3D printing allows the physical manufacturing of some unique geometries that are simply not possible with other processes. If you design around these strengths, it is possible to create parts that significantly outperform more conventional alternatives. With this in mind [Advanced Engineering Solutions] created a metal 3D printed heat exchanger that is half the size and four times the efficiency of the one it was designed to replace. Video after the break.
Made from an aluminum alloy using a Laser Powder Bed Fusion (LPBF) machine, the heat exchanger is intended to cool transmission oil on military helicopters by using fuel as the coolant. Looking somewhat similar to a Fabergé egg, it uses gyroid “infill” for the actual heat exchange part. An interesting characteristic of gyroids is that it creates two separate intermeshed volumes, making them perfect for this application.
It was printed in one piece, without any removable support, just an internal lattice that supports the gyroids at the inlet and outlets. The only post-processing required was threading and surface cleanup on the ports. Since metal 3D printing is still too expensive to really allow many iterative prints, a significant amount of design and simulation time was put in before the first print.
Whether you are printing heat exchangers, enclosures, or wings, be sure to keep the strengths (and weaknesses) of 3D printing in mind.
Thanks for the tip [Keith Olson]!
A very readable guide to gyroids for anyone like me who was unfamiliar with them, from a 3D printing point of view: https://makerindustry.com/gyroid-infill
As someone who is particularly interested in periodic minimal surfaces, it occurs to me to ask: is it proven that the gyroid is the best choice? There are lots of other possibilities of bicontinuous surfaces:
http://www-klinowski.ch.cam.ac.uk/pmsgal1.html
Also Bathsheba Grossman has been 3D printing periodic minimal surfaces in metal for many years, though as art pieces, not for engineering:
https://www.bathsheba.com/math/
I find that the gyroid on FF printers is hard to make watertight because of the large nearly-horizontal regions. So I’ve been a using a variant I came up with that has slope 1 everywhere except at one dimensionless point per unit cell. It seals tight every time. Its as simple as printing the gyroid with in-plane triangle waves instead of sinusoids. I don’t know if that’s represented in the gallery you shared.
I’d really like to make a heat exchanger to let fresh air into the house during the winter while saving heat.
Solid-oxide fuel cells work a lot like heat exchangers also.
Great idea, but in order to take it to a military application you’re going to need a bunch of testing.
Since it’s meant for deployment on a military vehicle, was making a video and posting about it smart??
Its a heat exchanger, not a secret weapon…
To be fair, I have to agree with robomonkey here.
A heat exchanger that is ~4x as efficient could reduce the needed volume for said heat exchanger inside of a vehicle. The additional room can be used for other applications, or to make the vehicle overall slightly smaller, or a combination of both better efficiency and a more compact design. (many small improvements can make huge differences in the end application.)
Military secrets are honestly not always directly about weapons. Plenty of other technology is likewise often kept secret since it provides strategic advantages.
So the statement “Its a heat exchanger, not a secret weapon…” is a bit too casual.
I’m not sure what the alternative is here, for a private sector company in a government contractor world. Unless the military is seeking a new supplier for this particular part, then you essentially have to pitch your product at trade show booths. People from Boeing, Lockheed, and Northrop Grumman walk around and decide whether to buy your product.
And you probably apply for a patent to prevent them from just taking the design. (Patents inherently involve public disclosure.)
In that context, there’s no harm in posting online.
“(Patents inherently involve public disclosure.)”
Unless government gets involved.
https://sgp.fas.org/othergov/invention/index.html
kinda late on that article, but I wanted to talk about a thing you mentionned that I don’t agree with:
“you essentially have to pitch your product at trade show booths”
some shows have a very highly filtered set of attendees, and also, some companies have to show their product behind closed curtains, confidential rooms & such so… not that much public. I’d imagine more something like that (well more formal than how I say it but you’ll get the point):
– hey we’re an enterprise that designed an innovative way about a peculiar piece of equipment, can we talk with your chief ?
– yep, call forwarded when we’ll check your background
(moments later, getting the confidential-able person)
– hi, we’d like to present you our product, not yet released, yaddi-yadda we got your ass and ours too. wanna share a though about it ? here are the stats we got from our simulations.
-yup got it. that’s interesting,I’ll talk about it to my chief, let’s meet and sign some paperwork aout confidentiality & stuff.
[product & powerpoint shown to some high-rank people & selected engineers]
-yep, we’ll buy but we’ll be our only client, here’s money, fair ’nuff ?
– yeah
(I know I removed maybe too much of the ultra formal part of it but I can’t help myself to do it :D )
Throw it hard enough at somebody’s head and it will be a weapon…
It isn’t new. For a couple of years now I have had a proof-of-concept 3D printed heat exchanger model on my windowsill that uses the same technique.
It was designed by an engineering buddy of mine.
Interesting that the gyroid infill works well to bring two fluids into close proximity without touching. Has me wondering about using a print material that can act as a dielectric and designing a 3D printable capacitor.
