Naked Science Forum

Non Life Sciences => Physics, Astronomy & Cosmology => Topic started by: thedoc on 16/10/2014 22:30:02

Title: Is there a structure so efficient at sinking heat it can freeze water?
Post by: thedoc on 16/10/2014 22:30:02
Woody asked the Naked Scientists:
   
Is there a material and/or structure that is so efficient at sinking heat that it can passively freeze water?

What do you think?
Title: Re: Is there a structure so efficient at sinking heat it can freeze water?
Post by: syhprum on 17/10/2014 22:07:29
No structure is required if an area of water is facing the cold of space with no cloud cover and no incoming heat from the ground it will freeze.
no heat sink can extract heat from water unless it is cooled in some way that would make the building of a much longed for perpetual motion machine child's play 
Title: Re: Is there a structure so efficient at sinking heat it can freeze water?
Post by: evan_au on 18/10/2014 03:54:30
Dry Ice (solid CO2) will freeze water.

It does it "passively" in the sense that there is no external injection of energy or extraction of heat from the dry ice+water system.

But it can only keep cooling water until the dry ice is exhausted, and the system reaches a uniform temperature. This will eventually happen if you keep pouring in warm water (it takes a lot of dry ice to freeze a small amount of water).

Can you clarify what you mean by "passively"?