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tahanson43206

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Registered: 2018-04-27

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Refrigeration Refrigerator Food Preservation Habitat Air Conditioning

This topic is offered with the expectation the information it contains will be needed by builders of:

1) Large Ships
2) Orbital Stations
3) Sub-planetary Stations
4) Planetary habitats

To lead off, here is a report on a refrigeration system designed for zero gravity:

https://www.msn.com/en-us/news/technolo … d=msedgntp

This design is somewhat similar to the prototypical vapor-compression refrigerator in your kitchen, but the key difference lies in its oil-free compressors. For that, the team from Purdue's School of Mechanical Engineering turned to Air Squared, a Broomfield, Colorado-based research and development firm that specializes in them.

(th)

SpaceNut

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Registered: 2004-07-22

Posts: 29,431

Re: Refrigeration Refrigerator Food Preservation Habitat Air Conditioning

The ISS has a zero g refrigerator which is using acoustics to move the working fluid...

https://lsda.jsc.nasa.gov/books/ground/4.4crewfood.pdf

https://www.colorado.edu/aerospace/2020 … ream-space

https://www.msn.com/en-us/news/technolo … r-BB19NO7x

https://techcrunch.com/2021/05/27/zero- … for-years/

https://www.sciencetimes.com/articles/3 … future.htm

tahanson43206

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Registered: 2018-04-27

Posts: 19,389

Re: Refrigeration Refrigerator Food Preservation Habitat Air Conditioning

For SpaceNut re #2

Thanks for the helpful list of links about refrigeration in the context of space going vessels, and related links.

This topic was created in hopes it would become a repository for useful knowledge, practical tips and whatever else might help someone in future.

Today I'd like to toss a question into the center of the ring, in hopes there is someone who might find it interesting and worth investigating ...

The inspiration for this question is the current spell of hot weather those who live in parts of the North American continent, and even (I understand) parts of Europe not used to high temperatures.

The air conditioner service people I talk to now and then seem to have a rule of thumb ... their equipment can deliver 20 degrees (Fahrenheit) of difference between the input and the output.  That rule of thumb seems to apply to the air circulating inside a building.  If the air inside a building can be protected from intake of hot outside air (insulation and closing openings) then it appears (at least from my experience) that a building can be kept to (let's say 74 F) even though the outside may exceed 94 degrees F.

However, at some point, the heated working fluid is not going to be sufficiently hot to facilitate flow of heat energy to the outside air.

So here is my question ... does it make sense to contemplate two-stage cooling for hot climates?

The first stage would deliver the existing hot working fluid to an exchanger which itself is part of a cooling system.  However, ** that ** secondary cooling system would be designed to deliver hot fluid into an environment of 120 degrees F or higher ** and ** achieve the needed heat flow efficiency.

I'm not sure what that working fluid temperature might need to be, but I would presume it would be well above 120 degrees.

If someone who is a member with posting privileges would be willing to take this on, I'd be interested in knowing the temperatures that are typical for an existing cooling system designed for "normal" outside temperatures, as well as what would be needed if the value of "normal" increases to 120 or more, as seems quite likely to become common.

If (by chance) there is a reader of this forum who has knowledge in this area, ** and ** who would like to contribute, ** and ** who is not yet a member, please read Recruiting post #2 and drop a note to the NewMars Portal.

(th)

SpaceNut

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Registered: 2004-07-22

Posts: 29,431

Re: Refrigeration Refrigerator Food Preservation Habitat Air Conditioning

Making use of the colder water table in deep well of a larger meter diameter to draw up the cold into the exchanger loop and then send the warmed fluids to a secondary well would be one way to get a greater amount of thermal cooling rather than the common single exchanging system of the AC. This is sort of like the heat pump design.

tahanson43206

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Re: Refrigeration Refrigerator Food Preservation Habitat Air Conditioning

Your suggestion in post #4 reminds me of the idea from many years ago, of trying to tease energy out of the temperature difference between the surface of the ocean and the temperature at depth.  That idea involved moving many tons of water from the depths, through the exchanger, and back to the ocean.  It was a massive movement of matter for a very small return.  A heat pump (as I understand the concept) moves hot working fluid into the cool water underground, so the amount of mass moved is kept to a minimum.

