APH Performance Calculator

The Air Preheater (APH) is an important component of a thermal power plant boiler. It recovers heat from the outgoing flue gas and transfers it to the incoming combustion air, improving boiler efficiency and combustion performance.

Monitoring APH performance helps identify problems such as excessive air leakage, poor heat transfer and increased flow resistance.

This APH Performance Calculator provides four useful calculations commonly associated with APH performance:

APH Air Leakage (%) – estimates air leakage based on oxygen concentration.
APH Gas-Side Efficiency (%) – evaluates the heat-transfer performance on the gas side.
APH X-Ratio – helps assess APH operating performance.
APH Heat Recovery – estimates the heat transferred to the air side.

Select the required calculation, enter the available operating values and click Calculate. The calculator also provides the formula and step-by-step calculation so you can understand how the result is obtained.

You can also use the Reset button to perform a new calculation and Download Calculation to save the calculation details for future reference.

APH Performance Calculator

Calculate important Air Preheater (APH) performance parameters including air leakage, gas-side efficiency, X-ratio and heat recovery.

Select Calculation

O₂ at APH Gas Inlet (%) O₂ at APH Gas Outlet (%)

Enter O₂ values on a dry-volume basis as used for APH performance measurement.

Gas Inlet Temperature, Tgi (°C) Gas Outlet Temperature, Tgo (°C) Air Inlet Temperature, Tai (°C) APH Air Leakage (%) Specific Heat of Air, Cpa (kcal/kg°C) Specific Heat of Gas, Cpg (kcal/kg°C)

Gas Inlet Temperature, Tgi (°C) Gas Outlet Temperature, Tgo (°C) Air Inlet Temperature, Tai (°C) Air Outlet Temperature, Tao (°C) APH Air Leakage (%) Specific Heat of Air, Cpa (kcal/kg°C) Specific Heat of Gas, Cpg (kcal/kg°C)

Air Mass Flow Rate (kg/s) Air Specific Heat, Cp (kJ/kg°C) Air Inlet Temperature, Tai (°C) Air Outlet Temperature, Tao (°C)

This calculation represents the heat gained by the air side of the APH.

Note: APH performance calculations can vary depending on the measurement method, test conditions and applicable plant/OEM calculation procedure. Use this calculator as a calculation aid and verify results with the applicable plant procedure or performance-test standard.