[jumpinjackoo]

how does one accelerate ice making using only conventional equipment like a freezer? can one add additives or non-toxic chemicals to accelerate the icing of water?

[billnotgatez]

In all of the cases I have observed adding something to water lowers the melting point. This would make it harder to freeze.  

[Chrataxe]

Yeah, to my knowledge, adding anything would depress the freezing point.  I think you could do something with pressure...though I don't know if you would have to raise or lower it...and how you would do it.  Off the top of my head, I would say raising the pressure would cause it freeze faster...but, its 6:30 in the morning and I'm am fueled my nicotene and no sleep....

[billnotgatez]

What would happen when you returned it to normal room pressure?

[Chrataxe]

I really don't know...don't even know if it would work.  But, in the assumption it would, when going back to normal pressure, I would think it would do quite a bit of sublimation.

[Chrataxe]

Upon second thought, I'm pretty sure increasing the pressure would work.  Pressure is inversly proportional to volume.  So, if you increase the pressure, you would decrease the volume.

[Borek]

Increasing the pressure lowers melting point, so basically it is of no use - unless you will do a trick

To make ice you have to take some heat from the water. Heat transfer through ice is a slow process, that's why all ice producing units make only in fact a thin layer of ice. But if you increase the pressure water will be liquid even below freezing point, thus you can speed up the heat transfer through mixing. Then you change the pressure back to normal and the water is overcooled, so it freezes almost instantly.

The problem is, you will probably need to use high pressures - over 100 atm to lower freezing point by 1 deg C IIRC.

[Chrataxe]

Hey Borek, after reading your reply, I have been thinking about it a lot...and I am just curious as to how that works.  My original thinking was increasing pressure would decrease volume...but H20 has a lower volume as a liquid...not a solid.  So, I do see some error in my way...but just curious how the whole process works.

[syko sykes]

we did an experiment in my chemistry class that might interest you:

we took a glass bottle of club soda and submerged it in very cold water for a few minutes. The water was made by using a salt to lower the freezing point and the adding a little bit of dry ice. After a few minutes had passed and the club soda had enough time to get cold, we removed the bottle and removed the lid. Carbon dioxide was then released from the soda and the water froze almost instantly.

I'm not sure if this helps you but maybe it could give you some ideas on how to use freezing point depression.

[rctrackstar2007]

we still had to super cool the club soda so it could freeze that quickly. it also melted in minutes. i don't think there is any way to speed up ice making because liquid water will remain at freezing temperature until the enitre solution is frozen so super cooling isn't an option for quicker ice making