Cajun Corner – Vol.
4, No. 39 – October 15, 2012
Bon
Jour! Welcome to Cajun
Stitchery’s weekly email and welcome to our family.
ΘΘΘΘΘ
Don’t forget to visit us at www.cajunstitchery.com, www.flickr.com/photos/cajunstitchery,
and, www.cajunstitchery.etsy.com
often. We are also on Twitter and
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Visit
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I apologize to all of our readers. I totally forgot to write Cajun Corner this
weekend. This must be a sign of age
creeping up on me.
A few weeks back I was at the fabric store
looking for some tailor chalk. They had
a pen with one side having a water soluble ink and the other side of the pen
was disappearing ink. I’ve never tried
either of these methods of marking fabric but I have heard a lot of positive
remarks from friends and on forums. The
pen was purchased and while making the recent tablecloth, the water soluble
part of the pen was used. The moment
came when the ink needed to go away. All
I did was get a damp cloth and apply water and the ink vanished. It didn’t get smeared like normal ink would;
it vanished completely. As the cloth
dried some of the ink came back. Not to
worry though. It will all disappear completely
once washed. The invisible ink on the
other end of the pen wasn’t used because the instructions say that it will
disappear in about 24-48 hours. That
part of the pen wasn’t used since the tablecloth took longer than 48 hours to
make and the reference marks were needed.
Goodbye tailor’s chalk. Hello
water soluble pen.
This past weekend towels were embroidered. One of the towels had a beautiful design of
mermaids playing with a dolphin. The design
had lots of shading and other items that distorted the main design. Many of the design parts were removed leaving
only the dolphin and mermaids. The
dolphin looked a bit goofy with all of the shading but didn’t look right
without any shading. Some of the shading
was removed and some remained. When the
design was stitched out a medium gray thread was used for the dolphin and black
was used for the shaded areas. Oh my
goodness, once stitched out the black made the dolphin look bad. Then I realized that one of the mermaids only
had half a tail. The design was redone
using a darker gray instead of the black and the mermaid tail was
repaired. It turned out much
better. The towel with the original design of the
dolphin with the black shading remains as scrap.
While on Facebook this past weekend a friend
inquired about a design of praying hands.
A search through our stock design revealed three designs of praying
hands. The photos were posted in reply
to the request. The lady was very
excited and ordered one of the designs.
However, she wanted the design the size of real hands. The design was increased to 7” tall. Her mother’s name was added. I asked what she would like the design
embroidered onto and she just didn’t understand. Finally, I told her that the design was
pretty heavy and would work well on denim; perhaps the density could be lowered
for a lighter fabric. She finally
realized what I was asking and said that she would like the design embroidered
on a doily to give to her mother for Christmas and thought denim would be
“cool.” Hmmmm, denim is an odd fabric
for a doily but just because it isn’t the usual, doesn’t mean that it wouldn’t
be lovely. A 10” denim circle with a
satin stitched edge and the design embroidered inside the circle was done. It wasn’t too bad but does need to be tweaked. Now I’m thinking about adding some lace around
the doily to give it a dainty look.
While sitting at our kitchen table one evening
this week, I heard something on the window and turned to see a large bug
crawling on the outside of our window.
It was a cicada. I’ve heard them
in the trees and I’ve seen their empty casings; but, I don’t think I’ve ever
actually seen a live and moving cicada.
They are not pretty and probably about 3 or 4 inches long. George looked it up on the internet and they
are not dangerous to humans unless you let them stay on your arm or appendage
for a long time. They apparently have a
long head and tongue hidden under their armor that bores into trees and lays
eggs in the wood and eats the inside of the wood. Sometimes they mistake a human arm or leg as
a tree branch but only if they have been on the arm or leg for a long
time. They do eat your garden. I refused to go outside until George killed
the thing. Ewwww, that was creepy.
We are still waiting for signs of tomatoes on the
beefsteak tomato plants. They have
flowers but so far no signs of fruit.
The cherry tomatoes have lots of little green tomatoes that we will be
harvesting as soon as they show signs of turning red.
It is October and Christmas is right around the
corner. Are you ready?
Ideas for embroidered Christmas gifts: linens, sheets, pillow cases, blankets,
bedcovers; towels, bath, beach, hand, wash, fingertip/tea; kitchen towels, pot
holds, trivets, coasters, napkins, tablecloth, placemats, apron, plastic bag
caddy; and, of course, handkerchiefs, shirts, jackets, and caps. We now offer embroidered doilies, too.
Have a
wonderful week.
If you are not a subscriber and
would like to receive Cajun Corner weekly, please email cajunstitchery@yahoo.com and let me
know to put you on our email list.
The
Solar Funnel Cooker
How to Make and Use the
BYU Solar Cooker/Cooler
by
Steven E. Jones, Professor of Physics
at Brigham Young University (BYU), with Colter Paulson, Jason Chesley, Jacob
Fugal, Derek Hullinger, Jamie Winterton, Jeannette Lawler, and Seth, David,
Nathan, and Danelle Jones.
Introduction
A few
years ago, I woke up to the fact that half of the world's peoples must burn
wood or dried dung in order to cook their food. It came as quite a shock to me,
especially as I learned of the illnesses caused by breathing smoke day in and
day out, and the environmental impacts of deforestation -not to mention the
time spent by people (mostly women) gathering sticks and dung to cook their
food. And yet, many of these billions of people live near the equator, where
sunshine is abundant and free. Ergo...
As
a University Professor of Physics with a background in energy usage, I set out
to develop a means of cooking food and sterilizing water using the free energy
of the sun. First, I looked at existing methods.
The
parabolic cooker involves a reflective dish that concentrates sunlight to a
point where the food is cooked. This approach is very dangerous since the sun's
energy is focused to a point which is very hot, but which cannot be seen. (BYU
students and I built one which will set paper on fire in about 3 seconds!) I
learned that an altruistic group had offered reflecting parabolas to the people
living at the Altiplano in Bolivia.
But more than once the parabolas had been stored next to a shed -- and the
passing sun set the sheds on fire! The people did not want these dangerous,
expensive devices, even though the Altiplano region has been stripped of fuel
wood.
The
box cooker: Basically an insulated box with a glass or plastic lid, often with
a reflecting lid to reflect sunlight into the box. Light enters through the top
glass (or plastic), to slowly heat up the box. Problems: energy enters only
through the top, while heat is escaping through all the other sides, which have
a tendency to draw heat away from the food. When the box is opened to put food
in or take it out, some of the heat escapes and is lost. Also, effective box
cookers tend to be more complicated to build than the funnel cooker.
While
studying this problem, I thought again and again of the great need for a safe,
inexpensive yet effective solar cooker. It finally came to me at
Christmastime a few years ago, a sort of hybrid between the parabola and a box
cooker. It looks like a large, deep funnel, and incorporates what I believe are
the best features of the parabolic cooker and the box cooker.
The
first reflector was made at my home out of aluminum foil glued onto cardboard,
then this was curved to form a reflective funnel. My children and I figured out
a way to make a large card-board funnel easily. (I'll tell you exactly how to
do this later on.)
The
Solar Funnel Cooker is safe and low cost, easy to make, yet very effective in
capturing the sun's energy for cooking and pasteurizing water -> Eureka!
Later,
I did extensive tests with students (including reflectivity tests) and found
that aluminized Mylar was good too, but relatively expensive and rather hard to
come by in large sheets. Besides, cardboard is found throughout the world and
is inexpensive, and aluminum foil is also easy to come by. And individuals can
make their own solar cookers easily, or start a cottage-industry to manufacture
them for others.
Prototypes
of the Solar Funnel Cooker were tested in
Bolivia, and outperformed an
expensive
solar box cooker
and a "
Solar Cookit"
- while costing much less.
Brigham
Young University
submitted a patent application, mainly to insure that no company would prevent
wide distribution of the Solar Funnel Cooker. BYU makes no profit from the invention.
(I later learned that a few people had had a similar idea, but with methods
differing from those developed and shown here.) So now I'm trying to get the
word out so that the invention can be used to capture the free energy of the
sun - for camping and for emergencies, yes, but also for every day cooking
where electricity is not available and even fuel wood is getting scarce.
How it Works
The
reflector is shaped like a giant funnel, and lined with aluminum foil. (Easy to
follow instructions will be given soon.) This funnel is rather like the
parabolic cooker, except that the sunlight is concentrated along a line (not a
point) at the bottom of the funnel. You can put your hand up the bottom of the
funnel and feel the sun's heat, but it will not burn you.
Next,
we paint a jar black on the outside, to collect heat, and place this at the
bottom of the funnel. Or one can use a black pot, with a lid. The black vessel
gets hot, fast. But not quite hot enough to cook with... We need some way to
build up the heat without letting the air cool it. So, I put a cheap plastic
bag around the jar -- voila, the solar funnel cooker was born! The plastic bag,
available in grocery stores as a "poultry bag", replaces the
cumbersome and expensive box and glass lid of the solar box ovens. You can use
the plastic bags used in American stores to put groceries in, as long as they
let a lot of sunlight pass. (Dark- colored bags will not do.)
I
recently tested a bag used for fruits and vegetables, nearly transparent and
available free at American grocery stores, that works great. This is stamped
"HDPE" for high-density polyethylene on the bag (ordinary
polyethylene melts too easily). A block of wood is placed under the jar to help
hold the heat in. (Any insulator, such as a hot pad or rope or even sticks,
will also work.)
A
friend of mine who is also a Physics Professor did not believe I could actually
boil water with the thing. So I showed him that with this new "solar
funnel cooker," I was able to boil water in Utah in the middle of winter! I laid the
funnel on its side since it was winter and pointed a large funnel towards the
sun to the south. I also had to suspend the black cooking vessel -- rather than
placing it on a wooden block. This allows the weaker sun rays to strike the
entire surface of the vessel.
Of
course, the Solar Funnel works much better outside of winter days (when the UV
index is 7 or greater). Most other solar cookers will not cook in the winter in
northern areas (or south of about 35 degrees, either).
I
thought that a pressure cooker would be great. But the prices in stores were
way too high for me. Wait, how about a canning jar? These little beauties are
designed to relieve pressure through the lid -- a nice pressure cooker. And
cooking time is cut in half for each 10º C we raise the temperature (Professor
Lee Hansen, private communication). I used one of my wife's wide-mouth canning
jars, spray-painted (flat) black on the outside, and it worked great. Food
cooks faster when you use a simple canning jar as a pressure cooker. However,
you can also put a black pot in the plastic bag instead if you want. But don't
use a sealed container with no pressure release like a mayonnaise jar -- it can
break as the steam builds up! (I've done it.)
How to Build Your Own
Solar Funnel Cooker
What
You will Need for the Funnel Cooker:
- A piece of flat cardboard,
about 2 feet wide by 4 feet long. (The length should be just twice the
width. The bigger, the better.)
- Ordinary aluminum foil.
- A glue such as white glue
(like Elmer's glue), and water to mix with it 50-50. Also, a brush to
apply the glue to the cardboard (or a cloth or paper towel will do). Or,
some may wish to use a cheap "spray adhesive" available in spray
cans. You can also use wheat
paste.
- Three wire brads-- or small
nuts and bolts, or string to hold the funnel together.
- For a cooking vessel, I
recommend a canning jar ("Ball" wide-mouth quart jars work fine
for me; the rubber ring on the lid is less likely to melt than for other
jars I've found. A two-quart canning jar is available and works fine for
larger quantities of food, although the cooking is somewhat slower.).
- The cooking jar (or vessel)
should be spray-painted black on the outside. I find that a cheap flat-black
spray paint works just fine. Scrape off a vertical stripe so that you have
a clear glass "window" to look into the vessel, to check the
food or water for boiling.
- A block of wood is used as an
insulator under the jar. I use a piece of 2"X4" board which is
cut into a square nominally 4" x 4" by about 2" thick.
(10cm square x 5cm thick.) One square piece of wood makes a great
insulator.
- A plastic bag is used to go
around the cooking-jar and block of wood, to provide a green-house effect.
Suggestions:
·
Reynolds™ Oven Bag, Regular Size works great:
transparent and won't melt. (Cost about 25 cents each in U.S. grocery
stores.)
·
Any nearly-transparent HDPE bag (High-density
Polyethylene). Look for "HDPE" stamped on the bag. I've tested HDPE
bags which I picked up for free at my grocery store, used for holding
vegetables and fruits. These are thin, but very inexpensive. Tested
side-by-side with an oven bag in two solar funnels, the HDPE bag worked just as
well! (Caution: we have found that some HDPE bags will melt should they contact
the hot cooking vessel. For this reason, we recommend using the oven-safe
plastic bag wherever possible.)
·
An
idea attributed to Roger Bernard and applied now to the BYU Funnel Cooker:
place a pot (having a blackened bottom and sides) in a glass bowl, and cover
with a lid. Try for a tight fit around the bottom to keep hot air trapped
inside. The metal pot or bowl should be supported around the rim only, with an
air space all around the bottom (where the sunlight strikes it). Put a
blackened lid on top of the pot. Then simply place this pot-in-bowl down in the
bottom of the funnel - no plastic bag is needed! This clever method also allows
the cook to simply remove the lid to check the food and to stir. I like this
idea - it makes the solar cooker a lot like cooking over a fire. See
Photographs for further details.
Construction Steps
Cut
a Half-circle out of the Cardboard
Cut
a half circle out of the cardboard, along the bottom as shown below. When the
funnel is formed, this becomes a full-circle and should be wide enough to go
around your cooking pot. So for a 7" diameter cooking pot, the
radius of the half-circle is 7". For a quart canning jar such as I
use, I cut a 5" radius half-circle out of the cardboard.
Form
the Funnel
To
form the funnel, you will bring side A towards side B, as shown in the figure.
The aluminum foil must go on the INSIDE of the funnel. Do this slowly, helping
the cardboard to the shape of a funnel by using one hand to form creases that
radiate out from the half-circle. Work your way around the funnel, bending it
in stages to form the funnel shape, until the two sides overlap and the
half-circle forms a complete circle. The aluminum foil will go on the INSIDE of
funnel. Open the funnel and lay it flat, "inside up", in preparation
for the next step.
Glue
Foil to Cardboard
Apply
glue or adhesive to the top (inner) surface of the cardboard, then quickly
apply the aluminum foil on top of the glue, to affix the foil to the cardboard.
Make sure the shiniest side of the foil is on top, since this becomes your
reflective surface in the Funnel. I like to put just enough glue for one width
of foil, so that the glue stays moist while the foil is applied. I also overlap
strips of foil by about 1" ( or 2 cm). Try to smooth out the aluminum foil
as much as you reasonably can, but small wrinkles won't make much difference.
(If even cardboard is not available, one can simply dig a funnel-shaped hole in
the ground and line it with a reflector, to make a fixed solar cooker for use
at mid-day.)
Join
side A to side B to keep the funnel together.
The
easiest way to do this is to punch three holes in the cardboard that line up on
side A and side B (see figure). Then put a metal brad through each hole and
fasten by pulling apart the metal tines. Or you can use a nut-and-bolt to
secure the two sides (A & B) together.
Be
creative here with what you have available. For example, by putting two holes
about a thumb-width apart, you can put a string, twine, small rope, wire or
twist-tie in one hole and out the other, and tie together.
When
A and B are connected together, you will have a "funnel with two
wings". The wings could be cut off, but these help to gather more
sunlight, so I leave them on.
Tape
or glue a piece of aluminum foil across the hole at the bottom of the funnel,
with shiny side in.
This
completes assembly of your solar funnel cooker.
For
stability, place the Funnel inside a cardboard or other box to provide support.
For long-term applications, one may wish to dig a hole in the ground to hold
the Funnel against strong winds.
Final Steps
At
this stage, you are ready to put food items or water into the cooking vessel or
jar, and put the lid on securely. (See instructions on food cooking times, to
follow.)
Place
a wooden block in the INSIDE bottom of the cooking bag. I use a piece of 2X4
board which is cut into a square nominally 4"X4" by about 2"
thick. Then place the cooking vessel containing the food or water on top of the
wooden block, inside the bag.
Next,
gather the top of the bag in your fingers and blow air into the bag, to
inflate it. This will form a small "greenhouse" around the
cooking vessel, to trap much of the heat inside. Close off the bag with a tight
twist tie or wire. Important: the bag should not touch the sides or lid of the
cooking vessel. The bag may be called a "convection shield," slowing
convection-cooling due to air currents.
Place
the entire bag and its contents inside the funnel near the bottom as shown in
the Photographs.
Place
the Solar Funnel Cooker so that it Faces the Sun
Remember:
Sunlight can hurt the eyes: Please wear sunglasses when using a Solar Cooker!
The Funnel Cooker is designed so that the hot region is deep down inside the
funnel, out of harm's way.
Put the Solar
Funnel Cooker in the sun pointing towards the sun, so that it captures as much
sunlight as possible. The design of the funnel allows it to collect solar
energy for about an hour without needing to be re-positioned. For longer
cooking times, readjust the position of the funnel to follow the sun's path.
It
helps to put the Solar Funnel Cooker in front of a south-facing wall or window
(in the Northern Hemisphere) to reflect additional sunlight into the funnel. A
reflective wall is most important in locations farther from the equator and in
winter. In the Southern Hemisphere, put the Solar Funnel Cooker in front of a
North-facing wall or window to reflect additional sunlight into your cooker.
After Cooking
Remember
that the cooking vessel will be very hot: Use cooking pads or gloves when
handling! If you are heating water in a canning jar, you may notice that the
water is boiling when the lid is first removed - it gets very hot!
Open
the plastic cooking bag by removing the twist-tie. Using gloves or a thick
cloth, lift the vessel out of the bag and place it on the ground or table.
Carefully open the vessel and check the food, to make sure it has finished
cooking. Let the hot food cool before eating.
Helpful Hints
- Avoid leaving fingerprints
and smudges on the inside surface of the cooker. Keep the inner surface
clean and shiny by wiping occasionally with a wet towel. This will keep
the Solar Funnel Cooker working at its best.
- If your funnel gets
out-of-round, it can be put back into a circular shape by attaching a rope
or string between opposite sides which need to be brought closer together.
- For long-term applications, a
hole in the ground will hold the Funnel Cooker securely against winds.
Bring the funnel inside or cover it during rain storms.
- The lids can be used over and
over. We have had some trouble with the rubber on some new canning-jar
lids becoming soft and "sticky." "Ball canning lids"
do not usually have this problem. Running new lids through very hot water
before the first use seems to help. The lids can be used over and over if
they are not bent too badly when opened (pry off lid carefully).
- The jar can be suspended near
the bottom of the funnel using fishing line or string (etc.), instead of
placing the jar on a block of wood. A plastic bag is placed around the jar
with air puffed inside, as usual, to trap the heat. The suspension method
allows sunlight to strike all surfaces of the jar, all around, so that
heats faster and more evenly. This suspension method is crucial for use in
winter months.
- Adjust the funnel to put as
much sunlight onto the cooking jar as possible. Look at the jar to check
where the sunlight is hitting, and to be sure the bottom is not in the
shadows. For long cooking times (over about an hour), readjust the
position of the funnel to follow the sun's path. During winter months,
when the sun is low on the horizon (e.g., in North
America), it is helpful to lay the funnel on its side, facing
the sun.
Tests in Utah
I
have personally used the Solar Funnel Cooker to cook lunches over many weeks.
My favorite foods to cook are potatoes (cut into logs or slices) and carrot
slices. Vegetables cook slowly in their own juices and taste delicious. I also
make rice, melted cheese sandwiches, and even bread in the Solar Funnel Cooker.
I usually put the food out around 11:30 and let it cook until 12:45 or 1 pm,
just to be sure that it has time to cook. I've never had any food burn in this
cooker.
I
have also cooked food in the mountains, at an altitude of around 8,300 feet. If
anything, the food cooked faster there - the sunlight filters through less
atmosphere at high altitudes.
I
find that people are surprised that the sun alone can actually cook food. And
they are further pleasantly surprised at the rich flavors in the foods which
cook slowly in the sun. This inexpensive device does it!
Students
at Brigham Young University
have performed numerous tests on the Solar Funnel Cooker along with other
cookers. We have consistently found much faster cooking using the Solar Funnel
Cooker. The efficiency/cost ratio is higher than any other solar cooking device
we have found to date. Mr. Hullinger also performed studies of transmissivity,
reflectivity and absorptivity of alternate materials which could be used in the
Solar Funnel Cooker. While there are better materials (such as solar-selective
absorbers), our goal has been to keep the cost of the Solar Cooker as low as
possible, while maintaining safety as a first priority.
Tests in Bolivia
The
BYU Benson Institute organized tests between the Solar Funnel Cooker and the
"old-fashioned" solar box oven. The solar box oven cost about $70 and
was made mostly of cardboard. It took nearly two hours just to reach water
pasteurization temperature. The Bolivian report notes that "food gets cold
every time the pots are taken from and into the oven." The solar box oven
failed even to cook boiled eggs. (More expensive box cookers would hopefully
work better.)
An
aluminized-mylar Solar Funnel Cooker was also tested in Bolivia, during
the Bolivian winter. Water pasteurization temperature was reached in 50
minutes, boiled eggs cooked in 70 minutes, and rice cooked in 75 minutes. The
Bolivian people were pleased by the performance. So were we! (La Paz, Bolivia,
August, 1996)
I
also donated two dozen solar funnel cookers for people in Guatemala.
These were taken there by a group of doctors going there for humanitarian
service. The people there also liked the idea of cooking with the sun's free
energy! For an aluminized-Mylar Solar Funnel Cooker kit, please contact CRM
(licensed manufacturer) at +1 (801) 292-9210.
Water and Milk
Pasteurization
Contaminated
drinking water or milk kills thousands of people each day, especially children.
WHO reports that 80% of illnesses in the world are spread through contaminated
water. Studies show that heating water to about 65º - 70º C (150º F) is
sufficient to kill coliform bacteria, rotaviruses, enteroviruses and even
Giardia. This is called pasteurization.
Pasteurization
depends on how hot and how long water is heated. But how do you know if the
water got hot enough? You could use a thermometer, but this would add to the
cost, of course. When steam leaves the canning jar (with lid on tight) and
forms "dew" on the inside of the cooking bag, then the water is
probably pasteurized to drink. (The goal is to heat to 160º Fahrenheit for at
least six minutes.) With a stripe of black paint scraped off the jar, one can
look through the bag and into the jar and see when the water is boiling - then
it is safe for sure.
Safety
Safety
was my first concern in designing the Solar Funnel Cooker, then came low cost
and effectiveness. But any time you have heat you need to take some
precautions.
- The cooking vessel (jar) is
going to get hot, else the food inside won't cook. Let the jar cool a bit
before opening. Handle only with gloves or tongs.
- Always wear dark glasses to
protect from the sun's rays. We naturally squint, but sunglasses are
important.
- Keep the plastic bag away
from children and away from nose and mouth to avoid any possibility of
suffocation.
Cooking with the Solar
Funnel Cooker
What
do you cook in a crock pot or moderate-temperature oven? The same foods will
cook about the same in the Solar Funnel Cooker -- without burning. The charts
below give approximate summer cooking times.
The
solar cooker works best when the UV index is 7 or higher. (Sun high overhead,
few clouds.)
Cooking
times are approximate. Increase cooking times for partly-cloudy days, sun not
overhead (e.g., wintertime) or for more than about 3 cups of food in the
cooking jar.
Stirring
is not necessary for most foods. Food generally will not burn in the solar
cooker.
Vegetables (Potatoes, carrots, squash,
beets, asparagus, etc.)
Preparation: No need to add water if fresh. Cut into slices or
"logs" to ensure uniform cooking. Corn will cook fine with or without
the cob.
Cooking Time: About 1.5 hours
Cereals and Grains (Rice,
wheat, barley, oats, millet, etc.)
Preparation: Mix 2 parts water to every 1 part grain. Amount may vary
according to individual taste. Let soak for a few hours for faster cooking. To
ensure uniform cooking, shake jar after 50 minutes. CAUTION: Jar will be
hot. Use gloves or cooking pads.
Cooking Time: 1.5-2 hours
Pasta and Dehydrated Soups
Preparation: First heat water to near boiling (50-70 minutes). Then
add the pasta or soup mix. Stir or shake, and cook 15 additional minutes.
Cooking Time: 65-85 minutes
Beans
Preparation: Let tough or dry beans soak overnight. Place in cooking jar
with water.
Cooking Time: 2-3 hours
Eggs
Preparation: No need to add water. Note: If cooked too long, egg
whites may darken, but taste remains the same.
Cooking Time: 1-1.5 hours, depending on desired yolk firmness.
Meats (Chicken, beef, and fish)
Preparation: No need to add water. Longer cooking makes the meat more
tender.
Cooking Time: Chicken: 1.5 hours cut up or 2.5 hours whole; Beef: 1.5
hours cut up or 2.5-3 hours for larger cuts; Fish: 1-1.5 hours
Baking
Preparation: Times vary based on amount of dough.
Cooking Times: Breads: 1-1.5 hours; Biscuits: 1-1.5 hours; Cookies: 1
hour
Roasted Nuts (Peanuts, almonds, pumpkin
seed, etc.)
Preparation: Place in jar. A little vegetable oil may be added if
desired.
Cooking Time: About 1.5 hours
MRE's and prepackaged foods
Preparation: For foods in dark containers, simply place the container in
the cooking bag in place of the black cooking jar.
Cooking Times: Cooking time varies with the amount of food and darkness
of package.
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 20º F (10º 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
78º 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.
I
would like to see the "Funnel Refrigerator" tried in desert climates,
especially where freezing temperatures are rarely reached. It should be
possible in this way to cheaply make ice for Hutus in Rwanda and for aborigines in Australia,
without using any electricity or other modern "tricks." We are in
effect bringing some of the cold of space to a little corner on earth. Please
let me know how this works for you.
Conclusion: Why We Need
Solar Cookers
The
BYU Funnel Cooker/Cooler can:
- Cook food without the need
for electricity or wood or petroleum or other fuels.
- Pasteurize water for safe
drinking, preventing many diseases.
- Save trees and other
resources.
- Avoid air pollution and
breathing smoke while cooking.
- Use the sun's free energy. A
renewable energy source.
- Cook food with little or no
stirring, without burning.
- Kill insects in grains.
- Dehydrate fruits, etc.
- Serve as a refrigerator at
night, to cool even freeze water.
The
burden for gathering the fuel wood and cooking falls mainly on women and
children. Joseph Kiai reports from
Dadaab,
Kenya: "Women who can't afford to buy wood start at 4 am to go
collecting and return about noon... They do this twice a week to get fuel for
cooking... The rapes are averaging one per week." From
Belize:
"Many times the women have to go into the forest dragging their small
children when they go to look for wood. It is a special hardship for pregnant
and nursing mothers to chop and drag trees back to the village... they are
exposed to venomous snakes and clouds of mosquitoes." (Anna K.) (Quoted in
newsletters by
Solar Cookers International.)
And
the forests are dwindling in many areas. Edwin Dobbs noted in Audubon
Magazine, Nov. 1992, "The world can choose sunlight or further
deforestation, solar cooking or widespread starvation..."
Americans
should be prepared for emergencies, incident to power failures. A Mormon
pioneer noted in her journal: "We were now following in their trail
traveling up the Platte
River. Timber was
sometimes very scarce and hard to get. We managed to do our cooking with what
little we could gather up..." (Eliza R. Snow) Now there's someone who
needed a light-weight Solar Cooker!
Here's
another reason to use a solar cooker. Many people in developing countries look
to see what's being done in America.
