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How to build your own portable thermoelectric device with a quadcopter motor.

This project might not have an electrifying impact to the world but it´s a baby brother to my first instructable (Thermoelectric Fan) and just had to be built. It´s much smaller than most similar projects and the top power device can be detached from the lower heat source base and be used as experiment in other areas. What does it do? It converts heat energy into kinetic energy, looks nice and sounds awesome!


Concept:

It uses a thermoelectric generator module (TEG) to power a motor with a fan. The heat source (candle) heat up the lower aluminium plate => creates a temperature difference over the module => generates electricity to the motor => increases air flow through heat sink => increases temperature difference => more power. Without the fan it would eventually stop generating power since the heat sink would get almost same temperature as the plate.


Experimental Areas:

Almost any heat source with enough temperature can be used to power the motor and this makes this small device easy and fun to experiment with. It´s very sensitive to temperature differences. I could run it on water with only 20C difference (23C air temp and 43C water temp). As seen in the video it´s powered from fire, hot water, food, and even used to cool a computer processor. The latter is an idea I had when i created my first build in 2013 and people said to me it cannot be done. It can and it´s stable for normal use but with further optimizations it could probably be even better. I don't think it can replace a regular CPU cooler but as it uses no electricity from the computer it´s somewhat environmental friendly. More information on last page.

Specifications:

  • Size base: 56x64x40mm
  • Size power device: 56x56x40mm (including fan)
  • Size total: 64x64x79mm
  • Weight base: 27g
  • Weight power device: 85g
  • Weight 3D print: 2.7g
  • Weight total:114.7g
  • Cost: ~12$


Construction

It require few parts, easy to build and you do not need any knowledge about electronics. You just need some mechanical tools for cutting, drilling and polishing the aluminium. If you want to build it, please read further.

Step 1: Materials and Tools

I think you can find everything on Ebay. Prices are estimated. Aluminium and bolts not included in price since it´s basically scrap metal.

  • 1x Motor: Hubsan x4 20x8mm (20x7mm also works) [$3]
  • 1x Propeller: Hubsan x4 propeller [$1]
  • 1x TEG: 40x40x4mm (My module is same as used in Powerpot5, but most TEG or TEC will work) [$4]
  • 1x Heatsink: 43x43x16.5mm (ICK PGA 17X17 8.6C/W by Fischer Electrinics) [$4]
  • 1x Aluminium sheet: 56x56x3mm
  • 1x Aluminum sheet: 75x65x3mm
  • 3x Bolts: M4x40mm
  • 2x Bolts: M3x15mm
  • 1x Wire: 0.5x150mm
  • 1x shrink tube: 30mm (optional)
  • 1x CPU thermal paste (optional for better heat transfer, I highly suggest it): For example Keratherm KP 92

Tools:

  • Hacksaw
  • File
  • Pliers
  • Screw driver
  • Drills: 2.5mm, 3.3mm, 4mm & 7 or 8mm depending on motor
  • Screw taps: M3, M4 (optional for better stability)
  • Soldering iron (optional)
  • Sandpaper: Different types from 100-1500 grit for smooth surfaces (optional for nice finish)
  • 3D printer with T-glase filament: For my special design part (optional)

Step 2: Construction

Wire (Used for fixating the heat sink)

  1. Fixate the two M3 bolts (CC=50mm) to use as template
  2. Bend the wire around the bolts and twist the ends

Heat Sink
If you use a 8mm motor you will need a 8mm centered hole in the heat sink.

  • Use pliers to cut the middle parts of the heat sink if possible
  • Drill a 8mm hole (not all way through the bottom)
  • Check that motor fits into the hole (wire goes beneath the motor if possible)

Bottom Aluminium Sheet

  1. Use hacksaw and file to make it nice 75x65mm
  2. Wait to cut it triangular to make easier to fixate in machines
  3. Draw edge lines (red) and mark up for three M4 holes, see image for measurements
  4. Drill three holes with 3.3mm drill if you want to use M4 threads, or 4mm if no threads
  5. [Optional] Create M4 threads with thread tap
  6. Cut the edge with hacksaw to get the triangle

Top Aluminium Sheet

  1. Use hacksaw and file to make it nice square 56x56mm
  2. Use the bottom sheet as template and mark up same three holes, see image for measurements
  3. Drill three 4mm holes (half way through), we use no threads here to make it easy to attach/detach
  4. Use the heat sink as template or my measurements to mark up the two M3 holes
  5. Create M3 threads with thread tap

Finish

  1. Chamfer all corners (10mm long (diagonal) bottom chamfers, 8mm long (diagonal) top chamfers
  2. For nice design, use sandpaper or other tools to create a nice finish of the two aluminium parts. I used step by step paper grit 200 up to 1500.

