mirkwood
09-12-2009, 12:45 AM
http://3.bp.blogspot.com/_vnDOor7Jic0/Sqq3Y-DzlfI/AAAAAAAABec/UuZNfEHO57Y/s400/frozen-fruit-on-tree.jpg (http://3.bp.blogspot.com/_vnDOor7Jic0/Sqq3Y-DzlfI/AAAAAAAABec/UuZNfEHO57Y/s1600-h/frozen-fruit-on-tree.jpg)
Chill Out
After our recent move we were without a refrigerator for a couple weeks (although it felt much longer) and it certainly drove home the desirability and convenience of refrigeration. It really made me think about what we would do in a long-term power outage.
On my old computer (may it rest in peace) was a file about 'cooling pots'; since I can no longer access that file I started prowling the web and discovered a couple things that caught my attention; I hope you'll find them of interest.
http://4.bp.blogspot.com/_vnDOor7Jic0/SqqgG4IozrI/AAAAAAAABeE/kl_eQVUEyks/s400/zeer_pots.jpg (http://4.bp.blogspot.com/_vnDOor7Jic0/SqqgG4IozrI/AAAAAAAABeE/kl_eQVUEyks/s1600-h/zeer_pots.jpg)
First the pots
Here's information taken from wikiHow.com (http://www.wikihow.com/Make-a-Pot-in-a-Pot-Refrigerator) on How to Make a Pot in Pot Refrigerator. They're called Zeer pots
In a community without electricity, storage of food long-term can be tricky. One simple solution is to build your own pot-in-a-pot fridge, using basic pots, sand and water. An idea revived by Muhammed Bah Abba, this neat item is now being used by many farmers in warm climates who need to preserve their food for a longer time and keep the insects away. Keeping the sand moist all the time enables evaporation to cool the produce kept inside the inner pot. This enables the storage of freshly grown vegetables to last much longer than usual in a hot climate. Here is how to make your own.
Steps
Obtain two large clay or terracotta pots [must be unglazed]. One pot must be smaller than the other pot. Check that the smaller pot fits inside the larger and that there is a space around it of at least one centimetre, up to three centimetres [roughly .4 inches to 1.2 inches].
Fill in any holes at the base of the pots. Use clay, large pebbles, cork, a homemade paste - anything suitable on hand to fill the hole. If you leave the holes open, the water will enter the inner pot and will also run out of the larger pot, making the fridge ineffective.
Fill the base of the larger pot with sand. Only fill to a height that will ensure the smaller pot sits even in height with the larger pot.
Place the small clay pot. Place it into the large pot on top of the lower layer of sand.
Fill all around the small pot with sand. Fill it right to the top.
Pour water into the sand. Do this until the sand is completely soaked and unable to take any more water.
Take a cloth or towel and dip it into water. Place it over the top of the inner pot so that it covers it completely.
Allow the inner pot to cool down. If you have a thermometer, you can use this, otherwise test with your hands.
Keep the pot-in-pot refrigerator in a dry, ventilated space for the water to evaporate effectively towards the outside.
Place your vegetables inside for storage. You will need to keep checking regularly for the dampness of the sand. Pour in more water as it becomes drier to keep it well moistened. Usually this will need to be done twice a day.
Tips
Try different types of vegetables and fruit to see how long they last using the pot. . . . eggplants can last for 27 days rather than three, African spinach can be kept for 12 days instead of spoiling after one day, while tomatoes and peppers stay fresh for three weeks.
It is also possible to store sorghum and millet grains this way - the pot-in-pot refrigerator protects against humidity and stops fungi growth.
Meat can be kept for up to two weeks, as opposed to a few hours without this device.
Water and other liquids can be kept at 15?C [59?F].
Evaporative cooling works most effectively in dry heat and this pot-in-pot refrigerator is no different. In high humidity, you will find that this solution does not work.
