Solar Cooker And Water Heater

Solar Cooker Cum Water Heater

INTRODUCTION ON SURYA, THE SUN GOD With bold might that spread all around, rises that sun. Who is Adiya, the origin of life stretching golden rays like this hands, Savita the creative solar energy, heating objects to shed fouluapours, moves on between Heaven & the Earth, removes away diseases projects, heat and rays of light, holding mid-region and the Heaven by his gravitational pull makes sunshine reach these. With the golden eye - Savita, the Sun-God, has come there over the stay, holding jewels of choicest splendour for one who distributes wealth to others. Yoked with wind forces.

He holds together towards Himself for their security, the creatures world and

features, and nourishing them, shines supreme over the various worlds The sources of most of our energy has been our renewable positive fuels, oil, coal, and natural gas. This is unfortunate from a long term point of view as these precious resources that took millions of years for nature to produce are being depleted in a few hundred years. Our present overdependence on non-renewable natural resources could lead to catastriphic consequences. There is real evidence that human being have outstripped the capacity of this planet to sustain present life styles. Until now the world is using the possible fuels, nuclear fuels for the power generations, but the stocks of these fuels is limited on the contrary consumption is large. The improved life standard of the man in this science age, seek over increasing power demand and to face with it, has become the serious problems. Again the monopoly of one or another nation in the possession of certain type of fuels has set international stresses. The energy crises cannot be solved over night in a few years or even by the end of this century. It is a long term problem, not only for this but for coming generation also. The two most significant source are nuclear and solar energy. Nuclear energy required advanced technology and costly means for it and reliable utilization and may have undesirable side-effects, solar energy on the other hand shows promise of becoming dependable energy source with the new requirement of highly

N.P.T.N. Achalpur

1

Solar Cooker Cum Water Heater technical & specialized nature for its widespread utilization. In addition, it appears to have no significant polluting effects from its use and it is also abundant This is freely available sources of energy & can meet small localized needs. It is becoming increasingly evident that solar energy could provide the only solution to supplying energy to the village with an approximate population of 500. Among the alternative sources of energy that deserves extensive exploitation, solar energy is the most promising one, particularly in India, which lies in between latitude – 800 N & 370 N. Solar energy is virtually inexhaustible. The typical in solution reaching the earth on the sunny day is about JKW/m2 at the equator. The sum gives out 3.7 x 1026 watts of energy into space, out of which earth intercepts only 5x10-10th part of solar energy output. The energy emitted by the sun within 3 minutes is equivalent to world's energy consumption during a year. Solar radiation is reduced in intensity in the atmosphere by clouds, haze, dust, smog, and fog. Intensity of solar energy on a sunny day in India is approximately 1.12KW/m2. SUN STRUCTURE The surface of inner sun as appears as a massaic of uniform background with bright granules, it is also called "Photosphere" and is source of our heat and light. CHROMOSPHERE - It is a 10000 Km this transparent layer of rarified gas, it is so called because of its red colour. The third and last layer is called as "Carona" It is made of highly ionised gases and extends for millions of kilometers in to space • Mass, M

= (1.991+0.002 )x 10 36 kg

• Radius, R

= (60960 + 0.001) x l08 km

• Average density

= 10410 + 0.002 gm/cm3 ( about 100 limes that of water )

• Distance from earth

= 1.5 10 8 km

• Average surface temp, T

= 5762 + 50 0 k

• Temp of core

= 1.5 x107 0 k

N.P.T.N. Achalpur

2

Solar Cooker Cum Water Heater CAUSE OF SOLAR EFFECT The sun’s great energy releases is the result of an elaborate chemical process in the sun's cores, A process of thermo nuclear fission will the reaction in hydrogen bomb At the tremendous heat of more than 45 million degree of farenhite in the sun's interior, hydrogen atoms fuse with helium atoms to produce the energy that powers our planets, so that energy can only be released in the from of radiation rays of heat energy. SUN EARTH RELATIONSHIP The eccentricity of our earth's orbit is such that the distance between the sun and the Earth varies by 3.4%. The angle subtended by the sun at mean earth varies distance of one astronomical unit is 320. The characteristic of sun and its special relationships to earth result in a nearly fixed intensity of solar radiation on the earths atmosphere. SOLAR CONSTANTS The sun, which is also known as " The Furnace In The Sky" shoots into our atmosphere at a fairly consistent rate. Thus the energy received by the Earth which is supplied by the Sun, per unit time, per unit area of surface perpendicular to radiation in the space called the 'Solar Constant' and it can be measured first on sq. foot of the outside of the Earth's protective layers gets a whopping average of 108.36 kcal/hr SOLAR RADIATION "Photons" are the tiny solar energy units contained by each of the sunlight waves. And these units are being fired at earth by the sun. They arrive in shorter wavelength, means more photons and thus more power. Most of the solar radiations reach the Earth in the form of electromagnetic wave, of about 0.2523 microns wavelength. About half of this radiation is visible light and rest is infrared which accounts for heat. The sun that actually reaches us is about 80% of visible light, 4°/o of ultraviolet light and 16% infrared. A very high percentage of this great energy can be captured if we have right equipment.

N.P.T.N. Achalpur

3

Solar Cooker Cum Water Heater GLOBAL, DIRECT & DIFFUSED RADIATION : There are three different forms in which sunrays come to us. They are 1) Direct parallel rays. 2) Diffuse radiation 3) Global radiation Some part of solar radiation entering the atmosphere is absorbed in atmosphere some is scattered and the rest penetrates the atmosphere. The penetrated rays are called “DIRECT RADIATION” Due to presence of “OZONE LAYER” most of the solar radiation are screened out, making life on earth possible. A lot of solar energy is reflected off, or absorbed, by our atmosphere and bounced back into outer space by clouds. When there is haze, cloud-cover, smoke or dust in the air, the parallel pattern is broken and rays are reflected off in many different direction by those particles of water or heat & light often seem to come at us from all parts of the sky. “DIFFUSE RADIATION” as this is called is still very strong and is useful to us if we have the right kind of solar collector. The term, diffused radiations means the relatively short wavelength radiation. Global solar radiation includes all the radiation, direct & diffuse incident on a horizontal plane. It also includes “REFLECTED RADIATIONS” which has been bounded straight of some surface. ABSORPTION OF ENERGY BY THE EARTH Only a small fraction of solar energy emitted by the sun is intercepted by the earth, here is what happens to the solar constant. Once solar rays heat our atmosphere (A) 5% is reflected of clouds, (B) 20% is reflected of the haze, (C) 23"/o reaches the ground as diffuse sunlight, (D) 25% is absorbed in the atmosphere and (E) Only 27% actually reaches us as direct parallel rays i.e. Beam radiation.

N.P.T.N. Achalpur

4

Solar Cooker Cum Water Heater After most of the strongest and most harmful rays have been filtered out, and a large share of the sun's energy has been dissipated. The average solar intensity on the ground is still 565 Kcal / hr. m2. BASIC EARTH SUN ANGLES In order to understand what follows for the calculation of solar radiations the definition of some of the basic terms are given. (i) LATITUDE It is the angle between the line joining the earth centres to the location and the rejection of line on the equatorial plan OR it may be defined as angular distance north or south of the equator measured from centre of earth. (ii) LONGITUDE The longitude is the angular distance of location, measured east or west of the prime meridian & from the prime meridian itself. (iii) HOUR ANGLE It is the angle through which the earth must turn to bring the meridian of a point directly in the line with the sun's rays. At solar noon the hour angle is 00 and it expresses the time of a day with respect to solar noon. It is measured positively westward from the observer and it may be expressed in hours, minutes and seconds, degrees minute, radians. (iv) SUN'S DECLINATION It is the angular distance of the sun's rays north ( on south of the equator). It is the angle between a line extending from the centre of the sun to the centre of the earth, and the propagation of this line upon the earth's equatorial plane.

N.P.T.N. Achalpur

5

Solar Cooker Cum Water Heater (v) ORIENTATION AND TILT Sunlight is to be collected in between 15 to 30 degree either north or south of the equator, because most of the radiation is quite direct and there are few clouds. Its accident that this is where the world's greatest deserts are one if we got beyond 35 degrees north or south there is a strong effect on insolation caused by changes in the seasons. When we move further north ( or South ) we have to plan carefully on orienting a solar collectors in relation to the sun. The rays must hit the collector at close to right angles as much of the time as possible As latitude gets higher, solar collectors have to tilted more and more towards vertical. The collector are oriented north south and normally recommended angle for a fixed solar collector is the latitude of the place plus 10 to 15 degrees. The energy absorbed by straight of some surface.

