Can we use infrared-transmitting materials like silicon (on upward-facing hemisphere of exhaust pipes) to dissipate heat energy from exhaust gases discharged from Generators, vehicles etc, through radiation, that can then be reflected towards space (upward forcing) by using deflectors (like aluminium coated surfaces)?
Mohd,
You would still need to decouple the cooled surface from ambient air.
If you can do that, then any high emissivity material is sufficient.
https://www.nature.com/articles/ncomms13729
James Garry Sir,
"The hot gases at 600K Temperature, flowing through a cylindrical Silicon pipe designed to dissipate the heat to ambient air." Would it(Silicon pipe) decouple the cooled (gases) from the atmosphere?
Mohd,
If you have gas at 600K, then it is 300K warmer than the environment. Is there a problem with simply blowing air past this article?
Thank you for Sir your help. Actually, I needed a portion of heat carried by gases to be transmitted through radiation (that can be directed/ reflected upward towards space) while rest of the heat may be transferred by blowing air (convection).
Do the gases also emit radiation as per Wien's law?
Mohd,
Indeed, gases will also radiate but Wien's law will not be simply applied - as they are not solid black bodies. You have to consider the wavelengths at which the gas may absorb or transmit radiation - it is not a trivial matter.
I can imagine an infra-red transparent tube (silicon, sapphire, etc.) at the focus of a parabolic trough. But, again, if you want to shift heat, a purely convective transport mechanism seems to be the most efficient.
May I ask what is the goal of this project?
@James Garry Sir. The project aims at radiative cooling of exhaust gases at 600K.
Mohd,
Well, that's an ambitious goal: but perfectly legitimate if you are constrained to dump a minimum amount of heat into the environment.
So.
Take two IR-transparent tubes (note, that sapphire is transparent from 1 through 4 micron) - one with a diameter smaller than the other. Fuse the circular ends, and evacuate the inner-wall space. You've now got a 'Thermos' flask that is a tube.
Pass the hot gas down this tube, and no heat will be conducted to the ambient surroundings (thanks to the vacuum between the tubes). Place the tube-like arrangement at the focus of a paraolic trough mirror, and aim it at the sky: guaranteeing the lowest temperature 'sink' for the radiation.
Thank you very much Sir. I would like to use Silicon wafer for cost reduction.
Could you please share any reference on spectroscopy of carbon dioxide other than CDSD-1000?
Thank you so much for your help.
Mohd,
I either use NIST or HITRAN.
NIST (graphic interface, easy to use)
https://webbook.nist.gov/cgi/inchi?ID=C124389&Type=IR-SPEC&Index=0#IR-SPEC
HITRAN (neither graphic nor easy to use)
https://hitran.org/
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