[nareshkumaran]

Is there any chemical by which i can make ice in a ice making Unit faster. for me it takes 24 hrs for making ice in my factory.

[Enthalpy]

Did we meet elsewhere...?

In addition to my previous suggestions: make snow using cold air, press snow to ice,

I can propose you a fast spinning metal cylinder, strongly cooled, on which you spray water at one place and from which you scrap your ice downstream. From outside at still a different place, or rather from inside for cleanliness, you spray the cooling fluid to keep the metal cold. It's the same method that makes metallic glass and exotic alloys.

Or as well: use a second fluid, below zero Celsius, non miscible with water. Let water droplets flow against the cold fluid, separate ice thereafter, recycle the cold fluid through the cold machine.

In every case, water is finely divided so its heat escapes quickly. I see no solution to solidify a big block quickly.

Maybe: produce ice stones, ice pebbles, ice sand, well mixed like for concrete, so that little void remains. They must be very cold. Let liquid water flow in and be solidified by the cold ice.

I'd rather produce snow or hail, then compress it. Compress under vacuum if air bubbles are undesired.

But first, is it water ice? Ice cream? Do you need cleanliness...?

[Enthalpy]

IF you want to produce blocks of water ice, what's their size, especially their thickness?

With 335kJ/kg or 308MJ/m3 heat of fusion and 1,7W/m/K ice conductivity, if you allow an efficient cold plate to be at -10°C, the slowness of growth is 18,000,000s/m at 1m thickness, so:
1m takes 105 days
1mm takes 9.1s
1s freezes 0.11mm
1min freezes 0.85mm
1h freezes 6.6mm
10h freeze 21mm
not very fast, is it? You can produce plates 40mm thick in 10 nightly hours, with flat metal moulds dipping in a circulating liquid at -10°C. Then you can assemble the plates with some water or by friction welding to get thicker blocks.

Producing the cold at -40°C would only double the thickness and cost more energy to produce.

An extruder, producing ice like aluminium profiles, would have a 100mm long cooling needle every 2mm for instance, and still produce only 1cm/s. My intuition shouts me this is the perfect way into trouble.

This is why I suggest to produce snow and compact it.

[Enthalpy]

One more design where water is cooled by the surrounding fluid, hence not limited by ice conductivity.

Imitate icing conditions encountered by aeroplanes.

That is, a fluid (air, nitrogen...) well below 0°C contains water that hasn't had time to turn to ice. Upon meeting a surface (like pre-existing ice), some water freezes immediately.

This is one unusual case where you can hope to produce compact ice from the beginning, even clear ice.

By the way, the usual explanation involves supercooled liquid water, but I suspect instead uncondensed vapour to build ice.

The machine would then compress a gas, inject water as liquid of vapour, expand the gas and let ice accumulate where desired... and probably everywhere. Expanding in a turbine would ice the blades, in a nozzle would ice the nozzle, in a big chamber with a piston would ice the piston... Maybe a vortex can expand the gas at its centre (where the ice block is produced) without touching any wall, and compress it again before exiting.

Looks fast. But can it be energy-efficient?

Marc Schaefer, aka Enthalpy

[Enthalpy]

In the coming machines, clear bubble-free compact ice is produced at the surface of already existing ice, hence by its cold, but the existing ice itself is cooled from its growing face, thus speed isn't limited by the thickness.

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One machine raises the existing ice against a cold plate (not too rigid) for a few seconds, then sinks it less than 1mm under the water level for a few seconds (possibly aided by a wave), so all the new water layer freezes (important to stabilize an even surface). One cycle gains about 0.5mm in 20s, so the thickness gains 90mm per hour. Less thickness per cycle would increase the rate.

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If the ice can be grown around a mandrel, then existing ice is cooled by gas or a liquid bath or jets on a fraction of a turn, and the proper small amount of additional water is brought (spray, bath, brush, sponge...) during the rest of the turn. Cooling and water can alternate several times a turn.

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Or build a large head that moves (for instance with small circular oscillations) over the growing ice face. It carries many nozzles blowing cold gas and many pipettes, in an alternating pattern like white and black squares on a chessboard for instance.

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In a continuous process, the thickening bar passes under alternated gates blowing cold gas and adding a bit of water.

