My peltier ice cube maker (dream)

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pcatterall

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I now believe that a peltier plate can freeze provided the volume to be frozen is small enough. I just want to freeze enough cubes for my evening g and t !!
I plan to use a very small water cooler and pump from my 100 gallon hull cooled water tank.
Am I dreaming or drunk in anticipation?
 
I have tried to freeze ice pops for the kids in the boat's icebox. The surface was frozen, yet after some 4 hours the ice pops were still liquid. This is with a normally working compressor driven fridge. I would be very surprised if a Peltier cooler gets your ice cubes hard frozen unless left running overnight.
 
I reckon it could work. You'd need a reliable way of removing heat from the hot side of the Peltier module (maybe water cooling??).
 
Normally a 20 degree temperature differential on a peltier unit so perhaps a cascade system would work - box within a box within a box.
 
superheat6k said:
I have tried to freeze ice pops for the kids in the boat's icebox. The surface was frozen, yet after some 4 hours the ice pops were still liquid. This is with a normally working compressor driven fridge. I would be very surprised if a Peltier cooler gets your ice cubes hard frozen unless left running overnight.
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Peltier are just fantastic





for running batteries down without freezing anything
 
superheat6k said:
I have tried to freeze ice pops for the kids in the boat's icebox. The surface was frozen, yet after some 4 hours the ice pops were still liquid. This is with a normally working compressor driven fridge.
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I've made ice cubes in Ariam's (compressor, not peltier) fridge a couple of times. I used one of those segmented plastic bags, hung against the cooling element. It freezes the milk from time to time when we're careless, so not surprisingly it was able to make cubes.

However, they melt in the drink far, far quicker than cubes from a domestic freezer would, presumably because they're only just below 0º. So not really satisfactory, and we normally just use a bag of supermarket cube ice at the bottom of the fridge to provide initial cooling when we arrive and then a few days' G&Ts.

Pete
 
If you have 240 volt on board then an icemaker is the way to go.
Mine takes 10 min for first cubes to appear then circa 5 mins thereafter for next batch.

Cost about £90 IIRC.
 
paulajayne said:
If you have 240 volt on board then an icemaker is the way to go.
Mine takes 10 min for first cubes to appear then circa 5 mins thereafter for next batch.

Cost about £90 IIRC.
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Same here - had Andrew Martin compact for last 9 years - runs off invertor if engine on or batteries fully charged in sunlight. Fridge then stops them melting for a few hours if needed.
 
Thanks all. I had always just thought of peltier cool boxes as just so many degrees below ambient. But have seen single plates with ice on the cold side so now think that the size of box and it's insulation is critical.
I wanted something even smaller that the counter top units.
Will let you know when to get them hats cooking!
 
Rather than messing around with Peltier plates, how about a domestic counter-top ice-maker powered through an inverter? They draw around 140W and can churn out enough ice to keep even the most devout quinine addict sated.

I've been seriously (well, maybe a bit tongue in check) toying with the idea of running a diesel/solar/ice hybrid system for those frustrating periods when the batteries are full but we're either motoring or there's still plenty of solar with nowhere to go. They're not huge, but size may be an issue on some boats. (Our landlubber version, which is brilliant, is 30x35x37cm.) They typically cost a little over £100.
 
macd said:
I've been seriously (well, maybe a bit tongue in check) toying with the idea of running a diesel/solar/ice hybrid system for those frustrating periods when the batteries are full but we're either motoring or there's still plenty of solar with nowhere to go.
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Admittedly it can't be dunked directly into a glass of gin, but my fridge system actually does something like this. When running on batteries it merely keeps the fridge cool, but when it detects that surplus power is available it goes into overdrive and also freezes a tank full of special gloop that holds more cold than ice would. When back on batteries alone (we don't have solar) the fridge can run off this stored coolth for quite a while, without needing to run the electric compressor at all.

Pete
 
prv: that sounds like a sensible set-up. Surprised it's not more widely used on boats. I think some domestic fridges use similar packs to sustain themselves through power cuts, although obviously with no need for your surplus power sensing.
I think the active ingredient of the gloop is propylene glycol, which isn't at all hard to get hold of...
 
The problem with making ice in a Peltier system is down to the marginal heat flows, and the latent heat of fusion.

To cool water, you need to remove just 4.2 joules per gramme, per degree C

Getting it down from 20 degrees to 0 degrees requires removing just 84 Joules per gramme of water with the Peltier device .. but it wont be frozen, it will just be water at 0 degrees.

Te get it to turn into ice at 0 degrees, you have to pump out a further 334 Joules per gramme of water ... roughly 4 times as much energy as it took to cool it down to zero in the first place. So, even if your Peltier device has enough "oomph" to pump the box down to 0 degrees C, it would take quite a while before any water turns to ice.
 
rszemeti said:
To cool water, you need to remove just 4.2 joules per gramme, per degree C

Getting it down from 20 degrees to 0 degrees requires removing just 84 Joules per gramme of water with the Peltier device .. but it wont be frozen, it will just be water at 0 degrees.

Te get it to turn into ice at 0 degrees, you have to pump out a further 334 Joules per gramme of water ... roughly 4 times as much energy as it took to cool it down to zero in the first place. So, even if your Peltier device has enough "oomph" to pump the box down to 0 degrees C, it would take quite a while before any water turns to ice.
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Some of us will be aware of the phenomenon you describe, but expressed in terms of the latent heat of freezing being around 80 times that of changing water temperature by 1ºC. Just trying to be more inclusive for the semi-educated ;)
 
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