Applying desiccant to surfaces (aluminum sheet or PLA/PETG)

  • Thread starter mess
  • Start date
  • Tags
    Surfaces
In summary, the conversation discusses different methods of applying a coating of silica to either aluminum strips or 3D printed parts made of PLA or PETG for the purpose of managing heat and humidity in a campervan project. The idea of using a spray adhesive and shaking off excess silica is proposed, as well as the idea of making a solution of silica and adhesive. Suggestions are also made to change the aspect ratio of the channels or use a larger disk. The possibility of using spun polyester mat or seeking advice from a manufacturer is also mentioned. Finally, the idea of surrounding the 3D printed part in silica powder and baking it is suggested. Some additional information about impregnated filamentous materials and their use in desiccant wheels
  • #1
mess
59
8
TL;DR Summary
I would like to prototype building my own enthalpy wheel (https://en.wikipedia.org/wiki/Thermal_wheel) and I need to apply some desiccant to the surface of the material that I will be making the wheel out of. How can I do this?
I will either be using aluminum strips wound up, or 3d printing it out of PLA or PETG. How can I apply a coating of silica to the surface of either of these materials so that it can hold and release the moisture of the incoming air/outgoing air?

This is to manage heat and humidity in my campervan project.

Ideally It would be easiest to 3d print the wheel, and PETG has much better thermal conductivity than PLA plastic, but both are significantly lower than aluminum.
 
Chemistry news on Phys.org
  • #2
After the wheel is constructed, use a spray adhesive on it then sprinkle the dessicant on. Then leave it alone for a bit. After the adhesive cures, shake off the excess dessicant.

Cheers,
Tom
<edit> Sprinkle gently so the dessicant doesn't bounce around and get covered with adhesive. </edit>
 
  • #3
and would i just use pure silica powder? I would have to toss it around in a bag of it or something because the channels in the wheel will probably be around 1-2 inches deep and extremely narrow.

It would be much better if i could make a solution of it that i dip the part into
 
  • #4
mess said:
and would i just use pure silica powder? I would have to toss it around in a bag of it or something because the channels in the wheel will probably be around 1-2 inches deep and extremely narrow.

It would be much better if i could make a solution of it that i dip the part into
If you make a solution of silica and an adhesive you end up with the silica completely coated with adhesive; seems rather counter-productive.

Or perhaps you were thinking of applying adhesive to the disk then shaking the sticky disk in a bag of silica. Could work if you can stop the adhesive from filling the channels due to surface tension.

Another perhaps: Maybe you can find an adhesive, say a powder, that will adhere in a thin film to the disk with static electricity, and will cure with heat (or maybe UV). Coat the disk, shake in a bag of silica, cure.

Sounds like the fix is to change the aspect ratio of the channels and/or use a larger disk. :oldcry:

How about making the disk of spun polyester mat, the kind used in COVID-19 masks? Then you can soak the disk in a water or alcohol suspension of silica and then 'regenerate' it. Of course a frame is needed to hold the mat in a disk shape.

Or, the "obvious" is to ask a manufacturer how they do it. You may have to ask several of them before one responds with an answer beyond "No comment."

As a last resort, by a replacement disk for a commercial unit.

end of brainstorm

Cheers,
Tom
 
  • Like
Likes mess
  • #5
I think i just thought of a great way to do this. I will try to get silica powder, and then surround my 3d printed part in the powder, and then I bake it, this way it will maintain its shape and a thin film of silica will stick to the printed part.

people are already doing this with salt in order to reinforce 3d printed parts, so i assume it should work fine with silica powder.Any thoughts on this idea?
 
  • Like
Likes Tom.G
  • #6
Last edited:
  • #7
mess said:
I think i just thought of a great way to do this. I will try to get silica powder, and then surround my 3d printed part in the powder, and then I bake it, this way it will maintain its shape and a thin film of silica will stick to the printed part.

people are already doing this with salt in order to reinforce 3d printed parts, so i assume it should work fine with silica powder.

