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Non Electrical Air Coolant Refrigerator

A very simple refrigerator anyone can make themselves for a couple dollars worth of recycled materials, using air as the coolant.

Photo of Daniel Connell

Written by

WHO BENEFITS?

This can be used to preserve food and vaccines. This is of clear benefit to a lot of people.

WHERE WILL YOUR IDEA BE IMPLEMENTED?

I'll produce a full construction and use tutorial which will be open source and freely available. People would ideally make their own from very basic local materials.

ARE YOU IMPLEMENTING IN AN ELIGIBLE COUNTRY?

  • Yes

EXPERTISE IN SECTOR

  • I do not have experience working in a sector related to my idea

EXPERIENCE IN IMPLEMENTATION COUNTRY(IES)

  • Yes, for one year or less.

A refrigerator consisting of a simple air compressor (which can be made from a food can, some bicycle rubber, and bike valves), a soft drink bottle as a pressure vessel, and a simple pressure release valve (probably based around magnets from a computer hard drive).

The compressor can be driven by pretty much anything, such as a small wind turbine, a motor run from a solar panel or the mains/battery, even by hand if necessary.

Air is compressed into the plastic bottle up to 2-3 bar, at which point it is released by the valve and due to adiabatic expansion rapidly cools. This now cold air enters into an insulated box = refrigerator.

The system can be further optimised by recycling the displaced cool air from the box to cool the plastic bottle, as well as a small amount of water to cool the compressing air internally.

The valve will be settable in terms of pressure and therefore temperature, and the system should be able to easily maintain internal temperatures around 0 C.

Due to the rapid cooling of the air, water will be produced as a by-product which can be collected. The system in an averagely humid environment should produce about 5-10 liters of drinking water per day.

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Spam
Photo of leerousi lee
Team

good

Spam
Photo of Mary Johnson
Team

Have you seen the non-electric Mitte Cool clay refrigerator and water purifier? It would be great to combine your ideas with the mitte cool concept, as well as use permaculture design/ ancient desert passive cooling design, to teach farming members how to build housing and warehousing infrastructure that had passively cooled storage areas built-in to their production.  

Using roof water collection and storage, and passive cooled ventilation built into housing, perhaps with a compressor based system for back up wold address multiple problems all at once.

I think that would allow you to use your great thinking on local materials for larger volumes of cool storage as well as other lifesaving co-bennefits as the high temp get even higher.

 The desert permaculture design I'm speaking of includes trellised verticle home gardens and food forest near the base of the building on the sunniest side and over the roof, to create shade. The shade then is also used by a cooling tunnel where cooler air sinks and enters a cooling chamber under the house which is lined with crushed charcoal, which is kept damp adding evaporative cooling.

Passive airflow passes over the extra cooling surface area of the charcoal, draft from the outdoor shade blows up through the house and ventilates the home and a cool storage room can also be a living space. 

Spam
Photo of Daniel Connell
Team

I like the simplicity of evaporative cooling based tech, but it does have a couple potential drawbacks.
Generally getting more than about a 10 C temp drop is a struggle, so tho it works well enough for prolonging the shelf life of plant produce, not necessarily advised for more spoilable items in hot climates. And high humidity pretty much kills the thing completely. Also goes through a fair amount of water.
In terms of living/growing space cooling I'm also working on a ground mass based air conditioning system which just involves pumping air through a 20 liter water container buried 1-2 meters in the ground where the temperature is usually stable and lowish day and year round. Doesn't work everywhere on earth, but is very simple and cheap, and requires very low power to run.

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Photo of Mary Johnson
Team

Yeah, a combination of these ideas could help reduce the overall energy demand on your system and if linked up well could provide redundancy so if one part broke down there would at least be a little cooling while the problem was being fixed. Id like to see an info graphic and also how what you are proposing might lokk like in comparison to what US small farms use which is a super insulated veggie storage room cooled by a typical commercial AC with a coolbot.  How does what you have designed compare in terms of cost, material availability, ease of construction and maintenance, reliability, and overall carbon footprint.  I'd also love to see you look into more regenerative insulation options. Things that are more readily available in rural and remote areas or that could be manufactured with less chemicals and overall negative impacts.  Theres a new innovative company that's using fungi to make ecofoam packaging materials and insulation. I bet a modification of their process could create an incredible local option from crop byproducts like rice hulls or coconut fiber. https://en.m.wikipedia.org/wiki/Ecovative_Design

Spam
Photo of Lunyiliko Komba
Team

Good Idea,
would also love to see a prototype features and what volume of storage can it accomodate? Is it ideal for vegetable and fruits storage?
rgds,
LK

Spam
Photo of Daniel Connell
Team

Volume comes down to mostly to insulation, and 10cm of polystyrene would be easily sourced and keep things cold for a very long time...
Fruit and veg, animal products, vaccines, you name it really.

Spam
Photo of Mark Laing
Team

Brilliant idea.
Do you have a prototype ?
What sort of electricity / energy demands do think it would have ?
I wonder if the compressor would survive use on a continuous basis for several months ?

Spam
Photo of Daniel Connell
Team

Not yet a full prototype, but have proof-of-concepted it. But then the concept is adiabatic expansion, which isn't exactly novel.
In terms of power; to take 3 liters of air to 3 bar pressure in 1 minute takes about 7 watts (at 100% efficiency), so 30 watts should be a very safe figure. If the air is then allowed to cool back to 25 C before expanding back to atmospheric pressure it should come out at about -70 C (things get very cold through this process).
This much power can be easily generated by a small solar PV panel, a wind turbine / solar Stirling (both of which I'm also developing), other low to medium energy producing options.
For the compressor I was just going to make a little diaphragm pump from a food tin, some inner tube rubber, and two bike valves. Will likely need some adaptation in process but then everything does. Should last a while, and pretty much free to replace if and when it needs it.

Spam
Photo of OpenIDEO
Team

Hi Daniel, interesting post! Any chance you could find an image to go along with it? Images help grab attention and tell a story with higher impact. You should be able to use the Edit Contribution button on the top of your post and follow the instructions to add images from there. Looking forward to seeing more of your inspiring insights on OpenIDEO.

Spam
Photo of Lisa
Team

I do not know anything about the technical aspects of this idea, so I can't comment on that, but what I really like is that fact that the components of the mechanism would be relatively easy to find/replace when this idea is used in places with fewer resources.  I think one problem that often arises when people come up with solutions for problems in places where there are few resources is that they forget that things break and that for a project to truly be successful it needs to be long lasting, which means that the users need to be able to afford and be able to easily source the materials required to repair the technology being used.  That said, in this case the source of power for the air compressor would need to be carefully considered.