Things you'll need
Two clay (terracotta) pots, one larger than the other
Sand
Water
Cloth to cover the pots
Clay, cork or other material to plug holes in the pots if they have them
<HR align=center width="15%" noShade SIZE=3>
http://2.bp.blogspot.com/_vnDOor7Jic0/SqqtnN0FKaI/AAAAAAAABeM/p7S4yavD24s/s400/ice_cubes_xs.jpg (http://2.bp.blogspot.com/_vnDOor7Jic0/SqqtnN0FKaI/AAAAAAAABeM/p7S4yavD24s/s1600-h/ice_cubes_xs.jpg)
Not everyone lives in a low-humidity climate but that doesn't mean there aren't electricity-free ways available to cool your food. Below is an excerpt of a post from Solar Cooking (http://solarcooking.org/radiant-fridge.htm). Solar Cooking?!? Yes, indeed . . . this is so cool - literally!
Using a Solar Oven as a
Radiant Refrigerator at Night
My first experiments were during a winter in 1997 in Kalgoorlie, an inland location of Western Australia: The ambient nighttime minimum was getting down to 2-3 degrees above zero (Celsius) [roughly 35-37 degrees Fahrenheit]. Using a box-cooker with a black base, I poured about half a centimeter deep of water into the bottom of the cooker and put it outside at night. The glass lid had to be removed as glass is opaque to infrared and would inhibit the cooling. I put the cooker (uncooker?) in a location where it saw a maximum amount of sky and no trees or buildings (on the roof of my house).
The sky needed to be clear all night, with still air. I was using rainwater as the town water contained additives which may have lowered the freezing point. I would set the alarm clock for about 5am, get out of bed and climb onto the roof in the near dark (unfun) and remove a solid disk of ice from the now uncooker (much fun). I got ice consistently over several nights, even though there was no frost on the ground, and pots of water sitting next to the box cooker did not freeze.
<HR align=center width="15%" noShade SIZE=3>
And, just so you don't think this can only be done in Australia, here's an excerpt from the writings of, now retired, BYU physics professor Steven Jones (http://www.solarcooking.org/plans/funnel.htm):
http://4.bp.blogspot.com/_vnDOor7Jic0/SqqxanxpSaI/AAAAAAAABeU/9wChn6jLZRY/s400/Solar+Funnel.jpg (http://4.bp.blogspot.com/_vnDOor7Jic0/SqqxanxpSaI/AAAAAAAABeU/9wChn6jLZRY/s1600-h/Solar+Funnel.jpg)
How to Use the Solar Funnel
as a Refrigerator/Cooler
A university student (Jamie Winterton) and I were the first to demonstrate that the BYU Solar Funnel Cooker can be used - at night - as a refrigerator. Here is how this is done.
The Solar Funnel Cooker is set-up just as you would during sun-light hours, with two exceptions:
1. The funnel is directed at the dark night sky. It should not "see" any buildings or even trees. (The thermal radiation from walls, trees, or even clouds will diminish the cooling effect.).
2. It helps to place 2 (two) bags around the jar instead of just one, with air spaces between the bags and between the inner bag and the jar. HDPE and ordinary polyethylene bags work well, since polyethylene is nearly transparent to infrared radiation, allowing it to escape into the "heat sink" of the dark sky.
During the day, the sun's rays are reflected onto the cooking vessel which becomes hot quickly. At night, heat from the vessel is radiated outward, towards empty space, which is very cold indeed (a "heat sink").
As a result, the cooking vessel now becomes a small refrigerator. We routinely achieve cooling of about 20? F (10? C) below ambient air temperature using this remarkably simple scheme.
In September 1999, we placed two funnels out in the evening, with double-bagged jars inside. One jar was on a block of wood and the other was suspended in the funnel using fishing line. The temperature that evening (in Provo, Utah) was 78? F. Using a Radio Shack indoor/outdoor thermometer, a BYU student (Colter Paulson) measured the temperature inside the funnel and outside in the open air. He found that the temperature of the air inside the funnel dropped quickly by about 15 degrees, as its heat was radiated upwards in the clear sky. That night, the minimum outdoor air temperature measured was 47.5 degrees - but the water in both jars had ICE. I invite others to try this, and please let me know if you get ice at 55 or even 60 degrees outside air temperature (minimum at night). A black PVC container may work even better than a black-painted jar, since PVC is a good infrared radiator - these matters are still being studied.