Step 3: 3D Printing (Optional)

For design purpose you can print this special part if you have a printer and transparent filament like T-glase.

I used a wanhao duplicator 4x printer and simplify 3D software. If you want it lower or higher you can simply scale it along Z.

Link to model:

Printer settings:

  • Layer height: 0.37mm (single outline corkscrew method (vase mode)
  • Shells: 1
  • Infill: 0
  • Top and bottom layers: 0
  • Extrusion multiplier: 1.15
  • Extrustion width: 0.5mm
  • Speed: 600mm/min (10mm/s)
  • Temp extruder: 235C
  • Temp bed: 80C

Step 4: Assembly

  1. The TEG module is placed between the heat sink and top aluminium plate
    1. Use thermal paste for better heat transfer on both side of the TEG
  2. Place motor in heat sink with both motor wires and steel wire loop beneath it
  3. Screw the heat sink using two M3 bolts and through the wire loop
  4. Connect the motor to TEG and solder it using shrink tubes (optional)
  5. Screw the M4 screws all way through bottom plate
  6. Place the module on top of base and use 3D printed part if you want (Gives a little more power as it shields the candle flame)

Step 5: Self-regulating CPU Cooler

The module could be used in a computer to replace a conventional CPU cooler. It uses only heat from the CPU to power the fan, which in turn transfer the hot air away from the CPU. It might not have enough efficiency for a modern CPU but this is more or less a proof of concept. It does not require a sensor, electronics or motor controller as the fan speed is self-regulated by CPU temp.

Currently tested on an AMD Athlon 64 3800+, 2400MHz single core, 89 Watts. Normal computer use was stable but I also did a 5 min stress analysis both with and without the motor fan compared to stock cooler. Clearly the fan helps to cool the CPU. The stock cooler is a 80x70x70mm heatsink (402g) plus a large fan compared to my small device (85g with motor & fan). Last thing I tried was to only use the small heat sink without any TEG in between but the result was exactly the same. The TEG surprisingly conduct heat quite good and with that I can finally conclude that using a TEG gives better cooling than without (with equal build volume).

  • Idle [stock cooler]: 30C
  • Idle [TEG-fan]: 37C
  • Idle [TEG-noFan]: 60C
  • Idle [Only heat sink, no TEG]: 60C
  • 100% load [stock cooler]: 49C
  • 100% load [TEG-fan]: 75C
  • 100% load [TEG-noFan]: Cancelled at 95C to not damage CPU
  • 100% load [Only heat sink, no TEG]: Cancelled at 95C to not damage CPU

After the test the CPU went back to stable 37C and fan RPM went to normal. Also be aware that I did not apply any down force on the device, it just rested on top of CPU and if you´re a computer builder you know that is not very efficient. The device is also way smaller than stock cooler and a larger TEG and heat sink would probably do a better job. Would be great to see someone else experiment with this! Though, I will not be held account for any CPU damage. This particular CPU has a rated max temp of 69C so I would not recommend the build as it is.

Update 1 (Second picture):
Also tested with added small heat sinks on the bottom plate for better cooling from left-over air. I did this to show that parameters can easily be optimized further. Just to be sure, I removed the extra aluminium during the test and temp increased to 75C as before.

