Calculate the theoretical flame temperature based on the given percentages of CO, N2, and excess air.
The theoretical flame temperature is the highest temperature achievable when a fuel burns with an oxidizer under ideal conditions, assuming no heat loss to the environment (adiabatic combustion). This calculator estimates the flame temperature for gas mixtures such as carbon monoxide (CO) and nitrogen (N₂), based on the mixture composition and the amount of excess air supplied.
CO Percentage (%): Enter the portion of carbon monoxide in the fuel mixture.
N₂ Percentage (%): Enter the portion of nitrogen in the fuel mixture. For a two-component mixture, this value usually complements the CO percentage to total 100%.
Excess Air (%): Input the percentage of excess air used in combustion. A value of 100% indicates the exact amount of oxygen needed for complete combustion. Higher values represent additional oxygen supplied to ensure full combustion.
The calculator uses basic combustion chemistry and energy balance principles to estimate the maximum flame temperature. The key steps involve determining the heat released from burning CO, adjusting for excess air, and then calculating how much the product gases heat up as they absorb this energy.
The combustion reaction is:
CO + 1/2 O₂ → CO₂
The heat released from the reaction is calculated as:
ΔH_reaction = ΔH_f°(CO₂) - ΔH_f°(CO)
Where:
The total heat released is then multiplied by the fraction of CO in the fuel mixture. This energy increases the temperature of the combustion products (CO₂, O₂, and N₂). The specific heat capacity of these products determines how much the temperature rises.
The flame temperature is found by balancing the heat released with the heat absorbed by the products using the following heat balance equation:
ΔH = Σ(Cp_i * m_i * ΔT)
Where:
The temperature rise can be estimated as:
ΔT = (ΔH_reaction × fraction of CO) / Σ(Cp_i * m_i)
Once the temperature rise is known, the final flame temperature is obtained by adding it to the initial temperature.
Our flame temperature calculator provides:
The following examples show how the calculator estimates flame temperature for CO and N₂ mixtures with varying excess air.
For a mixture containing 20% CO and 80% N₂ with 150% excess air, the calculation proceeds as follows:
1. The combustion reaction for CO is:
CO + 1/2 O₂ → CO₂
2. Heat of reaction:
ΔH_reaction = ΔH_f°(CO₂) - ΔH_f°(CO) = -94052 - (-26412) = 67640 cal/gmol
3. Total heat liberated from 1 mole of the gas mixture:
Heat Liberated = 67640 × 0.2 = 13528 cal
4. Composition of the product stream:
- CO₂ produced = 0.2 moles
- O₂ required = 0.1 moles
- O₂ with excess air = 0.25 moles
- N₂ with excess air = 0.9405 moles
- O₂ leaving = 0.15 moles
- N₂ leaving = 1.7405 moles
5. Adiabatic temperature calculation:
Total heat capacity = 16.73 cal/°C
Temperature rise = 13528 / 16.73 = 808.8°C
6. Final flame temperature:
Flame Temperature = 808.8 + 25 = 833.8°C
For a mixture containing 25% CO and 75% N₂ with 200% excess air, the calculation is:
1. The combustion reaction for CO is:
CO + 1/2 O₂ → CO₂
2. Heat of reaction:
ΔH_reaction = ΔH_f°(CO₂) - ΔH_f°(CO) = -94052 - (-26412) = 67640 cal/gmol
3. Total heat liberated from 1 mole of the gas mixture:
Heat Liberated = 67640 × 0.25 = 16910 cal
4. Composition of the product stream:
- CO₂ produced = 0.25 moles
- O₂ required = 0.125 moles
- O₂ with excess air = 0.375 moles
- N₂ with excess air = 1.4643 moles
- O₂ leaving = 0.25 moles
- N₂ leaving = 1.7143 moles
5. Adiabatic temperature calculation:
Total heat capacity = 20.14 cal/°C
Temperature rise = 16910 / 20.14 = 839.6°C
6. Final flame temperature:
Flame Temperature = 839.6 + 25 = 864.6°C
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