Chill Out
After our recent move we were without a refrigerator for a couple weeks (although it felt much longer) and it certainly drove home the desirability and convenience of refrigeration. It really made me think about what we would do in a long-term power outage.
On my old computer (may it rest in peace) was a file about 'cooling pots'; since I can no longer access that file I started prowling the web and discovered a couple things that caught my attention; I hope you'll find them of interest.
http://4.bp.blogspot.com/_vnDOor7Jic0/SqqgG4IozrI/AAAAAAAABeE/kl_eQVUEyks/s400/zeer_pots.jpg (http://4.bp.blogspot.com/_vnDOor7Jic0/SqqgG4IozrI/AAAAAAAABeE/kl_eQVUEyks/s1600-h/zeer_pots.jpg)
First the pots
Here's information taken from wikiHow.com (http://www.wikihow.com/Make-a-Pot-in-a-Pot-Refrigerator) on How to Make a Pot in Pot Refrigerator. They're called Zeer pots
In a community without electricity, storage of food long-term can be tricky. One simple solution is to build your own pot-in-a-pot fridge, using basic pots, sand and water. An idea revived by Muhammed Bah Abba, this neat item is now being used by many farmers in warm climates who need to preserve their food for a longer time and keep the insects away. Keeping the sand moist all the time enables evaporation to cool the produce kept inside the inner pot. This enables the storage of freshly grown vegetables to last much longer than usual in a hot climate. Here is how to make your own.
Steps
Obtain two large clay or terracotta pots [must be unglazed]. One pot must be smaller than the other pot. Check that the smaller pot fits inside the larger and that there is a space around it of at least one centimetre, up to three centimetres [roughly .4 inches to 1.2 inches].
Fill in any holes at the base of the pots. Use clay, large pebbles, cork, a homemade paste - anything suitable on hand to fill the hole. If you leave the holes open, the water will enter the inner pot and will also run out of the larger pot, making the fridge ineffective.
Fill the base of the larger pot with sand. Only fill to a height that will ensure the smaller pot sits even in height with the larger pot.
Place the small clay pot. Place it into the large pot on top of the lower layer of sand.
Fill all around the small pot with sand. Fill it right to the top.
Pour water into the sand. Do this until the sand is completely soaked and unable to take any more water.
Take a cloth or towel and dip it into water. Place it over the top of the inner pot so that it covers it completely.
Allow the inner pot to cool down. If you have a thermometer, you can use this, otherwise test with your hands.
Keep the pot-in-pot refrigerator in a dry, ventilated space for the water to evaporate effectively towards the outside.
Place your vegetables inside for storage. You will need to keep checking regularly for the dampness of the sand. Pour in more water as it becomes drier to keep it well moistened. Usually this will need to be done twice a day.
Tips
Try different types of vegetables and fruit to see how long they last using the pot. . . . eggplants can last for 27 days rather than three, African spinach can be kept for 12 days instead of spoiling after one day, while tomatoes and peppers stay fresh for three weeks.
It is also possible to store sorghum and millet grains this way - the pot-in-pot refrigerator protects against humidity and stops fungi growth.
Meat can be kept for up to two weeks, as opposed to a few hours without this device.
Water and other liquids can be kept at 15?C [59?F].
Evaporative cooling works most effectively in dry heat and this pot-in-pot refrigerator is no different. In high humidity, you will find that this solution does not work.
