The maximum adiabatic flame temperature in air contrasted with that in pure oxygen is_______________?
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Answer: A. Much lower
Explanation
Combuncting fuels in air yields much lower flame temperatures than burning them in pure oxygen. Air is composed mostly of nitrogen, which acts as a massive thermal ballast absorbing combustion heat. Pure oxygen eliminates this nitrogen ballast, allowing adiabatic flame temperatures to reach extreme peaks. Adiabatic flame temperature is the maximum theoretical temperature achieved without heat loss to surroundings. Nitrogen in air absorbs substantial sensible heat, lowering the peak temperature of the combustion gases. Oxy-fuel combustion technologies utilize pure oxygen to achieve high heat transfer rates and smaller furnace sizes.
Industrial glass melting and steel cutting torches use pure oxygen to generate intense, high-temperature flames. Standard boilers use air because oxygen separation is expensive and extreme flame temperatures damage refractories. Understanding flame temperature limits helps engineers select appropriate materials for burner construction. Option B incorrectly states air flame temperatures are much higher than oxygen flame temperatures. Option C claims they are the same, ignoring the massive thermal capacity of atmospheric nitrogen. Option D suggests it depends on fuel type, whereas nitrogen ballast consistently lowers air flame temperatures.
- Subject
- Engineering
- Category
- Chemical Engineering
- Topic
- —
- Difficulty
- medium
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