of solar cooker, energy and exergy analysis approach and economic evolution cooker. Thermal performance of box type and concentration type solar cookers. rachel andres, Director, Solar Cooker Project of Jewish World Watch solar cooker .. Appendix A contains detailed instructions on how to use a solar cooker. This booklet includes solar cooking concepts, solar cooker construction plans and Follow regular canning instructions: fill jars almost to the top with fruit and .
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of solar energy devices like solar cooker, solar water heater, solar .. Followings instructions are associated with the full load test of box type solar cooker. PDF | Solar cooking is one of the best clean and environment Different types of solar cookers are designed and developed around the world. PDF | Fossil fuels are today's most accessible sources of energy. However due to their limited resources and greenhouse gas emission, the use of renewable.
Skip to main content. Log In Sign Up. July, ] ISSN: All the conventional solar cooker designs have the disadvantage of inability to cook during off-shine and night hours. This disadvantage can be eliminated if the solar cooker is designed with thermal storage arrangement. In this paper, a hybrid solar cooker with evacuated tube collector and latent thermal storage unit and alternate electric heatingsource is simulated. The heat transfer fluid gets heated in the evacuated tube collector is used for cooking along with alternate electric heating source.
The principle of cooking meals from the sun was largely developed in the French Foreign Legion , in the s . Working Principles[ edit ] 1 Concentrating sunlight: A mirrored surface with high specular reflectivity is used to concentrate light from the sun onto a small cooking area.
Depending on the geometry of the surface, sunlight could be concentrated by several orders of magnitude producing temperatures high enough to melt salt and metal. For most household solar cooking applications, such high temperatures are not really required.
The interaction between the light energy and the receiver material converts light to heat and this is called conduction. This conversion is maximized by using materials that conduct and retain heat.
Pots and pans used on solar cookers should be matte black in color to maximize the absorption. Simply using a glass lid on your pot enhances light absorption from the top of the pan and provides a greenhouse effect that improves heat retention and minimizes convection loss.
This "glazing" transmits incoming visible sunlight but is opaque to escaping infrared thermal radiation. In resource constrained settings, a high-temperature plastic bag can serve a similar function, trapping air inside and making it possible to reach temperatures on cold and windy days similar to those possible on hot days.
Operation[ edit ] Solar oven in use Different kinds of solar cookers use somewhat different methods of cooking, but most follow the same basic principles.
Food is prepared as if for an oven or stove top. However, because food cooks faster when it is in smaller pieces, food placed inside a solar cooker is usually cut into smaller pieces than it might otherwise be. If several foods are to be cooked separately, then they are placed in different containers.
The container of food is placed inside the solar cooker, which may be elevated on a brick, rock, metal trivet , or other heat sink , and the solar cooker is placed in direct sunlight. Rice for a mid-day meal might be started early in the morning, with vegetables, cheese, or soup added to the solar cooker in the middle of the morning. Depending on the size of the solar cooker and the number and quantity of cooked foods, a family may use one or more solar cookers.
A solar oven is turned towards the sun and left until the food is cooked. Unlike cooking on a stove or over a fire, which may require more than an hour of constant supervision, food in a solar oven is generally not stirred or turned over, both because it is unnecessary and because opening the solar oven allows the trapped heat to escape and thereby slows the cooking process.
If wanted, the solar oven may be checked every one to two hours, to turn the oven to face the sun more precisely and to ensure that shadows from nearby buildings or plants have not blocked the sunlight. If the food is to be left untended for many hours during the day, then the solar oven is often turned to face the point where the sun will be when it is highest in the sky, instead of towards its current position.
Air temperature, wind, and latitude also affect performance. Food cooks faster in the two hours before and after the local solar noon than it does in either the early morning or the late afternoon. Large quantities of food, and food in large pieces, take longer to cook. As a result, only general figures can be given for cooking time. With a small solar panel cooker, it might be possible to melt butter in 15 minutes, to bake cookies in 2 hours, and to cook rice for four people in 4 hours.
With a high performing parabolic solar cooker, you may be able to grill a steak in minutes.