THE ENERGY CRISIS Quality of human life has undergone a significant change over the last four hundred years. Though today, the people of some countries are more affluent than those in others, the dispirely was much less in primitive times. Man had then to provide for all his needs on his own, using wood for his requirement of cooking and for keeping warm. The major economic inequality cause about the industrial revolution of the seventeenth century in Britain and to the other countries in west later. The process of mechanization started with the development of steam engine, which increased the demand for fuel and precipitated the first energy exists in Britain in the form of an acute shortage of trees resulting in large shortfalls in the supply of iron. The situation, however, improved when coal replaced wood as fuel and replaced charcoal as the reducing assent in the furnace. The industrial revolution created new techniques, which increased productivity and could support more people. Towards the end of nineteenth century, coal & steam based industries had reached their peaks and novel sources of energy were at their threshold. The emergence of oil as a primary fuel and the discovery of electric dynamo brought about a dramatize change in the pattern of life.

In life of European countries,

simultaneously, the IC engines were progressively coming into greater use of transportation and other industrial and form machinery. After the second world war, oil was much cheaper N.P.T.N. Achalpur

6

Solar Cooker Cum Water Heater than coal and most industries changed from coal to oil increasing the demand of oil very sharply. This changing pattern of fuel utilization with heavy industrialization and machine dependence of western society in particular has led to the shortage of fuel supplies commonly referred to as "Energy crisis". It is interesting to look into present day pattern of world in relation to the energy sources and option for the further. The oil embargo in autumn of 1973 followed by fourfold increase in the oil has had repercussions,

prior

to

the

embargo, the

major

international

major industrialized countries of Western

Europe and North - America as well as Japan had become increasingly dependent on low oil as a major energy source. This was also true for developing countries, which depended on petroleum products, not only for their energy needs but also as a source for modern fertilizers so necessary for increased agriculture productivity to meet the needs of their growing population. This has further added oil to the so called 'Energy Crises'. AN INQUEST OVER ENERGY CRISIS Because of present energy supplies are both final and non-renewable, our energy storage appears to be coming to an end. Warning signs in the from of oil shortage & blackouts have been given. There are also factors affecting energy production that have more to do with political and environmental decisions than with dividing natural resources. Antipollution measures have curbed the used of high sulphur coal. Construction of new nuclear power plants has been opposed on ground such as safety and radioactive disposal waste; offshore exploration for oil and gas has also been solved by environmental concerns. Solar Energy - Solution On Energy Crisis Solution for the energy crisis are strongly dependent on the technology of how well energy is provided and used To make a physical change in the world it is necessary to use tour resources-energy, matter, space and time. How well a task has been performed can be measured in terms of fuel consumed, the mass of material used the space occupied, the house of labour is accomplish and the ingenality with which these resources are used. Squandering of irreplaceable energy sources, waste of material or large expenditure of space and time can't be tolerated if the necessities of life are to be provided for all. N.P.T.N. Achalpur

7

Solar Cooker Cum Water Heater Renewed interest in the solar energy has manifested itself in a variety of ways. Research and development projects sponsored by different countries and private agencies, seminars , symposis and work-shop at national and international levels, efforts by industries to implant solar technology in its programme etc. This interest in the outcome of the recognition of the potential of solar energy as a viable supplementary source of energy and it should be sustained by a systematic and concerned efforts. Solar power seems to hold much promise for the future, as apart from its non-polluting qualities.

The amount of

energy which is available for conversion is several orders of magnitude greater than all present world requirements Moreover solar technology can be developed in less sophisticated laboratories with less expensive equipment's. The economic probability of solar energy utilization depends upon efficient collection, conversion and storage. Applications of Solar Energy The sources of all energy on Earth is the Sun and the energy flow from the sun to main consumption permit as shown –

N.P.T.N. Achalpur

8

Solar Cooker Cum Water Heater THE SOLAR OPTION Solar energy is a very large, inexhaustible source of energy. The power from the sun interrupted is approximately 1.8 x 10

MW, which is many times larger than the present

consumption rate on the Earth of all commercial energy sources. Thus, in principle, solar energy could supply all the present and future needs of the world on a continuing basis. This makes it one of the promising of the unconventional energy sources In addition to its SI/A solar energy has two factors, first unlike fossil fuels and nuclear power, it is an environmentally clean source of energy secondly it is free and available in adequate quantity in almost all parts of the world where people live The main problem is that is attitude source of energy. Consequently large collecting areas are read in many applications and these result in excessive initial cost. A broad classification of various methods of solar energy utilization is given in table below. Solar Energy Utilization

Direct Method

Thermal

Photovoltaic

Indirect Method

Water Power

Wind

Biomass

Wave Energy

Ocean Temp Difference

Some of the practical solar energy applications are as follows 1) Water heating 2) Air heating 3) Power generation 4) Cooking 5) Distillation 6) Refrigeration 7) Drying 8) Solar pond 9) In Space Vehicles. N.P.T.N. Achalpur

9

Solar Cooker Cum Water Heater A DECADE OF SERVICE Energy forms the Basis and a deciding factor in a country's development because if not only affects the economic but also affect the social, environmental and other sectors related to it. Concerning about these, science and industries dept. established a research center CASE in India, which would take responsibility of policies for development of infinite energy. Admiring the important work (research) of NRSE 1982, of India established (founded) Non-constraint

over broad work technology in

energy sources dept. DNHS which

was then converted (transformed as) complete dividing Non-Conventional energy sources ministry and NES in 1992. At present the of MNES has 9 divisional offices and 27 state model agencies spread all over India It has been known since a long provide that solar energy will render energy to few limited sectors Therefore there will be limited contribution, on the other hand it is said that, it will be more costly than conventional energy sources. Sr. No. A 1.

Sources/ Technologies

UNIT

ACHIEVEMENTS (UP TO 31/3/1997)

POWER GENERATION Wind Power

MW

900

2.

Small Hydro Power (up to 3 MW)

MW

144

3. 4. 5.

MW MW/Sq. Km MW MW

83 28 3.75 90.00

B

Biomass Power Solar Photovoltaic Power Urban and Municipal Wastes a) Installed b) Being taken up THERMAL APPLICATIONS

6

Solar Thermal Systems

MW/Sq.Km

a) Solar Water Heating

Sq. Mtr. Collector Area. Nos. No. in Millions

430000 2.5

Nos. in Millions

23.7

b) Solar Cookers 7. 8.

Biogas Plants Improved Biomass Stoves (Chulha)

N.P.T.N. Achalpur

400000

10

Solar Cooker Cum Water Heater

N.P.T.N. Achalpur

11

Solar Cooker Cum Water Heater Solar Electricity Production capacities (M.W.) No. Tax, No. Govt. Help Biomass Solar P.V. Solar Hybrid Geothermal Wind Small Hydroelectric co-production TOTAL Extra Govt. help Biomass Solar P.V. Solar Hybrid Geothermal Wind Small Hydroelectric co-production TOTAL Constant Tax. Biomass Solar P.V. Solar Hybrid Geothermal Wind Small Hydroelectric co-production TOTAL

N.P.T.N. Achalpur

1995 0.04 0.00 0.00 0.00 0.45 0.25 0.02

2005 2.28 0.15 0.08 0.02 0.88 0.62 0.22

2015 4.23 0.34 0.25 0.06 1.59 1.35 0.54

2025 6.57 0.64 0.72 0.12 2.46 1.97 0.96

2035 8.87 2.90 2.08 0.19 3.46 2.5 1.44

0.76

4.24

8.36

13.44

21.62

0.04 0.00 0.00 0.00 0.45 0.25 0.02

3.78 0.25 2.48 0.09 5.32 1.45 0.71

7.52 1.36 5.02 0.24 8.17 3.44 1.66

11.27 4.71 7.66 0.41 10.26 4.31 2.49

15.00 10.72 10.32 0.50 12.34 5.00 3.50

0.76

14.08

27.41

41.11

57.36

0.04 0.00 0.00 0.00 0.45 0.25 0.02

2.81 1.03 0.68 0.06 1.66 1.25 0.41

7.87 4.71 2.11 0.20 3.76 2.90 1.01

11.27 15.80 5.99 0.39 8.41 5.54 1.95

15.00

0.76

7.12

18.88

35.26

73.99

12.23 0.50 16.86 10.10 3.50

12

Solar Cooker Cum Water Heater

WATER HEATING Water heating is one of the solar energy application Water at ambient temp is sent through tubes contained in the collector.

