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Legit Thermo Electric Cooler Project

 Post subject: Legit Thermo Electric Cooler Project
PostPosted: Fri Nov 11, 2016 2:44 am 
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I'm an engineering student and for my senior survey and design class we were asked to do a senior project. I was working for an ice company and fixing ice chests outside gas stations at the time and I thought, "does a compressorsless cooler exist?" Well I stumbled upon these things after research and now my partner and I will be building a thermoelectric cooler.

With about a semester left, we've completed a conceptual design and are about to finish the budget and schedule. Next semester we will start modeling the cooler in solidworks and build it in March. So, everything is good so far and I found some pdf files of books on thermoelectrics and heatsinks. I was wondering if you guys could give me tips based on your experience with peltier pads.


So the cooler....
All electrics will be in the lid.

High efficiency 2" thick Polystyrene R-10 Insulation
2 Peltier units (including fans and heatsinks)
Thermostat
Computer battery (to run and while charging)
Solar panels (to extend use away from power source)
Steel exterior (supplied from my work)
Inside liner (We don't know what to use yet)

Inside dimensions
L=20in w=12in h=14in
The inside area of the cooler is 3360in^3


So my question is, how can I determine what peltier to use?

What can I use for my inside liner?

Does the area of the inside portion matter?

Also, if anyone wants a pdf copy of the chapters I found just post your email and I'll send them.
Thanks for reading.


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 Post subject: Re: Legit Thermo Electric Cooler Project
PostPosted: Mon Nov 14, 2016 1:01 pm 
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Hello

Well assuming a perfect seal and no loss to the outside environment ( not realistic ) But lets assume.. Then the difference between a 500Watt Qmax and a 50Watt Qmax TEC will be the time it takes to cool the the internal space.

You haven't mentioned the important parts to a TEC cooling solution and that's how your going to cool both sides of the TEC.

Also using a TEC to cool / freeze things is not a new idea but unfortunately its not cost efficient when needing to cool a large wattage load. (500 watts would be coincided large) to a very low temperature


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 Post subject: Re: Legit Thermo Electric Cooler Project
PostPosted: Tue Nov 15, 2016 2:17 am 
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Ultrasonic2 wrote:
Hello

Well assuming a perfect seal and no loss to the outside environment ( not realistic ) But lets assume.. Then the difference between a 500Watt Qmax and a 50Watt Qmax TEC will be the time it takes to cool the the internal space.

You haven't mentioned the important parts to a TEC cooling solution and that's how your going to cool both sides of the TEC.

Also using a TEC to cool / freeze things is not a new idea but unfortunately its not cost efficient when needing to cool a large wattage load. (500 watts would be coincided large) to a very low temperature



Thanks for the reply. What if the goal is to cool a room temperature can of pop to about 35 degrees with two peltiers with heatsinks and fans. I know that I'll have to do calculations on the sizes of the heat sinks.

I'm wondering what the important parts are of the tec cooling solution. I wanted to talk to people with experience with peltiers before i make the mistake and buy the wrong unit for my project.

I know its not a new idea but the project is to make something new or improve an existing product. Coleman and other big brands have peltier coolers but can apparently only operate while plugged into a power source. They are equipped with a 9v car charger.


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 Post subject: Re: Legit Thermo Electric Cooler Project
PostPosted: Tue Nov 22, 2016 10:11 am 
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Update on the cooler:

We are changing the location of the peltier and all other electronics from the lid to the bottom of the cooler. This way the lid will not be top heavy and vulnerable to damage. The cold side heat sink will now be the bottom of the inside liner with 2 TEC1-12706 peltiers placed on the bottom. Now, can or bottles can be placed directly on the cold aluminum sheet. The cooler will be on 2 8" pneumatic casters to be portable and allow the hot air to escape.

Any advice would be great. I know there is a calculator on this forum but I'm not able to get it to work. I'd like to know if anyone has any ideas or thoughts on this cooler. Thanks again.


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 Post subject: Re: Legit Thermo Electric Cooler Project
PostPosted: Wed Nov 23, 2016 8:56 am 
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i had a TEC cooled / Heated can thing... The problem being is the can is designed in such a way as to prevent as much thermal loss to the surface as possible and thus trying to cool or heat it via this method hardly works.

Is it still an enclosed space ? cos yeah this will be better cos you will get some direct transfer to the cans which you wouldn't have if the TEC was in the lid.. And making the Lid very heavy at that j


FYI you probably should be posting this on the FB page where more people are involved


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 Post subject: Re: Legit Thermo Electric Cooler Project
PostPosted: Tue Nov 29, 2016 9:53 am 
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Thank you Ultrasonic2, I will join the FB page.

The space will be enclosed and we are getting a universal refrigerator seal to get it the best we can. We are going to use 2" thick r-10 polystyrene insulation. The inner liner will be 1/16" 6063 aluminum for low heat transfer. The outer liner will be lightweight steel (in hopes to reflect sunlight).

