic Efficiency:

η_is = w_s / w_actual

Overall Efficiency:

η_overall = P_ideal / P_input

Compressor Efficiency Factor:

Efficiency Factor = η_overall × Load Factor

This page treats the efficiency factor as a composite diagnostic indicator. It is practical for comparison, but it is not a universal code-standard performance number.

How to Use This Calculator

Choose the compressor type to compare the result with a typical operating band.
Enter inlet and outlet absolute pressures, not gauge values.
Provide inlet temperature in degrees Celsius and mass flow in kilograms per second.
Enter measured electrical input power for the operating point being checked.
Set gas properties with specific heat ratio and gas constant.
Use compressibility factor if the gas departs from ideal behavior.
Enter motor efficiency, mechanical efficiency, load factor, and total stages.
Press calculate to display the result above the form, then export the report if needed.

FAQs

1. What does compressor efficiency factor mean here?

It is a load-adjusted composite indicator based on overall efficiency. It helps compare real operating performance across duty points, machines, and test cases with one summarized percentage.

2. Why must pressures be absolute?

Thermodynamic compression ratios require absolute pressure. Gauge pressure ignores atmospheric reference and can distort pressure ratio, outlet temperature, and work calculations.

3. Why are motor and mechanical efficiencies separate?

Electrical losses and mechanical transmission losses happen at different locations. Separating them gives a clearer view of where energy disappears before reaching the gas.

4. What does a result above 100% suggest?

It usually means the entered field data conflict. Common causes include incorrect flow, power, gas properties, or pressure values. Recheck the measurement basis first.

5. Can I use this for multistage compressors?

Yes. The stage count is used to estimate per-stage pressure ratio, which helps review stage loading and compare operating severity across designs.

6. Does this replace OEM performance testing?

No. It is a fast engineering calculator for screening and comparison. Contract acceptance, guarantees, and formal audits should use approved standards and manufacturer procedures.

7. What is compressibility factor used for?

Compressibility factor adjusts the ideal gas work estimate when real gas behavior matters. Use 1.00 for simple ideal approximations and measured values for better fidelity.

8. When should I export the CSV or PDF report?

Use CSV for spreadsheets, trending, and plant logs. Use PDF when you need a clean snapshot for reviews, maintenance records, or stakeholder reporting.