'solar bubble build'

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'solar bubble build'

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herbsandedibles

Joined: 31 May 2005
Posts: 14
Location: wrentham, suffolk

Posted: Thu Jun 02, 05 11:09 am Post subject: 'solar bubble build'
hi all. i just discovered downsizer the other day, so i am a newby. thought some of you might be interested in our greenhouse that we are building. it is the first of its kind in Europe. it is heated and cooled with liquid soap bubbles. here is a link to our site which tells all about it: www.solarbubblebuild.com

cab

Joined: 01 Nov 2004
Posts: 32429

Posted: Thu Jun 02, 05 12:12 pm Post subject:
Very neat! Think I'll work on my first polyunnel, get that sorted, before I consider something as major as that, though!

cab

Joined: 01 Nov 2004
Posts: 32429

Posted: Thu Jun 02, 05 1:58 pm Post subject:
Looking at that in more depth, I'm surious about this soap; Are we looking at a detergent, a foaming agent... What is it that you use that keeps its suds so long?

herbsandedibles

Joined: 31 May 2005
Posts: 14
Location: wrentham, suffolk

Posted: Thu Jun 02, 05 2:24 pm Post subject:

there is only three ingredients in the soap solution.
1. sodium laureth sulfate- the stuff that is in just about all soaps
2. glycerine- this makes the bubbles last longer
3 water

the bubble solution gets reused over and over again and will last for years.
if you go through the website, there are diagrams and lots of pictures of how it all works and pictures of it in action.

the soap solution is basically just washing up liquid with glycerine added.

cab

Joined: 01 Nov 2004
Posts: 32429

Posted: Thu Jun 02, 05 2:53 pm Post subject:

herbsandedibles wrote:

Not quite just washing up liquid... But a really simple solution for a lasting foam. SLS is also anti-bacterial, so it'll last for a long time. That's quite ingenious, the concept is so simple that I'm stunned

Herv

Joined: 04 Jun 2005
Posts: 3
Location: Wrentham, Suffolk

Posted: Sat Jun 04, 05 7:27 pm Post subject:

tell me cab, do you have a background in chemistry? i'm looking to pick someone's brain about my surfactant solution. unusualherbsandedibles is my mrs. she know some details about the solarbubblebuild, but really she is just into her plants. the thing that will destroy the bubbles is air movement. the cavity is well sealed thus the bubbles will remain for hours. on cold nights however they are replace more frequently before they cool down. introducing warm bubbles into the cavities is the systems mechanism for releasing stored heat back into the building.

tahir

Joined: 28 Oct 2004
Posts: 45714
Location: Essex

Posted: Sun Jun 05, 05 7:01 am Post subject:
Hi Herv, there are a couple of people here with chemistry know how, Cab is one of them, Sally In Wales is also somewhat of an expert in soaps, hope someone here can help you.

Herv

Joined: 04 Jun 2005
Posts: 3
Location: Wrentham, Suffolk

Posted: Sun Jun 05, 05 10:47 am Post subject:
thanks tahir

cab

Joined: 01 Nov 2004
Posts: 32429

Posted: Mon Jun 06, 05 8:53 am Post subject:

Herv wrote:

I'm not un-chemical, but by background I'm a microbiologist. My brains are yours for the picking, though

A lot of large scale microbiology (which isn't as daft a phrase as it sounds!) is foam management.

What are you looking for here, something to stabilise the bubbles on a cool night without the need for warm bubbles?

Herv

Joined: 04 Jun 2005
Posts: 3
Location: Wrentham, Suffolk

Posted: Mon Jun 06, 05 9:37 am Post subject:

Thanks for offering up your brains cab. My own knowledge of chemistry is a few cell beyond zero.

Replenishing the cavities with warm bubbles is the buildings mechanism for slowly releasing stored thermal energy back into the building on cold nights. So we want to keep warm bubbles.

In this barmy East Angian climate my surfactant solution seems to be behaving very well. In Canada where there have been a number of these buildings, anti-freeze has to be added to the solution. They also get problems with the solution separating in freezing conditions. This isn't a problem for me yet, but may be later. So this is the first gap in my knowledge: -

Finding an anti-freeze that is not going to kill the plants or me if it leaks + keeping this solution stable in cold conditions.

Interestingly, cold bubbles make the better insulator. As I understand it the primary factor that determines the insulating properties of a bubbles mass is water vapour migration within the bubbles. As the temperature approaches freezing the water vapour approaches almost nil. Not a lot of research has been done on this, but if you know of anything relevant, please do let me know. If it sounds like I'm talking rubbish also let me know. I do not have a scientific background.

Solaroof Technology is an open source project. There is a guy in Canada who has spent years (apparently) formulating a surfactant solution for solaroof applications. However, he will not reveal his recipe, hoping that people will buy this solution from him. I'm just wondering if what he has come up with is much different from what I have. I've done some research and it doesn't seem like rocket science. I don't imagine there is many additives that would benefit over and above what I have already described. Maybe a preserver might be useful if SLES degenerates over time. It has been used in Canada for 4 years continuous running so maybe not.

You say SLES is anti-bacterial. That's handy. I didn't know that. I was counting on the UV to keep bug growth at bay.

Cheers

cab

Joined: 01 Nov 2004
Posts: 32429

Posted: Mon Jun 06, 05 9:53 am Post subject:

Let me have a bit of a mull on that, maybe talk to some chemists I know too. I'm immediately thinking glycerol might be your best bet as an antifreeze, but glycerol might affect your suds.

I love the open source nature of the project, and I love that in many ways you're trying to do the opposite of most people in the petrochemcial and fermentation industries, i.e. trying to make a stable foam rather than trying to get rid of a fom.

SLS is a mild antibacterial agent; it pops open cell membranes, which is why it's so common in things like toothpaste.

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