My peltier ice cube maker (dream)

[pcatterall]

Great point. That dam latent heat issue again!
So....... I will cool my tonic down to zero and put in some glass cubes to get that magic tinkle????

 

[lw395]

Unless you want a lot of ice, the latent heat is not that big a problem. 334j/g.
100g of ice does a few drinks.
Say 33.4kJ, that's only 0.93Ah at 12V at an efficiency of 1.

The problem with peltier cooling is mostly about getting the heat away from the hot side.
And the reverse heat flow when the element isn't powered. If you use water to get the heat away, that might freeze...

For the avarage South Coast cruiser, bags of ice from supermarkets work OK.

 

[lw395]

Normally a 20 degree temperature differential on a peltier unit so perhaps a cascade system would work - box within a box within a box.

The amount of heat pumped from one side to the other reduces as the temperature difference increases, 20degC difference is a common spec point. The cooler you can keep the hot side , the better it works, cascaded systems are not unknown. They are used for cooling semiconductor devices, not just beer...

 

[lw395]

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

Eutectic plate.
Same effect as the camping shop blue cooler blocks, any solution tends to freeze at a lower temperature than a pure liquid.

 

[TLouth7]

I did this as a uni project. Firstly it is certainly possible to make ice, but if you want a complete system that makes and stores multiple "cubes" then that is a much bigger challenge.

We had a pin type heatsink on the cold side of the peltier which we moulded the ice cubes over. Thus they had lots of holes in them (so they melt faster in your drink). This was necessary to get high heat flow out of the water (we were aiming for ice fast). We never got as far as a mechanism to remove the cubes, but one thing you can do is run the peltier in reverse for a fraction of a second to melt the surface of the ice, releasing it.

In general stacking modules in series is not the way to go, because the hotter one also has to shift the waste heat from the cooler one you just end up in the same place as a single module. There is no free lunch (otherwise the manufacturers would stack junctions within a single module).

As mentioned hot-side cooling is the key challenge. There used to be a product for boat fridges that used conductive heat transfer through a braided pipe to a skin fitting. For serious heat flow you would be looking it a closed coolant loop.

 

[[70521]]

Why not try granite whisky stones from Lakeland?

Attach to a small bag and hang them off the cooling plate (mine usually has a layer of hoar frost).