Final Temperature of Combustion Gases

In summary, the individual is designing a burner to run off powdered biofuel and is trying to calculate the resulting temperature after combustion. Using a simple heat balance and assuming constant specific heat, the estimate of 6600F seems too high and the individual is looking for a rough approximation of the final temperature, which they believe should be around 2000F. The discussion also touches on the limitations of temperature in a powdered biofuel burner and the practical limit for this application.
  • #1
gdgt
1
0
Hopefully one of you guys can help me out..

I'm designing a burner that will run off powdered biofuel and I'm trying to calculate the resulting temperature after combustion. I have a higher heating value (HHV) of around 10,000 BTU/lb for the biofuel and for a complete stoichiometric combustion will need 6.2 pounds of air per pound of fuel.

My thinking is, that burning one pound of fuel will release 10,000 BTU's of energy which will heat the air. Using a simple heat balance and assuming constant specific heat:

10,000 (BTU)= 6.2 (pounds of air) * .24 (BTU/lb/F) * (T_final - 75F)

And solving for T_final...

T_final = 6645.43F

This seems way too hot so I'm pretty sure I'm doing something wrong here. I'm just looking for a rough approximation of the final temperature which I feel should be around 2000F. I'm probably using the heating value wrong and I think the final temperature might have something to do with the adiabatic flame temperature but I'm not sure. Anyone have any thoughts or recommendations?

Any help would be greatly appreciated!

Thank you
 
Engineering news on Phys.org
  • #2
You are quite right, the 6600F estimate is way too high.
You come close to that in an internal combustion process, where near stoichiometric conditions can be approximated, but a powdered biofuel burner will run with a huge excess of air with peak temperatures limited by the combustor linings.
I would be surprised if you get much over 2000F, reflecting the air flow through your combustor.
 
  • #3
With a great deal of time, money, and effort the gas turbine industry has hit a limit of 3500-4000 degrees F. That requires the use of high temperature super alloys and propriety coatings. Since that is much higher than the melting point of the alloys, they also use very creative methods to cool them.

A practical limit for your application would be as stated in the last post.
 

1. What is the final temperature of combustion gases?

The final temperature of combustion gases varies depending on several factors, such as the type of fuel, the amount of oxygen present, and the efficiency of the combustion process. In general, it can range from 1000°C to 1600°C.

2. How is the final temperature of combustion gases measured?

The final temperature of combustion gases is typically measured using a thermocouple or an infrared thermometer. These instruments can accurately measure the temperature of the gases in real-time.

3. What is the significance of the final temperature of combustion gases?

The final temperature of combustion gases is important because it can affect the efficiency of the combustion process and the amount of pollutants produced. It is also used to determine the energy output of a combustion system.

4. How does the final temperature of combustion gases impact the environment?

The final temperature of combustion gases can have a significant impact on the environment. High temperatures can lead to the production of harmful pollutants, such as nitrogen oxides and sulfur dioxide, which contribute to air pollution and acid rain.

5. What factors can influence the final temperature of combustion gases?

The final temperature of combustion gases can be influenced by several factors, such as the type of fuel used, the amount of oxygen present, the design of the combustion system, and the presence of any catalysts. Atmospheric conditions, such as altitude and temperature, can also play a role.

Similar threads

  • Engineering and Comp Sci Homework Help
Replies
1
Views
881
  • High Energy, Nuclear, Particle Physics
Replies
11
Views
1K
  • General Engineering
Replies
4
Views
2K
  • Engineering and Comp Sci Homework Help
Replies
33
Views
6K
Replies
1
Views
969
  • Mechanical Engineering
Replies
4
Views
2K
  • Biology and Chemistry Homework Help
Replies
10
Views
3K
  • Engineering and Comp Sci Homework Help
Replies
6
Views
3K
  • Engineering and Comp Sci Homework Help
Replies
7
Views
3K
  • Engineering and Comp Sci Homework Help
Replies
9
Views
7K
Back
Top