The tubes are generally made of copper or

aluminium. For continuous flow of hot water, mass flow rate of water is maintained low The solar radiations passing through the glass cover and strikes over the tubes which are coated, with dull black colour and whose absorptivity is high. The tubes containing water heats up and conveys, their heat to water inside it ( convection) . The water inside the tubes get heated and we can get hot water at outlet at temp. about 700 C to 800 C . The hot water obtained at outlet may be stored in a insulated storagetank and used for further purpose. TYPES OF CONCENTRATING COLLECTORS A no. of concentrater collector are possible to increase the solar radiation flux on absorber. These can be cylindrical to focus on a line or circular to focus on a point. The absorber can be concave, flat or convex. Hence concentrating or focusing collectors may be considered in two general categories:1) Line focusing and 2) Point focusing types. As per the number of concentrating collectors geometries, the main types of concentrating collectors are: 1) Flat plate collector type. 2) Compound parabolic concentrator type. 3) Cylindrical parabolic trough collector type. 4) Mirror strip reflector type. 5) Fresnel lens collector type. 1} FLAT PLATE COLLECTOR TYPE A flat plate collector as shown in fig. 1 with adjustable mirror at the edge to reflect the radiation on to the absorber plate is known as plane reflector or plane receiver concentrating. These are simple in design having concentrating ratio slightly above the unity. Lengths between two to four meters and are useful for attaining temp. to 1200 C to

N.P.T.N. Achalpur

13

Solar Cooker Cum Water Heater

Fig 1

Fig 2 Fig 3

N.P.T.N. Achalpur

14

Solar Cooker Cum Water Heater 1400 C which are slightly above the temp. of flat plate collector. The inclination angle of the reflector is given by = (A-B-ad + as ) / 3

Where,

B = slope of the collectors.

The surface of the absorber plate may be, a black paint with an appropriate primer or coating the selective material by electroplating. The primer coat should preferably be thin, since a thick under- coat of paint would increase the resistance to heat transfer. The primer should be of self etching type. 2) COMPOUND PARABOLIC CONCENTRATOR TYPE The CPC concentrator is as shown in fig. 3 It is also known as winston’s collector. CPC is a trough like arrangement, of two facing parabolic mirrors. The CPC is nonfocusing, but solar radiation from many direction is reflected towards the bottom of the trough. Because of this characteristic, a large proportion of solar radiation, including diffused ( scattered ) radiation, entering through the opening is collected on a small area. In addition to collecting both direct and diffused radiation. An advantage of the CPC is that the it provide moderately good concentration, although less than a focusing collector is an East -West direction without adjustment for sun tracking, it is possible to concentrate solar radiation by factor of 10th without directional tracking. Using this type of collector temp. range obtained is up to 400°C. 3) CYLINDRICAL PARABOLIC TROUGH COLLECTOR TYPE The cylindrical parabolic collector as shown in fig is also referred to as a parabolic trough or a linear parabolic collector. The basic element making up a conventional collector are: 1) The absorber tube located at the focal axis trough which the liquid to be heated flows. 2) The concentric transparent cover. 3) The parabolic concentrator. The aperture areas of commercially available collector ranges from l to 5m2 with the length being larger than the aperture width concentration ratio range from 5 to 30, & rim angles from 800 C to 1200 C the temp. range obtained in between 3000 C to 6000 C. The absorber tube of usually made of mild steel or copper & has a dia. of 2/5 to 5 cm. It is coated with heat resistant black paint as it is generally surrounded by a concentric N.P.T.N. Achalpur

15

Solar Cooker Cum Water Heater

Fig 4

Fig 5

Fig 6

glass cover with an annular gap of 1 to 2 cm. In the case of high performance collectors, the absorber tube is coated with a selective surface like black-chrome and the space between the tube and the glass cover is evacuated. N.P.T.N. Achalpur

16

Solar Cooker Cum Water Heater The reflected surface is often made from anodized aluminum sheet. Aluminized miler or aluminized acrylic fixed or a parabolic contour & curved black silvered glass a new absorbed .All these materials have good secular reflectivity. 4) MIRROR STRIP COLLECTOR This collector receiver has a fixed

concentrator and moving receiver. The

concentrator is an array of tiny, narrow, flat mirror strips fixed along a cylindrical surface. The mirror strips produce a narrow like emerge which follows a circular path as the sun moves. This path is on the same circle on which the mirror strips are fixed. Thus the receiver has to be moved along the circular path. The concentrator ratio for such lies between 10 to 30 and temp. achieved is up to the range of 5000 C . 5) FRESNEL LENS CONCENTRATING COLLECTORS The fresnel lens concentrating collector has been developed utilized the focusing effect of a fresnel lens. For a trough type of collector the leans in rectangle about 4 -7m. in overall length and 0.95 m. in width. The fresnel lens is a thin sheet, flat an one side with fine longitudinal grooves on the other. The angles of these grooves are such that radiation is brought at a line focus. The lens is usually made of entrusted acrylic plastic sheets-line focusing collector usually have concentration ratio between 10 to 30 and yield temp. between 150° C to 3000 C .

TYPES OF SOLAR COOKER

N.P.T.N. Achalpur

17

Solar Cooker Cum Water Heater "Food cooked by Solar heat is lovely in appearance, aroma,

flavors and taste. It is the ultimate medicine for manly vigour and glorious skin complexion" India is consider to be land a land of villages and in villages the major portion of energy i.e. 95% is consumed for cooking. The conventional fuel like coal, kerosene cooking gas, firewood, fire woods cattle during cakes and agricultural wastes, which are in user getting depleted. The conventional fuel which are in used are now reducing day by day as the population is increasing, increasing consumption of fuels. These conventional fuel creating an havoc to the health of a man by polluting the environment.

So it seems

necessary to developed a cooking system which is non-polluting and the fuel used for cooking on the system should be available in abundant and therefore the birth of solar cooker using sun's radiation which are available in abundant and are non-polluting made the solar cooker to gain its popularity through out the world. In India the first solar cooker is made by Adam way-back in 1876 using plate mirror arranged in the light sided paramedical structure. Up till now several cookers have been developed by various institution working in the field of non-conventional energy sources. In India there are basically three design of solar cookers developed. They are, 1) Flute plate box type solar cooker, single or multi reflector type. 2) Multi reflector type solar oven cooker 3) Parabolic concentrator type solar cooker VARIOUS TYPES OF SOLAR COOKERS 1. ADAM'S SOLAR COOKER Adam, an Englishman, was the first man in India who started investigating the various solar devices.

He was the man responsible for introducing the solar cooking

technique in India. He may be called as an inventor of solar cooker in India. He used plate mirror arranged in an eight sided paramedical structure for his solar cooker. It was about 2 ft. 4 inches in diameter at the longer end. The food box was placed in cylindrical copper container enveloped by a glass cover. N.P.T.N. Achalpur

18

Solar Cooker Cum Water Heater 2. ABBOT’S SOLAR COOKER The other man, who worked in field of using solar energy for cooking was ABBOT. He made is a solar cooker in 1939. The cooker was an indirect type, in which there was an parabolic fluid coil was heated to a high temp. (Up to 6000 F) using solar radiation's and then was circulated through a sort of an exchanger, which in task heated the cooking over.

Fig 7

N.P.T.N. Achalpur

19

Solar Cooker Cum Water Heater For this, 60 gallons of oil was used for heat transfer and storage. The size of concentrator used for heating the fluid was 4 ft. X 8 ft. 3. BOX TYPE COOKERS i) SINGLE REFLECTOR TYPE This is of the simplest solar cooker being developed in India. The maximum no load temp. Attained in this type of cooker was 160 0 C. It is developed for convenient and efficient performance. The cooker requires the adjustment after every 30 minutes towards the sun. The food like rice, potatoes, vegetables and dal was satisfactorily cooked in this cooker simultaneously. The food remains warm at the time of dinner. ii) PARABOLIC REFLECTOR TYPE SOLAR COOKER This type of cooker is being developed at physical laboratory in New Delhi and at central Arid Zone Research Institute, Jodhpur. The cooker consists of a parabolic reflector and the cooking box is placed at the focus of the parabolic. The reflector is made either of small pieces of round glasses pasted on a sheet which is curved in parabolic shape or of this Aluminum sheet. When this cooker was experimented it was observe that when the bottom of the pot is blackened one litre of water boils within 25 to 30 minutes. Under the clear sky condition and wind speed up to 3 to 4 km/hr. While when a wind speed is about 10 to 15 km/hr. The water never reached the boiling point and the maximum temperature record under such conditions was 700 C to 800. The performance of cooker is very much by the wind speed and the dusty atmosphere. There are always chances of dust falling in the cooking pot and this cooker cannot withstand the pressure. This requires frequent adjustment towards the sun after every 10 to 15 minutes and continuous stirring to prevent scorching of food. iii) SOLAR OVEN These cooker are used for cooking purpose. The insulated over has glass windows to admit the solar radiation. Dr. Telka developed an oven which is an insulated box with a cooking

vessels of 10 sq. inch fitted towards the sun and adjusted every half an hour as

the sun moves during the day. Four slanting reflector of bright aluminum at the sides of the oven reflect the light down through the windows into the oven temperature about 200 0 C and higher more obtained. N.P.T.N. Achalpur

20

Solar Cooker Cum Water Heater

Fig 8

N.P.T.N. Achalpur

21

Solar Cooker Cum Water Heater

Fig 9

Another design was made at central Arid Zone Research institute Jodhpur, installed in villages for demonstration cum test purpose.

