Peltier Cooler as Dehumidifier Grows Ice Crystals

[SuperThePhoenix]

I see a few shortcomings in your experiment. It's an old video but yea, I've been thinking if peltier coolers could make efficient and cheap air conditioners. I'm kinda interested in this topic and so I'm making this comments. I'd like to really try out these kinda stuff but right now I don't have that much of resources.

[Baraquiel62]

would it be cool on apply on PC?

[prorsoft]

Are you not afraid that the water causes a short circuit between the terminals and shorts your power supply, or limits the current going through the peltier element?

[field16]

@prorsoft Hi, there was no shorting observed.  The voltage was low, just 12V and the water was pure with no salt. Without salt, or ions, it's nearly impossible to get such a low voltage to send current through the water.

[Unasigad]

@field16 A couple of days back I bought a 60W peltier module. It is running on 12V and it is running on the Thermaltake MaxOrb and still it is not cooling well. Can you please tell me what is wrong with it? (After 15 mins the temp. on the cold side reads 2C)

Thanks!

[field16]

@Unasigad Hi, I think it's great you are testing. You are getting really close to freezing at 2C. Did you apply thermal paste for good conductivity?

[Unasigad]

@field16 Yeah. I applied the Arctic Cooling MX3.

[85kanuto]

@Unasigad I would prefer running the peltier-element at 8 to 9 Volt,because how higher your voltage on the pletier element is, so more heat will be generated from it's natural resistion. Well I've tried my 68 W peltier element on 8.45 V and I was able to get - 4.6 °C . If I tried on lower or higher voltage, the peltier didn't cooled enough or it heated up to much. Otherways you can use a thermal paste to increase the cooling effect.

[Unasigad]

@85kanuto Alright!

Thanks! ;)

[field16]

@Unasigad Hi, thanks for both of your comments. Regarding the safety of the water, I would expect the dehumidifier water to be cleaner than what my government sends down the pipes. The government puts Chlorine and Fluoride in our water, among other things. The dehumidifier water would have no impurities. It's like distilled water. I would be sure to collect the water in clean containers... probably made of Copper.

I have not tested the water so I cannot recommend you drink it, but I would.

[RDELAPLAZA]

h t t p (colon) (slash) (slash) w w w dot tellurex dot com (slash) technology (slash) peltier (minus sign) faq (dot) php

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replace slash with (forward slash) SHHH T C R # P O site

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[field16]

@RDELAPLAZA This is interesting. I did not realize that within a single module, there could be parallel circuits.

I visited the link you provided and see the recommendation to keep pressure on the hot side of the unit, properly connected to a heat sink. I did not see how the circuit was made: quantity and layout of parallel circuits inside a typical unit.

[RDELAPLAZA]

I'm an electronic engineer and my thesis was "design of cooling systems for high power semiconductors" Have fun and learn a lot

[field16]

@RDELAPLAZA Good luck with your work! Thanks for the tips! I hope to see some of your work in the future.

[RDELAPLAZA]

There is a lot of tech info about the peltier modules at

3w's dot tellurex dot com-slash-technology-slash-pel­tier-slash-faq.php

Heat transfer depends on the contact pressure, so if the module is not pressed against the heat sink the heat transfer will be poor, the thermal compound layer has to be as thin as possible. squeeze out the excess and keep it pressed like heat sinks in pc CPU's.

this comment window don't like forward slashes

[RDELAPLAZA]

yes, depending on the module type the so called "peltier junctions" are connected in series and then those series in parallel, if one opens a whole section will be off.

[field16]

I guess if some of my modules have blown junctions, the rest of the unit can continue to be useful and if there is an open circuit in the defective area, at least no power is being lost in that section. If it's open, no power can get in. Thanks.

[RDELAPLAZA]

There are a lot of tiny little "blocks" inside a peltier module made of Bismuth Telluride, they work all togheter, each ne pumping a little of the heat in the device. If the module is overheated the little blocks get destroyed, or the thermal expansion of the mounting plates rips them apart, or simply they get burnt or melt; anyway extreme heat destroys them, and if you dont absorb the heat produced the temperature wll raise to destroy the module

[field16]

@RDELAPLAZA Would this failure mode you are describing cause an open circuit?

