Stainless Steel in Hot Sun

tmeyer3

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I'm not too educated on the electromagnetic resonance of stainless steel, but I do know that it's actually a pretty decent insulator. Granted, not quite as good as common body panels made of ppe or abs (thermo plastics / fiber glass mixes, etc). What blows my mind are there trucks with aluminum body panels! Aluminum is literally used for heat dissipation because it's so thermally conductive.

ppe/abs is around .2 W/(mK) (watts per Kelvin per meter)
Stainless steel is around 20 W/(mK)
Aluminum is around 200 W/(mK)

On a hot, sunny day ALL of these materials will get hot enough to cook an egg. The key difference is how much of that thermal energy is passed THROUGH to the cabin? If you're going to use a metal for thermal conductivity and rigidity, stainless steel is one of the best options. This is also why the starship is made from it.
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ajdelange

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The solution is to put, in either case, some abs behind the metal. Assuming equal thicknesses of metal and abs the conductivity of stainless/abs is 0.1908 and of aluminum/abs 0.1998 W/m-K
 

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I have per-ordered a Cyber Truck and I got thinking about the stainless steel Tesla is going to use which was described as similar to the materials used in cooking pans. If so, I imagine the body of the Cyber Truck is going to get too hot to touch after spending time in the summer sun. This could be a major safety issue if my perception is correct. Did the DeLorean get too hot to touch in the summer? Does anyone know? Your thoughts?
I know the OP's post is from a year ago, but I'll weigh in:

Yes, it does. I have a sign that I place on my DeLorean's windshield at shows that states " Please look, don't touch". It is more than a reminder to use common courtesy or to avoid fingerprints. It is a warning. Bare stainless steel in the summer sun can burn skin. I am never far away from my car but routinely see people touching or leaning against the car (usually for a photo op) and invariably retract their body part like they touched a hot stove. I pay particular attention to children around the car to ensure their parents are aware of the situation.

It will be the same situation for the Cybertruck, although the height of the vehicle will preclude anyone laying their tender forearm on the roof to lean in for a photo. 😬. I'll probably carry the same sign for the CT.

002.JPG
 
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tmeyer3

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Sorry, new to the forums and didn't even realize how old this thread is, haha! Just looked at the "read these!" section and it drew me in.

The solution is to put, in either case, some abs behind the metal. Assuming equal thicknesses of metal and abs the conductivity of stainless/abs is 0.1908 and of aluminum/abs 0.1998 W/m-K
Like house insulation! I live in the Mojave Desert and plan to leave the truck outside for the most part. So I'm going to tint the crap out of the windows to assist that AC. I think it might make sense to add a thin layer of some very lightweight insulation (not abs, haha too rigid) but like 3-4cm of light weight, high density foam insulation to deaden noise and act as a barrier between the "cooking surface" and my precious AC. 😂
 

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Polishing the top should make it cooler as it reflects sun/heat. Not much metal on the roof though, so maybe a roof visor that is reflective? I may actually do something (decal or other) to make the hood as dull as I can so the Sun won’t reflect off it, right at me when it is lower in the sky.

I wonder how effective it will be to “pre-cool” the cab before entering?
I am not very sanguine about running the a/c while the truck is sitting there, seems like a massive battery drain, though maybe that is my old ICE bias showing? Maybe it is the same exact drain whether driving or sitting? If so, that might be the antidote.
The batteries are maintained at a safe and effective temperature so you have no control over that. A non-painted car made of a reflective material should be cooler than just about any painted car.
 

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Starship is also using the steel for heat dissipation. It's an insulator compared to copper or aluminum, but it's a conductor compared to composite surfaces.

The outside getting hot on a hot day (like aluminum) actually makes the interior insulation work better, because there's a shorter temperature gradient across the surface of the insulation. Less conductive surfaces create hot spots which then exceed the resistance of the internal layer of insulation.

-Crissa
 

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Talking about cooling. Our cars don't have tinted windshield. I cut a silver windshield screen to fit top of dash. Covered it with black towel. Now air doing from vents is really cold cause it ain't cooling dash. I put same dash screen up on sunroof, now my head don't get fried after six hours in car.
 

tmeyer3

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Talking about cooling. Our cars don't have tinted windshield. I cut a silver windshield screen to fit top of dash. Covered it with black towel. Now air doing from vents is really cold cause it ain't cooling dash. I put same dash screen up on sunroof, now my head don't get fried after six hours in car.
One thing I do with my cars where I live is a 90% (almost clear) vlt tint on the windshield, it really helps! The magic is in the non visible light. Good tints can block most uv and a lot of ir while still looking perfectly clear. It's definitely worth the cost imo and really helps the car feel cooler while preventing your dash from turning into alligator skin after a few years.
 

Jhodgesatmb

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Our Model 3 upper window is tinted as are the back windows and the upper portion of the windshield. I suspect the CT will be the same or similar.
 

ajdelange

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Glass doesn't transmit IR very well.

IMG_1323_IR.PNG


This is a picture of me or rather my reflection in a sheet of glass. I am standing in front of a full length glass door and the camera is pointing at the door. What you can't see in the pic is my SO who is on the other side of the glass. IR from her is blocked by the glass.

What heats the interior of a car is visible light and NIR which get converted to heat which is reradiated as long wave IR which can't get out through the glass. This is greenhouse effect. thua it is visible and NIR you want to block. It is also important to block UV to prevent deterioration of the internal furnishings of the car (and your skin when you are in it).
 

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Talking about cooling. Our cars don't have tinted windshield. I cut a silver windshield screen to fit top of dash. Covered it with black towel. Now air doing from vents is really cold cause it ain't cooling dash. I put same dash screen up on sunroof, now my head don't get fried after six hours in car.
I'm wondering what kind of cars you have? You might consider switching to a Tesla. They have state of the art coatings on the upper glass so your head will no longer get fried. It blocks the UV and IR very effectively. It is kind of dark but that's because it blocks much of the visible light as well.

It's been 102-104 F degrees here the last two days and the most comfortable place is inside the Model 3's. I even drove through an area that was 108 F degrees in the middle of the afternoon with the sun beating down and the Model 3 remained comfy.
 

HaulingAss

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One thing I do with my cars where I live is a 90% (almost clear) vlt tint on the windshield, it really helps! The magic is in the non visible light. Good tints can block most uv and a lot of ir while still looking perfectly clear. It's definitely worth the cost imo and really helps the car feel cooler while preventing your dash from turning into alligator skin after a few years.
Tesla windshields already have this built-in. I had a Volvo that had the same thing and it makes a big difference. On the Volvo they called it an IR reflecting windscreen and sold it as part of a rather expensive "Summer Package". Tesla doesn't make much of a deal about it but it seems just as effective.
 

ajdelange

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They have state of the art coatings on the upper glass so your head will no longer get fried. It blocks the UV and IR very effectively. It is kind of dark but that's because it blocks much of the visible light as well.
It has to because it is the visible and NIR that heat your scalp - not the IR and UV (which does other bad things).
 

HaulingAss

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It has to because it is the visible and NIR that heat your scalp - not the IR and UV (which does other bad things).
The Infra-red spectrum would definitely heat your scalp if allowed to pass through. All of these wavelengths will be converted into heat when absorbed by the object they are striking.
 

ajdelange

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Well yes but the infa-red can't come through. Glass won't pass it. That's what the picture shows.
 
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