N.P.T.N. Achalpur

22

Solar Cooker Cum Water Heater This is multi reflector type. The reflector of this type of solar cooker is made of Aluminum sheet shaped inform of octagon (Four of square shape and four of triangular shape) and on which silvered painted mirrors are placed. The box portion of this cooker is made up of wood and is parabolic in shape. It is rather a complicated type cooker which has got many parts also needed precision fitting. iv) REFLECTOR TYPE COOKER This cooker consist of reflectors which are inclined at 600 to 700 is the most suitable angle for concentrating most of the reflector rays at the centre of the box. Construction of this cooker is simple and easy. The temperature of 950 C – 1000 C was obtained in this cooker. In summer the time is required to reach the above temp. is 45 minute to I hour and in winter it is one and half hours. v) FOLDING - TWO STEP ASYMMETRIC REFLECTOR SOLAR COOKER The design of this type of solar cooker retain most of the desirable feature of the single reflector box cooker . It differ from the box cooker in the following ways. A new reflector system named as folding two step a symmetric reflector has been used in place of single reflector used in box type std. Solar cooker. This new reflector system enhances the solar input into the hot box appreciably as compare to single reflector cooker. The concentration of this cooker is 2. It is rectangular in shape and of size 40 x 85 cm. It consist of a hot box and reflector assembly. Performance of this cooker was studied in Ludhiana.

The maximum temp

obtained was 1720 C (tracking mode) 1670 C (fixed mode) was obtained. vi) KISAN COOKER This is one of the simplest cooker being developed in India. These cookers use mainly prepared in villages. A hole of size 12 ft x 12 ft is digged in the ground. The hole digged in the ground is exposed to sun rays throughout the day. A blacked tray is placed inside the hole after packing the sides of pit by straw paddy, husk of ash or glass wool. The

N.P.T.N. Achalpur

23

Solar Cooker Cum Water Heater

Fig 10

N.P.T.N. Achalpur

24

Solar Cooker Cum Water Heater

Fig 11

farmer can place the utensil with food inside the blackened tray cover the tray with the glass cover and leaves it for his work. After 3 to 4 hours according to weather food is ready. 4) LEN"S TYPE COOKER

N.P.T.N. Achalpur

25

Solar Cooker Cum Water Heater In this type of cooker the utensils are placed at the focus, where the sunrays are concentrated through convex lenses.

Up till now solar cooker based on this principle of

deflection grating have been developed which is reported to be quite effective. The various centres working in the field of unconventional energy sources are researching on developing a new type of lens cooker in which water is placed inside curved plastics sheets. Some successes have been achieved in this field and it has given good results but a lot more it to be done in this field of solar cooker development. 5) PLASTIC REFLECTOR SOLAR COOKER In this type of solar cooker plastic sheets were used Reflector shape is parabolic cooking unit comprising such reflectors in combustion, with suitable supports of food holders used in the solar cookers were fabricated by plastics. Recent model used in drape formed high impact polystyrene shell of a thickness of 0.6 stiffened at the sun with a ring of thin wall aluminum tubing of about one half inch diameter. These shell are light in weight are sufficiently stiff and use resistant to damage by bending and are readily formed in compound curvatures required by simple forming technique.

A reflective lining of

aluminum polyester film is Applied to the shells with adhesive so that the clear films forms a protective covering over the secular surface. The secular reflectivity of this material when new is in the range of 70 to 80 percentage. 6 ) SOLAR STEAM COOKER This cooker is first developed at Brace Research Institute, Canada by R Award and then modified in India by C. L. Gupta at Aero Solar International, Pandicherry and H.P.Garg at CAZRI , Jodhpur. This cooker is consist of a tube in flat plate collector and a well insulated steam cooker. The collector plate, having an absorbing area of 0.75 m2 is made of sheet aluminum with a copper pipe welded on it. The pipe is 3.5 m long and wound three fold. The copper outlet of the pipe is connected to the bottom of the steam cooker. The blackened absorber plate is placed in a wooden tray with double glass cover and 10 cm thick fibre

N.P.T.N. Achalpur

26

Solar Cooker Cum Water Heater

Fig 12

glass insulation. The inclination of the collector can be adjusted according to the geographical latitude. In this cooker water starts boiling with in 30 to 45 minutes of sunrise and continue to boil till the sun shines on the collector. This is very slow cooker and can be used for boiling

N.P.T.N. Achalpur

27

Solar Cooker Cum Water Heater of cereals, rice, potatoes, dal, vegetables etc. The only advantage of this type of cooker is that it does not required any adjustment towards the sun. 7) HAND REFLECTING SOLAR COOKER Hand Reflecting Solar Cooker developed by Roger Bernord. In this the cooking pot is kept in double wall glass case, it serves the purpose of hot box. The reflector surface is consist of several small mirror fixed to focus on glass case. The system can be attained temperature of 2500 C – 3000 C in a short time. To maintain constant temp. Inside box some times iron chips are used which stores the energy and increase during low sun shine hours. If solar intensity of 900 - 1200 watt per sq. meter for rice, omelets and roasting, 45, 15, 90 min. Respectively wats per sq. meter the cooking time for rice. omelets and roasting ,45,15,90,min. respectively.

Fig 13

SOLAR COOKER CUM WATER HEATER As the technology grows, more and more attention is paid to increase the performance of any technology. The efforts are made to increase the output of the product. N.P.T.N. Achalpur

28

Solar Cooker Cum Water Heater The research and developments are continuously going on to achieve the flexibility in any machine

or

equipment.

The

result

is

that

multipurpose

products

are

coming into market which has more number of uses as compare to the old one. The idea of solar cooker cum water heater is a step in the same direction. There is lot of solar cookers and solar water heaters are developed in India. But if we go under the analysis of cooking and water heating-then we find that water heating is generally required during morning hours and cooking is required at noon. To achieve these goals by solar applications, requires separate cooker and water heater, which is consumable one. Hence the idea of solar cooker cum water heater came into picture.. There is a lot of space available inside the solar cooker. If we fit a copper tubing inside it. Then our duel purpose can be solved satisfactorily. This arrangement of the Copper tube do not consume large space and can be fitted easily without disturbing the cooker mechanism. In our project the inside box of cooker has semicircular portion (

35) at bottom

height of 32.5 cm and width 35 cm. We can easily place a copper tubing in the plane of bottom semi-circular portion. To increase the volume of Copper tube inside the box so that it capture large amount of heat the tube is bended in U shape proper lengths. Then this bending increases the length of tube in less space. The bending is done accurately and proper care is taken so that, the tube should not damage during bending. Then this folded tube is given a curvature as that of curvature of the bottom surface of inside the box. An inlet and outlet is provided at proper positions. The inlet is connected to water supply tank. Thus the solar cooker cum water heater is ready for operation. SELECTIVE SURFACE Such surfaces lire desirable because they maximize the absorption of solar energy and minimizes the emission of radioactive loss. Thus they help in increasing the collector efficiency.

N.P.T.N. Achalpur

29

Solar Cooker Cum Water Heater

Fig 14

Metal oxidized by heating give rise to spectrally selective surfaces from the Antireflection oxide Films. These films may be rough, porous, non-homogeneous and absorbing as well. However, it is found that spectral and directional characteristics of oxidized titanium has sufficient interference effects. The desirable material for selective absorber should have the following Properties. 1. Low reflectance. N.P.T.N. Achalpur

30

Solar Cooker Cum Water Heater 2. A resistance to atmospheric attack or vaporization in space. 3. A sufficiently low absorption co-efficient in infrared region and high absorption coefficient in the visible region. 4

Its properties should not change with its use.

5. It cost should be reasonable. PROPERTIES OF SELECTIVE COATINGS An efficient utilization of solar energy requires collector surface with the following optical and physical properties.  Absorption over the solar spectrum (0.3 - 2.0 micro meter) must be high.  Emissivity for wavelength greater than (0.2 micro meter) must be low.  The spectral transition between the region of high absorption and low emittance should be as short as possible.  The optical and physical properties of the coating must remain stable under long term  Operation at elevated temps repeated thermal cycling, air exposure, ultraviolet, Radiation, etc.  Adherence of the coating to the substrate must be good.  Coating should easily applied to collectors of desired size and shape.  Coating must be economical.

PROPERTIES OF SOME SELECTIVE SURFACES S.N. SURFACES 1. “Nickel Black” Containing oxides and sulphides of 2. 3.

Ni and Zn, on polished Ni “Nickel Black” on galvanized iron “Nick Black” 2 layers on electroplated Ni on mild

N.P.T.N. Achalpur

∝ 0.91-0.94

E 0.11

0.89 0.94

0.12 0.07 31

Solar Cooker Cum Water Heater 4.

steel CuO on Ni, made by electrodeposition of Cu and

0.81

0.17

5. 6.

subsequent oxidation. Co3O4 on silver, by deposition and oxidation. CuO on Al, by spraying dilute Cu(NO3)2 solution on

0.90 0.93

0.27 0.11

7.

hot Al plate and baking “Copper Black” on Cu, by heating Cu with

0.89

0.17

8.

solution of NaOH and NaClO2 CuO on anodized Al, treat Al with hot Cu

0.85

0.11

9. 10.