However, depending on local conditions and the solar cooker type, these projects could take half as long, or twice as long. It is difficult to burn food in a solar cooker. The exception to this rule is some green vegetables, which quickly change from a perfectly cooked bright green to olive drab , while still retaining the desirable texture. For most foods, such as rice, the typical person would be unable to tell how it was cooked from looking at the final product.
There are some differences, however: Bread and cakes brown on their tops instead of on the bottom. Compared to cooking over a fire, the food does not have a smoky flavor. Box and panel designs[ edit ] HotPot panel solar cooker A box cooker has a transparent glass or plastic top, and it may have additional reflectors to concentrate sunlight into the box.
The top can usually be removed to allow dark pots containing food to be placed inside. One or more reflectors of shiny metal or foil-lined material may be positioned to bounce extra light into the interior of the oven chamber.
Cooking containers and the inside bottom of the cooker should be dark-colored or black. Inside walls should be reflective to reduce radiative heat loss and bounce the light towards the pots and the dark bottom, which is in contact with the pots. The box should have insulated sides. Crumpled newspaper, wool, rags, dry grass, sheets of cardboard, etc.
This is not as hot as a standard oven, but still hot enough to cook food over a somewhat longer period of time. A Solar Oven made of cardboard, newspapers, and reflective tape Panel solar cookers are inexpensive solar cookers that use reflective panels to direct sunlight to a cooking pot that is enclosed in a clear plastic bag.
Solar Oven science experiments are regularly done as projects in high schools and colleges, such as the "Solar Oven Throwdown" at the University of Arizona. Main article: parabolic reflector Parabolic solar cookers concentrate sunlight to a single point.
When this point is focused on the bottom of a pot, it can heat the pot quickly to very high temperatures which can often be comparable with the temperatures achieved in gas and charcoal grills. These types of solar cookers are widely used in several regions of the world, most notably in China and India where hundreds of thousands of families currently use parabolic solar cookers for preparing food and heating water. Some parabolic solar cooker projects in China abate between tons of carbon dioxide per year and receive carbon credits through the Clean Development Mechanism CDM and Gold Standard.
Others are large enough to feed thousands of people each day, such as the solar bowl at Auroville in India, which makes 2 meals per day for 1, people. If the axis of symmetry is aimed at the sun, any object that is located at the focus receives highly concentrated sunlight, and therefore becomes very hot.
This is the basis for the use of this kind of reflector for solar cooking. Paraboloidal reflectors[ edit ] A parabolic solar cooker with segmented construction.
Although paraboloidal solar cookers can cook as well as or better than a conventional stove, they are difficult to construct by hand. Frequently, these reflectors are made using many small segments that are all single curves which together approximate compound curves. Although paraboloids are difficult to make from flat sheets of solid material, they can be made quite simply by rotating open-topped containers which hold liquids.
The top surface of a liquid which is being rotated at constant speed around a vertical axis naturally takes the form of a paraboloid.
Centrifugal force causes material to move outward from the axis of rotation until a deep enough depression is formed in the surface for the force to be balanced by the levelling effect of gravity. It turns out that the depression is an exact paraboloid. See Liquid mirror telescope. If the material solidifies while it is rotating, the paraboloidal shape is maintained after the rotation stops, and can be used to make a reflector.
Devices for constructing such paraboloids are known as rotating furnaces. Paraboloidal reflectors generate high temperatures and cook quickly, but require frequent adjustment and supervision for safe operation.
Several hundred thousand exist, mainly in China. A Scheffler cooker. The Earth receives about 3. Solar energy covers a wide variety of applications in order to harness this available energy resources. Besides the environmental and economic burden of firewood use, there are some serious health problems originate from the utilization of firewood.
Therefore, there is a rising attention concerning the renewable energy options to meet the cooking requirements of people in developing countries. Utilization of solar cookers provides many advantageous like no recurring costs,high nutritional value of food, potential to reduce drudgery and high durability. Also,solar cookers have many advantages, on the health, time and income of the users and on the environment.
High-performance parabolic solar cookers can attain temperatures above C. They can be used to grill meats, stir-fry vegetables, make soup, bake bread and boil water in minutes.
Conventional solar box cookers attain temperatures up to C. Solar cookers use no fuel which saves cost as well as reduces environmental damage caused by fuel use.