  • Idle [TEG-extra cooling]: 37C
  • 100% load [TEG-extra cooling]: 71C
<p>nice idea :)</p>
<p>Nice alternative design!</p>
Hello Joohansson, I find your instructable fascinating. I understand the necessity of the fan to keep the heat sink from matching the temperature on the other side of the plate, is there a way to adapt this design to power a small LED? Or is it a simple matter of wiring to add that?
Nice!!<br>But what is teg?<br>And is it possible to make this without TEG??
<p>Thermoelectric Generator :)</p>
<p>Can soemone link me to a cheap teg. I could only find them for $30. </p>
<p>Better late then never :P</p><p>http://www.ebay.com/itm/Thermoelectric-Power-Generation-Peltier-TEG-Module-High-Temperature-150-40-40mm-/201229071773?hash=item2eda2ff59d:g:T~YAAOSwaNBUeSzK</p>
Very good design!!<br>I have a question can I connect two devices in series to increase the voltage and go for a about 5K to 10K temperature difference to power up the fan continuously keep it running ??
Very good design!!<br>I have a question can I connect two devices in series to increase the voltage and go for a about 5K to 10K temperature difference to power up the fan continuously keep it running ??
<p>I am looking on amazon for a TEG and all i can find are high temperature ones, does that matter?</p>
<p>does TEC works too ?</p>
Yes but more easy to damage if it gets too hot.
would it be possible to make a self running minifridge? once u start it it could make enuf or at least some energy to power itself<br>
currently thermoelectric modules are only about 5% efficient, so no you couldn't do that.
Great instructable! I built a similar but much larger system that is self powered off of the computers waste heat! And I was able to reach core tempatures of 4.2 degrees Celsius! <br><br>http://instructables.com/id/Self-Powered-Computer-Super-Cooler/<br>
<p>funny :D</p>
<p>Hey,thank you for nice project.I would like to ask something,can we build this without the fan? I mean can we store the power we produce instead of dissipate it? Or just the fan is something important here?Thank you!</p>
Without the fan the temperature difference will converge to almost 0 (no airflow to transport heat) and the thermoelectric module will not produce much electricity. Sure, you will store heat energy but for what? The fan keeps this system going:)
<p>Make it a turbine</p>
<p>Awesome idea! Works great! Keep up the cool instructables!</p>
<p>Great!! =DDD</p>
<p>I made a sort of variant about 30 years ago. It looked like a small wrought iron chair with the fan blowing thru the back and sat on a pot belly stove. The chair seat and base were separated by the Peltier Junction. The heat blew all over the room and no batteries needed. The real secret is a good differential in temperature between the sides of the Peltier that is were the stand(chair legs) made a difference.</p>
<p>Nice! Where did it go, did you sell it or trash it?</p>
That was 30 years ago. I probably left it when i moved. ---<br><br>Think about the way a swivel chair is made, a top seat and a base. Now replace the swivel with the Peltier and make the back of the seat a heat sink, open with bars running down and mount the fan blowing thru it. --- <br><br>For scale the base legs were around 2.75 inches (remember the peltier is 3/16 thick) and the back of the seat was probably 3 inches based on the fan diameter for an overall 6 inch height. --- <br><br>I used wrought iron because i had access to a welder and had the scrap, however most any metal would work. I just thought it was going to sit on black iron anyway why not make it look right too.<br>
<p>If this could be up-scaled and applied to a wood heater, then I think you could market this at off grid solar homes. A lot (including myself) run a wood (or other) heater for 6 months every year which is also the lowest solar input time of the year. This could offset the need to run a backup generator. My wood heater goes 24/7 which makes your application very attractive as another alternative power source.</p>
<p>Google Ecofan. They are a bit expensive, if I were you I would build one myself. Like this one but with a 40x40mm high power TEG:<br>https://www.instructables.com/id/Thermoelectric-Fan-Driven-by-a-Candle/</p>
<p>you can get these &quot;Up-Scaled&quot; fans through Most hardware stores which you place on your (wood burning)Stove and the fan powers up and helps move the air. </p>
<p>Very nice. I was just thinking if it would be possible to make a base plate with four small suction cups, so that the whole thing could be attached to a warm, flat/smooth surface, like maybe a window in the sun? That would make a nice, little portable fan.</p><p>If using suction cups, the 'height' of the cups would probably need to be adjustable, for fine-tuning (the suction cups would need to be almost fully compressed when the alu plate is touching the glass/whatever) Maybe mounting the suction cups on small M3 screws...</p>
<p>Thanks, You probably can, if you need a fan on the window =)</p>
<p>~(:-})={&gt;---- ] Imagine that. Voted - Faved, Thank You.</p>
<p>I recognise that tune in the vid, where was it from? :0</p>
A very old Amiga chiptune, don't remember which one.
i used to have it in my Mod/XM collection years ago x3<br>lost them all tho and havent been able to 'track' many down again
Couple questions. <br><br>Do I need to have the plate in a triangle shape? <br><br>Do the plates need to be aluminum, as I only have copper at the moment? <br><br>And approximately how long did this take you? <br><br>I wish there was a video of this!!!
<p>Triangle not needed. Copper will work even better. I put a lot of effort to making the design, planning for the instructable, taking photos, keeping high precision of everything and polishing etc. The construction took about 14h in total I think but half of that was to make the aluminium look nice. Then another 8h writing, preparing photos and creating video. As with my other instructables I make them on the fly along with inventing the stuff. That makes it difficult to record videos. Would be easier if I would make another copy with same design but that will unfortunately not happen.</p>
nice, would be awesome to use as a Raspberri Pi (or similar) cooling system since it doesn't cost any extra power

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Bio: I like to design, construct and experiment with both old and new technology, especially when it includes mechatronics. I'm also devoted to photography, computers ... More »
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