(No3)2 – KmnO4 solution and bake Black chrome on Aluminium, steel Lead sulphite crystals on Aluminium

0.87 0.89

0.88 0.20

DESIGN AND CONSTRUCTIONAL DETAILS DESIGN OF REFLECTOR In any design of solar equipment the first requirement is to decide the area through which the solar radiation enters. The efficient working of solar equipment can be achieved only when the required amount of solar radiation enters in the equipment. For our project it is necessary to determine the aperture area through which solar radiation enters. a) Aperture area from heat requirement point of view.

N.P.T.N. Achalpur

32

Solar Cooker Cum Water Heater The present equipment is designed to fulfill the requirement of a family of four members. The requirement of a family is about 250 gm of rice. Similarly the family requires hot water for different needs like bathing, cleaning etc. throughout the day. I) The heat required to cook 250 gm of rice = The latent heat of 300 gm. Of water + Sensible heat of water and rice + heat of reaction between water and rice for water to penetrate into rice. Total heat required to cook the rice = Heat required

for vaporization

of water +

sensible heat of water and rice + Reaction heat II) Latent heat of water for vaporization = 2257.2 KJ/Kg Heat required for 300 gm. Of water =

300 × 2257.2 1000

= 677.16 III) Sensible heat of rice

= 41.8 KJ

IV) Sensible heat of water

= mw Cpw Tw =0.3 x 4.186 x (95-30) =81.627KJ

V) Assuming the reaction heat i.e. heat required to remove the resistance of rice to absorb the water as 836 KJ/Kg (from standard data book of food) Reaction heat required for 250 gm. Of rice

=

836 × 250 1000

= 209 0 KJ Total heat required to cook the rice

= 677.16+ 41.84+ 81.63+ 209 = 1008.63 KJ

The amount of solar radiation 's falling on the earth surface in Vidarbha region is generally 5016 KJ/m2 hr. Considering the collector efficiency as 50 % Required surface area for collection is, S=

qt 1 1 × × q t η

Where, qt = Heat required q = Amount of heat available t = Time required for above operation N.P.T.N. Achalpur

33

Solar Cooker Cum Water Heater = 55 min. of efficiency of collector. S=

1008.63 5016

1 ( 55 / 60)

1 50

S = 0.4387 m2 II) Considering the water heating process Generally the water required for bathing and cleaning is should have temperature of about 500 C. Considering the flow of 150 ml/min, then the heat absorbed by the water can be as, Q = mw Cpw Tw = 0.15x4.186 x (50-25) = 15.6975KJ/min Hence heat absorbed in I hr = 941.85 KJ/hr Hence the required collector area, S= =

qt 1 1 × × q t η 941.85 1 1 × × 5016 ( 60 60 ) 0.5

S= 0.3755 m2 We assume the maximum collector area required i.e 0.4387 m2 for further design.

N.P.T.N. Achalpur

34

Solar Cooker Cum Water Heater

b) APERTURE AREA FROM MATHEMATICAL CALCULATIONSWe have chosen the multireflector type solar reflector, which has collector angle of 60° so as to reduce the reflection losses of glazing rays and to avoid the losses due to shadowing. If we take collector angle to 90 then the purpose of use of reflector is totally get diverted as the area on the top of the reflector will be same up to bottom, more over it also disturb the entry of diffuse radiations. On the other hand if we have collector angle less than 30 then the reflected rays will not fall inside the box and may go outside. Hence the N.P.T.N. Achalpur

35

Solar Cooker Cum Water Heater collector angle is fixed as 60 due to which, the solar radiations get concentrated inside the box. From the ∆ OAB, we can calculate the length AB, AB = Cos 60 x 0.35 = 1.75m Now projected area of aperture = A( PQRS) - 4 [A ( ∆ LMS)] = (0.71 x0.71)-4(l/2x0.175x0.175) = 0.44285m2 The designed aperture area is nearly equal to the fabricated one. Hence our design is safe and we do further fabrication regarding to these design parameters. 2. DESIGN OF INNER BOX The inner box is so designed that a pot of capacity 1.5 liter can be kept easily inside it. The bottom of the box is specially prepared semicircular for the arrangement of tubing for water heating. A provision for fixing main absorber plate is also made so that the absorber plate can swing freely about the point of pivots. An opening of sufficient and maintenance of the equipment. After considering all factors it is finalized to have dimensions of box as height of 32.5 cm with semi cylindrical bottom. The upper cylindrical surface area is of 35 cm x 35 cm.

3. DESIGN OF COPPER TUBING The Copper tubing is properly fixed on the bottom surface of the inner box. Taking the area available for tube fitting and flow requirement a Copper tube of ½ inch (1 .27 cm) outside diameter is selected. The width of inner box is 35 cm, hence we can easily fit a tube in 5 rows having spacing of 7 cm in between two successive rows. The spacing between rows is designed such that it gives freedom in bending process and bending can be done easily with destroying the shape of the tube. To increase the more collective surface the tube N.P.T.N. Achalpur

36

Solar Cooker Cum Water Heater is given a round inside the box shown. The sufficient Copper tube is kept outside the equipment for inlet and outlet attachments.

CONSTRUCTIONAL DETAILS 1) DESCRIPTION The box type solar cooker cum water heater is a concentrated type collector system. The solar oven is made of inner M.S. sheet box and outer wooden box, with a top cover having a opening in which two plain glasses are fitted with sufficient gap (2 cm) in between them. The inner box and main absorber plate is painted black with a selective material, so that they can absorb maximum solar radiation’s. A multi reflector frame with mirrors is

N.P.T.N. Achalpur

37

Solar Cooker Cum Water Heater mounted on the top. Provision is made to adjust the whole unit at different angles by mounting the equipment in a frame. 2) MATERIAL REQUIREMENT The material required for construction of solar cooker cum water heater is readily available in market and the requirement is as under – MATERIAL Wood (Kitply) MS sheet MS square pipe Glass wool Plain glass mirrors Reflector glass Reflector glass Copper tube Miscellaneous

QUANTITY NOS 2 1m 8 Kg 410 cm 5 kg (37.5 x 37.5 x 3 mm) 2 no (35 cm x 35 cm x 3 mm) 4 no (35 cm x 25 cm x 22 cm x 3 4 no mm) ½ inch diameter, 16 BWG 4m gauge Nails, Nut & bolts, Handle, Rubber sealing, Roller wheels, favicol, fasteners, screws, Black & Colour paints, ms flat wing nut etc.

3 CONSTRUCTION The location of Achalpur 770 35 East latitude and 2005.

North latitude.

The

dimensions of solar cooker cum water heater are selected on the available solar intensity basis so that maximum radiation’s reaching to earth surface can be utilized for cooking and water heating. The overall dimensions of the unit are 85 cm x 60 cm x 54 cm and its weight is about 35 kg. A) OUTER WOODEN BOX The outer semi-cylindrical wooden box is fabricated such that is has height 40 cm and bottom radius 25 cm. The material used for fabrication is thick kitply. The box is designed such that it will be suited for all climate conditions. The top cover of box has N.P.T.N. Achalpur

38

Solar Cooker Cum Water Heater center hole of dimension 35 cm x 35 cm. On this cover two plain glasses mounted with a gap of 2 cm is between them. The rubber gasket is provided at all the edges of these glasses to make it fix and shock proof. Both the glasses are fitted exactly over each other. On the one side of box a window is cut of size 30 cm x 20 cm for easy placing and removal of cooking pot. This window door is provided with handle for easy operation. B) INNER MS SHEET BOX AND MAIN ABSORBER PLATE The MS sheet of 22 gauge is used for fabrication of inner box.

The

dimensions of inner box are height 32.5 cm, width 35 cm and length 35 cm. The bottom surface is made semi-circular one with radius 17.5 cm. A window is cut on the same side as that of outer box of same dimension. The box is fabricated by riveting and folding. A main absorber plate is also fabricated of length 34 cm and height 15 cm. The aligned holes are drilled in both ears of the tray, so that the tray can be hanged with nut and bolts are drilled in both ears of the tray, so that the tray can be hanged with nut and bolts inside the box. Both tray and inside box are painted with black paint (selective one) so that they could absorb maximum solar radiations. C) GLASS WOOL INSULATION The glass wool which has low thermal conductivity (0.038 w/mk) is selected as a insulating material. The glass wool is filled in between the spacing of inner and outer boxes. The insulation is provided to minimize the conductional heat losses from the inner box. D) COPPER TUBING As per the design a copper tube is bend at suitable length so that it form a compact structure with 5 rows. The bending process is done very preciously. First the sand is filled inside the tue which provides a strong back-up support from inside and also allows smooth bending. Then the tube is marked at regular intervals and then bending is done. The each bending has ‘U’ shape. Then all the rows are bender with the same curvature as that of bottom curvature of inside box. After the complete bending process the sand is taken out from tube. Then the complete compact structure is fitted inside the inner box and inlet and outlet connections are taken out by drilling holes at proper location. As the Cu tube is ductile and any laziness can cause clogging of tube, proper care is taken during the process.

