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I've a small Peltier cooler which I used to store some chemical stuffs. So, I recently modded the design to make it more bigger and improve its cooling + insulation.

I've added an aluminium piece plate as the base which is in contact with the cold part of the Peltier, the other four sides are covered with thermocole. I keep it running 24x7 on my atx power supply. I have installed a refrigerator gas expansion thermostat in it to turn-off once it is sufficiently cool inside(-1C to 0C).

My question is how does the cooling change if I stick aluminum tape on the inside of the thermocole insulation (interior of the cooling cabin) and make it reflective? Will it increase the cooling capacity and reduce the power-on time?

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    $\begingroup$ At those temperatures probably not noticably - radiation loss is very low. I would concentrate on no airleaks into the cold volume and making sure you have good cooling of the peltier hot side (good heatsink and fan) $\endgroup$
    – Martin Beckett
    Commented Nov 4, 2017 at 15:59
  • $\begingroup$ Thanks Martin. So, I guess it would make no difference. I've used a big HP CPU heat sink and a 12V 0.7A fan. I think its quite powerful and adequate. I've one small question, does it make a difference if I change the gas-expansion thermostat to an electronic one? $\endgroup$
    – The_Vintage_Collector
    Commented Nov 4, 2017 at 16:11
  • $\begingroup$ Unless you need precise temperature control you can normally just adjust the Peltier current to set the temperature. If the outside temperature of the room is constant the internal temperature will only depend on the Peltier power $\endgroup$
    – Martin Beckett
    Commented Nov 4, 2017 at 20:33

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We make the inside of cryogenic instruments reflective to reduce the radiation load from the hot (room temperature) outer walls to the cold load inside. The radiation transfer is very strongly dependent on the temperature difference so is important for devices cooled to very low temperatures.

For your use with only a 0 - 20 degC temperature difference there isn't much radiation transfer. The inside of the insulation is probably covered with reflective foil more to protect the soft foam and make it easier to clean.

You can add more insulation foam to reduce the heat flow from outside but a bigger source is probably warm air leaking in (especially if the air is moist) so make sure that the lid seals well.

Another inefficiency of peltiers is cooling the hot side properly. Make sure you have a good heatsink tightly connected to the peltier (ideally with something like CPU heatsink paste) and cooled with a fan (or better chilled water)

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  • $\begingroup$ I've used this heat sink. cdn.wccftech.com/images/news/Thermalright-CPUCoolers/T3.jpg $\endgroup$
    – The_Vintage_Collector
    Commented Nov 4, 2017 at 16:18
  • $\begingroup$ I've used a good quality ceramic thermal paste also to increase the heat transfer and the fan is also quite powerful. So, it dissipates the heat fast as the fan is quite powerful. $\endgroup$
    – The_Vintage_Collector
    Commented Nov 4, 2017 at 16:20
  • $\begingroup$ Was thinking of adding a small fan inside the cooling chamber. Will it make any significant difference? $\endgroup$
    – The_Vintage_Collector
    Commented Nov 4, 2017 at 16:21
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    $\begingroup$ No you don't want a fan inside, you just want to keep the hot side of the peltier as cool as possible - remember it is making a difference between the hot/cold side $\endgroup$
    – Martin Beckett
    Commented Nov 4, 2017 at 20:31
  • $\begingroup$ You are right after the mod once the thermostat shuts down the cooler it seems to turn back on faster, which means there is a leak now. Also I did try with a fan, but maybe due to the after leak it seems to loose temperature lot faster with the fan inside to circulate. I just tried to add the fan to replicate like in my household refrigerator. $\endgroup$
    – The_Vintage_Collector
    Commented Nov 4, 2017 at 20:47

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