My partner and I are trying to decide whether the peltier+fans should be in the lid or on the bottom of the cooler. The moment you roll the cooler over a tall sand hill, you are at risk of damaging the bottom of the fans. If it is in the top of the cooler, it will be vulnerable to water damage. If the units are on bottom, then the direct heat transfer will be in our benefit. If in the lid, it will take longer to cool but a more promissing life expectancy. As of now, we are leaning towards the lid. This is because we plan to build a case for the battery and other electronics underneath the inner liner. If the peltier was on the bottom, we'd be left with finding a solution for the hot air to escape and another place for the small 12v 6amp 12aH battery we have.

So with everything in the lid, we are trying to decide on a peltier without breaking our budget. We are looking up and down ebay for the perfect unit. It would be best to get an assembly because it will save us time but it is risky because we don't know how great a peltier from china will be.

So the final inside dimensions are 21" x 10.474" x 10.225" = 2249" cubed.
If 2249 in cubed of space lined with 6063 aluminum holding 32 cans/bottles needs to be cooled to 34-39ºF, what size peltier should we get if we are testing in a 80ºF environment?

We found a dual peltier with heat sinks and fans. 120W of total power. I don't think this is enough. We cannot upgrade our battery for different peltier models since we are limited to 6 amps. So what is a good peltier module that will do the job and won't break the bank?

I saw some youtube videos and their worked good but they are probably in a room temperature and their enclosed space is a lot smaller. Hopefully the aluminum liner will perform as expected and help keep the temperature if we undersize by mistake.


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 Post subject: Re: Legit Thermo Electric Cooler Project
PostPosted: Tue Nov 29, 2016 12:48 pm 
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like i said before the only difference between a 240watt TEC or 120watt TEC will be the time it takes to cool the environment.. 240watt TEC will obviously take 1/2 the time BUT pull twice the amps... Based on your battery you have you can only pull 144watts for an hour and the battery will be flat. ( 144 watts for an hour )

But back to the question id get two TEC's and wire them in series(6v each) which will greatly increase the COP (efficiency) than running them in parallel.
If this is meant to be mobile id bin the lead battery because it weights to much and buy lithium ion pouch batteries ( NOT cells like 18650) and obviously take alot more wattage so it can run longer

IS this cooler meant to be mobile ? to take to the beach or something ?


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 Post subject: Re: Legit Thermo Electric Cooler Project
PostPosted: Wed Nov 30, 2016 2:42 am 
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Thanks for the battery tip, I found this one on ebay just now. its a higher ampere hour than the lead acid clunker we would've been using. This could fit right in the lid of the cooler.

http://www.ebay.com/itm/20000mAh-Lithiu ... 25112#rwid

This cooler is meant to be mobile. We're going to put 2 6" pneumatic rigid casters on it. Since we are doing that, we don't want the cooler to look funny by being small and on two big wheels. We also don't want to oversize the cooler and the peltiers cant cool the inside aluminum liner. We are trying to find the perfect medium for efficient cooling.

I made the bottom half of the cooler yesterday on autocad. Just so I have an idea what I need and some measurements to go off of when its building time. Does anyone here use autocad?


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 Post subject: Re: Legit Thermo Electric Cooler Project
PostPosted: Wed Nov 30, 2016 9:00 am 
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i think you should buy one of those batteries and test it .. it wreaks of being fake... Also though i couldn't find that particular version of that battery the ones i could find they do not have BMS which means they are bombs.. They will will be fine from that respect for testing though.

We can work out the max tec wattage "used" based on the battery and how long you want it to run for... so how long do you want it to run constantly for ?


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 Post subject: Re: Legit Thermo Electric Cooler Project
PostPosted: Thu Dec 01, 2016 5:17 am 
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I will get a battery and test it. They only weigh about 1.25lbs compared to the 9lb battery. My partner suggested getting 4 of them so we would have 80aH if we wired the batteries in parallel. if we use the cheapo ebay peltier unit that is 10amps we would have 8 hours of constant run time but that isn't it turning on and off from the thermostat. We will probably go with 3 batteries considering the thermostat will relay and since idk anybody that needs a cooler for over 8 hours. I hope these batteries aren't junk, the only review on that link doesn't really help.

Cheap Peltier we are thinking about...
http://www.ebay.com/itm/141690352652
Idk where they get 10amps, i thought it'd be at least 12amps with the tec1-12706.

Thermostat DC 12V 10A
http://www.ebay.com/itm/AC-DC12V-Digita ... 5731.m3795

I'd like to get at least 6 hours of run time... so with he aluminum liner, r-10 polystyrene foam board, and a magnetic refrigerator seal I think we could get 7-8 hours when it's done. Only testing will prove that.


Last edited by jhagema on Thu Dec 01, 2016 5:52 am, edited 1 time in total.

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