N.P.T.N. Achalpur

39

Solar Cooker Cum Water Heater E) GLASS COVER The glass has high reflectivity and as the solar radiation’s enters through it cannot escape out easily. To avoid such reflections from inside two glass covers are fitted above the box with a spacing of 2 cm in between them. If any radiations are reflected back from inside then it strikes to glass cover and reflected again inside and thus, efficiency of unit is increased. F) MULTI-REFLECTOR A multi reflector is having square shape at bottom and octagonal at the top. The multi reflector is made up ms sheet. It consist of 4 square plates of 35 cm x 35 cm and 4 triangular plates of 35 cm x 25 cm x 22 cm. Then these plates are joined by welding to form a reflector. Then mirrors are fastened to these ms sheets from the inside. Then this reflector is mounted on the top of the outer box so that hole of reflector matches with the hole of wooden box. G) STAND A stand is made from MS square pipe. The dimensions of stand are 60 cm x 45 cm x 45 cm. The stand has two triangular structures by the sides. Guide is also provided on one side of stand, to make provision for adjusting the unit at required angle. The guide is very important because tracking is required for all day so that the reflector face is always keep facing towards sun. Then the assembled unit is fixed in the frame with the help of nut & bolt at the centre of box.

COST OF FABRICATION Material 1. Kitply 2. MS Sheet 3. MS Square 4. Plain Glass 5. Mirror 6. Glass Wool 7. Copper Tube 8. Seal N.P.T.N. Achalpur

Specification

Quantity

Cost

19 mm 22 Gauge 37.5 cm x 37.5cm x 3 mm 35 cm x 35 cm x 3 mm 35 cm x 25 cm x 22 cm x 3 mm ½ inch F, 16 BWG 100 gm

1 m2 8 Kg. 410 2 No 4 No 4 No 5 Kg. 4m 5 No

(Rs.) 450 775 62 80 310 250 200 520 100 40

Solar Cooker Cum Water Heater 9. Rollers 10. Black paint 11. Nails, Rivets, MS flat,

-

4 No 750 ml -

60 47 250

Wheel handle, wing next colour etc. TOTAL

3104

TESTING AND PERFORMANCE 1. TESTING The cooking and water heating trials of solar cooker cum water heater were conducted on dates 02/03/03, 03/03/03, 10/03/03, 11/03/03 & 13/03/03. And temperature was recorded on hously basis for ambient and inside of the solar oven on the above dates. For trial of water heater we heated water at different times throughout the day, at different flow rates and tabulated the day, at different flow rates and tabulated the readings obtained. We had cooked rice, pulse and had also boiled eggs for trial of the cooker. The tests were carried out separately for water heater and cooker. 2. SAMPLE CALCULATION FOR SOLAR RADIATIONS. The calculation for 20th March 2003 are as follows. The PAGE suggested the relation,

 S  Hg = (a + b )   Ho  (S max ) 

Where,

Hg = average daily global radiations.

According to Klein, Ho

=

24 Isc 360 (1 + 0.033 Cos n) Pi 365 x ( W8 sin θsin δ + cosθcosδ ) sin W8

N.P.T.N. Achalpur

41

Solar Cooker Cum Water Heater - a and b are the constant for location is equal to 0.27 & 0.5 respectively for Nagpur. Date 20th March 2003 φ= 220 (latitude for Achalpur) n = 41 ( no of day of year ) β= 0.9 = 0.9 x 22 = 200 Declination (δ)

= 23.45 sin {360 (284 + n)/365} = 23.45 sin {360 (284 + 41)/365} = -14.90

Sunrise hour angle, W,

= cos-1 (-tan (ϕ- β) tan δ) = cos-1 (-tan (22-20) tan ( - 14.9 ) = 74.560 or 1.301 radiation

Day length, Smax

=

(2 × Ws) 15

= ( 2 x 74.56 ) / 15 = 9.94 hours Now, Ho

= ( 24/3.14) x 4871 { 1 + 0.33 x cos ( 360 + 41 )/365 } x { ( 1.301 x sin 220 x sin ( - 14-9 ) } + ( cos 220 x cos ( - 14.9 ) x sin 74.560 }

Hg

Heat required to cook rice

=

28163 KJ/m2 – day.

=

{ 0.27 + 0.5 (8.9/9.94) } x 28163

=

20212.19 KJ/m2 – day

=

2271.011 KJ/m2 – hr.

=

1025 KJ

We require 1025 KJ of heat to cook rice and we are getting heat from sun per meter squence of earth and per hour 2271.011. The Solar instability measured by the pyranometer was found and recorded as below Time N.P.T.N. Achalpur

Solar Intensity 42

Solar Cooker Cum Water Heater Date – 15/03/03 (Reading with Pyranometer ) -

1 :10 2.0 3.0

Constant of measuring instrument

=

5.1 5.2 5.3

5.2 mV / Cal /cm2 /hr

CALCULATION S.1

=

5.2/5.2 mV/ Cal/cm2/min.

=

(5.2/5.2) x 4.187 x 10-3 KJ/cm2/min.

=

4.187 x 10-3 x 104 KJ/m2/min.

=

(41.87/60) KJ/m2/sec.

=

0.6978 KW/m2

=

697.8 W/m2

DESCRIPTION OF VARIOUS TABLES Successful fabrication of this multi-reflector type solar cooker cum water heater was done in workshop of our college. The performance test were carried out on difficult dates it on 02/03/03, 03/03/03, 10/03/03, 11/03/03 & 13/03/03 VARIATION OF TEMPERATURE WITH TIME Date of Test : 02/03/03

Atmosphere condition – Normal

Loading conditions – No load

Starting Time – 10.00 A. M.

Duration of Test = 10.00 A.M. to 5.00 P.M.

Time 9.00 a.m. N.P.T.N. Achalpur

No load condition Ambient Inside Temp. Tem. 220C 250C 43

Solar Cooker Cum Water Heater 280C 300C 310C 310C 310C 310C 290C 280C 260C

10.00 a.m. 11.00 a.m. 12.00 p.m. 1.00 p.m. 2.00 p.m. 3.00 p.m. 4.00 p.m. 5.00 p.m. 6.00 p.m. Date : 03/03/03 Time 9.00 a.m. 10.00 a.m. 11.00 a.m. 12.00 noon 1.00 p.m. 2.00 p.m. 3.00 p.m.

450C 820C 1040C 1140C 1220C 1180C 1080C 900C 700C

With water heater (flow of water = 100ml/min.) Ambient Temp. Inside Temp. Water inlet Temp. Water inlet Temp. 190C 220C 250C 250C 250C 320C 250C 290C 0 0 0 28 C 50 C 26 C 320C 300C 800C 260C 340C 0 0 0 30 C 84 C 28 C 380C 0 0 0 30 C 85 C 30 C 420C 310C 950C 270C 420C (with out water)

4.00 p.m

300C

5.00 p.m. 6.00 p.m.

280C 260C

800C

260C

380C

650C 250C 0 60 C 250C – Little Cloudy

320C 290C

(with water)

Weather

Date :10/3/03 Time

Ambient Temp.

Inside Temp.

10.00 am. 12.45 a.m. 2.00 p.m. 3.00 p.m. 4.00 p.m. 5.00 p.m.

320C 360C 360C 360C 320C 280C

750C 870C 850C 840C 840C 750C

N.P.T.N. Achalpur

With water heater Water inlet Water outlet Temp. Temp. 300C 300C 360C 360C 360C 340C

700C 500C 500C 470C 420C 400C

Flow of water (ml/min.) 100 150 100 150 75 150

44

Solar Cooker Cum Water Heater

Date :10/3/03 Ambient

With water heating Inside Temp. Water inlet Water outlet

Flow of

Time

Temp.

Temp.

Temp.

water

10.30 a.m. 11.30 a.m. 12.30 p.m. 1.30 p.m. 3.30 p.m. 4.30 p.m.

0

0

27 C 310C 350C 360C 360C 360C

0

39 C 450C 480C 550C 550C 510C

(ml./min.) 100 100 100 100 100 100

Starting time

Time of

Time taken

Date

0

28 C 310C 310C 310C 310C 300C

Dishes

70 C 850C 850C 900C 800C 700C

Quantity

11/3/03

RICE

200gm rice

2.45 p.m.

withdrawing 3.40 p.m.

13/3/03

RICE

+300 ml water 200gm rice

10.30 p.m.

11.30 p.m.

60 min.

14/3/03

PULSE

+300ml water 200gm pulse

2.00 p.m.

3.50 p.m.

110

15/3/03

EGG

+ 400ml water 1 No. Egg

1.30 p.m.

2.20 p.m.

50 min.

18/3/03

RICE

+200ml water 200gm rice

10.00 p.m.

11.15 p.m.

75 min.

