Welcome to Tesla Motors Club
Discuss Tesla's Model S, Model 3, Model X, Model Y, Cybertruck, Roadster and More.
Register

Thermodynamics (out of main)

KarenRei

ᴉǝɹuǝɹɐʞ
Jul 18, 2017
9,619
104,589
Iceland
Pretty efficient global warming solution. Use fossil fuels to power outdoor air conditioning!

https://www.washingtonpost.com/grap...imate-change-qatar-air-conditioning-outdoors/

Brought to you by Wile E. Coyote Engineering, Inc.

EC0E7idWwAIEFvm.jpg
 

MarcusMaximus

Active Member
Jan 2, 2017
3,789
16,747
Los Gatos
This joke-solution is not as dumb as it sounds first. If they built a space-elevator (powered by clean renewable energy) to lift big containers of water from the ocean high enough to freeze than bring it back down using heat-shield on re-entry, it could almost work...

Something something first/second law of thermodynamics something...
 
  • Funny
Reactions: kbM3 and Curt Renz

mongo

Well-Known Member
May 3, 2017
13,513
42,346
Michigan
The solar panels to power this space elevator might be large enough to help cool the planet from the shading. Everything else about the idea violates thermodynamics.

Something something first/second law of thermodynamics something...

As I read it, this does not violate any thermo laws.
It is displaced radiant cooling. Would be simpler to pump a liquid to space into black radiators to cool and then back down. Technically, the colder water is more dense so with a large pipe, you would get free therm buoyant pumping. Similar to the Alaskan pipeline and its ammonia based permafrost refrigeration system. That gets you the efficiency of the phase change.

(original idea would not need heat shield since the down weight would cancel the upweight)
 

SOULPEDL

Active Member
Jul 25, 2016
3,498
14,298
Arizona
Something something first/second law of thermodynamics something...
This is so OT, it's all gonna get moved to "Stupid ways to cool the outdoors".

Meanwhile, assuming there is wind, just fly about 2,000 kites at various levels and force the upper atmosphere down into the stadium. The same device also gathers drinking water through "cloud harvesting." Kites paid for by marketing Hi-Fliers.
 
  • Funny
Reactions: AZRI11 and LTC_RRR

MarcusMaximus

Active Member
Jan 2, 2017
3,789
16,747
Los Gatos
As I read it, this does not violate any thermo laws.
It is displaced radiant cooling. Would be simpler to pump a liquid to space into black radiators to cool and then back down. Technically, the colder water is more dense so with a large pipe, you would get free therm buoyant pumping. Similar to the Alaskan pipeline and its ammonia based permafrost refrigeration system. That gets you the efficiency of the phase change.

(original idea would not need heat shield since the down weight would cancel the upweight)

For radiant cooling, you need something on the outside to radiate the thermal energy to. On the surface, you get that for free using surface pressure air. In space, you have little to no atmosphere, so your only radiation would be light-based(far IR mostly at these temps). You could use the water, itself, to radiate the heat, but then you’re losing your free pumping, and that pumping, itself, is going to generate a lot of heat on the surface.

Earth isn’t quite a closed system, but it’s awfully close. We only lose energy to space in the form of reflected and radiated light.
 

mongo

Well-Known Member
May 3, 2017
13,513
42,346
Michigan
This is so OT, it's all gonna get moved to "Stupid ways to cool the outdoors".
Probably .

For radiant cooling, you need something on the outside to radiate the thermal energy to. On the surface, you get that for free using surface pressure air. In space, you have little to no atmosphere, so your only radiation would be light-based(far IR mostly at these temps). You could use the water, itself, to radiate the heat, but then you’re losing your free pumping, and that pumping, itself, is going to generate a lot of heat on the surface.

Earth isn’t quite a closed system, but it’s awfully close. We only lose energy to space in the form of reflected and radiated light.

I think you are talking convection at the beginning. Cooling via radiation is the only type that occurs in space. You don't radiate the energy to something, it just travels away. if it hits something and bounces back, you loose cooling efficiency. That is why dry deserts are so cold at night, no cloud cover to reflect the heat back. The Merlin vacuum engine bell is radiantly cooled (temperature^4).

Yeah, Earth (in space) loses heat via radiation, that is what green house gasses prevent by reflecting IR back to the surface.
Thus saying you need to pump to space, outside of the atmosphere.
 

ZsoZso

cat at play-time
Supporting Member
Apr 24, 2014
1,863
11,878
Mount-island
As I read it, this does not violate any thermo laws.
It is displaced radiant cooling. Would be simpler to pump a liquid to space into black radiators to cool and then back down. Technically, the colder water is more dense so with a large pipe, you would get free therm buoyant pumping. Similar to the Alaskan pipeline and its ammonia based permafrost refrigeration system. That gets you the efficiency of the phase change.

