Measuring the temperature of a combustion

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Discussion Overview

The discussion revolves around measuring the peak temperatures achieved during the combustion of hydrogen, specifically in the context of quick explosions rather than continuous combustion. Participants explore methods for measuring these temperatures and the implications for nitrogen oxide formation.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested

Main Points Raised

  • One participant expresses uncertainty about the best method to measure peak temperatures during brief combustion events and raises concerns about nitrogen oxide formation.
  • Another participant clarifies that the focus is on explosions rather than continuous combustion.
  • A participant suggests using a real-time thermal imaging camera for temperature measurement, noting the need to consider the camera's equilibration time and calibration for peak temperature.
  • There is a question about the possibility of calculating peak temperature and whether to use the heat capacity of nitrogen or air for calculations related to nitrogen deprotonation.

Areas of Agreement / Disagreement

Participants do not reach a consensus on the best method for measuring peak temperatures or the appropriate calculations for assessing nitrogen behavior during combustion. Multiple competing views and uncertainties remain.

Contextual Notes

Limitations include the uncertainty regarding the duration of combustion events, the calibration of measurement devices, and the specific conditions under which nitrogen oxides may form.

SMD1990
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I am not 100% certain this is the best place for this. Moderators, if you think a different board would be better, please relocate this. Anyway...

I am wanting to measure the peak temperatures of my combustions of hydrogen. I got to thinking, "If I am using air as the source of oxygen, then nitrogen is also present. Ergo, nitrogen oxides could be forming."

Problem is, I have no idea how to even go about measuring the peak temperatures achieved. It is such a brief thing. I cannot really even measure just how short the instantaneous little bangs are.

Do you guys have any thoughts or ideas? I can assume a certain number of Joules based on the amount of hydrogen. But I cannot measure the duration of a combustion, nor do I know of a way to measure the peak air temperature during it.

From what I have read, I need to keep it below 1540 degrees Celsius to avoid the production of oxides of nitrogen. I am guessing that using no more than a certain amount of hydrogen in a given time period will allow me to achieve such. Again, I do not know how to go about measuring just how high the temperature of the air is getting, so as to confirm such and set a limit.
 
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Just to clarify: seems like you are dealing with explosions, not continuous combustion (like in a burner)?
 
Yes. Quick explosions, not a continuous combustion.

I am ultimately looking to produce a succession of little pops.

Currently, I am thinking about 50 mL (at atmospheric pressure) per second. Should that result in peak temperatures in excess of about 1500° C, I will want to reduce it to whatever lesser amount is necessary.
 
The first idea that comes to my mind is real time thermal imaging camera, the same that's used for flame detection and similar? And then find a calibration to peak temp. However one would have to look at the spec to see what equilibration time is needed, I have no clue.

But there are some heat cameras that surely go up to 2000C and that at least give a framerate of 50Hz. But still 20ms is a large timeframe for an explosion :frown:

One company I know of is http://www.flir.com/thermography/eurasia/en/content/?id=32092

If this fails then maybe more subtle ideas are needed.

/Fredrik
 
Is it possible to calculate the peak temperature? And, if so, for calculating whether the N2 is getting hot enough to deprotonate, should I use the heat capacity of nitrogen, or that of air?
 

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