Design of Heat Electric Radiation Oven for Electrostatic Powder Paint Curing 1

[CRisReD]

Hello everyone, I am new to this forum and at my first job, so I'm kinda nervous. The thing is that they entrusted me to design a radiation oven to curate some Fire equipment tubes and boxes. I will give you my background I am a recently graduate mechatronics engineer, I took some heat transfer, but the course was more geared towards fin design for PCB boards, so I think I have some idea about how to tackle this, but I would like some tips and advice.
As the materials are not that big (some are tall) I was thinking in a 1x1x2.5 meters design with the resistors to the sides and the pieces hanging from a stroller used to paint them before. For the resistor choice I have seen somewhere else that I should use around 100 to 150 Watt per cubic foot, I used 125 and got around 11 kW value.
The materials I want to use for the calculations are cold rolled steel for the inside and outside walls and glass fiber for the insulation.
Here I have my first question, for the resistors calculations what factors should I take into consideration?
I think the first would be the heat lost from each side of the walls (Inside convection, Conduction through the walls and Outside Convection except for the ground which would have conduction to the ground) another factor would be the heat needed to heat the inside air by the radiation and last the heat needed to raise the temperature the material to the desired amount (180 degrees Celsius).
Is there something I am missing here?
Then I would need to do the structure design, I plan to do it in Solid works as it has a Static Simulator. Is there any other software recommended doing something like this?
I plan to keep updating this as I advance in the project. Thanks for reading, and any advice would be helpful here.

 

[EdStainless]

Is there no specialist company in your region that designs and builds such ovens?
Yes, they are usually steel walls with fiber insulation.
The framing for the door and the mounting points for supporting the heaters is often the trickiest part.
The selection of heating elements is usually driven by the temperature that you are trying to achieve.
IF you are really trying to rely on radiant heating then your elements need to be hot enough to radiate effectively.
This is likely a lot hotter than you are trying to reach so control becomes a big issue.
Some of this work is also done in forced convection furnaces.

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P.E. Metallurgy, consulting work welcomed

 

[georgeverghese]

They've thrown you in at the deep end of the pool.
There is design info in the section on thermal radiation in enclosures in Perry and DQ Kern, but these may be a steep uphill climb for you. The appropriate View factors should be used.
@IRstuff would have more to say here.

 

[CRisReD]

@EdStainless Sadly there are not such companies the ones that have ovens for electrostatic painting only will give us the service to paint our components (at a disproportionate price) maybe it would be better to buy it but i don't think we would have the budget for it. Thanks for the advice on the heating elements, I will keep it in mind. Don't know how much use I can get, but the SolidWorks simulation package includes a thermal simulator, so I can use it to not under power my system and achieve my goal temperature.

@georgeverghese It feels this way to be honest being my first job, at least I can not say it is boring. I will take a look in the book as a resource, thank you very much.

 

[EdStainless]

You might be able to research what is out there in use.
A local to me is Wisconsin Oven.
They make many different types of industrial ovens.
Maybe someone like that would share enough information to get you started the right direction.

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P.E. Metallurgy, consulting work welcomed

 

[Compositepro]

https://www.heraeus.com/en/hng/indu...d_heat/infrared_heat_is_energy_efficient.html

This link is a starting point for you. Infrared ovens are very complex to design and are therefore relatively rare compared to convection ovens. There are specific applications where they can save time and money in processing but they are not versatile and will generally only work for the one thing they were designed for. The heating process is dynamic and does not usually reach any steady state temperature.

Given your experience level, I do not think it would be a good idea to try this on your own. Convection ovens are far easier to understand and even these have more complexity than a novice realizes.

 

[EdStainless]

The catch with radiant ovens is that the only surfaces that heat are ones with direct line of sight to the elements.
So if your product isn't flat plates it may not work.
It also means that one part cannot be in front of another.

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P.E. Metallurgy, consulting work welcomed

 

[IRstuff]

radiation oven to curate some Fire equipment tubes and boxes.

These don't seem to me to go together very well, since the interiors and non-line-of-sight surfaces can only be heated through conduction or reflection, neither of which are optimal, unless it's only exterior surfaces that are to be "curated" (cured?). Nevertheless, convection might still be required to ensure consistent curing, since the line-of-sight to any given surface might be blocked by other objects.

TTFN (ta ta for now)
I can do absolutely anything. I'm an expert!

https://www.youtube.com/watch?v=BKorP55Aqvg

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[CRisReD]

@EdStainless yes the fact that radiation works best for plates, but we want to use it on boxes and tube the link sent by @Compositepro shows very complex designs, but it gives me clue or not if using radiation might be feasible or not. I will also try to reach out to local companies if they can give me some info. @IRstuff it will be for curing paint and yes i was thinking to add some fans for the air to reach the inside of the boxes which will be the hardest part for sure. The sketch is kinda the way i feel now (

https://www.youtube.com/watch?v=BKorP55Aqvg)

 

[IRstuff]

Is there supposed to be some advantage to using IR? Seems to me that the thermal uniformity would be a big issue and that a purely convective solution would result in better results.

TTFN (ta ta for now)
I can do absolutely anything. I'm an expert!

https://www.youtube.com/watch?v=BKorP55Aqvg

faq731-376 forum1529 Entire Forum list

http://www.eng-tips.com/forumlist.cfm

 

[CRisReD]

@IRstuff it is not necessarily by radiation after some research and I found some resources that could allow me to build an oven here (

https://www.youtube.com/watch?v=8j0JyVFBjOo&list=WL&index=1

and

https://www.powdercoatguide.com/2014/09/how-to-build-powder-coating-oven.html)

the temperatures I would need are achievable with this type of set-ups and adding some fans for convection would help to the fact that the boxes' interior are not heated evenly.

 

[EdStainless]

They us radiant for strip and sheet products because you can get the surface to temperature without heating the entire space.
The trouble with using radiant as a heat source is that the parts that can see the heaters will get very hot.
Forced convection furnaces usually just use resistive heaters in the return line from the fan.

= = = = = = = = = = = = = = = = = = = =
P.E. Metallurgy, consulting work welcomed

 

[Compositepro]

IR is popular for curing powder coatings. To cure powder, it has to be above a certain temperature for sufficient time, throughout the coating thickness. Yet, coating will be damaged by too high a temperature. IR can transfer heat to the coating at a much higher rate than convection alone. In fact, the air flow helps to keep the coating from over or underheating by radiation alone. With convection alone, the air temperature has to be very high to get equivalent heat flow rate into a part. Powder coating is highly absorptive of IR, and a metal substrate acts as a IR reflector for any IR that that passes through.

 

[SwinnyGG]

This seems like an opportunity for you to learn Actual Engineering Rule Number 1: never build something if building something yourself is slower and more expensive than buying it would be.

This is a buy-not-build situation.