Since 2. Any type of cooking may evaporate grease, oil, and other material into the air, hence there may be less cleanup. A solar cooker is a device which uses the energy of direct sunlight to heat, cook or pasteurize food or drink.
The available solar cookers are mainly classified into two groups. Solar Cookers without storage Solar cookers without storage are classified into direct and indirect solar cookers according to the heat transfer mechanism to the cooking vessel.
Figure 1: Different types of direct solar cookers a Panel type b Box type c Prabolic type a Panel type solar cooker Solar panel cookers may be considered the most simple type available due to their ease of construction and low-cost material. In solar panel cookers,sunlight is concentrated from above as shown in Fig. Panel cookers have a flat panel which reflects and focuses sunlight for cooking and heating. This method of solar cooking is not very desirable since it provides a limited cooking power.
Solar panel cookers utilize reflective equipment in order to direct sunlight to a cooking vessel which is enclosed in a clear plastic bag. Solar box cookers are the most common and inexpensive type of solar cookers.
These box cookers have a very simple construction and they are made of low cost materials, which essentially consists of a black painted metallic trapezoidal tray and is usually covered with a double glass window base shown in Fig. However, a parabolic cooker includes risk of burning the food if left unattended for any length of time because of the concentrated power. A solar parabolic cooker simply consists of a parabolic reflector with a cooking pot which is located on the focus point of the cooker and a stand to support the cooking system as shown in Fig.
A very high temperature of between C to C can be reached because of a combination of the circular design, the size and the polished aluminium. These types of solar cooker provide high thermal storage, temperature without tracking and at the same time cooking can take place in shadow or in conventional kitchen inside buildings.
Three types are categorized under indirect solar cookers,one which uses flat plate collector,other with evacuated tube collector and last one with concentrating type. In concentrating type of collector either parabolic or spherical shape is used to concentrate the solar radiation.
Solar Cookers with Storage Cooking outdoors and impossibility of cooking food in late evening hours are the main problems associated with solar cooking systems. Therefore, thermal energy storage is essentially needed to increase the utility and reliability of the solar cookers.
Solar cookers can be equipped with sensible heat storage or latent heat storage methods. Using solar cookers may require food preparation start hours before the meal. The cooking pot is always exposed to the outdoor conditions which is also not much desirable as compared to indoor cooking. Hybrid indirect solar cooker Many designs of solar cookers have been developed by many researchers but all those were fully dependent on solar radiation availability or along with stored thermal energy.
The design of a solar cooker with evacuated tube collector,latent heat storage and alternate electric heating source will be much efficient than conventional cookers since an alternate source is also applied along with the solar energy.
The auxiliary source of energy like LPG or electrical heating is used for supplementing the stored or indirect solar energy. Figure 2: Proposed hybrid solar cooker Energy required from the auxiliary source is to be optimized for the given system,solar insolation at the location and the load profile. Evacuated tube solar cookers are essentially a vacuum sealed between two layers of glass.
The vacuum allows the tube to act both as a super greenhouse and an insulator. It consists of an ETC,a closed loop pumping line containing water as the heat transfer fluid HTF , a PCM storage unit, cooking unit,pump, relief valve, flow meter and a stainless steel tube,heat exchanger.
Thermal storage unit provides facility of cooking food at night also. The proposed indirect hybrid solar cooking unit consists of an evacuated tube collector, thermal storage tank, heat exchanger,alternate electric supply respectively. The heat was supplied by heat transfer fluid to thermal storage unit by natural convection process.
In this system supply of energy was two way, firstly energy supplied by the heat transfer fluid to the cooking pot and secondly energy supplied by electrical means.
This system provides the facility of using electricity and solar energy according to the temperature available at the cooking pot.
The temperature at different points can be monitored using temperature sensors. The temperature thus obtained can be set as the input to compare with a reference value set in the data logger say a PIC micro-controller through a simple program.
The performance of this cooking unit can be controlled effectively by varying the fluid flow rate from collector to thermal storage unit and from thermal storage unit to the heat exchanger. Modeling Equations The solar cooker can be modelled by considering all the inputs,losses and outputs. The input to the solar cooker is purely from sunlight and the electric supply will be actuated only if the solar power is not sufficient.
So for normal analysis,here considering only the solar power input to the collector and the stored heat energy in PCM material as a result of this.