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Design, construction and operation of spherical solar cooker with automaticsun tracking systemRiyad Abu-Malouh, Salah Abdallah, Iyad M. MuslihDepartment of Mechanical and Industrial Engineering, Applied Science University, Amman 11931, Jordana r t i c l ei n f oArticle history:Received 15 March 2009Received in revised form 2 December 2009Accepted 21 July 2010Available online 6 September 2010Keywords:Solar cookingSun trackingPLC controlFrequency controla b s t r a c tIn this work, the effect of two axes tracking on a solar cooking system was studied. A dish was built toconcentrate solar radiation on a pan that is fixed at the focus of the dish. The dish tracks the sun usinga two axes sun tracking system. This system was built and tested. Experimental results obtained showthat the temperature inside the pan reached more than 93 ?C in a day where the maximum ambient tem-perature was 32 ?C. This temperature is suitable for cooking purposes and this was achieved by using thetwo axes sun tracking system.? 2010 Elsevier Ltd. All rights reserved.1. IntroductionThe energy section in Jordan depends heavily on the importedoil and gas products. This energy policy put the country in tougheconomic situations and slowed down the economical growth inthe last years. This situation is worsening by the dramatic increasein the crude oil prices worldwide and in the increased demand onenergy consumption. Jordan lies in high solar insolation band,where the average insolation intensity on horizontal surface isapproximately 57 kW h/m2/day, which is one of the highest inthe world 1.Biermann et al. 2 conducted a 1 year comparative field test of different types of cooking appliances including seven brands ofsolar cookers. The test took place in three study areas in South Afri-ca and involved 66 families, who expressed their preferences forcertain cooker types. Solar and wood (stoves and open fires) cook-ers were the most used cooking appliances. The families used solarcookers for about 38% of overall test days and for 35% of overallcooked meals and used wood cooking appliances for 42% of overalltest days. Fuel consumption measurements showed overall fuelsavings of 38% resulting in estimated payback periods (throughmonetary fuel savings) from 8 months onwards, depending onthe cooker type and region.Solar cooking in boarding schools and communal centers in iso-lated areas demands heating of large quantities of food. Francoet al. 3 presented three different kinds of absorbers, optimizedto fulfill different functions in a concentrator of an area of 2 m2.These alternatives allowed the possibility of satisfying the needsof a communal dining center, cooking for up to 30 children, onceeach concentrator has been installed.The policy formulation for substituting cooking energy byrenewable energy is addressed in multi-criteria context. In this re-gard, a survey was conducted to evaluate the perceptions of differ-ent decision making groups on present dissemination of variouscooking energy alternatives in India 4,5. Nine cooking energyalternatives were evaluated based on 30 different criteria, amongwhich were technical, economic, environmental, social, behavioraland commercial issues. It was found that liquefied petroleum gasstove is the most preferred device, followed by kerosene stove,box type solar cooker (BSC) and parabolic solar cooker (PSC).PSC were investigated by many researchers. Ozturk 6 con-structed and designed a low cost PSC and experimentally evaluatedits energy and exergy efficiencies. The energy output of the PSCvaried between 20.9 and 78.1 W, whereas its exergy output wasin the range of 2.96.6 W. It was found that the energy and exergyefficiencies of the PSC were in the range of 2.815.7 and 0.41.25respectively. Petela 7 analyzed a PSC of cylindrical trough shapefrom exergy point of view. Equations for heat transfer betweenthree surfaces: (i) cooking pot, (ii) reflector, and (iii) imagined sur-face making up the system were derived. The exergy efficiency ofthe PSC was found to be relatively very low (equals approximately1%), and about 10 times smaller than the respective energy effi-ciency which was in agreement with experimental data. Sonuneand Philip 8 designed a Fresnel type domestic concentrating coo-ker, which has an aperture area of 1.5 m2and a focal length of0196-8904/$ - see front matter ? 2010 Elsevier Ltd. All rights reserved.doi:10.1016/j.enconman.2010.07.037Corresponding author. Tel.: +962 5 3740026.