Fascinating stuff!
“3D printing allows the physical manufacturing of some unique geometries that are simply not possible with other processes.”
Which is why the democratization of the technology is so interesting. Imagine if this was as common as the home printer?
Powder bed metal printer will never become a household or even a home garage item because fine metal powders in large amounts are actually kind-of an explosion and a fire hazard whether you spill them or wet them, and they need to be handled in an airless environment to prevent oxidation. They can also be incredibly toxic, like fine chromium powder if you ever intend to make stainless steel parts.
I’m convinced economics will prevent these printers from being a household item rather than the danger of their reagents.
Keep in mind you can go to most any sporting store and buy hundreds of lbs of nitrocellulose smokeless gun powder, or just straight up binary explosive which is half metal powder.
Yes and no.
In terms of safety the consumer is ultimately responsible. You can go to just about any Walmart in the U.S. and buy in bulk the components for a half dozen different types of binary explosives that rival the mining and construction grade stuff. It is an even bet that many homes already have at least two or three sitting next to one another in a cabinet somewhere. Hell, we let 16 year olds handle gasoline on a regular basis and give etch-a-sketches (very fine aluminum powder) to toddlers.
All of that being said… There are some interesting things being done with bound powders that are “locked up” in a waxy polymer that’s easy to wash way or burn off, while still being safe to handle with bare hands. I’ve seen some concepts for powder printer cartridges similar to the ink ones we’ve been price gouged on for decades. It could make the materials as safe to handle as car batteries.
The biggest hurdle here is the airless environment you mentioned. Industrial grade vacuum forge chambers aren’t cheap or small, or cheap to run. A garage/shop size metal printer would likely still require 3 phase power and be as big as a medium sized refrigerator for a relatively small print chamber.
Either way, we are still years out from your average hobbyist buying or building one on a tight budget. If NASA puts one in space it may accelerate the tech similar to what happened to batteries and portable drills. Exciting to think about.
Services such as send-cut-send and Xometry have made inroads in offering these print-on-demand services to regular Joes and Janes. You could always whip a few up in plastic first before spending the money for a metal part.
Andreas is amazing!
Damn, I designed a simple muffler for an air tool that used the gyroid infill as a baffle. Was wondering why it was so restrictive for its size. Never realized half of the volume wasn’t being used.
>”… by using fuel as the coolant.”
Is no one going to comment on the use of fuel as a coolant? First off, I believe most hydrocarbon-based fuels are volatile and then secondly, what happens when you run low on fuel?
I’m pretty sure given your question your not had’s target reader but I’ll try and answer. Heat does not equal combustion. Most hydrocarbons have a flash point or a temperature at which they will ignite even at it’s hottest that transmission fluid will be far below the flash point of the fuel. Running low on fuel wouldn’t stop the cooling only running out of fuel, in which case you have bigger problems in a helicopter. As final bit, the heat pumped into the fuel most likely helps keep it atomized aiding in engine efficiency.
Fuel as a coolant makes perfect sense in this application. It isn’t all that volatile, likely needs to be preheated for best engine performance, is not incompatible with lubricating oils, and doesn’t add weight like aqueous coolants would. It could probably substitute for lubricant, briefly, in a pinch. (Think injector pumps in diesel engines.) Considering the gearbox sump likely has a thermal reservoir, when running out of fuel, gravity is much more significant than gearbox temperature.
The hydrocarbon processing industry has a long history of using volatile or flammable stuff on both sides of their heat exchangers.
Autos since 1975 or earlier that have in tank fuel pumps use the fuel they are submerged in as a coolant for the little electric pump. Sealed systems with little to no access to oxygen are less volatile.
“what happens when you run low on fuel” in a helicopter?
I’m guessing gravity happens.
Check auto rotation. If a helicopter is high enough they can land just fine, and even decide where to land
Kerosene fuel auto ignites at ~430° F. Heli engine oil is around 150° in hotspots, and breaks down around 250°.
I’m gonna guess nobody is commenting about it because it doesn’t matter.
> what happens when you run low on fuel?
Nothing, until you run out, but then you have no more heat output from the engine.
If you run low on fuel you have bigger problems.
Sig is using 3d printing for it’s suppressors on the new XM5 for similar reasons. To make something otherwise impossible with traditional manufacturing methods.
I can’t see to read this article or comments without the Disney character Gyro Gearloose coming to mind.
https://en.m.wikipedia.org/wiki/Gyro_Gearloose
It sounds strange for me to listen that they replace a shell&tube type with this one, that is comparable to a plate exchanger to me.
S&T are cleanable. This one is not.
S&T are huge compared to plate.
An efficiency comparison with a brazed plate exchanger could be more appropriate to my mind.
However, supercool!
Hi, do you kknow if this kind of complex could be built by different processes than metal 3d printing? Maybe by lost foam casting, what do you think ?