chapter.2
DESCRIPTION
SOLAR COOKERTRANSCRIPT
CHAPTER-2
VARIOUS DESIGN OF SOLAR COOKER
2.1 SOLAR COOKER
Cuce and Cuce Defines solar cooker as: “A solar cooker or solar oven is a device which
utilizes solar energy to cook food. Solar cookers also enable some significant processes such as
pasteurization and sterilization.” The vast majority of solar cookers presently in use are very
cheap, low-tech devices. Because they use no fuel, no operational cost and zero maintenance,
governments of many countries are promoting their use worldwide in order to help reduce fuel
costs and air pollution, and to slow down the deforestation and desertification caused by
gathering firewood for cooking. Solar cooking is a form of outdoor cooking and is often used in
situations where minimal fuel consumption is important, or the danger of accidental fires is high.
2.2 HISTORIC BACKGROUND OF SOLAR COOKER (Cuce and Cuce 2012)
The first experiments on solar cookers were carried out by a German Physicist named
Tschirnhausen (1651–1708). Second attempt was made by French–Swiss Physicist Horace de
Saussure in 1767. He constructed a miniature greenhouse with 5 layers of glass boxes turned
upside down on a black table and reported cooking fruit. An English astronomer Sir John
Herschel also attempts to cook food in a similar insulated in South Africa in 1830. Great French
Mathematician Augustin Mouchot incorporated the heat trap idea with that of the burning mirror
in 1860 and built an efficient solar oven. He also succeeded to create a solar steam engine but it
was too large to be practical. In 1876, W. Adams developed an octagonal oven equipped with 8
mirrors and he reported that the oven cooked rations for 7 soldiers in 2 h. After one year,
Mouchot designed solar cookers for French soldiers in Algeria, including a shiny metal cone,
made from a 105.5 degree section of a circle.
In 1930s India began to investigate solar energy as an option for avoiding deforestation.
The first commercial box-type solar cooker was produced by an Indian pioneer named Sri M.K.
Ghosh in 1945. In 1950s, Indian researchers devised and constructed commercial solar ovens and
solar reflectors, but they were not readily accepted due to the lower-cost alternatives. United
Nations Food and Agriculture Association (FAO) also investigated water-heating capacities of a
parabolic cooker and an oven type cooker. In 1961, a United Nations Conference on New
Sources of Energy including many authorities on solar cooking technology was held. In 1970s,
as a result of the increasing fuel prices due to the oil crisis, an intensive interest on renewable
energy technologies was observed worldwide especially in China and India. In 1980s, especially
the Governments of India and China expanded national promotion of box-type solar cookers.
Mullick et al. presented a method to analyze the thermal performance of solar cookers in
1987. In 2000, Funk proposed an international standard for testing solar cookers. It was observed
that the resulting solar cooker power curve is a useful device for evaluating the capacity and heat
storage ability of a solar cooker. Especially in recent years, intensive efforts have been made to
be able to enhance the cooking power capacity of solar cookers.
