Idea: peltier hotend cooling?

Nxt-1

While I was looking at the state of art in terms of water cooling hotends, my brain drifted towards peltier elements. A quick google leads me to believe that round axial elements don't readily exist. (I was thinking sliding one over an existing E3D threaded heatsink).
This got me thinking, maybe a custom aluminium sleeve, square outside and d22mm hole in the center, can be fit around an existing heatsink. This would open up four flat spots to mount PEC on.

I have to look into PEC performance and heat transfer etc but I am interested to see what you guys think. The idea a little crazy for sure .

If you're going to do a custom aluminium sleeve, you might as well do away with the E3D heatsink and have it machined to fit a standard heatbreak instead. However you still need to cool the hot side of the peltier element, so not sure what you gain in terms of practicality?

Nxt-1

@bearer said in Idea: peltier hotend cooling?:

If you're going to do a custom aluminium sleeve, you might as well do away with the E3D heatsink and have it machined to fit a standard heatbreak instead. However you still need to cool the hot side of the peltier element, so not sure what you gain in terms of practicality?

You might be right, usually large heatsinking on the hotside of the elements allows for good passive cooling. But in this application the space is limited and there isn't really room for heavy heatsinks either.

And I might be wrong as I have very little practical experience with peltier elements for cooling, I've only used them to harvest thermal energy.

If you can utilize the excess heat for the heat block then you might be onto something, but with the limited surface area the effect would likely be quite limited. Otherwise you'll just end up with more heat to dissipate then you started out with i would recon.

denke

I concur, it would not be practical to put a peltier on the hotend, but you may cool the water with it to reach sub room temperature input water on a water cooled hotend...

NitroFreak

what would you want the lower temperature for? PLA prints well with a PTFE tube and all other high temperature plastics have an increased temperature resistance anyway, which means they will not get soft so fast in/before the heatbreak.
I‘ve printed PPSU with a passively cooled heatsink which got up to 150C and it was fine. Printed almost better than PLA.

All you will get in a sub room temperature coldend is condensation which you do not want.
I‘d go so far as to say a higher temperature in the cold end is better because then the hot end will not have to heat up the filament as far and it enables faster printing.

Nxt-1

@bearer said in Idea: peltier hotend cooling?:

And I might be wrong as I have very little practical experience with peltier elements for cooling, I've only used them to harvest thermal energy.

If you can utilize the excess heat for the heat block then you might be onto something, but with the limited surface area the effect would likely be quite limited. Otherwise you'll just end up with more heat to dissipate then you started out with i would recon.

You would definitely end up with more heat to dissipate as PEC's are quite inefficient. A slight advantage can be had due to the higher temperature differential between the ambient air and the hot side of the PEC. Overall efficiency will most likely be worse though.

@denke said in Idea: peltier hotend cooling?:

I concur, it would not be practical to put a peltier on the hotend, but you may cool the water with it to reach sub room temperature input water on a water cooled hotend...

@nitrofreak said in Idea: peltier hotend cooling?:

what would you want the lower temperature for? PLA prints well with a PTFE tube and all other high temperature plastics have an increased temperature resistance anyway, which means they will not get soft so fast in/before the heatbreak.
I‘ve printed PPSU with a passively cooled heatsink which got up to 150C and it was fine. Printed almost better than PLA.

All you will get in a sub room temperature coldend is condensation which you do not want.
I‘d go so far as to say a higher temperature in the cold end is better because then the hot end will not have to heat up the filament as far and it enables faster printing.

I am not really looking into sub ambient cooling. My only goal was to get rid of the hotend cooling fan.

zapta

How much power does the heatsink needs to dissipate?

denke

Same here, at the moment I'm considering putting two pwm controlled high compression 24V centrifugal blowers on the flying extruder rig and connect those with hoses to the hotend radiator and the part cooler nozzles.

@nxt-1 said in Idea: peltier hotend cooling?:

A slight advantage can be had due to the higher temperature differential between the ambient air and the hot side of the PEC

But the higher differential will only benefit you if the current heatsink temperature is somehow too high. And unless you add more fan cooling you won't be able achieve the increased differential in any case - so if the goal is to remove the fan then I'd be surprised if this was the way to go.

Not knowing much about the geometry, maybe heatpipes would allow you to transport the heat to an area where there is more room for heatsinks and/or fans?