Google came up with this snippet:

Ocean thermal energy conversion (OTEC) is a process or technology for producing energy by harnessing the temperature differences (thermal gradients) between ocean surface waters and deep ocean waters. ... This temperature difference can be used to produce electricity and to desalinate ocean water.
Ocean thermal energy conversion - U.S. Energy Information ... - EIA
www.eia.gov › energyexplained › hydropower › ocean-thermal-energy-co...

A variation of that idea is to send energy down a pipe (photons collected by mirrors) and return electrons via the wall of the pipe.

The benefit would be minimal movement of matter.  The challenge would be having to maneuver the solar mirrors to deliver photons throughout the day.

Edit#1: I ran a search of the archive, looking for OTEC, and discovered that Void has mentioned the technology multiple times in various contexts.

However, the post that ** really ** rang a bell is this one: http://newmars.com/forums/viewtopic.php … 54#p129154

Tom Kalbus reports being a member of the Third Millennial Institute, which is a name I did not recall, but his description reminded me of the Living Universe Foundation which was created after the previous organization failed or was dissolved. 

(th)

louis

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Posts: 7,208

Re: Refrigeration Refrigerator Food Preservation Habitat Air Conditioning

Presumably large scale refrigeration on Mars is simple in that you could build a poorly insulated unit in a shaded part of the surface and then top up the temperature to the required level using heating.

---

Let's Go to Mars...Google on: Fast Track to Mars blogspot.com

tahanson43206

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Registered: 2018-04-27

Posts: 19,389

Re: Refrigeration Refrigerator Food Preservation Habitat Air Conditioning

Air conditioning is on the minds of many (on Earth) as heat extremes test the patience of the population.

https://www.yahoo.com/news/ac-feels-gre … 13456.html

The article at the link above provides a summary of the history of the technology, and makes observations about the drawbacks of the chemicals used as working fluids at various times.

A concern I've had is included in the article ... air that is cooled for those lucky enough to have air conditioning is cooled by transferring heat energy to the outside environment.  That means the air in a city (for example) may be considerably hotter for those who are outside than it would have been if there were no air conditioning going on.

***
In post #6, Louis makes the point that the need for air conditioning to cool air inside habitats on Mars is likely to be low, whereas the need to heat habitat air seems likely to be an ever present one. 

(th)

SpaceNut

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Re: Refrigeration Refrigerator Food Preservation Habitat Air Conditioning

If we were teraforming using the oceans for inland sea's we could run the cold of the waters entering into heat exchangers reducing the need for cooling for our homes.

tahanson43206

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Re: Refrigeration Refrigerator Food Preservation Habitat Air Conditioning

For SpaceNut re #8 ...

The oceans are warming.

As the oceans warm, they expand.

What is needed (to protect the planet) is a way to transmit thermal energy to space, to to reduce the amount being added to the system.

(th)

SpaceNut

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Re: Refrigeration Refrigerator Food Preservation Habitat Air Conditioning

ya now I see that the post was more for voids topic..which wants to move the ocean to gain the water...

Its not just the oceans warming as the air and even the land is getting hotter...

Saw an article that was placing cloth to reflect the sun from warming a glacier in Europe I think. googling...

tahanson43206

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Registered: 2018-04-27

Posts: 19,389

Re: Refrigeration Refrigerator Food Preservation Habitat Air Conditioning

For SpaceNut re #10

Thanks for the hint about protecting a glacier by covering it with reflective material.  While the cost may prevent adoption of this idea at scale, it ** is ** simple and doable by ordinary humans, and it definitely would send photons back to space.

Covering glaciers with solar panels would have a similar effect and the energy would be preserved on Earth in electricity if it can be stored.

Again, the cost may preclude adoption at scale, but it ** is ** something practical that could be done.

At present, my understanding is that particles floating in the air settle on the ice and heat up with solar radiation, causing local melting that rots the ice. As the surface of ice liquefies, apparently it collects photons rather than reflecting them, so heating increases.

A nation state like China could organize millions of people to perform an activity like that.  It seems unlikely to me that the disorganized bulk of humanity can do anything on that scale.

(th)

SpaceNut

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Posts: 29,431

Re: Refrigeration Refrigerator Food Preservation Habitat Air Conditioning

Solar panels are dark and would cause the air to become warm as the absorbed IR would radiate from them. Yes they would create shade but its reflection which is needed as well as the shade.