2.2.1 Journey of solar cooking, from 1767 to 2000
Table 1 Contribution of some legendary researchers in solar cooking. (Saxena et al 2011)
1767- Saussure’s was made efforts to cook food by sun energy. He built a small
greenhouse with 5 layers of glass boxes turned upside down on a black table and reported
cooking fruit
1830- English astronomer Sir John Herschell cooked food in a similar insulated box on
an expedition to South Africa
1860- Augustin Mouchot was the first to combine the box/oven heat trap and burning
mirrors concepts to create a solar cooker/oven. He saw great commercial potential in
France’s sun-rich, fuel-poor colonies in North Africa and Asia
1876- In India, W. Adams developed an octagonal oven with 8 mirrors which cooked
food for 7 soldiers in 2 h. Dr. Charles G. Abbot, Secretary of the American Smithsonian
Institution, was the first recorded inventor of solar cookers in which the heat collector
was outside but the cooker was inside house, with heat carried from collector to cooker
by circulating oil
1877- Mouchot devised solar cookers for French soldiers in Algeria, including a shiny
metal cone, made from a 105.5◦ section of a circle. He built a separate cooker to steam
vegetables and also wrote the first book on Solar Energy and its Industrial Applications
1884- Another Smithsonian scientist, Dr. Samuel P. Langley, solar cooked meals atop
Mt. Whitney in California
1894- Xiao’s Duck Shop in Sichuan, China, roasted ducks by solar cooking
1930s- India began to investigate solar energy as a substitute for dwindling wood and
depletion of soil from burning crop residues and dung
1940s- Dr. Maria Telkes in the U.S.A. researched several combination types of solar
cookers, including some with heat retention chemicals and published a book, Solar
Ovens, in 1968
1945- Indian pioneer Sri M.K. Ghosh has been designed the first solar box cooker to be
commercially produced
1950s- Indian scientists in government laboratories designed and manufactured
commercial solar cookers and ovens, but they were not readily accepted, partly because
there were still lower-cost alternatives. Farrington Daniels and George Lof at the U. of
Wisconsin, USA, introduced concentrator cookers in northern Mexico, with some
acceptance
1955- The International Solar Energy Society (ISES) began as the Association for
Applied Solar Energy, whose first conference in Phoenix, AZ, USA, introduced many
practical solar cookers. By then the technical basics of solar cooking were known.
Exhibited solar cookers included parabolic by M.L. Ghai of India, Georg O.G. Lof (US),
Adnan Tarcici (Lebanon) and S. Goto (Japan) and box cookers by Maria Telkes (US) and
Freddy Ba Hli (Burma)
1961- A United Nations Conference on New Sources of energy included many types of
solar cooker pioneers, including, M. Telkes, Lof, Duffie, Pruta and Abu-Hussein
1970s- Spreading deforestation prompted research and promotion of solar cooking by
governments of India and China. A fuel shortage temporarily created new interest in
renewable energy worldwide
1973- Barbara Kerr, USA, built many types of concentrating and box solar cookers from
descriptions, including Ghosh’s box cooker in India. She used simplest materials inspired
by retained heat cookers (‘hay boxes’) and developed low-cost, simple solar cookers
using recycled materials and aluminium foil
1978- Kerr and Cole began small-scale production and promotion of solar cookers and
planed for people to make their own. Prof. Metcalf learned about Kerr–Cole cookers
through Fred Barrett, U.S.D.A, bought one, and immediately became a regular user and
began research on their germ-killing capacities. Hurry he became a promoter of solar
cookers both in the Sacramento area
1980s- The governments of India and China expanded national promotion of box
cookers. A lot of researches have been carried out in this era. Brace Research Institute,
McGill U., Canada, researched and field tested solar cookers. Prof. S.S. Nandwani in
Costa Rica researched solar cookers. Box cookers were distributed to 20,000 Afghan
refugees in Pakistan by SERVE (Serving emergency Relief and Vocational Enterprises).
M.H. Gurley Larson wrote first U.S. solar cookbook, Solar Cooking Naturally, in’83
Metcalf. In’84 Metcalf published his 9-page instructions for building solar box cookers.
ULOG was started by Ulrich and Lisel Oehler to promote box and parabolic cookers in
many countries. With Kerr–Cole instructions, solar cookers were built in Kitui, Kenya
in’85
1987- In India, Mullick, et al. carried out the thermal evaluation of box-type solar
cookers and generated two figures of merit (F1 and F2) to find out the cooker’s
performance
2000- Dr. Paul Funk proposed an international standard in terms of cooking power (W)
for testing solar cookers and reporting performance was applied to historical solar cooker
test data to show that it is a useful tool for evaluating the relative performance of
dissimilar designs. Accepted also by ASAE
2.3 CLASSIFICATION OF SOLAR COOKER:
It is a clear fact that there are countless styles of solar cookers in the world and they are
continually improved by researchers and manufacturers. Therefore, classification of solar
cookers is a hard work. However, it may be asserted that most of the solar cookers today fall
within three main categories namely:-
a) Solar panel cookers.
b) Solar box cookers.
c) Solar parabolic cookers.
as shown in Fig. 1 .