* Corresponding author.E-mail addresses: mallouh (R. Abu-Malouh), Salahabdalah_1964 (S. Abdallah).Energy Conversion and Management 52 (2011) 615620Contents lists available at ScienceDirectEnergy Conversion and Managementjournal homepage: /locate/enconman0.75 m and was found to provide an adequate temperature neededfor cooking, frying and preparation of chapattis and capable ofcooking food for a family of 45 persons.The BSC has also been a subject of investigations conducted bymany researchers. El-Sebaii and Aboul-Enein 9 presented a tran-sient mathematical model for a BSC with one step outer reflectorhinged at the top of the cooker. The model was validated by com-paring the temperature distribution obtained by computer simula-tionwithexperimentalresults.Goodagreementbetweenexperimental and theoretical results was observed. The perfor-mance of a BSC with auxiliary heating was studied and analyzedwith the aid of (i) a built-in heating coil inside the cooker and(ii) a retrofit electric bulb in a black painted cylinder 10. The re-sults showed that with the use of auxiliary energy, when neces-sary, a solar cooker may be used throughout the year in areaswhere electricity is available. The study also recommended (i) toplace electric heating elements below the absorber tray in solarcookers which are to be built and (ii) to place a retrofit electric bulbfor heating on the absorber tray for year-round cooking for cookerswhich have been already built. El-Sebaii 11 presented a simplemathematical model for a BSC with outerinner reflectors based on analytical solution of the energy-balance equations fordifferent elements of the cooker. The cooker performance wasinvestigated by computer simulation in terms of the cooker effi-ciency as well as characteristic and specific boiling times.Numerical calculations were carried out for different tilt anglesof the outer reflector on a typical winter day in Tanta/Egypt. It wasshown that at the optimum tilt angle of the outer reflector, whichequals 60 ?C, the specific and characteristic boiling times are de-creased by 50% and 35%, respectively, compared to the case with-out the outer reflector. The overall utilization efficiency of thecooker was found to be 31%. A hot BSC was designed, manufac-tured and tested in Istanbul Technical University 12. In the theo-retical analysis, the differential equations have been solvednumerically by the fourth-order RungeKutta method.The obtained theoretical results were compared with the exper-imental ones and showed a good match. A model to predict thecooking power of a solar cooker based on three controlled param-eters (solar intercept area, overall heat loss coefficient and absor-ber plate thermal conductivity) and three uncontrolled variables(solar insolation, temperature difference and load distribution) was presented 13. The model was validated for commerciallyavailable solar cookers of both the box and concentrating types.The model basis was a fundamental energy-balance equation.Coefficients for each term in the model were determined by regres-sion analysis of experimental data. The valid range of model appli-cation included most of the feasible design space for family-sizedsolar cookers. The model was found to be applicable for estimatingthe cooking capacity of existing box type and concentrating typesolar cookers and for determining the combinations of interceptarea and heat loss coefficient required to cook a given quantity offood in a given climate. A simple wooden, hot box, with one reflec-tor solar cooker was designed and several demonstration unitswere fabricated by El-Ghetany and Abdel Dayem 14. The unitswere field tested and showed acceptable performance. Maximuminner temperature of the units reached 160 ?C under field condi-tions of Giza, Egypt (30?N).Different foods were cooked successfully such as rice, meat, fish,and beans. The time of cooking ranged from 1 to 2.5 h. A series oftests were carried out during nine days to compare the SudaneseBSC with some similar Indian designs 15.Sudanese BSC showed better thermal performance. Using inter-nal, external reflectors and sloping of the top cover enhanced sig-nificantly the thermal performance. This was revealed by theamount of heat absorbed and hence the achieved plate tempera-ture. Algifri and Al-Towaie 16 outlined a method to determinea reflectors performance and its orientation factors that dependupon the elevation angle of the sun, the solar surface azimuth an-gle and the reflector tilt angle. The analysis was applied to a cookerplaced in the city of Aden in Yemen. The results indicated withproper cooker orientation improvement in the performance ofthe cooker due to the reflector. It reached during the winter sea-son more than 100% at lower elevation angles and more than 60%at high elevation angles.Factors governing the operation of three BSC models (HS7534,HS7033 and HS5521) were described 17. The results showed thatHS552I is cheaper, and its volume is only 35% compared to HS7033.Comparing the performance of HS7033 and HS5521 was also per-formed based on the data collected during testing with and with-out load. The results showed that the HS5521 has the same heatcollection rate and is able to cook as fast as HS7033. Ekechukwuand Ugwuoke 18 presented the design philosophy, constructionand measured performance of a plane reflector augmented BSC.The experimental solar cooker consisted of aluminum plate absor-ber painted with