PULSE

+300 ml water 200gm pulse

2.45 p.m.

4.45 p.m.

120 min.

26/3/03

to cook 55 min.

+ 400 ml water

Date : 26/3/03 Time 1.00 p.m. N.P.T.N. Achalpur

With water hearing Water inlet Water outlet

Ambient

Inside

Temp.

Temp.

Temp.

Temp.

( 0C ) 34

( 0C )

( 0C )

( 0C )

76

30

45

Flow of water (ml/min.) 100 45

Solar Cooker Cum Water Heater 2.15 p.m. 3.15 p.m. 4.15 p.m. 5.15 p.m. Food Cooked

35 76 33 78 33 77 32 75 250gms of rice

+

36 37 36 35 100gms Dal +

47 48 46 44 500 ml of water

100 100 100 100

Utensils made of thin metal with tight lids and painted dull black from outside are best suited for the cooking. But it is possible to cook even with ordinary stainless steel vessels but it requires more time. Use of tight vessel increases the pressure & temp. Inside the vessed and lowers the cooking time lesser will be the depth of food faster will be the cooking. For this the vessels with large bottom area are generally used. The maximum height of food material, which can be used is 60 mm. If more amounts are required to cook then use two separate vessels. Proper water quantity must be added with the food material so that it facilitates the cooking in optimum time. Cooking techniques with solar cooker can be classified as under – 1. As the supply of heat is from the top, convection current are set up hence slow process of boiling of food. The hard foods like pulses are hard to cook and require more time. Hence it is useful to soak these materials in water for 2 to 3 hours prior to putting in solar cooker. Due to this the food will absorb same amount of water & becomes soft. Then add less amount of water with it when it is placed for cooking. 2. Bread, Cake, Biscuits are prepared by baking process. Some vegetables like pumpkin, Brinjals, tomatoes etc. requires some high temp. (1000C). Hence these have to cook during peak intensity hours of the day, when sun is at zenith.

3. Some foods are better cooked with gradual rise of temp. such as milk preparations like ‘khir’, pudding and all root vegetables. They cook very delicious if they are cooked at 800C to 900C for longer time. Solar cooker is most suitable such applications during late hours i.e. 3-6 p.m. 4. Food items prepared by process of roasting are also well cooked in the solar cooker. All the roots like potato, sweet potatoes, groundnut etc. can be easily roasted in cooker

N.P.T.N. Achalpur

46

Solar Cooker Cum Water Heater without any water. Eggs can also be cooked without water. For this the food items must kept in open utensils or even directly on the absorber plate.

COOKING TIME AND TEMPERATURES The optimum temperature necessary to start cooking and time for cooking after reaching optimum temperature for different types of food are tabulated as under – Sr. No.

Type of food

1.

Very easily cooked food such as

2

cabbage, carrots and leafy vegetables. Easily cooked food such as root

3.

vegetables, mug and rice Harder to cook food like bread, cake

4.

some vegetable etc. Very hard to cook food like hard unbroken pulses, meat, special dishes

Optimum temperature necessary to start cooking.

Time for cooking after reaching the optimum temp.

700C

45 minutes

750C

55 minutes

800C

90 minutes

850C

120 minutes

etc.

WATER HEATING For water heating it is essential to adjust the flow of water as per requirement for normal operation. The temperature of water can be raised from 250C to 550C with flow of 150 ml/min. on a clear shiny day. The temperature of water can be increased by decreasing the flow rate. Low flow rate will allow the water to remain inside the box for more time and consequently the temperature of water coming out of the equipment will be higher. The maximum temperature of water is achieved during the period of 11 p.m. to 3 p.m. The collected data with different flow of water heater is as under. Sr.

Water flow

N.P.T.N. Achalpur

Water inlet temperature

Water outlet temperature 47

Solar Cooker Cum Water Heater No. 1 2. 3. 4.

(ml/min.) 50 100 150 200

( 0C ) 25 25 25 25

( 0C ) 92 77 55 47

ECONOMICS OF SOLAR COOKER CUM WATER HEATER COMPARISON WITH TRADITIONAL METHODS :In traditional cooking and water heating some mean is used to produce fire and then cooking material or water filled in some utensil is kept on this fire. The material of utensils may be Brass, Steel, Copper or Aluminum. Thus the heat from fire is transferred to the bottom of the utensil and then to the food or water through conduction & convection. But in case of solar applications the heat in the form of solar radiations is enter from the top of utensils and then this heat is used for cooking or water heating purpose. 1. In traditional methods flame temperature is very high hence cooking or water heating is achieved in less time. But in solar appliances temperature is raised slowly hence the cooking or water heating requires some more time. In other words the heat supply rate N.P.T.N. Achalpur

48

Solar Cooker Cum Water Heater in traditional methods is high about 1.0 to 1.5 kw. Whereas the heat supply rate of solar applications is less i.e. 0.5 Kw. But the research and developments are growing so fastly that we can a achieve application of solar appliances with less time, shortly. 2. The initial cost of solar applications is high as compared to others but its operating cost is negligible. Hence the Customer can get his money back in short payback period. Moreover the Govt. is giving about 40% subsidies on solar appliances. 3. Experimently it is provided that the food or water heated using solar radiations has medicinal properties and is effective for good health. 4. Solar applications also has no pollution problem & hence eco-friendly. We have carried out comparative study of solar cooking & water heating with some traditional resources. In India conventional sources used for cooking & water heating are. i) L. P. G.

ii) Kerosene Oil

iii) Coal

iv) Wood

v) Cattle dung cake

vi) Electricity

The following analysis clearly indicates the effectiveness of solar cooking & water heating over traditional methods.

1) LPG Liquid petroleum Gas is the most widely used fuel in Urban areas, and its use is growing rapidly day by day. Assuming that 35 kg.of water is heated in a day and cooking is done for 2 time a day. The total energy consumed in cooking – a) Energy to cook 200 gms of rice

=

840 KJ

b) Energy to cook 200 gms of Dal

=

1000 KJ

c) Energy to cook 2 vegetable

=

1500 KJ

Energy saved

= ( mwcpw∇Tw) +2 (Energy saved in cooking) = 35 x 4.18 x (50-25) + 2 x 3340 = 10337.5 KJ

N.P.T.N. Achalpur

49

Solar Cooker Cum Water Heater Calorific value of LPG Amount of LPG saved per day

= 50000 KJ/kg =

10337.5 50000

= 0.2068 kg/day Assuming that the equipment is used for 220 days in a year, Hence the total LPG saved

= 0.2068 x 220 = 45.5 Kg

Net amount saved per year

= 45.5 x 10 = 455 Rs/year

The cost of LPG unit is 2000 Rs. Pay back period = =

(Cost of Solar coo ker cum water heater − Cost of LPG unit Amount saved per year 2400 − 2000 455

= 0.879 years

2) KEROSENE Kerosene is widely used for poor peoples and its calorific Value is 30000 KJ/kh Amount of Kerosene saved per day = =

10337.5 30000

=

0.3445 lit/day

Amount of Kerosene saved in 220 days The total money saved

N.P.T.N. Achalpur

Total energy saved C.V.of Kerosene

=

0.3445 x 220

=

75.8 lit.

=

75.8 x 4

=

303.2 Rs/year

50

Solar Cooker Cum Water Heater =

2400 − 500 303.2

=

6.26 years

The cost of Kerosene stove is 500 Rs. Which is much less than solar equipment. Payback period =

Cost of solar coo ker cum water heater − Cost of ker osene stove Amount saved per year

3) WOOD Wood is the most promising source of energy for the peoples living in ruler areas. But use of wood has destroying effect is using of trees which results in environmental imbalance. Hence use of solar appliances in rural area is the best. calorific Value of wood Total amount of wood saved/day

=

16000KJ/Kg

=

Amount of energy saved CV of wood

=

10337.5 16000

= 0.646 Kg/day Total amount of wood saved in a year

= 0.646 x 220

( assuming 220 days of working in a year)

=

142.14 Kg/Year

Total money saved per year assuming

=

142.1 x 2

=

284.28 Rs.

As cost of 1 kg of wood as Rs.2 as the cost of wood ‘Chulla’s is very small it can be negelect. Pay back period

=

Cost of solar coo ker cum water heater Amount saved

=

2400 284.28

=

8.44 years

4) CATTLE DUNG CAKE – N.P.T.N. Achalpur

51

Solar Cooker Cum Water Heater Cattle dung cake is the most cheapest (Free of cost) and popular energy source for villagers. The calorific value of cattle dung

=

11500KJ/Kg

Amount of cattle dung saved

=

Amount of energy saved CV of cattle dung cake

=

10337.5 11500

=

0.8989 kg

Though the use of this fuel costs no money but it may be more effective if used as agricultural fertilizer. As the cattle dung has more nutritious value then artificial fertilizers and it also not contain any harmful chemical it is best as agricultural fertilizer instead of fuel. Moreover the use of solar cooker cum water heater also saves the time, which will consume in preparation of cattle dung cake.

