Hot Air in Jet Engines: Fuel Burn and CO2 Formation

In summary, the hot gases thrown out of the back of a jet engine consist primarily of oxygen, inert gases, water vapor, and carbon dioxide, with additional emissions of carbon monoxide, oxides of nitrogen, smoke, and unburned hydrocarbons. The burning fuel quickly transfers heat to the surrounding air, with turbine inlet temperatures spiking up in less time than it takes for the human eye to notice. In addition to these emissions, jet engines also produce atmospheric nitrogen and NOx, which can damage the ozone layer at high altitudes.
  • #1
sid_galt
502
1
When fuel is burnt in the jet engine, what is the major component of the hot gases thrown out of the back - the CO2 formed (I know CO2 is not the only component but it is the major one) from the fuel or the air entering the jet as a whole?

In other words, does the heat of the burning fuel spread very quickly to the surrounding air in the jet or does it take a lot of time?
 
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  • #2
sid_galt said:
When fuel is burnt in the jet engine, what is the major component of the hot gases thrown out of the back
Basic turbine emissions are Oxygen, some trace inert gases, water vapor and carbon dioxide. When we do emissions testing for our certification programs the basic areas we focus in on are:

- CO (carbon monoxide)
- NOx (oxides of nitrogen)
- smoke
- Unburned hydrocarbons

The basic fuel used in civil aviation is JET-A which is a kerosene based fuel.

sid_galt said:
In other words, does the heat of the burning fuel spread very quickly to the surrounding air in the jet or does it take a lot of time?
I'm not quite sure what you are asking here. The cycle is a continuous process, so once it starts, it is constantly going. Obviously, the rate at which the heat gets to the airflow in the engine will depend on quite a few things, but the effect happens quite quickly. Turbine inlet temps (ITT's) can spike up in less time than it takes your eyes to notice it has happened.
 
  • #3
H20 makes up the majority of just about any fuel being burned.
 
  • #4
sid_galt said:
When fuel is burnt in the jet engine, what is the major component of the hot gases thrown out of the back

I'd suggest atmospheric nitrogen...
 
  • #5
brewnog said:
I'd suggest atmospheric nitrogen...

In addition to what Fred has said, I would say the main damage of Jet turbines are NOx. Although all heat engines exhaust NOx, Jet turbines are the unique which do this at high altittude.

Usually NOx compounds need a lot of time (of order of years) to reach high atmospheric layers. On the other hand, jet engines exhaust NOx just at high heights saving up that time of delay and damaging the Ozone Layer.
 

Related to Hot Air in Jet Engines: Fuel Burn and CO2 Formation

What is hot air in jet engines?

Hot air in jet engines refers to the high temperature air that is produced during the combustion process. This air is used to generate thrust and propel the aircraft forward.

How does fuel burn affect hot air in jet engines?

Fuel burn is a critical factor in the production of hot air in jet engines. The amount of fuel burned directly impacts the temperature of the air, and therefore, affects the performance and efficiency of the engine.

What role does CO2 formation play in hot air in jet engines?

CO2 formation is a byproduct of the combustion process in jet engines. As fuel is burned, it releases carbon dioxide into the air, which contributes to the greenhouse effect and climate change.

How do jet engines minimize CO2 formation?

Jet engines use advanced technologies to minimize CO2 formation. This includes fuel injection systems, which allow for more precise control of the fuel-air mixture, and exhaust gas recirculation, which helps reduce the amount of CO2 emitted.

What impact does hot air in jet engines have on the environment?

The hot air produced by jet engines can have a negative impact on the environment due to the release of greenhouse gases like CO2. However, advancements in engine design and alternative fuels are helping to minimize this impact.

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