black matt and a double glazed lid. Predictedwater boiling time using the two figures of merit compared favor-ably with the measured values.The performance of the cooker with the plane reflector was im-proved tremendously compared to the cooker performance with-out the reflector. A hot BSC with used engine oil as a storagematerial was designed, fabricated and tested to enable cookingeven in the late evening 19. The performance and testing of thecooker was investigated by measuring the stagnation temperaturesand conducting cooking trials. The efficiency of the hot box storagesolar cooker was found to be 27.5%. Kumar investigated the topheat losses, constituting the major losses in the BSC and affectingits thermal performance 20.The investigation revealed that the pot water required less timeto reach a certain temperature with an increase in solar radiationlevel while, as expected, it took longer time with higher values ofload of water in the pots. Reddy and Rao 21 showed that the per-formance of conventional BSC can be improved by better designs ofcooking vessels with proper understanding of the heat flow to thematerial to be cooked. An attempt was made to arrive at a mathe-matical model to understand the heat flow process to the cookingvessel and thereby to the food to be cooked. The mathematicalmodel considered a double glazed hot BSC loaded with twodifferent types of vessels, kept either on the floor of the cooker oron lugs.It was found experimentally and by modeling that the cook-ing vessel with a central cylindrical cavity lugs results in highertemperature of the thermal fluid than that of a conventional vesselon the floor or on lugs. El-Sebaii and Ibrahim constructed andtested a BSC with one or four cooking pots under the weather con-ditions of Tanta city in Egypt 22. Experiments were performedduring July 2002 using the cooker with and without load. The coo-ker was able to cook most food kinds with an overall utilizationefficiency of 26.7%. Amer introduced a novel design of solar cooker,in which the absorber is exposed to solar radiation from top andbottom sides 23.A set of plane diffuse reflectors were used to direct the radiationonto lower side of the absorber plate. The performance of the newcooker and the conventional BSC was investigated under sameoperating conditions. The obtained results show that the absorbersof the BSC and the double exposure cooker attain 140 ?C and 165 ?Crespectively. Sharma et al. investigated the thermal performance ofa prototype solar cooker based on an evacuated tube solar collectorwith phase change material (PCM) storage unit with commercialgrade erythritol as a latent heat storage material 24. Solar energywas stored in the PCM storage unit during sunshine hours and wasutilized for cooking in late evening/night time. Noon and eveningcooking experiments were conducted with different loads and616R. Abu-Malouh et al./Energy Conversion and Management 52 (2011) 615620loading times. Cooking experiments and PCM storage processeswere carried out simultaneously.The system was found capable to cook successfully twice (noonand evening) in a single day during Japanese summer months.Noon cooking did not affect evening cooking, and the eveningcooking using the PCM heat storage was found to be faster thannoon cooking. It was noticed that the PCM did not melt in January(winter) in Japan. In summer, PCM temperatures reached morethan 110 ?C at the time of evening cooking. Hence, erythritol wasfound to be a promising PCM for solar cooking. Sharaf 25 revealedthe concept of conical focus and explained the design of a solarcooker on its basis. The conical cooker was practically tested forgrilling both white and red meat in a record time and a methodfor obtaining real boiling temperature of water (100 ?C) using a so-lar heater was reported. The results showed that the conical cookerhas advantages regarding ease of manufacture, low price, light-weight and efficiency. It also demonstrated its ability and suitabil-ity for cooking different kinds of meat and legumes. Narasimha Raoand Subramanyam investigated the role of the vessel inside the so-lar cooker 26. It was found that raising the vessel by providingfew lugs made the bottom of the vessel a heat transfer surface. Thischange improved the systems performance by improving the heattransfer rates in both heating and cooling modes.Despite their ability to provide adequate temperatures neededfor cooking, frying and preparation of chapattis, all the aforemen-tioned types of concentrating solar cookers, suffer like all concen-trating solar cookers with manual tracking from their lowefficiency. This low efficiency is due to the fact that the solar raysare not perpendicular to the cookers surface most of the day.Accordingly, it is expected that the efficiency can be considerablyimproved by keeping the solar rays perpendicular to the cookerssurface by using an automatic sun tracking system 8,27 withthe solar cooker. In this context, this