[RDELAPLAZA]

1.- you should have used thermal compound and some pressure to attach the peltier module to the heat sink, you didn't have enough heat transfer capability and blew some of the junctions in the peltier module

2.- you sould use a piece of metal that give you more ambient moisture condensing area to get more water out of the air.

[field16]

@RDELAPLAZA Hi... What does it mean to blow junctions? Is there a specification and limits for the failure mode you are describing? (By the way, I did use thermal compound and it acted like glue, connecting the unit to a water cooler with pump. I believe the back side of the cooler never got higher than about 28C.)

I agree with you on point #2, but Danster82 beat you to it 6 days ago.

Thanks.

[Danster82]

if you attach a heatsink or just a metal plate to the peltier it will disperse the cold across the plate therefore reducing its temperate across a larger surface area and the whole thing should just start dripping rather than icing up.

[field16]

@Danster82 Thanks for the idea. We probably just need the temp of the plate to be at the dew point to begin the condensation and your idea with the metal plate should work. It was fun to watch the ice crystals form, though. :-)

[mythbuster204]

Do you know why is there an hot spot on cold side, on my peltier hot spot is in corner by red wire and it is hotter than the rest of the side from start, not after some time?

[logos2600]

haha that music sounds like a remix of the battle toads pause music. Cool experiment, I was thinking about making a dehumidifier but maybe not after this.

[field16]

@logos2600 Thank you. The remix was something I put together.

[derdernixcheckt]

ok i use a pc power supply :D

[derdernixcheckt]

Hi! Why dont u use the pc power supply as an power supply fpr the peltier element??

[field16]

@derdernixcheckt Well, the PSU in the video was old and no longer worked. If you have a working computer PSU, you could power a Peliter cooler with it.

[huggybear100]

just to let you know, if u havent figured it out already , the ice acts as an insulator, so when u take a temperature reading of the top of the peltier cooler ur actully taking the temperature of the ice, and not the surface of the peltier. to get accurate meausrement, you woudl need to scrape away part of the ice , down the the surface .

[doynick]

Im planning of using this TEC as a replacement of my car's aircon. Do you think its enough to cool my car? My idea is to pump the cooled water to evaporator while the hot water will be pump to the radiator for cooling.

[THEtechknight]

i think the battery was getting low towards the end is why the ice wasnt forming too well.

[field16]

@THEtechknight That's a good possibility. Thanks for that tip.

[joshrozich]

why the corner stopped doing ice is because the water got in the center of the device and shorted it out seal the unit first

[field16]

Thanks for your comment. The devices used in this video were advertised as "Sealed for moisture protection". There is a white material all around the middle of the device, so it looks like it's already sealed.

[bg0821]

Hey by the way peltier coolers are used commercially in dehumidifiers I looked it up on the net. How many watts is that one? I damaged two 545 watt ones because my heatsink wasn't large enough either time. One day I found a coleman thermo cooler in the garbage, bought it home took out the peltier and it works. smaller than the 545 but its good. Also that little grill thingy works well if carrage bolts are fed into the holes to make legs and a single wick style sterno can used I did it.

[field16]

I have two dehumidifiers and they both use a compressor. Interesting that you found some that use Peltier coolers. I wonder which is more economical. I know the Peltiers would be quieter. :-)

I have Peltier coolers ranging between 140W ~ 170W. You had some monsters! Yes, they sure get hot on one side.

[bg0821]

Look at wikepedia on the net it mentions dehumidifiers. They don't take long to burn out once past the critical temperature. the two that don't make freezing temps still make 1.5 volts it ice is placed on top and heat source on the bottom. not much 1.5 volts I never threw them away 30 bucks ea I paid for them on ebay.

[huggybear100]

@bg0821 love the grammer , plz tell me english isnt ur first language, only excuse

[flmustang913]

@huggybear100 'grammer' Yea I love that also

[batlin]

According to what I've read, dehumidifiers based on the Peltier effect are less energy efficient, and have far less throughput (the "entry level" ones I've seen on the net only extract 250-350ml of water per DAY).

It's a shame since compressors are so damned loud!

[doug2877]

very interesting(5stars)