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Fillament to print a Heat exchanger?  

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PrusaPrinters profile
(@prusaprinters-profile)
Estimable Member
Fillament to print a Heat exchanger?

Hi
When I finish my Build and the Printer works I am interested to print a Heat exchanger for the exhaust of an Diesel Ofen.
Before someone ask the are currently on the way and not here yet. I watched many Video and People say the exhaust are still warm after a short metal Pipe. So I would like use that heat to heat up some Water to maybe use them in a Shower or what ever depend on the Heat I can extract.

Which Material is the best? (Yes I will measure the Temperature if I arrive here!)
https://www.prusa3d.com/product/prusament-pc-blend-natural-970g/ ?
Thanks

Posted : 04/12/2021 11:50 pm
Diem
 Diem
(@diem)
Famed Member

I am not familiar with 'Ofen' as a vehicle marque and quick searches direct me to German cookery so this is a generalised reply.

Direct diesel exhaust is going to be too hot for thermoplastic.  Wet exhausts, as used on marine diesels, are still too hot but the circulated water might be redirected through a heat exchanger, thermoplastic is unlikely to transfer heat quickly enough to be of much use here though.

Engine exhausts arrive in a series of high pressure pulses that will quickly disrupt anything brittle so most ceramics are unsuitable too.  They tend to be acidic which excludes several metals.

You need a material that has a high melting point, is resilient to vibration and repeated shocks and is resistant to the acidic combustion products, it must be able to transfer heat quickly and be resistant to the medium to which the heat is transferred, in this case I will assume water.

There is a reason most exhausts are made of steel ... but very few water heat exchangers are because it rusts.

Pretty much your only option is stainless steel but even then it will be important to incorporate a little air/oxygen to maintain the 'stainless' character or it too will corrode.

So:

You can prototype your part in printable thermoplastic but don't expect it to be practical.

Once you have the shape as you want you can send the print file to a metal printing service and so obtain your own design in a practical form.

It's not cheap but for prototypes and otherwise unobtainable parts it makes things possible which before would have been pipedreams.  I have done this with specialised engineering parts for boats which needed to adapt outdated, foreign, components to modern, obtainable, substitutes.

The short version of this answer is that, yes, you can create this part via a fdm printing procedure and yes, you can do the design iterations with your new Prusa but no, you will not be able to print it directly.

(There are some highly specialised filaments which can be reduced to metals in a furnace but these are not for beginners and I do not know of one that would be suitable.)

... and in general I would suggest you put this project aside for a few months while you get used to the medium with less challenging ones.

Welcome to the forums,

Cheerio,

 

 

Posted : 05/12/2021 1:24 am
PrusaPrinters profile
(@prusaprinters-profile)
Estimable Member
Topic starter answered:
RE: Fillament to print a Heat exchanger?

I am not familiar with 'Ofen'

Sry for choose an "f" instead of an "v"....-> https://en.wikipedia.org/wiki/Oven

Direct diesel exhaust

The would get vent truth a Metal Pipe.

is resilient to vibration

What I understand there arent any since its not an Engine. There is "just" a Chamber where the Diesel get burned like a Wood Oven but the just use Liquid Fuel.

Well another idea came right in mind how about the good old Copper pipes who run around the exhaust and the outer side of the Copper Pipe get held together by a 3D Printed clamp? So the 3D Printed Part never came in contact with the host exhaust pipe and the Copper Pipe get held firmly together. Sure I think about an Machined Part for the future who the exhaust Gas get pushed truth and just separate with a small wall a Liquid flow beside. That must be done by some 3rd Party Company if it is worth. Linus show us that various thinks could be Watercooled by low tech Design.

Posted : 05/12/2021 1:21 pm
Diem
 Diem
(@diem)
Famed Member
RE: Fillament to print a Heat exchanger?

There are two issues; thermoplastics deform when hot and they are poor transmitters of heat.

Even your clamp idea may be problematic.  It might be easier to print a mould from which to cast something more suitable.

Cheerio,

Posted : 05/12/2021 2:51 pm
Nick
 Nick
(@nick-5)
Active Member
RE: Fillament to print a Heat exchanger?

Could you use a cooling method other than a heat exchanger to pre-cool the exhaust gases? Evaporative cooling comes to mind, and could bring the temp down to something suitable for a 3D printed heat exchanger.

Posted : 27/12/2021 10:35 pm
PrusaPrinters profile
(@prusaprinters-profile)
Estimable Member
Topic starter answered:
RE: Fillament to print a Heat exchanger?

Hi
I bought an Cooler: https://www.ebay.de/sch/i.html?_from=R40&_nkw=AGR+K%C3%BChler&_sacat=0&_sop=15&rt=nc&LH_PrefLoc=2

Sadly the Company who deliver the Heater cancel my order... 🤬 

Posted : 28/12/2021 7:09 pm
Washington15
(@washington15)
New Member
RE: Fillament to print a Heat exchanger?

A good understanding of the heat transfer in fused filament fabrication is crucial for an accurate stress prediction and subsequently for repetitive, high-quality printing. This work focuses on two challenges that have been presented when it comes to the accuracy and efficiency in simulating the heat transfer in the fused filament fabrication process. With the prospect of choosing correct thermal boundary conditions expressing the natural convection between printed material and its environment, values for the convective heat transfer coefficient and ambient temperature were calibrated through numerical data fitting of experimental thermal measurements. Furthermore, modeling simplifications were proposed for an efficient numerical discretization of infill structures. Samples were printed with varying infill characteristics, such as varying air void size, infill densities and infill patterns. Thermal measurements were performed to investigate the role of these parameters on the heat transfer and based on these observations, possible modeling simplifications were studied in the numerical simulations.

 

Posted : 30/12/2021 9:26 am
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