paper presents the design,construction and operation of a solar cooker with automatic twoaxes sun tracking programmable logic controller (PLC) system,characterized by a fairly simple electromechanical setup which re-duces cost, maintenance and the possibility of failure.2. The automatic sun tracking system design and controlThe amount of power produced by solar system depends on theamount of sunlight to which it is exposed. As the suns positionchanges throughout the day, the solar system must be adjustedso that it is always aimed precisely at the sun and, as a result, pro-duces the maximum possible power. Single axis tracking systemsare considerably cheaper and easier to construct, but their effi-ciency is lower than that of two axes sun tracking systems. Onthe other hand, some solar systems require only two axes tracking,such as point focus concentrators.Two axes sun tracking systems can be applied in all types of so-lar systems to increase their efficiency. A large number of investi-gations have been performed to design and employ two axes suntracking systems, however, only a few were cited in the literaturethat investigated the effect of using two axes sun tracking systemscontrolled by a modern computerized control system, such as aprogrammable logic controller (PLC) control system. Barakatet al. 28 designed a two axes sun tracking system with closedloop system and with complicated typical electronic control cir-cuits. They found that the energy available to the two axes trackeris higher by 20%.Neville 29 presented a theoretical comparative study betweenthe energy available to a two axes tracker, an eastwest trackerand a fixed surface. It was found that the energy available to theideal tracker is higher by 510% and 50% than the eastwest track-er and the fixed surface, respectively. Khalifa 30 performed anexperimental study to investigate the effect of using a two axessun tracking system on the thermal performance of compound par-abolic concentrators (CPC).The tracking CPC collector showed a better performance with anincrease in the collected energy of up to 75% compared with anidentical fixed collector. Hession and Bonwick 31 introduced asun tracking system for use with various collectors or platforms.The system used both analog and digital techniques with sun sens-ing phototransistors that enabled the suns position to be resolvedto a precision of better than 0.1?. Baltas et al. 32 made a compar-ative study between continuous and stepwise tracking. Theyshowed that unlike concentrating systems, flat plate photovoltaic(FPPV) arrays yielded almost the same energy when tracking in astepwise fashion. Tracking motors could be idle for 1 or 2 h andyet obtain more than 98% of the energy obtained from a continuoustracking array. Brunotte et al. 33 presented a prototype two stagephotovoltaic concentrator with concentration ratios up to 300?with one axis tracking. Such concentrators are very promising inreducing the cost of solar electricity conversion.In this work, the design of two axes tracking system was per-formed using an open loop control that is based on programmablelogic controllers (PLC). The block diagram of the hardware compo-nents of the solar cooker with two axes sun tracking system isshown in Fig. 1.The PLC has a programmable memory in which the instructionsare stored to implement the various functions that are used to con-trol the tracking motors into the calculated positions. The electro-mechanical system shown in Fig. 1 was designed to drive thespherical solar cooker by means of two motors, one for trackingthe sun around the vertical axis which is 220 VAC and another24 VDC motor for eastwest tracking. A bridge rectifier suppliedthe 24 VDC motor with the required voltage. A frequency inverterprovided the 220 VAC motor with the desired controlled voltageand frequency. A screw gear is used to reduce the speed of the24 VDC motor and to transfer the rotational motion of the motorinto translational one which is suitable to drive the spherical coo-ker in the up and down directions. A spur gear is used to reduce thespeed of the 220 VAC motor and amplify the torque of the motor todrive the spherical cooker around the vertical axis.Spherical solar cooker tracks the sun by moving in prescribedway to maximize the incident radiation beam.3. The governing equationsThe surface position is defined by two angles, b andcas shownin 34. b is the slope of the surface andcis the surface azimuth an-gle. The calculated angles b andc(as a function of time) should beb input inputPLCcontrollerBridgerectifierFrequencyinverter24VDCmotor220VACmotorScrewgearSpurgearSpherical solr cookerFig. 