Combustion Processes and Combustion Efficiency
Typical furnace combustion efficiencies - fireplaces, space heater, boiler and more
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Combustion is the oxidation of carbon-containing material in the presence of sufficient oxygen to complete the process.
C + O2 > CO2
Typical combustion process efficiencies can be summarized as
- home fireplace: 10 - 40 %
- space heater: 50 - 80 %
- gas boiler: 70 - 80 %
- residential gas furnace with low efficiency atmospheric burner: 70 - 80 %
- oil burner heating system: 70 - 85 %
- gas powered boiler: 75 - 85 %
- high efficiency gas or oil condensing furnace: 85 - 95 %
Furnace Performance Indices
The performance of a furnace is usually assessed by the following indices
Thermal Efficiency
μt = 100 Eo / Ei (1)
where
μt = thermal efficiency
Eo = fuel energy output (W, Btu/h)
Ei = fuel energy input (W, Btu/h)
Annual Fuel Utilization Efficiency - AFUE
AFUE measures the annual amount of heat actually delivered compared to the amount of fuel supplied to the furnace.
AFUE = 100 Eao / Eai (2)
where
AFUE = annual fuel utilization efficiency
Eao = annual fuel energy output (W, Btu/h)
Eai = annual fuel energy input (W, Btu/h)
Steady-state Efficiency - SSE
Steady State Efficiency measures how efficiently a furnace converts fuel to heat, once the furnace has warmed up and is running steadily and can be expressed as
SSE= 100 (Ei - El) / Ei (2)
where
SSE = steady-state efficiency
Ei = fuel energy input (W, Btu/h)
El = fuel energy loss (W, Btu/h)
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Related Topics
- Combustion - Boiler house topics - fuels like oil, gas, coal, wood - chimneys, safety valves, tanks - combustion efficiency
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Related Documents
- Boiler Efficiency - Boiler efficiency - combustion gross and net calorific value
- Classifications of Boilers - Classification of boilers according ASME Boiler and Pressure Vessel Code
- Combustion Testing - Combusting testing of fuel oil and gas burners
- Optimal Combustion Processes - Fuels and Excess Air - Stable and efficient combustion conditions require correct mixtures of fuels and oxygen