Any thoughts on this idea?
Certainly worth trying! Nicely creative too.
I suggest trying it first on a small scale to work out all the 'unknowns.'

I have no experience in 3D printing, but an 'unknown' that comes to mind is you may have to apply some pressure (as in forcefully compacting the powder) to partially imbed the silica powder in the surface to get adhesion.

Cheers,
Tom
 
  • Like
Likes mess
  • #8
chemisttree said:
Try this.

Or this.
Thank you but I am not seeing any relevant (how its made) info on either of those links. I hope i didnt miss anything.
 
  • #9
mess said:
Thank you but I am not seeing any relevant (how its made) info on either of those links. I hope i didnt miss anything.
Did you read the patent? Column 2, lines 8-56, for example?

This picture on the Munters site should describe in enough detail what needs to be done.
1610223031008.jpeg


Impregnated filamentous material means fiberboard or cardboard and excelsior means wood shavings. Incorporating silica into that occurs during its manufacture. A slurry of fibers and silica is poured out onto a screen mold and residual moisture is pressed out (like how you make paper) and then dried. That’s “impregnated” paper. From that paper a cardboard stack is made. From the cardboard stack is cut out a round shape and then it is fixed to an arbor.

You are going to have lots of trouble if you can’t follow bread crumbs like these...
 
Last edited:
  • Haha
Likes Tom.G
  • #10
chemisttree said:
Did you read the patent? Column 2, lines 8-56, for example?

This picture on the Munters site should describe in enough detail what needs to be done.
View attachment 275928

Impregnated filamentous material means fiberboard or cardboard and excelsior means wood shavings. Incorporating silica into that occurs during its manufacture. A slurry of fibers and silica is poured out onto a screen mold and residual moisture is pressed out (like how you make paper) and then dried. That’s “impregnated” paper. From that paper a cardboard stack is made. From the cardboard stack is cut out a round shape and then it is fixed to an arbor.

You are going to have lots of trouble if you can’t follow bread crumbs like these...

Thanks for your suggestion. Also a descant wheel is not an ERV wheel (which is why I specified I need to apply it to aluminum or a plastic capable of heat transfer). They do different things and are manufactured differently.
 

1. What is a desiccant and why is it used on surfaces?

A desiccant is a substance that is used to absorb moisture from the surrounding environment. It is commonly used on surfaces, such as aluminum sheets or PLA/PETG, to prevent moisture from damaging the material. Moisture can cause corrosion, mold growth, and other forms of damage, so desiccants help to protect the surface and extend its lifespan.

2. How does desiccant work on surfaces?

Desiccants work by absorbing moisture through a process called adsorption. This means that the moisture molecules adhere to the surface of the desiccant, effectively removing them from the surrounding environment. By removing moisture, desiccants help to keep the surface dry and prevent any potential damage.

3. What types of desiccants are commonly used on surfaces?

Silica gel, activated carbon, and molecular sieves are some of the most commonly used desiccants for surfaces. These materials are effective at absorbing moisture and are safe to use on a variety of surfaces. Other types of desiccants, such as calcium chloride or bentonite clay, may also be used depending on the specific needs of the surface.

4. How do I apply desiccant to a surface?

The method of applying desiccant to a surface will depend on the type of desiccant being used. In general, desiccants can be applied by sprinkling or spreading them evenly over the surface, or by placing them in a container or pouch and then placing it on the surface. It is important to follow the instructions provided by the manufacturer to ensure proper application and effectiveness.

5. How long does desiccant last on a surface?

The longevity of desiccant on a surface will vary depending on factors such as the type of desiccant, the amount used, and the level of moisture in the environment. In general, desiccants will need to be replaced or recharged periodically to maintain their effectiveness. This may range from a few weeks to several months, so it is important to monitor the surface and replace the desiccant as needed.

Similar threads

  • Materials and Chemical Engineering
Replies
8
Views
1K
  • DIY Projects
2
Replies
36
Views
3K
Replies
4
Views
5K
  • General Discussion
Replies
1
Views
8K
Back
Top