Solar furnace - what coating, what insulation?

[seb1000]

Hello everyone,

I start creating a solar oven.
I made a first draft this morning with just:
- 2 boxes in cartons insulated from each other roughly by balloon newspaper
- the flaps of the outer box covered with aluminum papers and oriented appropriately
- a piece of sheet metal at the bottom of the inner box; the bottom of this box painted black (with coal and water)
- a piece of transparent plastic on the top.

the thermometer indicated 60 ° C I removed it before it breaks, and I replaced it with an egg casserole :-)

at the moment I am speaking to you, the white of egg has bleached on the edges, and the cheese has begun to melt.

the goal is to build a solar oven / hob made of wood, with a pseudo-parabolic mirror and reflecting mirrors, but I wanted to make a first test and have some advice:
- which black "paint" is suitable for cooking food, ie non-toxic even when subjected to high temperatures, apply to the bottom of the oven, and to the metal plate?
- what non-dangerous insulation (no glass wool or rock) put between 2 boxes?
- what plastic / glass / pane put on the top to prevent fogging on the inside of the oven?

Thank you in advance for your replies.

please

[seb1000]

Damn, I was hoping to find experts in the field.

know where I can have this kind of information?
(forum, magazine, website ....)

[Christophe]

We are but it happens that we zap certain messages (we can not be everywhere at once)

Start by reading these 2 topics about possible reflection materials:

https://www.econologie.com/forums/materiau-p ... 10662.html
https://www.econologie.com/forums/produit-de ... t9584.html

I have a book on solar ovens. I will look at what they are saying in relation to your other questions.

Do not hesitate to abuse: https://www.econologie.com/forums/search.php

[dedeleco]

On google there are plenty of sites especially in English to help underdeveloped countries and help them save wood with solar cookers easy to build!

on google with solar cooking or another variant solar cooker !!

http://solarcooking.wikia.com/wiki/CooKit
and embodiment in 56 pages:
http://images4.wikia.nocookie.net/__cb2 ... _plans.pdf
http://images3.wikia.nocookie.net/__cb2 ... nglish.pdf

http://www.google.fr/search?client=fire ... 2&aql=&oq=

http://en.wikipedia.org/wiki/Solar_cooker
http://fr.wikipedia.org/wiki/Four_solaire
http://www.atlascuisinesolaire.com/index.php
http://www.atlascuisinesolaire.com/plan ... olaire.php

etc ....

And if for cooking we continue to CO2 in the world, I do not understand!

[Christophe]

Here is the info for a solar oven / cooker Ulog type:



- Already, as the mirror is flat, a glazier mirror or better synthetic (unbreakable and lighter) seems to me the most suitable. They use a mylar (reflective sticker). Aluminum paper possible.

- Oven tank: painted aluminum plate no details on the paint except "if possible without toxic". Must withstand 160 ° C. Solar varnish, exhaust paint (er not toxic ???), matt black, powder coating (hu?)

Otherwise find a plate of aluminum or black lacquered steel ...

- insulation: sheep wool, very durable apparently.

- glass: single glazing

[Christophe]

I have re-flipped through the book, there are many examples: I would say that 8 on 10 do not have the tank that is painted, it is left in aluminum (sheet or foil). It does not affect performance (up to 200 ° C)

My favorite is the butterfly: http://www.solar-papillon.com/



and metal fresnel optics: (Professional quality: 300 to 400 ° C)

I'll do some pictures tomorrow.

[seb1000]

here is the project that I intend to carry out, with in addition a removable "box" which could be placed above the heating plate, to take advantage of the greenhouse effect, and I also intend to add 3 flat reflectors above this box: it should make an approximate total of 1,4m².

I tried to post an image: you just have to imagine the removable box.


I spent 6 or 7h doing diagrams and calculations today, the plan is done.

in fact I have already come across these sites that you recommend Christophe, some have also been useful.

the sites in English, I had not thought about it, but I'm pretty bad .... I'll look at the pictures

about "mirrors" I have what it takes: polished stainless steel: a real mirror (but not in sufficient quantity .... it is even on)

about painting, i think i will stay on my idea water + coal powder ... i would change easily if need be.

about the glass, I read that superimposing 2 single glazing with an air gap between 2 was advisable to avoid heat losses. I do not know enough to evaluate the compromise radiation losses / reflection of solar radiation

about sheep's wool, we'll have to find some, but above all, it does not catch fire? I have never seen a sheep-torch at the same time ...

another question not raised: how to perfect the tightness of the box (between the wooden boards, around the door ...) without toxic product .... the seal for oven door?

[dedeleco]

For this choice in the armada, the details are on:
http://www.impi.ch/idees-cook/Plans_cui ... iDCook.pdf


this one seems simpler ??
http://solarcooking.org/plans/funnel.htm

http://four-solaire.iguane.org/

http://solarcooking.wikia.com/wiki/CooKit
and embodiment in 56 pages:
http://images4.wikia.nocookie.net/__cb2 ... _plans.pdf
http://images3.wikia.nocookie.net/__cb2 ... nglish.pdf
http://www.backyardnature.net/j/solardsh.htm

http://www.google.fr/search?client=fire ... 2&aql=&oq=
http://www.kyoto-energy.com/kyoto-box.html
http://idcook.com/four-solaire/56-four- ... ooker.html
http://en.wikipedia.org/wiki/Solar_cooker
http://fr.wikipedia.org/wiki/Four_solaire
http://www.atlascuisinesolaire.com/index.php
http://www.atlascuisinesolaire.com/plan ... olaire.php

etc ....

And if for cooking we continue to CO2 in the world, I do not understand!

[seb1000]

I had found just about all these links except 1 !! the one that seems to me the most interesting for my case:
Nice guy who built his IDCOOK oven to share his passion and long hours of passionate work.
thanks to you for the link.

about insulators, crates, cardboard and polystyrene .... it's average. cardboard and crates certainly contain harmful or toxic products that can be released to heat and polystyrene certainly in addition to being not top level environment.

about the glass, only one seems to suffice according to the document.

I have in any case 2 choice: continue with my project that works on paper that seems more complicated but more effective if everything goes as planned, and it is not won, or follow the construction mode presented in this document .
as I like to tinker, I think I will try my plan ...

[dedeleco]

This one seems to me very simple and effective as parabola, cardboard and aluminum foil, insulating plastic bag for cooking:
http://solarcooking.org/plans/funnel.htm


In the game of simple and effective, I seem winner!

Read the explanations (google can translate pretty much, except grammar)

and other simple plans:
http://solarcooking.wikia.com/wiki/Construction_plans

To insulate thermally it is enough to cut the air currents with a transparent plastic film at high temperature (microwave), glass or two layers of this film separated roughly from each other and far enough from the fireplace not to heat up too much. plastic.