- #1
Red_CCF
- 532
- 0
Hello
I was wondering about explanation of the auto ignition temperature (AIT). From the definition in ASTM E659:
What I get from the last sentence is that fuel-air reaction at some level occurs at any temperature, but the number of particles reacting is not large enough to produce enough energy for sustained combustion until fuel temperature is above AIT. Is any of the two following reasons for this correct:
1) Higher temperature means higher reaction rate from Arrhenius's equation
2) Higher vapour pressure due to the higher liquid temperature
Is there an assumption behind what the oxidizer temperature for fuel AIT? In ASTM E659, the experiment involves heating a small quantity of fuel inside a large flask of air at a pre-determined temperature, but since they are heating the flask I'm not sure how it is possible to control the temperature of the air.
Thank you very much
I was wondering about explanation of the auto ignition temperature (AIT). From the definition in ASTM E659:
AIT (auto-ignition temperature) is the lowest temperature at which the substance will produce hot-flame ignition in air at atmospheric pressure without the aid of an external energy source such as spark or flame. It is the lowest temperature to which a combustible mixture must be raised, so that the rate of heat evolved by the exothermic oxidation reaction will overbalance the rate at which heat is lost to the surroundings and cause ignition.
What I get from the last sentence is that fuel-air reaction at some level occurs at any temperature, but the number of particles reacting is not large enough to produce enough energy for sustained combustion until fuel temperature is above AIT. Is any of the two following reasons for this correct:
1) Higher temperature means higher reaction rate from Arrhenius's equation
2) Higher vapour pressure due to the higher liquid temperature
Is there an assumption behind what the oxidizer temperature for fuel AIT? In ASTM E659, the experiment involves heating a small quantity of fuel inside a large flask of air at a pre-determined temperature, but since they are heating the flask I'm not sure how it is possible to control the temperature of the air.
Thank you very much