5) ELECTRICITY – In modern peoples the use of electrical water heater, ovens etc. is increasing rapidly as it requires less time for cooking and heating and also is pollution free. The cost of 1 kw-hr of electricity

=

Rs.1.25

Heat saved per day

=

10337.5 KJ

Assuming available voltage

=

230 V

And current (for a coil of 1000 watt)

=

4.347 Amp.

Time required to produce the required heat

=

10337.5x10 3 230 × 4.347

=

103375 Sec.

N.P.T.N. Achalpur

52

Solar Cooker Cum Water Heater =

2.87 hrs.

=

2.87 x 1.25

=

3.589 Rs.

Amount saved in a year

=

3.589 x 220

(assuming 220 days working)

=

790 Rs/Yr.

=

2400 − 2000 790

=

0.51 year

Amount of saved in a year per day

The cost of electric equipment is about 2000 Rs. Payback period

DISCUSSION COMMERCIALIZATION OF SOLAR COOKERS Ever since the inception of Department of Non-conventional Energy Sources [Presently Ministry of Non-conventional Energy Sources (MNES) ], the desire of the government to popularize and promote solar cookers is evident. But So far, this has been done without the active involvement of commercial interest. The few manufacturers of solar cookers are really local entrepreneurs, without much support for manufacturing infrastructure, R & D, and market development. Vehicles of promotion such as media advertisement, provision of subsidy, marketing, testing, etc. had so far been in the control of N.P.T.N. Achalpur

53

Solar Cooker Cum Water Heater government agencies, chiefly the nodal agencies. The GEDA experience shows what can be achieved and what cannot be. It is obvious that commercialization of solar cookers, whose target market is clearly the urban middle class, is best done by leaders in the appliance industry such as those making pressure cookers, electric ovens, etc. But the absence of a similar product in the developed country markets does not enthuse the local manufacturers to enter into development and production of solar cookers.

One way to bring some

enlightened manufacturers into the solar cooker business is to provide incentives for product development, such as cost sharing, R & D support from reputed institutes/individuals, etc. The latter aspect is very important because without R & D support, development of a product (solar cookers) – as special and as complicated in its own way – would not be feasible. After the laboratory development and testing of a model, or indeed a range of models, the product can be launched with a brand name, using the existing marketing network of the manufacturer. As is the case with the growing buyers market in India, the product is likely to undergo changes in design and appearance, but with consistent support of the government. Solar cooker can make inroads into the vast and growing market of domestic appliances in India.

SOLAR HEAT ENERGY PROGRAMME TARGET FOR NINETH PLANE (1997-2002)

Solar water heating Solar cooker(Nos.) Other Solar Systems

N.P.T.N. Achalpur

I

II 1996-

Upto

97

III

IV

V

TOTAL

1999-

1998-

1999-

2000-

2001-

98

99

00

01

02

34000

35000

25000

37500

50000

0 41000

(Target) 25000

0 10000

0 15000

0 20000

0

(Target) 5000

0

0

0

5000

5000

5000

15000

(Target)

625000 250000 5000

IX

75000 0 30000 0 5000

54

PLAN

2500000 1000000 25000

Solar Cooker Cum Water Heater Slow-room Divisional testing

8

10

10

10

10

10

10

50

centre W/S in field

6

50

50

50

50

50

50

250

62

30

40

40

40

40

40

200

18 15 Reports (Nos.) Demonstration(Nos.) 1 10 20,00,000 Sq. meter domestic systems

20

30

40

50

60

200

15

20

25

30

35

125

of solar thermal W/S in field of solar passive (Nos.) Broad programmes

5,00,000 Sq. meter Industrial systems

SALIENT FEATURES & LIMITATIONS SALIENT FEATURES 1. No need of fuel, maintenance hence saves large amount of money. 2. Simple to use and easy to manufacture. 3. Cooking or water heating is not affected by wind hence more efficient. 4. No change of dust falling in utensils. 5. The food can be kept warm if kept inside the over for hours, even after sunset. 6. Due to multi-reflector type, maximum solar radiations are reflected inside the box and maximum temperature can be achieved which makes the operation more fast. 7. A crodle like cooking platform is provided to keep the utensile horizontal irrespective of sun. 8. The maximum inside box temperature can be achieved up to 200 0C in summer and 1500C in winter, on a clean day. N.P.T.N. Achalpur

55

Solar Cooker Cum Water Heater 9. All type of nutritive delicious foods can be prepared like cooking, roasting backing etc. 10. The hot water can be collected throughout the day. 11. Under normal flow conditions ( 150 ml/min.) the temperature of water is achieved up to 650C on clear day. 12. The temperature of water can be varied by varying the flow flowing through tube. The temperature of water can be achieved up to 900C if flow is maintained at 75 ml/min. 13. Easy for transportation as rollers wheels are provided. 14. The solar applications do not produce any pollution and hence Eco-friends. 15. Solar cooker is a domestic appliance. A domestic appliance has: i)

To perform a given task reliably at any time and in any place.

ii)

To be convenient to use and

iii)

To be aesthetically and economically attractive.

A thorough study of the market, product development, and market development, which includes promotional campaign, establishment of a dealer network etc. by the manufacturer are the usual steps involved in the process of launching a new product in the market. LIMITATIONS 1. One has to pre-plan the menu and has to cook according to the sun hours. 2. Time required for cooking & water heating is quite more as compare to the traditional one. 3. The equipment is not effective during night, or during rainy or cloudy days. 4. One has to continuously adjust the equipment in the direction of sun. 5. The equipment should be placed at such place where the sun rays can enter directly and is available for whole day without any shadow disturbances. Generally it should be kept on terrace of home.

N.P.T.N. Achalpur

56

Solar Cooker Cum Water Heater 6. Water poured in food material for cooking utensils and may get condensed on lower surface of glass. This reduces the transmissivity of the surface and lowers the efficiency. Hence frequent cleaning of the bottom surface of glass is required. 7. It is too bulky and unwidely to use. 8. The spacing between two glazings can not be cleaned. With such dire limitations, the question is whether it is possible to commercialize solar cookers at all. Or, the question can be posed in a different way. Considering the limitations of using an energy source such as solar which is characterized by a low energy density and wide fluctuations in intensity, what kind of product could be developed, that is marketable and user-friendly ? From this point of view, some basic issues of solar cooking have to be examined closely.

CONCLUSION The energy requirement is increasing very rapidly day by day. But we know that the fossile fuel are going to last within a short period of time. As per the survey the present sources of fossile fuels may lasts upto next 40 years. But the daily demand of energy is continuously increasing, hence the renewable energy sources can play an important role for fulfilling our requirement. Basically India has ruler based economy. But the ruler peoples are still away from efficient technological energy inputs. They are still using old methods of cooking & water heating. Hence other foreigners called us as ‘Backward’. But we have a great energy source available i.e. sun energy. We can efficiently use the solar energy for cooking & water heating. Because of this a great amount of fuel can be saved and people may get introduced to new technologies of solar. Solar energy is only non-exhaustible energy source and its use is clean, safe and environmentally sound. It has main advantage of no-pollution. Today the world is facing to a dangerous problem of pollution and which may cause imbalance of nature and may lead to a huge loss. Hence it is essential to control the pollution. The solar application is the best

N.P.T.N. Achalpur

57

Solar Cooker Cum Water Heater solution to this problem as 0% pollution is produced by the solar applications. Hence the popularization of solar energy is the demand of today. Government is also working for popularization of solar applications and is providing 40% subsidy on these equipments. Moreover India is a Hot country hence the use of solar equipment is very effective for this region. Hence the plan must be prepared to have a countrywide network of solar energy use, and must be actuated in the picture. It is now the time to plan for society that operates with a frame network for environmental consciousness as well as social & economical stability. The solar cooker program in India has been analysed, with special reference to product development efforts. The program of GEDA to market the existing solar cooker designs has been studied in detail and it was concluded that the failure of the program was directly related to the limitations of the product being promoted. Several issues such as basic R & D needs of cooking at low temperatures, heat transfer processes occurring in the box type solar cooker, testing and standardization, and applied research for user friendliness have also been examined.

REFERENCES 1.G. D. RAI. “ SOLAR ENERGY UTILIZATION’ Text Book 2. N. K. BANSAL , S. B. KESI “ IREDA NEWS ” - P. P. 84 – 89

Sept.97

3. H. H. GARG. “ TREATISE ON SOLAR ENERGY ” Text Book Vol. 1 P. P. – 50 – 59 4. JUSTIN A. BERENY. “ SOLAR ENERGY SYSTEM ECONOMICS ” SURVEY OF THE EMERGING SOLAR ENERGY INDUSTRY P.P. – 226 – 237 N.P.T.N. Achalpur

58

Solar Cooker Cum Water Heater “ DESIGN OF MODIFIED SOLAR WATER HEATER ” N. C. Proceedings - P. P. -

N.P.T.N. Achalpur

59