Comments by "Mikko Rantalainen" (@MikkoRantalainen) on "Thermoelectric cooling: it's not great." video.

  1. If you swapped the factory included fan to high quality one, you could get a small nearly silent minifridge. Granted the total heat transfer performance is really low and energy consumption is high. If you only need to keep stuff cool instead of cooling down hot stuff, and the peltier minifridge actually had proper insulation (spoiler alert, the cheap stuff doesn't) it could be an acceptable solution, especially with a thermostat. If somebody could create a peltier element with higher efficiency (e.g. 50% efficient meaning it would need 20W to cool down 10W) then using a peltier element based systems would make a lot more sense.
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  2. It would be interesting to see if a stack of peltier elements, each doing just 1 °C temperature difference would result in usable COP over the whole stack. Of course, the total energy transfer power would also plummet even if the efficiency would increase.
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  3. Our big fridge has an optional feature (with a toggle switch inside) to keep one box in very accurate temperature around +0.1 °C and it doesn't have documentation about the implementation but everything suggests that it has a peltier element between the inside of the fridge and the inside of the box. Our fridge is around +2.0 °C otherwise so this peltier element only needs to cool down on average 1.9 °C and it can do that very accurately. Of course, that little box requires additional temperature sensor (or multiple because the whole point of this box is accurate temperature control) and since the whole fridge is already controlled by a small CPU on a small motherboard, having a couple of extra sensors and a controller for the peltier element is pretty easy. The manufacturer does warn that if you want to achieve the official efficiency posted on the ad, you cannot enable this feature. This obviously suggests that the implementation is not very efficient which points to peltier element. The advertised use for this box is to keep highly sensitive foods as close to freezing temperature as possible without accidentally freezing the foods even momentarily. Peltier elements are also used in physics experiements for accurate temperature control. In that case, the peltier element is used between main cooling element and the actual scientific instrument the temperature of which needs to be controlled accurately. As you can run peltier element with PWM controller in closed loop setup with a simple microcontroller, you can achieve highly accurate temperature control as long as your main cooling setup can get close enough to target temperature even without the peltier element.
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