this post was submitted on 12 Jan 2024
102 points (100.0% liked)

Ask Science

8676 readers
12 users here now

Ask a science question, get a science answer.


Community Rules


Rule 1: Be respectful and inclusive.Treat others with respect, and maintain a positive atmosphere.


Rule 2: No harassment, hate speech, bigotry, or trolling.Avoid any form of harassment, hate speech, bigotry, or offensive behavior.


Rule 3: Engage in constructive discussions.Contribute to meaningful and constructive discussions that enhance scientific understanding.


Rule 4: No AI-generated answers.Strictly prohibit the use of AI-generated answers. Providing answers generated by AI systems is not allowed and may result in a ban.


Rule 5: Follow guidelines and moderators' instructions.Adhere to community guidelines and comply with instructions given by moderators.


Rule 6: Use appropriate language and tone.Communicate using suitable language and maintain a professional and respectful tone.


Rule 7: Report violations.Report any violations of the community rules to the moderators for appropriate action.


Rule 8: Foster a continuous learning environment.Encourage a continuous learning environment where members can share knowledge and engage in scientific discussions.


Rule 9: Source required for answers.Provide credible sources for answers. Failure to include a source may result in the removal of the answer to ensure information reliability.


By adhering to these rules, we create a welcoming and informative environment where science-related questions receive accurate and credible answers. Thank you for your cooperation in making the Ask Science community a valuable resource for scientific knowledge.

We retain the discretion to modify the rules as we deem necessary.


founded 1 year ago
MODERATORS
 

I under stand that the lower the air pressure, the lower the boiling point of water. Also, some primitive desalination kits are basically evaporators.

Could you make a really big tank without a bottom and paint it black. Then, submerge it partly in the ocean . Pump the air out of the top. The water would rise up into the tank, a bit, but not all the way.

You wouldn’t need to have a perfect vacuum, just lower the air pressure enough to make boiling easier. Let the sun heat the black tank, and viola, steam.

Collect that steam from the air you are pumping out of the top of your tank, and you’ve got fresh water, right?

Edit: nevermind. Found it on google. Leaving this here to display my shame.

top 20 comments
sorted by: hot top controversial new old
[–] athos77@kbin.social 64 points 10 months ago (2 children)

Leaving this here to display my shame.

Why be ashamed? You had an idea that's probably never occurred to the majority of the people on this planet, and you asked for validation. A) that's original thinking and b) that's the first steps in science: I have an idea, is it reasonable, how can I experiment with it? I think this is a fantastic post!

[–] CaptainMcMonkey@lemmy.world 44 points 10 months ago (2 children)

Self depreciation is a load bearing coping mechanism. I’m not sure I can turn it off.

[–] 4am@lemm.ee 5 points 10 months ago
[–] CanadaPlus 7 points 10 months ago

Yeah, OP didn't even phrase it like nobody else could have thought of it, which is a frequent pitfall for these kinds of questions. The experts that can give the best answers hate that. It's implicitly saying their years of study aren't worth much.

[–] milkisklim@lemm.ee 30 points 10 months ago (1 children)

Honestly there is never any shame about sharing what you've learned. I didn't ever think about this and now I've learned something. Keep asking questions and searching for answers!

[–] CaptainMcMonkey@lemmy.world 7 points 10 months ago (1 children)

I mean, my last question was about crapping my space pants, so maybe I shouldn’t aim too high, lol.

[–] WalrusByte@lemmy.world 2 points 10 months ago

I laughed pretty hard at this comment! Shoot for the moon, and if you miss, you'll crap your pants among the stars!

[–] cron@feddit.de 21 points 10 months ago

According to your link, this is actually used in big plants:

Vacuum distillation is often used in large industrial plants as an efficient way to remove salt from ocean water, in order to produce fresh water. This is known as desalination. The ocean water is placed under a vacuum to lower its boiling point and has a heat source applied, allowing the fresh water to boil off and be condensed.

[–] CrayonRosary@lemmy.world 16 points 10 months ago (2 children)

Leaving this hear to display my shame.

This is your real shame.

[–] CaptainMcMonkey@lemmy.world 11 points 10 months ago (1 children)

I appreciate you’re help in pointing that out! I know its easy too get lazy and skip proof reading. I went back and changed it so its like it was never they’re! Its the principal of the matter.

[–] lobelia581@lemmy.dbzer0.com 4 points 10 months ago

i see what you did their

[–] MxM111@kbin.social 4 points 10 months ago

You should have written "you're" to share the shame.

[–] missing_forklift@sh.itjust.works 6 points 10 months ago* (last edited 10 months ago)

yes you can do this, however notice: this is wasteful as you have to run pump and heat from steam condensing is not recovered. You can heat up incoming water with condensing steam - this is called vapour recompression distillation. alternatively you can use heat pump to move heat around

[–] xkforce@lemmy.world 5 points 10 months ago* (last edited 10 months ago)

You could but the reality is that using a semipermeable membrane and a difference in pressure is more energy efficient.

[–] Steve@startrek.website 1 points 10 months ago (1 children)

I could be wrong, but iirc even tho you can boil the water at lower temperature, it still takes the same amount of energy to change phase, so the efficiency gain isnt as spectacular as you might expect.

[–] Brokkr@lemmy.world 2 points 10 months ago (2 children)

The energy to change phase, the latent heat of vaporization, does decreases. Enough such that the ambient temperature is able to supply sufficient heat for vaporization (that is, boiling). The latent heat of vaporization is temperature and pressure dependent for most materials.

[–] Steve@startrek.website 1 points 10 months ago* (last edited 10 months ago) (1 children)
[–] Brokkr@lemmy.world 1 points 10 months ago

I could have gotten it backwards. Depends on how the system is being defined and which direction the heat is going.

[–] Steve@startrek.website 1 points 10 months ago

I do agree that at some point ambient temperature does the job, which is obviously super convenient.