Thermal Radiation from a Liquid or Gas

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Discussion Overview

The discussion centers around the calculation of heat loss from gases or liquids in relation to temperature, with a focus on the complexities involved in modeling this as a gray-body problem rather than a simple blackbody scenario. Participants seek insights and references on this topic.

Discussion Character

  • Exploratory, Technical explanation, Debate/contested

Main Points Raised

  • One participant expresses difficulty in finding resources on calculating heat loss from gases or liquids, suggesting it is a gray-body problem rather than a straightforward blackbody issue.
  • Another participant proposes that radiation heat losses can be calculated using the temperature-weighted blackbody curve and the spectrally-weighted emissivity, indicating that this approach integrates over all wavelengths.
  • It is noted that other heat transfer processes, such as conduction and convection, may complicate the overall heat loss calculations depending on the geometry involved.
  • A reference to Rohsenow & Hartnett is mentioned, possibly as a source for further information.

Areas of Agreement / Disagreement

Participants do not appear to reach a consensus, as there are differing views on the complexity of the problem and the methods for calculating heat loss.

Contextual Notes

The discussion highlights the potential complications arising from different heat transfer processes and the need for specific geometrical considerations, which may not have been fully addressed.

radiatorguy
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Hello,

I've been trying to find out how to calculate heat loss from a gas or liquid vs. temp. My understanding is that this is not a simple blackbody problem for a variety of reasons... guess it's more a gray-body problem. Have not been successful at finding papers or texts which deal with this specific issue. Are there simple ways to get approximate solutions to this problem or is this much simpler than I realize. Any insights or leads would be appreciated.

Thanks
 
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Radiation heat losses are reasonably straightforward to calculate- the total power radiated is a product of the temperature-weighted blackbody curve with the spectrally-weighted emissivity, integrated over all wavelengths.

There can be other processes- conduction and convection- that cause heat transfer as well. Those can be much more complicated, depending on the geometry.
 
Rohsenow & Hartnett
 
Thanks for the help Andy and Bystander.
 

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