Fig.1. Types of solar cookers: (Cuce and Cuce 2012).
(a) solar panel cooker.
(b) solar parabolic cooker.
(c) solar box cooker.
2.3.1. SOLAR PANEL COOKER:
Solar panel cookers may be considered the most common type available due to their ease
of construction and low-cost material. In solar panel cookers, sunlight is concentrated from
above. This method of solar cooking is not very desirable since it provides a limited cooking
power. On the other hand, this type of solar cookers is highly appreciated by people living or
travelling alone. Solar panel cookers utilize reflective equipment in order to direct sunlight to a
cooking vessel which is enclosed in a clear plastic bag. It was an affordable, convenient and
effective solar cooker which enabled to preserve nutrients without burning or drying out.
Performance of solar panel cookers highly depend on reflected radiation thus, they do not seem
effective under cloudy conditions. In recent years, some efforts have been made in order to
expand the utilization areas of panel cookers. Kerr and Scott 2006 designed and built a solar
powered apparatus for sterilization. They also indicated that the prescribed system can be used
for cooking and food preserving purposes.
Fig.2. Panel Solar Cooker (Patil et al 2012)
2.3.2. SOLAR BOX COOKER:
A solar box cooker basically consists of an insulated box with a transparent glass cover
and reflective surfaces to direct sunlight into the box. The inner part of the box is painted black
in order to maximize the sunlight absorption. Maximum 4 cooking vessels are placed inside the
box. A detailed description of solar box cookers is illustrated in Fig. 2. Each component of the
box cooker has a significant influence on cooking power. Therefore, optimization of these
parameters is vital for obtaining maximum efficiency.
Fig. 2. Components of a solar box cooker (Saxena et al. 2011).
The first solar box cooker was invented by a French–Swiss naturalist named Horace de
Saussure in 1767. Especially in the twentieth century, this solar cooker type demonstrated a
considerable development in terms of design and performance parameters.
Box type solar cooker is being mostly used for domestic applications. Temperature
around 100-120o C can be achieved with a good design in the box type solar cooker on a sunny
day, so that pulses, rice, vegetables, etc. can be cooked in 2-3 hours. Box type cookers are slow
to heat up, but work well even where there is diffuse radiation, convective heat loss caused by
wind, intermittent cloud cover and low ambient temperatures. After the 1980s, optimization of
geometry parameters of solar box cookers was done by some researchers since they have a
dominant effect on performance. They studied the effect of booster mirrors, concentrators, flat
plate collector integrated with cooker, multi-step inner reflector, stepped outer reflector, storage
unit with or without phase change materials, orientation and different glazing materials on the
performance of the cooker.
Fig. 3. (a) Conventional box-type solar cooker with south facing mirror.
(b) Solar box cooker with south tilted collecting surface and south facing mirror.
(c) Cooker with south tilted collecting surface and north facing mirror.
(d) Cooker with south tilted collecting surface, north facing mirror and a fixed south
facing vertical mirror (Mirdha and Dhariwal, 2008).
2.3.3. SOLAR PARABOLIC COOKER:
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.4. These type of cookers attracted people immediately all over the world due to
their outstanding performance. Solar parabolic cookers can reach extremely high temperatures in
a very short time and unlike the panel cookers or box cookers, they do not need a special cooking
vessel. However, a parabolic cooker includes risk of burning the food if left unattended for any
length of time because of the concentrated power. Parabolic solar cookers are very efficient.
However conventional parabolic cookers need frequent adjustment to track the sun. It cooks at
substantially constant power for two hours without adjustment.
Fig.4. Side view and top view of the reflector supported by a frame and a spacer on a flat base.
The first solar parabolic cooker was developed by Ghai in the early 1950s at the National
Physical Laboratory, in India. Then Lof and Fester investigated various geometries and mounting
configurations of parabolic cookers.