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For SpaceNut .... there were three topics containing the word cooling.
This topic is designed and intended to collect practical solutions to real-Universe problems.
One topic is that of Quaoar; Zero boil-off active cooling for LH2
I would like for this new topic to ultimately contain a Zero boil-off PASSIVE cooling solution for LH2.
In addition, I would like for this new topic to contain a Zero boil-off PASSIVE cooling solution for liquid Helium.
Two topics are available with a focus on Venus. They are:
cooling venus with solar energy beamed blind by SpaceNut
and
Cooling Venus using Lunar dust by Antius
The inspiration for this new topic is the work of dedicated scientists and engineers to build the James Webb space telescope (a) and (b) the recent posts added to the forum in a topic on cloud seeding.
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SearchTerm:Passive cooling of liquid oxygen and liquid methane in deep space
It would appear that the scientists and engineers who built the James Webb space telescope will provide sustained temperatures of 50 Kelvin on the deep space side of the telescope.
The 50 Kelvin temperature is low enough to keep both liquid Oxygen and liquid methane in liquid form with zero-boil-off for transport to Mars.
A "frontier" of science and engineering is to achieve practical shaded cooling for liquid hydrogen and ultimately liquid helium in deep space.
This goal ** should ** be achievable .... per Google:
You can't see the CMB with your naked eye, but it is everywhere in the universe. It is invisible to humans because it is so cold, just 2.725 degrees above absolute zero (minus 459.67 degrees Fahrenheit, or minus 273.15 degrees Celsius.)
Aug 23, 2018
Cosmic Microwave Background: Remnant of the Big Bang | Space
www.space.com › 33892-cosmic-microwave-background
About Featured Snippets
The efficiency of radiation of thermal energy to space will (probably) decrease as the apparatus decends from 50 Kelvin to 3 degrees Kelvin.
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For the Earth applications side of this new topic, I'd like to see a practical solution to the problem of hurricanes and tornados which are problems primarily for the United States.
Both weather phenomena are the result of accumulation of thermal energy in the atmosphere.
Both weather phenomena could be tempered or even eliminated by removal of thermal energy from the atmosphere.
I'd like to open this new line of inquiry within this new topic, but asking for calculation of the amount of liquid air that would be needed to significantly impact the damage causing capability of both tornados and hurricanes.
Per Google:
Liquid nitrogen has a boiling point of –320°F (–196°C). The temperature difference between the product and the surrounding environment, even in winter, is substantial.
Liquid nitrogen - Air Products
www.airproducts.co.uk › media › airproducts › files › 900-13-081-us...
About Featured Snippets
Liquid oxygen - Wikipedia
en.wikipedia.org › wiki › Liquid_oxygen
Liquid oxygen has a density of 1.141 kg/L (1.141 g/ml), slightly denser than liquid water, and is cryogenic with a freezing point of 54.36 K (−218.79 °C; − ...
Physical properties · Uses · In rocket propellant · History
It is likely that liquid nitrogen would distill out before oxygen, but I expect it would be wise to maintain the "natural" ratio of nitrogen to oxygen in the product delivered to a job site so as to insure the same ratio persists when the liquid returns to gas.
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TH, what exactly do you mean by passive cooling? It is one thing to insulate a tank of cryogenic liquid and reduce heat flux into it. But you cannot reverse the temperature gradient and passively cool it unless you are either boiling off the tank or the outside temperatures are colder. Temperatures on Earth and Mars are greater than the boiling point of oxygen and nitrogen everywhere, all the time and much higher than the boiling point of hydrogen. To cool the liquid, you need some sort of reverse heat engine or sacrificial fluid that is boiled off.
Active cooling doesn't have to be hugely complicated or power hungry, but it is tough to achieve without moving parts. You need a compressor, expander and radiator. Coefficient of performance will be poor cooling liquid hydrogen. The way to limit power consumption is to insulate well.
Last edited by Calliban (2021-12-12 08:04:43)
"Plan and prepare for every possibility, and you will never act. It is nobler to have courage as we stumble into half the things we fear than to analyse every possible obstacle and begin nothing. Great things are achieved by embracing great dangers."
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For Calliban re #4
First, thanks for helping to give this new topic a running start!
Second, this new topic was inspired by the work of scientists and engineers who built the James Webb telescope, as reported last night in the hybrid meeting of the North Houston chapter of the National Space Society. The talk is available for viewing at www.northhoustonnss.org.
You will learn (if you did not know already) that the scientists needed 50 Kelvin temperatures for their instruments, and the engineers developed a passive cooling system to deliver that temperature for years on end. There is information briefly summarized elsewhere in the forum today.
In the specific case of James Webb, the background radiation of (about) 3 degrees Kelvin is the "outside cooler" that your posts reference.
There is NO need for active cooling. All cooling is to be accomplished by radiation into the background field.
However, there ** is ** active cooling needed to keep helium liquid for the spectrograph. The purpose of ** this ** topic is to (try to) encourage bright (probably younger but not necessarily) people to tackle the stage of radiative cooling between 50 Kelvin and 3 Kelvin.
Thanks again for helping to give this new topic a boost.
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FriendOfQuark1 has written via email about the opportunity and challenge of radiative cooling in deep space. The discussion came up when I quoted a comment by Calliban some time ago, about what a spacecraft might experience if it burrowed into a rubble pile asteroid to seek shelter from severe radiation storms.
The point of interest in the discussion is/was about how the spacecraft would continue to dump heat to avoid overheating. In open space, radiation panels would generate infrared waves as hot fluid moves through ribs in the radiators. Those infrared waves would represent work done to generate them, and as the waves travel away from the radiator, they are effectively "cooling" the radiator by removing energy.
In discussion with FriendOfQuark1, he referred to a discussion with a NASA engineer who was trying to explain how radiators work to keep the ISS cool. The explanation included reference to Quantum Mechanics, which tells me that if we in this forum want to understand radiative cooling, a willingness to venture into QM would seem appropriate.
In any case, I think this topic is relevant to the sheltering spacecraft problem, and hope that members may be inspired to do some investigating.
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Void has opened an entire topic on radiators in space:
http://newmars.com/forums/viewtopic.php?id=10886
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