Thermo Electric Peltier Cooling idea

[Eric Ulbrich]

So were out shooting in hot weather today, the camera is working great but I wanted to cool it off. So out came the ice packs. As I was putting them on I had a slightly brilliant possibly silly idea. Is there a better way to cool the camera?

I started looking into thermal electric Peltier Modules. Now Im curious to see what you all think.

Could there be a way to design a Peltier blanket comprised of numerous units all woven together in an enclosure that could provide cooling to the camera? It would have to be flexible to wrap around the body as well as self powered. Or power could come from either a p-tap or 12V AUX connector on the camera.

If people are interested, let me know, ill start looking into fabrication and cost.

Think of a sort of electric heating blanket, but in reverse....

I found an interesting company that makes small Peltier modules that require little power consumption

http://customthermoelectric.com/

Any thoughts?

 

[Shane Betts]

And of course, being custom designed for the Red, vents would be included to allow the camera's inbuilt cooling to continue. Would also serve to blimp the camera (although it's hardly an issue as it is). Any idea what kind of weight/cost/power consumption you'd be looking at? Sounds like it could be a goer for certain locations.

 

[Christoph Bruggaier]

Nice idea Eric, thanks for your contribution!
But there is a downside (as almost always when you'd find something appealing):
The amount of energy you would need to cool down the camera (= the amount of thermal energy you would pull out of the camera) equals the amount of energy you'd have to put into the Peltier element, plus you'd have to add the dissipated energy which is lost because the limited efficiency of the Peltier element itself.
Wow, that seems complicated, but is not! Here comes the energy conservation law, one of many physical principles.
It states that in general the overall amount of energy stays constant within a closed system. Meaning: what you put in will come out.
In practical terms: If you want to cool down a camera by dragging away thermal energy, you would have to do that by investing exactly the same amount of (electrical, hydraulic, magnetic, pneumatic, you name it) energy plus the losses of the transferring system.
Example: a RED consumes about 6,5 Amps at 14.4V = Amps x Volt = 93.6W. Most of this energy will dissipate into heat, let's say 90W. Please, RED guys, hit me when I'm wrong!
The average efficiency of a Peltier element lays somewhere around 60%. To drag 90W out of a system you would have to invest roundabout 90W/60% * 100% = 150W including the losses. Just for cooling down the system! In addition to the 93.6W the camera drags, that's 243,6W in total!

Jeeez!

BTW: your ice bag does the same job very well, but somebody in the past has dragged a big chunk of energy out of a bucket of water to cool it down to ice... ;o)

Heads up, German camera people: I will release a detailed article about energy on the film set in the upcoming August issue of the German Kameramann magazine...

 

[Evin Grant]

Cristoph, you're math is correct but your conclusion is not. The reason being is you do not have to cool the camera down to ambient temperature, you only need to keep it below the overheating threshold of around 104º F. I don't know if the Peltiers can handle this either but I believe the bar is lower than your calculations might suggest.

 

[Christoph Bruggaier]

Evin, you are right within the parameters you set, too.
I wanted to keep it simple and assumed a closed system to be able to easily describe the problem. If I would have preferred a detailed calculation, my post would probably be too 'geeky' because of all the equations needed for explanation.

To make an exact calculation, we would need to know the amount of excessive heat (proportional to energy per time, Q(i) ) which usually gets dragged out of the camera by the fans to keep the camera right below 104°F (maybe you can give me a rough number about that). In an exact calculation, we only would take care about the temperature difference between the temperature equilibrium settling in a camera running hot with disconnected fans relative to the temperature equilibrium of a camera cooled down to the upper limit of the specified operating temperature by fans. Opening the system (thermo-technically spoken) around the camera now would result in a energy flow from the camera to the environment as the now new 'outer system'. This resulting energy flow has to be compensated by the energy flow induced into the Peltier element Q(o), where Q(o) = nmax * Q(i) and

equals the efficiency of the thermoelectric device.
Z*T describes the dimensionless figure of merit which widely depends on the average temperature difference between the hot and the cold area of the Peltier element and the utilized materials:

, given that TH = temp hot area, TC= temp cold area, Sp, Sn = Seebeck coefficients of positive and negative donated (semiconductor) areas in the Peltier element, T= average temperature in junction, rho = electrical resistivity and kappa = the thermical resistivity. The p and n annexes indicate the donated areas, again.


Scared? I was: about the user's reaction. That's the reason why I decided to keep things simple. Sorry for being scientifically blurry... )

Chris

 

[Steve Sherrick]

I am going to need one of those Peltier blankets, as my brain just overheated.

 

[Christoph Bruggaier]

...see what happens: overheated users! I'm so terribly sorry for that ) !

 

[Jonathan Stevenson]

I would love to see some Peltier cooling underwear to go with my Red cooling unit, because if the camera is hot, that means my nether regions are probably sweltering!

 

[Anson Fogel]

We are all agreed that your theory is crazy. The question is whether it is crazy enough enough to be have a chance of being correct. Our feeling is that it is not crazy enough.

- Niels Bohr

 

[PatrickW]

Computer enthusiasts (overclockers), have been using TEC (Termo-Electric Cooling) inside computers (on CPU and GPUs) for years.

One of the issues that has developed is condensation. Because the one side gets so cold and the other is hot, sufficient insulation needs to be installed into a computer around the parts that are being cool.

The other addition issue is the power draw which is not unsubstantial.

 

[Stuart English]

Assisted cooling.

Assisted cooling.

The math is reasonable ... a more practical solution is to plug a small D.C fan into one of the 12V AUX outputs...

... i.e. increase the airflow over the top of the camera casing.

 

[Stephen Lovett]

What Stuart said.

I played around with these a couple of years ago in an attempt to offset pump heat in a nanocube reef tank. It turned out that the easier/better solution was to use one of the small silentx computer fans to move a little more air around.

The lower rpm versions of these guys can be powered by usb. I slapped together a little usb frankenfan to validate that it would work and it does.

 

[Eric Ulbrich]

Ive also seen AC's on set whip out CPU GPU heatsinks and affix them to the top and sides of the camera. Oddly enough...it worked quite well along a USB fan or small DC fan. Now all we need to do is have the boys at RED make the housing of the camera an insulated conductive phase changing unit! That would be the s**t. :sifone: