Good day to all comrades!
I want to offer to your attention an interesting article about alternative energy — solar ovens. In my opinion a very topical and ellementarnye device to BP as well as after it. These furnaces have a huge number of advantages, what you will be convinced after reading the article.
Hopefully someone will find something important
Hopefully not happen BP associated with nuclear winter, and that such a device would not make effective.
]Successful use of solar cookers (Plates) was observed in Europe and India as early as the 18th century. Solar cookers and ovens, absorb solar energy and convert it into heat that builds up inside the enclosed space. Absorbed heat is used for cooking, roasting and baking. The temperature in the solar oven can reach 200 degrees Celsius.
Solar cookers come in different shapes and sizes.
Here are a few examples: oven, stove Hub reflector solar steam cookers, etc. With all the variety of models, all furnaces trap heat it in a thermally insulated chamber. In most models, sunlight directly affects food.
Box-type solar OVENS
Pans for solar cookers consist of a well-insulated box, painted in black, which is placed in the black pots with food. Box covered with a double-layered «window» that lets solar radiation enter the box and keeps the heat inside. In addition to securing the cover it with a mirror on the inside, which, when folded, to amplify the incident radiation, and in a closed form improves the thermal insulation of the furnace.
The main advantages of box solar cookers:
-Use of both direct and diffuse solar radiation.
-They can be heated at the same time a couple of pans.
-They are lightweight, portable and easy to handle.
-They do not need to track the sun.
-Moderate temperatures make stirring unnecessary.
-The food stays warm all day.
-They are easy to make and repair using locally available materials.
-They are relatively inexpensive (compared to other types of solar furnaces).
Inherent in them, of course, some drawbacks:
-With their help, you can prepare only in the daytime.
-The moderate temperatures for long cooking time.
-Glass lid leads to a significant loss of heat.
-Such ovens «can not» fry.
Due to their advantages, Solar cooking boxes are the most common type of solar cooker. They come in different types: industrial, artisanal and homemade; shapes resembling a suitcase or a low box. There are also stationary oven made of clay, with a horizontal cover (in tropical and subtropical areas) or inclined (in temperate climates). For a family of five Standard models with aperture area (entrance area) of about 0.25 m2. In trade, and larger versions measuring
Why is better to cook food in a solar oven?
Food cooked in a solar oven is always fresh, tasty, fragrant and useful!
Cooking in a solar oven like magic — you put raw food in a black box and took out a juicy, tender, cooked lunch, the sun itself. You can enjoy a day off, knowing that the sun at this time working hard on preparing your dinner. The food cooked by the sun, not foothills, does not stick to the pan and not digested. Solar oven all turns into a gourmet, even those who do not know how to cook.
Solar oven does not require monetary investment, you pay for it only once when buying it! You do not have to pay more for electricity, buy coal or gas cylinders. You can prepare meals in the street during the summer, thus keeping you cool inside the house and reducing the cost of air conditioning.
Solar ovens cook food and do not harm the environment. The air is not polluted by smoke or greenhouse gases, and the furnace does not require any fossil fuels or electricity.
Cooking in a solar oven can be even in parks where breeding is generally prohibited by the open fire. Solar oven does not pose any risk of fire.
The sun rises every morning, but the use of solar energy for cooking does not deplete the earth’s resources.
The use of solar ovens for cooking dinner can become a pleasant and opportunities to spend time with children. You can turn off the TV and the computer, turn on the answering the phone and go to the yard or go to the country, and there family cook sunny sandwiches. Children not only have healthy food, but also be able to learn something new about the sun, its energy of natural phenomena in general. Get interesting, exciting, and most importantly, delicious and informative tutorial!
With solar oven you have the option of choosing between the time you need to spend on cooking dinner and the time it takes to move a solar furnace following the movement of the sun. Solar oven is very easy to move from place to place, so you can use it not only on his own backyard, but also in the park, on the beach, in the campaign and even during water travel on your own boat or yacht.
Thanks to solar oven you spend much less time to cook even the most difficult dishes. You can put a piece in the early morning of frozen meat in your solar oven, put it in a place where there is sun in the middle of the day, and coming home from work to get ready dinner as the oven not only unfreeze meat, but cook it during your absence.
Solar oven does not require special care, it is very easy to wash, because thanks to a uniform temperature distribution in the products it does not Pidgir’ya not pestered to the bottom of the pan.
Owning a solar oven forever protect you from a variety of natural disasters, which usually entail disconnection from the power supply. You can always boil water or cook dinner in the event of an accident at a power plant.
Recommendations for the construction of a solar furnace
Since the heat absorbed by the inner surface of the box needs to be casseroles, best choice of material — aluminum, having high thermal conductivity. Moreover, aluminum is subject to corrosion. For example, steel box, even galvanized, can not long withstand the hot and humid environment inside the oven during cooking. Sheet copper is prohibitively expensive.
Outside of the box can not be attached metal parts that can create thermal bridges. The insulation may consist of glass, rock wool or some natural material (peanut hulls, coconut, rice, corn, etc.). Whichever material is used, it must be kept dry.
The cover may consist of one or two glass sheets with an air gap. The distance between two layers of glass is typically 10-20 mm. Studies have shown that the use of a transparent material with cellular structure, which divides the inner space into small vertical compartments may significantly reduce heat loss furnace, thereby increasing its efficiency. The inner glass is subjected to thermal effects, so often used tempered glass; or both layers may consist of normal glass with a thickness of about 3 mm.
Outer cover of solar oven is a reflector, amplify the incident radiation. Reflective surface can an ordinary glass mirror, plastic sheet with a reflective coating or a metal mirror unbreakable. In a pinch, you can use the foil from cigarette packs.
External solar furnace box may be made of wood, fiberglass or metal. Fiberglass is lightweight, inexpensive and resistant, but not stable enough for continuous use. Wood is more stable, but heavier and more susceptible to deterioration due to moisture. Aluminum sheets with wooden bracing offers the best finish, resistant to mechanical stress, temperature changes and humidity. Aluminum-clad wooden box is the most durable, but it is expensive and heavy, besides its production takes time.
Performance standard solar oven an aperture with an area of 0.25 m2 reaches about 4 kg of food per day, i.e. sufficient for a family of five.
Peak temperature inside the solar oven can reach more than 150 ° C. on a sunny day in the tropics; is approximately 120 º C above the ambient temperature. Since the water content of food is not heated above 100 º C, the temperature inside the oven will always be filled with correspondingly lower.
The temperature in the solar furnace drops off sharply when it placed the dishes with food. It is also important that the temperature remains well below 100 º C most of the cooking time. But the boiling point of 100 º C is not necessary for most vegetables and cereals.
Average time cooking in a solar oven is 1-3 hours for good insolation and a reasonable boot.
Thin-walled aluminum pans much shorter cooking times compared to stainless steel cookware.
Moreover, such influence and factors:
-Cooking time is shortened by strong light, and vice versa.
-High ambient temperatures shorten the cooking time, and vice versa.
-A small amount of food in a single cooking reduces cooking time — and vice versa.
Solar radiation furnace
The main prerequisite for the successful use of a solar furnace is adequate illumination with a small number of cloudy days during the year. Duration and intensity of the solar radiation must allow solar furnace over longer periods. While in Central Europe cooking with solar energy possible on a sunny summer day, solar furnace is desirable for the minimum amount of solar energy in 1500 kWh/m2 per year (corresponding to an average daily insolation of 4 kWh/m2). But annual data can sometimes be misleading. The essential condition for a solar furnace — a stable summer weather, that is regular, predictable periods of cloudless days.
Solar energy resources in different countries differ greatly even within the tropical zone in the third world. For example, solar radiation in most parts of India is considered to be very good in terms of the use of solar energy. The average amount of solar energy is from 5 to 7 kWh/m2 per day depending on the region. Most parts of the insolation reaches its minimum during the rainy season and nearly as weak during December and January.
Climate and solar potential of Kenya favorable to the use of solar cookers. Kenya is located close to the equator and therefore has a tropical climate. In Nairobi, the amount of solar energy is 3.5 kWh/m2 per day in July to 6.5 kWh/m2 per day in February, but in other areas remains virtually unchanged (6.0 — 6.5 kWh/m2 per day in Lodwar). Solar irradiation in Nairobi is adequate for cooking with solar energy nine months of the year (except June-August). On the other hand, on cloudy or hazy days have to rely on traditional fuels. However, the Lodwar solar cookers can be used all year round.
Solar cookers for developing countries
The purpose of solar ovens, undoubtedly, is to save energy in the face of a double energy crisis: the crisis of the poor, is the increasing scarcity of firewood, and nation’s energy crisis — growing pressure on its balance of payments.
Compared with other countries, developing countries consume very little power. For example, the rate of energy consumption per capita in India in 1982 — 7325 GJ — was one of the lowest in the world. But the level of energy consumption in this country is growing almost twice as fast as its gross national product. The same thing happens in other developing countries.
Most people in developing countries receives the bulk of their energy in a non-traditional local sources of energy and their own physical labor. They simply can not afford to buy the right amount of commercial energy.
The logical consequence of this — relative shortage of fuel for the poor, whose living conditions deteriorate even more as a result. Solar cookers — this is a step towards improving their living conditions.
Of all the «poor majority» of citizens of third world countries, solar cookers must be used primarily rural population.
Daily fuel requirement depends on what kind of food being cooked and the quantity. A resident of a developing country burns, on average, 1 ton of firewood per year. A typical Indian family need 3-7 kg of wood per day; in cooler regions, the daily firewood demand is nearly 20 kg and 14 kg in the winter summer. In the south of Mali, the average family (consisting of 15 people) burns about 15 kg of wood per day. A study in an Afghan refugee camp in Pakistan, showed a daily firewood demand of up to 19 kg per family. More than half of the wood in a typical household goes for baking, and others — used for cooking. In winter, of course, requires more firewood.
Despite the fact that amount of energy needed for cooking, is different, solar cookers provide significant energy savings. The primary function of solar cookers — reduced need for firewood, which are still the most important fuel for cooking. The problem is that the wood is inexpensive as compared with the kerosene, bottled gas and electricity. Increasing uncontrolled felling of trees for their own use and for sale is a major cause of deforestation, expanding deserts, soil erosion, groundwater level decline, and has long-term adverse effects on the ecological balance. Meager forest in Pakistan and rampant deforestation in Kenya show that fears about it are not exaggerated. If deforestation in Sudan does not slow down soon from them nothing left.
In general, solar ovens are unlikely to make a significant contribution to the national energy. However, they can very significantly improve the living conditions of the poor, to help them overcome personal energy crisis.
Better than conventional solar oven?
You can bake, boil and even smoke any kind of products using solar energy — you do not need any fuel!
-Temperature reaches 180-200 ° C.
-Cooking in a solar oven is safe as there is no danger of fire and no need to heat the dinner again!
-Solar oven — is a versatile device that is incredibly easy to use. In addition, the kiln can always take with you as a small suitcase!
Cooking food in a solar cooker is easy and fun, and the products retain all the nutrients. In addition, using solar oven, you are helping to protect the environment.
Solar ovens — ideal for everyday use, on a picnic in the country, in the yard of a country home, on vacation or in case of a power outage. They also provide shade in your home, as all the heat from cooking will remain on the street.
Though called a solar furnace and the furnace, it is possible not only to bake anything but cooking, bloating and at temperatures from 180 ° to 200 ° C.
In the solar furnace is no movement of air that allows the food to be juicy, tender and flavorful. Fried foods cooked in solar ovens, much tastier and juicier, and baked in a bread oven has no incomparable taste. Flavor of the dishes from the solar oven will not leave you indifferent!
Heating temperature in the solar furnace increases slowly and evenly, allowing complex carbohydrates converted into monosaccharides and giving food delicate flavor. Because the temperature rises evenly, the food will burn not, and therefore you will not need to stir the dishes during cooking.
There are two ways of cooking in a solar oven.
If every 25-30 minutes turning the solar oven so that it followed the movement of the sun, and the cooking time will be the same way as when cooking in the microwave or in a conventional stove. At the same time, solar oven can be used for slow cooking in medlennovarke. You can prepare all the ingredients for dinner, load them into the solar oven, place the oven in the place where the sun is expected to be when you’re already halfway home. Leave everything as is and go home to a delicious dinner and slowly cooked. Even if you linger in the way, you do not worry about anything, as a solar oven will keep your lunch warm, juicy and fresh for a few hours!
And more information about this type of ovens: Homemade solar kitchen
Homemade solar oven (+ video instruction)
And lastly interesting information about Large Solar Furnace «>