Incomplete diesel fuel combustion equation

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jean241104
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I discovered econologic
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Registration: 28/02/11, 09:53

Incomplete diesel fuel combustion equation




by jean241104 » 28/02/11, 10:44

Hello everyone

on the site, in the rubric physics / chemistry-combustion equation, it is written that there will be an article on the detail of a non-ideal combustion or incomplete equation

this subject interests me greatly

news ???

thank you all in advance
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Christophe
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by Christophe » 08/03/11, 23:58

Here are some info found in a personal mail:

Combustion (very simplified)

Combustion is the complete or partial chemical reaction of carbon and hydrogen with the usual fuels by oxidation. We consider that the ideal combustion equation is written in the following simplified form:

C1 + C2 = C3 with:
C1 = CH4 (Combustible, here methane)
C2 = 2O2 + 8N2 (Oxidant: air, also called oxidant)
C3 = CO2 + 2H2O + 8N2 (Products of Combustion)


THERE ARE FOUR TYPES OF COMBUSTION:
- 1) STOICHIOMETRIC Combustion or neutral, which is the reference: it is only theoretical, (air supply just necessary for complete combustion).
- 2) Combustion COMPLETE by EXCESSIVE AIR or oxidizing, ie without unburnt, neither solid nor gaseous, it is the objective to reach (to note that the excess of air decreases the temperature of the fumes ).
- 3) INCOMPLETE Combustion in AIR FAULT (semi-reducing): It is prohibited for the health and the safety, being able to produce CO (unburned gaseous) or soot (unburned solid) each being prejudicial to the health, to consumption and the environment.
- 4) Combustion INCOMPLETE with AIR EXCESSIVE (semi oxidizing): Same as above, but there is unburned oxygen as in the case No. 2.

Beware of the confusion! CO2 calculations and performance are false.

The air (20,9% O2 + 78,2% nitrogen) which serves to ensure the complete oxidation of carbon and hydrogen in the fuel is called "stochiometric air". Complete combustion in excess of air is combustion with a volume of air greater than stochiometric air. The excess air does not participate in combustion and is found in the combustion products. During a stochiometric combustion, there is no more oxygen (completely consumed)
and the CO2 level is maximum. The oxygen level is therefore an indicator of the excess air when the combustion is complete and allows to evaluate the level of CO2 which is diluted by the same excess air.

Excess air is frequently expressed as an air factor. The air factor ("n" or Lambda) is equal to 1 at the stochiometric point. For example, for a small power, it could be from 1,2 to 1,25, ie an excess of air of 20 to 25% (or even "n" or Lambda = 1,2 to 1,25).

Packages

CO2 calculated from the O2
CO2 = CO2max x ((20,9-O2) / 20,9) in%

Losses
The determination of losses is made according to the following Siegert formula:
Losses = (Tac - Tab) x ((A2 / (21-O2)) + B) in%
Or = (Tac - Tab) x ((A1 / (CO2)) + B) in%
Tab = ambient air temperature
Tac = Combustion air temperature
A2 = (21 x A1) / CO2max

(See google for more details)

Excess of air
Lambda = CO2max / CO2 = 20,9 / (20,9 - O2)

Performance calculation
Yield = 100 -% Losses
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jean241104
I discovered econologic
I discovered econologic
posts: 2
Registration: 28/02/11, 09:53




by jean241104 » 14/03/11, 10:27

thank you for your answer but in reality what interests me is incomplete combustion for automotive engines ie the proportions of imbrulees and toxic molecules

please
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