Irradition to base of cylindric gray gas volume

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Discussion Overview

The discussion revolves around calculating the irradiation (W/m²) to the base of a cylinder containing a gray gas that emits thermal radiation. Participants explore the complexities of the problem, including the geometry of the cylinder and the properties of the gas involved.

Discussion Character

  • Exploratory
  • Technical explanation
  • Conceptual clarification

Main Points Raised

  • One participant seeks assistance in calculating the irradiation to the base of a cylinder with specific parameters, including radius, height, absorption coefficient, and temperature.
  • Another participant questions the terminology used, asking for clarification on "irradition" and whether it refers to irradiation, as well as the type of radiation being discussed.
  • A participant suggests that the issue may involve multiple path lengths from the illumination point to the base, but notes the confusion between a cylinder and a cone in the context of light entry.
  • Clarification is provided that the thermal radiation is generated inside the cylinder, with no collimated light entering the system.
  • Questions are raised about the properties of the gray gas, including its transparency to infrared radiation and the mechanisms by which it emits IR radiation.
  • A participant identifies the gray gas as being related to fire, specifically mentioning the contributions from CO2, H2O, and soot radiation.

Areas of Agreement / Disagreement

Participants express uncertainty regarding the definitions and properties of the gray gas and its radiation characteristics. There is no consensus on the best approach to calculate the irradiation, and multiple viewpoints regarding the nature of the problem remain unresolved.

Contextual Notes

Participants have not yet established the specific assumptions regarding the gray gas's properties, the geometry of the cylinder, or the nature of the thermal radiation involved. The discussion lacks clarity on the definitions and implications of the terms used.

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TL;DR
What is the irradiation [W/m2] to the base of a cylinder with gray gas?
Anyone who has an idea for how to calculate the irradition [W/m2] to the base of a cylinder with radius R, height H, absorption coefficient k, and temperature T? I've looked at the approach with mean beam length by Hottel but cannot figure out what to do when it is the base of the cylinder that is the area of interest. Any help would be very much appreciated.
 
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M_1 said:
Summary:: What is the irradiation [W/m2] to the base of a cylinder with gray gas?

Anyone who has an idea for how to calculate the irradition [W/m2] to the base of a cylinder with radius R, height H, absorption coefficient k, and temperature T? I've looked at the approach with mean beam length by Hottel but cannot figure out what to do when it is the base of the cylinder that is the area of interest. Any help would be very much appreciated.
Sorry, what is "irradition"? Do you mean irradiation? If so, what sort of radiation? Light, particles, other?

And if light, is the issue the multiple path lengths that are taken from the illumination point at the top of the cone down to the flat base area? But you seem to be asking about a cylinder instead of a cone -- is the light collimated when entering the top surface of the cylinder?

Can you attach a sketch or figure of the problem?
 
Thanks for answer and sorry for not being clear. I mean a gray gas that emits thermal radiation. So the thermal radiation is created inside the cylinder and I need to figure out the irradiation hitting the base of the cylinder. So there is no collimated light and no light entering the cylinder.
 
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What exactly is "gray gas"? How transparent it it to IR? What is the mechanism for this gas emitting IR radiation?
 
The gray gas is a fire. So the emitting parts are mainly CO2, H2O and graybody radiation from soot.
 

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