Help me design a Vacuum Drying system

In summary: One of the biggest uses of energy in a paper mill is to dry the paper. The cost of energy to dry paper is a huge fraction of the cost of making the paper. As a result, paper companies are always looking for ways to improve drying. Don't be surprised if you find vacuum drying to be an expensive proposal.In summary, the conversation discusses the development of a Vacuum Drying System for instant drying of automotive parts after washing. The system must be able to dry the parts in less than 30 seconds and the parts will be wet and at an elevated temperature of approximately 50 degrees Celsius. The discussion also mentions the need for a vacuum pump and a sealed chamber with a pneumatic cylinder for applying force. The
  • #1
kunalv
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Hello all,

I've been entrusted a project of developing a Vacuum Drying System for my company. This system will be used for instant drying of automotive parts after washing. Needless to say the parts will be wet and at an elevated temperature (approx 50 degree C). The requirement is to dry the parts in less than 30 seconds.

How do I go about this? What will be the type of vacuum pump required? And what are the other parts of a Vacuum Drying system?

The parts loaded in the machine shall be sealed in a chamber (size approx 300mm x 300mm x 300mm) with a Pneumatic cylinder applying force from the top.

For reference - https://grabcad.com/library/vacuum-drying-machine-1

Any help will be appreciated. Thanks

Thread moved to DIY
 
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  • #2
This has the feel of an undergraduate senior/internship design project. Otherwise it is an awfully odd/specific/expensive(!) thing to be coming to an internet forum for help on! Can you give us more background on you, the project and its constraints? Just about everything you gave us must have a "why" behind it.

I'm an HVAC and I guess you could say process engineer in the pharma industry. Companies come to me for help designing and implementing ...parts... washers. But out of the gate they always have an existing system, relationships with vendors, ideas about what they need and why, etc. It's a rigorous, professional process, and it must be to justify spending hundreds of thousands or millions of dollars and ensure you are spending it effectively.
 
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  • #3
kunalv said:
This system will be used for instant drying of automotive parts after washing. Needless to say the parts will be wet and at an elevated temperature (approx 50 degree C). The requirement is to dry the parts in less than 30 seconds.
@russ_watters is much better qualified than I am to help you with this project, but to me it seems a poor fit to use vacuum drying for the application you have outlined.

If you want to dry parts very quickly, I would think that a high velocity hot/dry air knife approach would work much better. There's a reason that air knifes are used at car wash businesses as the last step in the car wash process... (well, plus a vacuum would kill the car occupants, but ignoring that inconvenient aspect...) :smile:
 
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  • #4
berkeman said:
@russ_watters is much better qualified than I am to help you with this project, but to me it seems a poor fit to use vacuum drying for the application you have outlined.

If you want to dry parts very quickly, I would think that a high velocity hot/dry air knife approach would work much better.
I've carved out a little niche for this in my company, but mostly by luck of assignment. Drying is fairly simple and any generic mechanical engineer should be able to figure this stuff out and help design a machine. It's just the needs could be highly specific...

Drying in air is just convection and evaporation. To dry something faster, just use more, hotter air, like you said - it was my first thought as well. I don't associate a vacuum chamber with "fast". But if what you are drying is light, fragile, heat sensitive, porous, hydroscopic, wet with something besides water, etc., there might be a reason hotter and more air won't work. I can't think of a reason that would apply to "car parts", but it's probably in one of those "why"s, I asked for.
 
  • #5
russ_watters said:
Drying in air is just convection and evaporation.
Isn't there a 3rd factor; water drops falling off by gravity or by high velocity air, without evaporation? Or is that part of convection?
 
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  • #6
anorlunda said:
Isn't there a 3rd factor; water drops falling off by gravity or by high velocity air, without evaporation? Or is that part of convection?
I'd say you're right that that's an additional process/factor. I don't want to start a quibble about definitions; mechanically removing liquid water isn't strictly "drying", but certainly part of what can be done to remove water from an object!
 
  • #7
kunalv said:
Hello all,

I've been entrusted a project of developing a Vacuum Drying System for my company. This system will be used for instant drying of automotive parts after washing. Needless to say the parts will be wet and at an elevated temperature (approx 50 degree C). The requirement is to dry the parts in less than 30 seconds.

How do I go about this? What will be the type of vacuum pump required? And what are the other parts of a Vacuum Drying system?

The parts loaded in the machine shall be sealed in a chamber (size approx 300mm x 300mm x 300mm) with a Pneumatic cylinder applying force from the top.

For reference - https://grabcad.com/library/vacuum-drying-machine-1

Any help will be appreciated. Thanks

Thread moved to DIY
Basically, for fastest possible drying without making over-engineering, you need pump inlet pressure about half of water vapour pressure at 50C. It mean ~6kPa pump. The main problem is actually heater, not the pump - the vaporization of 0.1mm layer of water absorb ~220 kJ of heat from each square meter, and to deliver it in 30 second you likely need infrared heater about 7 kW/m2. Also, you need to ensure water vapour flow of at least ~4000 liters/minute per every square meter of part to keep 6kPa pressure during drying (plus if you take into account time to bring pressure to 6 kPa). I think this cover the pump specs.
 
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  • #8
Search Minton vacuum dryer for information on using vacuum to dry paper in paper mills. Vacuum drying of paper was done in the 1920's, but various practical realities made the process not economical. One link: https://www.tandfonline.com/doi/abs/10.1080/07373938508916270.

Finding better ways to dry paper is huge in the paper industry. The paper mill where I once worked evaporated over 200,000 gallons of water per day as part of the papermaking process.
 

Related to Help me design a Vacuum Drying system

1. How does a vacuum drying system work?

A vacuum drying system works by creating a low-pressure environment which lowers the boiling point of water, causing it to evaporate at a lower temperature. This process removes moisture from the materials being dried, resulting in a faster and more efficient drying process.

2. What factors should be considered when designing a vacuum drying system?

When designing a vacuum drying system, factors such as the type and amount of material being dried, desired moisture content, temperature and pressure requirements, and the type of vacuum pump used should be considered. Other factors include the size and shape of the drying chamber, the placement of heating elements, and any necessary safety precautions.

3. What are the advantages of using a vacuum drying system?

The advantages of using a vacuum drying system include faster and more efficient drying times, lower energy costs, and the ability to dry temperature-sensitive materials without damaging them. Additionally, the low oxygen environment can prevent oxidation and preserve the quality of the dried product.

4. How do you choose the right vacuum pump for a vacuum drying system?

The right vacuum pump for a vacuum drying system depends on several factors such as the required vacuum level, the type and amount of material being dried, and the desired drying time. Common types of vacuum pumps used in drying systems include rotary vane pumps, liquid ring pumps, and dry screw pumps.

5. Are there any safety considerations when using a vacuum drying system?

Yes, there are several safety considerations when using a vacuum drying system. These include the risk of implosion if the chamber is not strong enough to withstand the vacuum pressure, the potential for gas or vapor release when drying volatile materials, and the need for proper ventilation to prevent the build-up of flammable or toxic gases. It is important to follow safety guidelines and regularly maintain the system to ensure safe operation.

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