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These machines are energy-efficient, as they need little more cold than the latent heat of fusion, and at a temperature not much colder than 0°C. The three last ones can be nicely fast.

Man, am I good.

Incidentally, it could be interesting to have a look at how normal people produce ice. After all, it has been done for quite a few decades, so methods must exist, and not necessarily bad ones. Sometimes inventions that I thought mines existed before, or even better ones - how insolent - but checking it would take me too much time. Other people are welcome to check it.

Marc Schaefer, aka Enthalpy

[Enthalpy]

Finally I did have a quick look at how present machines work, and didn't find the equivalent of my proposals, nor methods that would look better or as good.

To produce ice blocks, present machines freeze water in containers from the outside in, which is slow and limits the thickness to some 250mm:
http://fontecchioicesculptures.com/FAQs.htm#Where_is_the_ice_from

producing such forms:


the bubbles indicate the centre freezes last.

To produce smaller ice chunks, machines flow water on inside-chilled tubes, and separate the ice regularly. Thin ice is produced faster, but the cold is still provided from the side opposed to ice growth.

Finally, ice chips are made in cold gas.

In half an hour search, I've found no machine like my proposals, that cools the ice from the same side where new water is brought to freeze. Not only is it faster, especially for thick blocks, it also produces bubble-free ice.

[Enthalpy]

On can produce ice blocks during night and use them in the day to cool air in houses.

This was done between Winter and Summer a century ago with huge insulated warehouses but had been out-fashioned by air conditioners.

Now, in circumstances where electricity production doesn't meet daytime peak demand, for instance in Japan this summer after the Fukushima Dai-ichi disaster let stop many nuclear power plants, this scheme is an indirect way to store electricity between night and day.

Thicker ice blocks last longer without added insulation, and are produced more easily with my process.

Marc Schaefer, aka Enthalpy

[okoloandokolo]

can anyone help with the name of chemical used in making ice faster

[curiouscat]

can anyone help with the name of chemical used in making ice faster

Dihydrogenoxide?

[curiouscat]

Incidentally, it could be interesting to have a look at how normal people produce ice. After all, it has been done for quite a few decades, so methods must exist, and not necessarily bad ones. Sometimes inventions that I thought mines existed before, or even better ones - how insolent - but checking it would take me too much time. Other people are welcome to check it.

Marc Schaefer, aka Enthalpy

Have you thought of patenting any of that? Cool ideas!

[Enthalpy]

The methods I proposed in:
Reply #4 on: January 25, 2011
are not patented by me, and I expect them to be better than the ones used commonly.
So feel free to use them, but before, check that nobody else has patented them before.

I have thought of patenting some ideas, and my former employers did so.
But if I publish an idea on a forum, I don't plan to patent it. That would be incompatible.

[curiouscat]

The methods I proposed in:
Reply #4 on: January 25, 2011
are not patented by me, and I expect them to be better than the ones used commonly.
So feel free to use them, but before, check that nobody else has patented them before.

I have thought of patenting some ideas, and my former employers did so.
But if I publish an idea on a forum, I don't plan to patent it. That would be incompatible.

I was encouraging you to patent them. 

[Enthalpy]

Finally, sketches of the machines with many nozzles and pipettes. Real machines will have many more than sketched to be compact and fast. The cooling gas can be air. The water can be pre-cooled around the freezing point.

The batch machine can let the head oscillate to spread water drops better, while the continuous process machine can offset the pipettes over the rows. Experiments will tell better if drops splattering and rolling need these measures at all; black ice does not. Injectors would create smaller droplets than pipettes do, but the water must not freeze before touching the existing ice. The continuous machine may have elastomer wipers between the watery and cooling zones.

Elastomer moulds, especially silicone, ease the removal. The conveyor belt may perhaps be a continuous elastomer, preferably reinforced with fibres over a small thickness; or be thin continuous metal, preferably covered with nickel with embedded Pfte; or have joints.

Stereolithography may help manufacture the head. A (disk) saw would cut the blocks more precisely than the sketched guillotine. Real-time local thickness measurement and feedback looks useful.

Marc Schaefer, aka Enthalpy

[danteOne]

If you boiled the water before starting to freeze it, it would freeze faster.

[Archer]

If you boiled the water before starting to freeze it, it would freeze faster.

Just like melting ice becomes water vapour faster than 90°C water when you heat it.

There is an important variable missing here.