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Old 08-04-14, 11:39 PM   #1
AC_Hacker
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Default Space Suit = Multi-Layer Insulation (MLI)

I have wondered if NASA space suit technology could be useful for me.

I did some investigation and found that the general principle was the use of multiple layers of radiant energy reflection material. It turns out that in space, the principle of convective heat loss is not operative because, being in a near vacuum there is no fluid, no gas that could enable convection. That leaves only radiant losses.


The solution was to use thin layers of reflective material, alternated between spacer material sometimes referred to as 'bridal veil'. It may in fact actually be bridal veil.

But the principle was that 1 layer of the reflective material could stop nearly 97% of the heat loss, and the next would stop 97% of what was left, etc., etc. for 10 to 60 layers.

So I thought it would be an interesting thing to try to use the principle, to see if it could be useful in preventing heat loss.

Being as how it is August, the hottest month after all, I thought I might design and make a vest using the principle of Multi Layer Insulation.

I did some searching around, and found out that those crinkly cheap "Space Blankets" actually do work, so I thought that they would be an excellent candidate for my MLI vest.

I checked on Amazon and ordered a pack of 10 Space Blankets. Turns out that they are pretty cheap in August, at $7 for 10. I also ordered a couple of yards of Thinsulate, it may not be enough, but I figure it would be enough for a test of concept.

The idea is alternating layers of Space Blanket and Thinsulate and Space Blanket and Thinsulate, etc. til I run out of material. I am expecting my MLI vest will be warm and crinkly.

So, the MLI materials are on the way.

So I guess what I will be testing, though in a non-scientific way, is the efficacy of reflective insulation, since I don't live in a near-vacuum.

* * *

But, along the way, while I was researching, I came across some very interesting tidbits... namely that MLI insulation is being used to great effect in the UK and also in New Zealand.

[EDIT: The bad link in the paragraph below has been corrected.]
If you look into these products, be sure to convert the specified R-valurs to U-values by deviding 1 by the specifiec R-value and then using the Conversion Tool that I posted in the "Tools" section...

The R-values actually are quite good, once you have properly converted them.

-AC

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Old 08-05-14, 05:00 PM   #2
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That foil is R 3.5 for over 2" thick. Not too good from where I sit. Also remember they are talking about an assembly which doesn't let you get an accurate picture of the product value. What is the concrete wall without the foil, for example.

We had the same issue with foil sided bubble tarp. Totally de-bunked.
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Old 08-05-14, 07:28 PM   #3
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Originally Posted by Mikesolar View Post
That foil is R 3.5 for over 2" thick. Not too good from where I sit.
OK, my bad my link to the conversion tool was incorrect...

Here is the correct link.

I use this conversion too so often that I have downloaded the SWF file to my computer, and book-marked it (local) in my browser.

So, here is how the conversion sequence goes:

R3.5, when reciprocated is 0.2857142857142857 (The U-value in SI inits)

When you look this up in the calculator, using SI units, you will see that the R-value, in units we are accustomed to, is not R3.5 but is actually R19.8.

My apologies for the bad link, but the correct values are absolutely worth paying attention to (and the real reason I posted the entry).

-AC
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Old 08-06-14, 01:26 AM   #4
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I think you have something there. Near R-38 for a 2x4 wall. Layered radiants have a lot of potential. The bubble wrap thing is different. Space is an extreme environment, super cold but the sun is super hot. Shade: -148F (-100C); Sunlight: 248F (120C). It makes sense they would use a heavily insulated radiant barrier. Would it turn your house into a giant faraday cage?
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Old 08-06-14, 12:04 PM   #5
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Originally Posted by gtojohn View Post
I think you have something there. Near R-38 for a 2x4 wall. Layered radiants have a lot of potential. The bubble wrap thing is different. Space is an extreme environment, super cold but the sun is super hot. Shade: -148F (-100C); Sunlight: 248F (120C). It makes sense they would use a heavily insulated radiant barrier. Would it turn your house into a giant faraday cage?
I am very interested in the layered reflective insulation idea.

The real deal about the space environment is not so much the temperature extremes, it is that of the three modes of heat loss & gain:
  • conductive
  • convective
  • radiant
Only radiant is operative, and the only way to deal with radiant heat loss/gain is with reflective methods.

But, with the issue of the Faraday Cage, I think that all the metalized materials would need to be electrically connected into a continuous surround for the Faraday Cage effect to work.

-AC
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Old 08-08-14, 03:22 PM   #6
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Default Space Blankets Are Here!!

My Mylar Space Blankets (10 for $7) have just arrived from Amazonia.

So I did a test to see if they were worth a flip.

Here is a photo of my carefully constructed test apparatus:


I am testing two pieces of black rubber belly-pan material that came from the bottom of my car. The piece on the right is not covered by the Space Blanket and the one on the left is underneath the space blanket.


Here is a temp reading taken of my control specimen, pretty hot, huh?



This is a temp reading taken of my actual test specimen that was shielded by the space blanket, pretty cool, huh?

The measured ambient temp was about 84 degrees F.

Conclusion, Space Blankets are definitely worth a flip.

-AC
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Old 08-08-14, 06:12 PM   #7
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You've got a dense thick black absorber versus what is essentially a thin flexible mirror. Granted there are other forces in play here but it's a no brainer that the thin reflective layer will have a cooler result. I would have figured a more fair comparison would be a thin white control, white paper or white thin plastic bag perhaps. Granted the aluminized mylar should still perform better than a white body but the difference won't be as dramatic as your homemade solar collector control.
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Old 08-08-14, 07:04 PM   #8
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I would have figured a more fair comparison would be a thin white control, white paper or white thin plastic bag perhaps.
It's really getting to be getting ridiculously affordable to do your own testing...

Non-Contact IR thermometers are only $10.

It's absolutely amazing what you can test and what you can learn from your testing.

No need to guess anymore.

-AC
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Old 08-10-14, 04:30 AM   #9
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I IR temped the sky and it is around 18-20F range. So, at night time, the effect of radiant cooling should be equivalent to standing next to a 20F wall. If you could build something that can is perfectly transparent to radiation, but zero conductivity, I wonder if it will cool down to 20F if you leave it under the night sky.
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Old 08-10-14, 02:31 PM   #10
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Originally Posted by ICanHas View Post
I IR temped the sky and it is around 18-20F range. So, at night time, the effect of radiant cooling should be equivalent to standing next to a 20F wall. If you could build something that can is perfectly transparent to radiation, but zero conductivity, I wonder if it will cool down to 20F if you leave it under the night sky.
Sounds like an interesting and easily-staged experiment.

I'd like to see your results!

BTW, I have IR measured the night sky before and it goes surprisingly lower than 18-20F.

-AC

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