1. Block diagram of the spherical solar cooker with two axes sun tracking system.R. Abu-Malouh et al./Energy Conversion and Management 52 (2011) 615620617inserted into the PLC system as a program 35. The PLC systemwill control the work of the actuator so that it will track the posi-tions of the sun. This programming method of the control functionof real time is used in this work. It works efficiently in all weatherconditions regardless of the presence of heavy dusty or cloudyconditions. To implement this method for two axes tracking, thesurface positions are determined as follows:b hz1ccs2where hzis the zenith angle of the sun andcsis the solar azimuthangle.The model that is used to calculate hzandcsvalues for Amman(latitude angle of / = 32?) is given as:d 23:45sin 360284 n365?3where d is the declination angle and n is the number of the day inthe year.Andcoshz cos/cosdcosx sin/sind4wherexis the hour angle.Andcosxewtandtan/5wherexewis the eastwest hour angle.cs C1C2c0s C31 ? C1C22? 1806wheretanc0ssinxsindcosx? cos/tand7C11ifjxj 6xew?1ifjxj xew?8C21if/ ? d P 0?1if / ? d 0?9C31ifxP 0?1ifx 0?104. Mechanical design of the solar cookerThe spherical solar cocker is a device that is used to collect thesun light by using a set of concentrating mirrors. The system wasdesigned using simple electromechanical setup to reduce cost,maintenance and possibility of failure. This system can also be eas-ily installed and assembled. It is composed of a cocking pan fixed atthe focus of a spherical dish. This dish collects the solar energyincident on it and concentrates it using 256 concentrating mirrors.These mirrors are fixed in place using silicon glue. The dimensionof each mirror is of 6 by 6 cm.This dish is designed to track the sun by moving in a prescribedmanner to minimize the angle of incidence of the radiation beamon its surface. This was achieved using a two axes tracking system.This system is composed of the two motors shown in Fig. 2. One ofthem rotates the dish around the horizontal axes. This motion re-sults in a rotation in the yz plane (up and down motion). The othermotor rotates the dish around the vertical axes. This motion resultsin a rotation in the xz plane (left and right). The combination ofthese two motions results in a precise tracking of the incident radi-ation beam. The rotation of the two motors is controlled by the twoaxes sun tracking system with PLC control designed before.This system actuates the two motors to rotate the dish in thedesired direction that guarantees achievement of our goal desiredfrom this design, which is to track the incident solar beams. Allhardware components are located in the same control box, exceptthe motors and their gears. Furthermore, in order to conserve thesolar energy, plastic bags are used to cover the reflecting mirrorsand the receptacle creating a green house effect and keeping theheat trapped.5. Experimentation and resultsThe spherical solar cooker with two axes sun tracking systemwas manufactured according to the desired design in the work-shops at Applied Science University, in Amman Jordan. Photo-graphs of this system are shown in Fig. 3. Experiments weredone on the spherical solar cooker in the renewable energy labora-tory on three days; 13/5/2008, 4/6/2008 and 12/8/2008.The measuring electronic parts were tested and calibratedbefore being used on the various tests. The global solar radiationon a horizontal surface was measured using Kipp and Zonenpyranometer with a sensitivity of 15.53lV/W/m2. Two differentcalibrated thermocouples (type-K) coupled to digital thermometerFig. 2. Parts of the mechanical design of the solar cooker.618R. Abu-Malouh et al./Energy Conversion and Management 52 (2011) 615620with a range of 50150 ?C were used to measure the temperatureinside pan and outside pan. The thermocouples were of Testo 110type with an accuracy of 0.2 ?C for a temperature range of (?25 to+75 ?C). The experiments started from 8:30 morning to 4:30 after-noon. Figs. 4 and 5 show the variation in ambient temperature andthe variation in the solar intensity through three summer days.Figs. 6 and 7 show the variation in temperature inside pan as afunction of time and the variation of the outside pan temperatureas a function of time. The figures show an increase in the temper-ature inside the pan during early hours of the day until it reachesthe maximum values around noon correspondingly to the highestsolar radiation and then decreases due sunset.From the curve of temperature inside pan variation as a func-tion of time it is seen that the temperature inside the pan reached93 ?C in a normal summer day, where the maximum ambient tem-perature registered 32 ?C. This shows that the temperature insidethe pan could still reach further higher rates on hotter days. It isnoticed after studying all the curves, that the temperature insidethe pan increases when the ambient temperature is hotter orwhere the solar intensity is prevalent. When using this system(a)(b)(c)Fig. 3. Photographs showing: (a) the whole system, (b) the pan and the dish, and (c) the control components.20253035891011121314151617Time (hr)Ambient Temperature (oC)13 / 5 / 20084 / 6 / 200812 / 6 / 2008Fig. 4. Ambient temperature variation as a function of time.50150250350450550650750850950891011121314151617Time (hr)Solar Intensity (W/m2) 13 / 5 / 20084 / 6 / 200812 / 6 / 2008Fig. 5. The solar intensity variation as a function of time.2030405060708090100891011121314151617Time (hr)Temperature Inside Pan (oC)13 / 5 / 20084 / 6 / 200812 / 6 / 2008Fig. 6. Inside pan temperature variation as a function of time.2030405060708090100891011121314151617Time (hr)Temperature Outside Pan (oC)13 / 5 / 20084 / 6 / 200812 / 6 / 2008Fig. 7. Outside pan temperature variation as a function of time.R. Abu-Malouh et al./Energy Conversion and Management 52 (2011) 615620619for cooking or simply heating water, the latitude of location, sea-son, and wind speed and weather conditions as cloudy days ordusty days should be considered. It should be remembered thatfood containing moisture cannot get much hotter than 100 ?C inany case, so it is not necessary to cook at the high temperaturesas indicated in standard cookbooks. Because the food does notreach too high temperature, it can be safely left in the cooker allday without burning. This type of cookers can be used to warmfood, drinks and can also be used to pasteurize water or milk.On the other hand, from Fig. 4, it can be seen that the ambienttemperature increases from the morning till noon, after that, it de-creases gradually till sunset. This same phenomena can also beseen for solar intensity in Fig. 5, temperature inside pan in Fig. 6and temperature outside pan in Fig. 7.It can also be seen from Fig. 4 that the ambient temperature atany given time in 13/5 is less than that for the same time in 4/6 andthey both are less than that in 12/6. This is expected because 13/5is at the end of spring season while 4/6 is at the beginning of sum-mer and 12/6 is expected to be hotter than 13/5 and 4/6. This samephenomena can also be seen for solar intensity in Fig. 5, tempera-ture inside pan in Fig. 6 and temperature outside pan in Fig. 7.Finally comparing the maximum ambient temperature (32 ?C)with the maximum achieved temperature inside the pan (93 ?C),it can be seen that the temperature inside the pan is considerablygreater than the ambient temperature. This was achieved due tothe solar beam concentrating system combined with the two axesautomatic sun tracking system. The results of using parabolic solarcooker with automatic tracking 36 showed that the water tem-perature inside the cookers tube reached 90 ?C in a typical sum-mer day, when the maximum registered ambient temperaturewas 36 ?C.6. ConclusionA spherical solar cooker was designed and constructed. A twoaxes sun tracking system was designed and constructed to controlthe spherical solar cooker rotation. This sun tracking system de-pends on PLC and frequency control. It assures that the sun lightbeam is normal to the dish at any time of the day. This results inthe highest possible efficiency that can be achieved for the solarcooker. The new system was constructed and tested for three dif-ferent days.By comparing the results of the spherical solar cooker in thisstudy compared with the results of the parabolic solar cooker withautomatic sun tracking system in 36, the simple comparisonshows that; the spherical solar cooker provided higher power thanthe parabolic solar cooker. Where, the water temperature insidethe cookers tube reached 90 ?C in typical summer days when themaximum registered ambient temperature was 36 ?C. While forthe system in this study, results show that a temperature as highas 93 ?C or higher can be achieved. This temperature is sufficientand safe for cooking purposes especially for sites that are far fromany city.References1 Badran O. Study in industrial applications of solar energy and the range of itsutilization in Jordan. Renew Energy 2001;24:48590.2 Biermann E, Grupp M, Palmer R. Solar cooker acceptance in South Africa:results of a comparative field test. Energy 1999;66:4017.3 Franco J, Cadena C, Saravia L. Multiple use communal solar cookers. Sol Energy2004;77:21723.4 Pohekar S, Ramachandran M. Multi-criteria evaluation of cooking energyalternatives for promoting parabolic solar cooker in India. Renew Energy2004;22:144960.5 Pohekar S, Ramacharidran M. Multi-criteria evaluation of cooking devices withspecial reference to utility of parabolic solar cooker in India. Energy2006;31:121527.6 Ozturk H. Experimental determination of energy and exergy efficiency of thesolar parabolic cooker. Sol Energy 2004;77:6771.7 Petela R. Exergy analysis of the solar cylindrical parabolic cooker. Sol Energy2005;79:22133.8 Sonune A, Philip S. Development of a domestic concentrating cooker. RenewEnergy 2003;28:122534.9 El-Sebaii A, Aboul-Enein S. A box type solar cooker with one stop outerreflector. Energy 1997;22:51524.10 Hussain M, Das K, Huda A. The performance of a box type solar cooker withauxiliary heating. Renew Energy 1997;12:1515.11 El-Sebaii A. Thermal performance of a box type solar cooker with outerinnerreflectors. Energy 1997;22:96978.12 Binark A, Turkmen N. Modeling of a hot box solar cooker. Energy ConversManage 1996;37:30310.13 Funk