Can a Peltier device are cold enough to convert water to ice cubes?
So far most article I read, Peltier device is only used as cooler or warmer or both together… I am just curious that, will the Peltier device able to reach at least -5 Celsius on the cold side? if two Peltier device are cascaded together, will the temperature difference increase? by how much? Is it double? If there are two peltier devices are being cascaded together can it reach below -5 Celsius and would it able to freeze one liter of water?
The peltier effect is mostly just a electrical version of the mechanical refrigeration device. And it is woefully inefficient. It is limited by the Carnot cycle just like the refrigeration is :Th- Tc / Th * 100%.
A mechanical refrigerator easily exceeds 60% of theoretical efficiency. The best peltier device barely reaches 10%. So it is similar to trying to freeze water in a refrigerator by leaving the door open…there just isn’t enough cooling power to push it to the low side
You can’t cascade peltier devices. It is just like trying to put a refrigerator inside of another refrigerator. Doing so wouldn’t make the interior refrigerator colder because the refrigerator comes from the expansion of a ambient temperature liquid that gets cold from phase change to a gas (Freon).
Peltier are used because they are cheap and there is nothing to break. No moving parts. But they generally will only lower ambient temperature by 25F or so. If it is 80F outside you will be lucky for the refrigerator temp to be 50F. Real lucky.
The peltier device works by the temperature difference on one side of the device which is heated by electricity and the cold side panel of the device. The greater the temperature difference between the two panel halves, the more potential cooling effect. Since the two halves are in such close proximity to each other, it is difficult to heat one panel up without some of that heat transferring over to the cool panel and in a way “short circuiting” the device. So there are rather low limits of how much you can heat up the hot side before efficiency actually gets worse instead of better