I'm told that if Americans are using something, then they will want to try it,
too. The more people there are cooking with the sun, the more others will want
to join in. A good way to spread this technology is to encourage small local
industries or families to make these simple yet reliable solar cookers for
others at low cost. I've used this cooker for three summers and I enjoy it.
Cooking and making ice with the funnel cooker/cooler will permit a significant
change in lifestyle. If you think about it, this could help a lot of people.
The BYU Solar Funnel Cooker uses the glorious sunshine -- and the energy of the
sun is a free gift from God for all to use!
Will the cooker work in winter (in the United States)?
As
the sun moves closer to the southern horizon in the winter, the solar cooker is
naturally less effective. A good measure of the solar intensity is the “UV
index” which is often reported with the weather. When the ultraviolet or UV
index is 7 or above– common in summer months– the solar cooker works very well.
In Salt Lake City
in October, the UV index was reported to be 3.5 on a sunny day. We were able to
boil water in the Solar Funnel Cooker during this time, but we had to suspend
the black jar in the funnel so that sunlight struck all sides. (We ran a
fishing line under the screw-on lid, and looped the fishing line over a rod
above the funnel. As usual, a plastic bag was placed around the jar, and this
was closed at the top to let the fishing line out for suspending the jar.)
The
solar “minimum” for the northern hemisphere occurs on winter solstice, about
December 21st each year. The solar “maximum” occurs six months later, June
21st. Solar cooking works best from about March 20 - October 1 in the north. If
people try to cook with the sun for the first time outside of this time window,
they should not be discouraged. Try again when the sun is more directly
overhead. (One may also suspend the jar in the funnel, which will make cooking
faster any time of the year.)
It
is interesting to note that most developing countries are located near the
equator where the sun is nearly directly overhead all the time. Solar Cookers
will then serve year-round, as long as the sun is shining, for these fortunate
people. They may be the first to apply fusion energy (of the sun) on a large
scale! And they may accomplish this without the expensive infrastructure of
electrical power grids that we take for granted in America.
How
do you cook bread in a jar?
I
have cooked bread by simply putting dough in the bottom of the jar and placing
it in the funnel in the usual way. Rising and baking took place inside the jar
in about an hour (during summer). One should put vegetable oil inside the jar
before cooking to make removal of the bread easier. I would also suggest that
using a 2-quart wide-mouth canning jar instead of a 1-quart jar would make
baking a loaf of bread easier.
What
is the optimum “opening angle” for the funnel cooker?
A
graduate student at Brigham
Young University
did a calculus calculation over two years ago to assess the best shape or
opening angle for the Solar Funnel. Jeannette Lawler assumed that the best
operation would occur when the sun’s rays bounced no more than once before
hitting the cooking jar, while keeping the opening angle as large as possible
to admit more sunlight. (Some sunlight is lost each time the light reflects
from the shiny surface. If the sunlight misses on the first bounce, it can
bounce again and again until being absorbed by the black bottle.) She set up an
approximate equation for this situation, took the calculus-derivative with
respect to the opening angle and set the derivative equal to zero. Optimizing
in this way, she found that the optimum opening angle is about 45 degrees, when
the funnel is pointed directly towards the sun.
But
we don’t want to have to “track the sun” by turning the funnel every few
minutes. The sun moves (apparently) 360 degrees in 24 hours, or about 15
degrees per hour. So we finally chose a 60-degree opening angle so that the
cooker is effective for about 1.2 hours. This turned out to be long enough to
cook most vegetables, breads, boil water, etc. with the Solar Funnel Cooker. We
also used a laser pointer to simulate sun rays entering the funnel at different
angles, and found that the 60-degree cone was quite effective in concentrating
the rays at the bottom of the funnel where the cooking jar sits.
For
questions regarding the complete Solar Funnel Cooker kit using aluminized Mylar
and a jar for the cooking vessel, please contact CRM at +1 (801) 292-9210.
Recent updates to this project can be found at http://physics1.byu.edu/jones/rel491/solarbowl.htm.
C’est tout, mes amis
Peggy Henshall
Cajun Stitchery
(850) 261-2462
P.S. You are always
welcome to stop by and look at all of the catalogs and pass some time with me,
cher.
