quote:

---

Originally posted by keys

file this under either
"what will they think of next"
or
"everything that is old is new again"

You must be logged in to see this link.

Solar powered devices aren’t new – you can recharge your iPod and laptop in the most remote locations, stay in a solar-powered resort and buy any number of ‘cool’ gadgets - but English student Emily Cummins has developed a way of using the sun’s power to help impoverished communities in Africa. Her eco-friendly, sustainable fridge is based on a simple principle: it uses the sun’s rays to evaporate water, which in turn keeps the contents cool.

The cylindrical fridge, so shaped as it has fewer areas where bacteria can build-up, can store perishable items for several days at a temperature of 43 ºF /6 ºC (a second generation fridge that maintains an even lower temperature and is more energy efficient is in development).

Emily spent five months living in a township in Namibia during her Gap Year, testing the fridge, looking at available materials within the community and showing local people how to make their own fridges.

The fridge is made using two cylinders, one inside the other.
The inner cylinder is made of metal while the outer cylinder can be made from any solid material with holes drilled in the side, enabling communities to recycle and use local, sustainable resources.
The space between the cylinders is packed with sand, wool or soil, and then water is added. As the sun warms the mixture the water evaporates cooling the inner cylinder.
Fresh water is added to the mixture as needed.

While the fridge helps people keep their perishables such as meat and milk cold, it could also be used to carry valuable medical supplies in hot climates.

Australian ingenuity came up with a similar idea back in the tough gold rush days in the 1890s when necessity was the mother of invention. The Coolgardie Safe used the same principles of heat transfer and water evaporation to keep food cool in the harsh Australian climate and was still used up until the mid 1900s.


You must be logged in to see this link.

Coolgardie safe

For the prospectors who had rushed here to find their fortune, the harsh desert climate created great challenges. One such challenge was to extend the life of their perishable foods — hence the invention of the Coolgardie safe.

The safe was invented in the late 1890s by Arthur Patrick McCormick, who used the same principle as explorers and travelers in the Outback used to cool their canvas water bags: when the canvas bag is wet the fibers expand and it holds water. Some water seeps out and evaporates, especially if it is in a breeze, and this keeps the stored water cool.

This technology in turn is commonly thought to have been adopted by explorer and scientist Sir Thomas Livingstone Mitchell, who had observed the way some Aborigines used kangaroo skins to carry water.

Principles of operation

The Coolgardie Safe was made of wire mesh, hessian, a wooden frame and had a galvanised iron tray on top. The galvanised iron tray was filled with water. The hessian bag was hung over the side with one of the ends in the tray to soak up the water.

Gradually the hessian bag would get wet. When a breeze came it would go through the wet bag and evaporate the water. This would cool the air and in turn cool the food stored in the safe.

It was usually placed on a veranda where there was a breeze. The Coolgardie safe was a common household item in Australia up to the mid-twentieth century. Safes could be purchased ready-made or fairly easily constructed at home. Some of the metal panel safes are very highly decorated, showing the creativity of their makers.

---

quote:

---

Originally posted by horgad

You could cool a whole house that way! It might be difficult to design and build it so you would not get water damage, but your AC bill would be as cheap as the cost of running a water pump.

Neighbor, "Why do you have a waterfall coming off of your roof?"

Me, "Oh I am just running the AC."

---