(original idea would not need heat shield since the down weight would cancel the upweight)

Yes, basically a giant (and very inefficient) heat-pump from surface to space.
If the motors operating the elevator/pump are outside the atmosphere, then even their waste-heat is released to space.
What makes it impossible is not thermodynamics, but the required tensile-strength of the material to build the elevator / pipe to withstand the gravitational force acting on it.
 

mongo

Well-Known Member
May 3, 2017
13,513
42,346
Michigan
Yes, basically a giant (and very inefficient) heat-pump from surface to space.
If the motors operating the elevator/pump are outside the atmosphere, then even their waste-heat is released to space.
What makes it impossible is not thermodynamics, but the required tensile-strength of the material to build the elevator / pipe to withstand the gravitational force acting on it.

For fun:
Since you do not care about achieving orbital velocity, a sufficiently tall tower would work (Ad Astra style). Lower sections could be supported by hydrogen bags.

Taken further, one could imagine heating water at Earth's surface, letting that migrate to the upper atmosphere where it would partly radiate its energy to space, then return to surface to repeat the cycle. Side benefit could be reflecting sunlight while in the upper atmosphere. :)
 

Oil4AsphaultOnly

Supporting Member
Supporting Member
Mar 14, 2015
2,042
5,903
Arcadia, CA
As I read it, this does not violate any thermo laws.
It is displaced radiant cooling. Would be simpler to pump a liquid to space into black radiators to cool and then back down. Technically, the colder water is more dense so with a large pipe, you would get free therm buoyant pumping. Similar to the Alaskan pipeline and its ammonia based permafrost refrigeration system. That gets you the efficiency of the phase change.

(original idea would not need heat shield since the down weight would cancel the upweight)

Replying to this post (since it has its own thread now), since it brings us back to the joke comment's feasibility. Your points about heat radiating are fine, but the thermo dynamics is violated with the poster's suggestion of a heat shield - heat is lost through conduction into the atmosphere.

Besides, to get high enough where most of the heat is lost through radiation versus conduction would also evaporate the water wouldn't it?
 

mongo

Well-Known Member
May 3, 2017
13,513
42,346
Michigan
Replying to this post (since it has its own thread now), since it brings us back to the joke comment's feasibility. Your points about heat radiating are fine, but the thermo dynamics is violated with the poster's suggestion of a heat shield - heat is lost through conduction into the atmosphere.

Besides, to get high enough where most of the heat is lost through radiation versus conduction would also evaporate the water wouldn't it?

Yeah, the kinetic energy converted to heat is a net heat detractor. I was picturing a sealed vessel of water (with some expansion space), so no evaporation.
 

Oil4AsphaultOnly

Supporting Member
Supporting Member
Mar 14, 2015
2,042
5,903
Arcadia, CA
Yeah, the kinetic energy converted to heat is a net heat detractor. I was picturing a sealed vessel of water (with some expansion space), so no evaporation.

Ah. Hmmm ... In that case, haul up tropical water in water bag, freeze in space, unwrap (why bother heat-shielding ICE?!) and drop an ice bomb on any unsuspecting pirate ships? Sorry, my mind has juvenile tendencies, and dropping heavy things from high up fits right in.
 

mongo

Well-Known Member
May 3, 2017
13,513
42,346
Michigan
Ah. Hmmm ... In that case, haul up tropical water in water bag, freeze in space, unwrap (why bother heat-shielding ICE?!) and drop an ice bomb on any unsuspecting pirate ships? Sorry, my mind has juvenile tendencies, and dropping heavy things from high up fits right in.

The ice pirates would love that!
 

Doggydogworld

Active Member
Mar 4, 2019
1,749
6,794
Texas
Ah. Hmmm ... In that case, haul up tropical water in water bag, freeze in space, unwrap (why bother heat-shielding ICE?!) and drop an ice bomb on any unsuspecting pirate ships? Sorry, my mind has juvenile tendencies, and dropping heavy things from high up fits right in.
Unless you insulate the bag well or lift it quickly the water will freeze before it gets to space. Temp above 36k feet is -70F.
 

Doggydogworld

Active Member
Mar 4, 2019
1,749
6,794
Texas
Wouldn't insulating the bag kind of defeat the purpose of freezing the water through radiation?
You'd have to 'uninsulate' it when you got to space. Otherwise you're just moving heat from the surface to the stratosphere. IPCC theory is a little CO2-based high altitude warming kicks off a feedback cycle that increases water vapor (the real greenhouse gas). Based on that theory transferring heat to the stratosphere would be the last thing you'd want to do.
 

Products we're discussing on TMC...

About Us

Formed in 2006, Tesla Motors Club (TMC) was the first independent online Tesla community. Today it remains the largest and most dynamic community of Tesla enthusiasts. Learn more.

Do you value your experience at TMC? Consider becoming a Supporting Member of Tesla Motors Club. As a thank you for your contribution, you'll get nearly no ads in the Community and Groups sections. Additional perks are available depending on the level of contribution. Please visit the Account Upgrades page for more details.


SUPPORT TMC
Top