Things you'll need
Two clay (terracotta) pots, one larger than the other
Sand
Water
Cloth to cover the pots
Clay, cork or other material to plug holes in the pots if they have them
<HR align=center width="15%" noShade SIZE=3>
http://2.bp.blogspot.com/_vnDOor7Jic0/SqqtnN0FKaI/AAAAAAAABeM/p7S4yavD24s/s400/ice_cubes_xs.jpg (http://2.bp.blogspot.com/_vnDOor7Jic0/SqqtnN0FKaI/AAAAAAAABeM/p7S4yavD24s/s1600-h/ice_cubes_xs.jpg)
Not everyone lives in a low-humidity climate but that doesn't mean there aren't electricity-free ways available to cool your food. Below is an excerpt of a post from Solar Cooking (http://solarcooking.org/radiant-fridge.htm). Solar Cooking?!? Yes, indeed . . . this is so cool - literally!
Using a Solar Oven as a
Radiant Refrigerator at Night
My first experiments were during a winter in 1997 in Kalgoorlie, an inland location of Western Australia: The ambient nighttime minimum was getting down to 2-3 degrees above zero (Celsius) [roughly 35-37 degrees Fahrenheit]. Using a box-cooker with a black base, I poured about half a centimeter deep of water into the bottom of the cooker and put it outside at night. The glass lid had to be removed as glass is opaque to infrared and would inhibit the cooling. I put the cooker (uncooker?) in a location where it saw a maximum amount of sky and no trees or buildings (on the roof of my house).
The sky needed to be clear all night, with still air. I was using rainwater as the town water contained additives which may have lowered the freezing point. I would set the alarm clock for about 5am, get out of bed and climb onto the roof in the near dark (unfun) and remove a solid disk of ice from the now uncooker (much fun). I got ice consistently over several nights, even though there was no frost on the ground, and pots of water sitting next to the box cooker did not freeze.
<HR align=center width="15%" noShade SIZE=3>
And, just so you don't think this can only be done in Australia, here's an excerpt from the writings of, now retired, BYU physics professor Steven Jones (http://www.solarcooking.org/plans/funnel.htm):
http://4.bp.blogspot.com/_vnDOor7Jic0/SqqxanxpSaI/AAAAAAAABeU/9wChn6jLZRY/s400/Solar+Funnel.jpg (http://4.bp.blogspot.com/_vnDOor7Jic0/SqqxanxpSaI/AAAAAAAABeU/9wChn6jLZRY/s1600-h/Solar+Funnel.jpg)
How to Use the Solar Funnel
as a Refrigerator/Cooler
A university student (Jamie Winterton) and I were the first to demonstrate that the BYU Solar Funnel Cooker can be used - at night - as a refrigerator. Here is how this is done.
The Solar Funnel Cooker is set-up just as you would during sun-light hours, with two exceptions:
1. The funnel is directed at the dark night sky. It should not "see" any buildings or even trees. (The thermal radiation from walls, trees, or even clouds will diminish the cooling effect.).
2. It helps to place 2 (two) bags around the jar instead of just one, with air spaces between the bags and between the inner bag and the jar. HDPE and ordinary polyethylene bags work well, since polyethylene is nearly transparent to infrared radiation, allowing it to escape into the "heat sink" of the dark sky.
During the day, the sun's rays are reflected onto the cooking vessel which becomes hot quickly. At night, heat from the vessel is radiated outward, towards empty space, which is very cold indeed (a "heat sink").
As a result, the cooking vessel now becomes a small refrigerator. We routinely achieve cooling of about 20? F (10? C) below ambient air temperature using this remarkably simple scheme.
In September 1999, we placed two funnels out in the evening, with double-bagged jars inside. One jar was on a block of wood and the other was suspended in the funnel using fishing line. The temperature that evening (in Provo, Utah) was 78? F. Using a Radio Shack indoor/outdoor thermometer, a BYU student (Colter Paulson) measured the temperature inside the funnel and outside in the open air. He found that the temperature of the air inside the funnel dropped quickly by about 15 degrees, as its heat was radiated upwards in the clear sky. That night, the minimum outdoor air temperature measured was 47.5 degrees - but the water in both jars had ICE. I invite others to try this, and please let me know if you get ice at 55 or even 60 degrees outside air temperature (minimum at night). A black PVC container may work even better than a black-painted jar, since PVC is a good infrared radiator - these matters are still being studied.