Design,development and testing of a novel non-tracking solar cooker

A novel solar cooker that does not require any tracking, has been designed, fabricated and tested and its performance has been compared with the hot-box solar cooker. The performance of the novel solar cooker is almost similar with the hot-box solar cooker though it is kept fixed while the hot box is tracked towards the sun every hour. The overall efficiency of the novel solar cooker has been found to be 29·5%. The payback period varies between 1·30 and 3·29 years depending upon the fuel it replaces. The payback periods are in the increasing order with respect to fuels such as firewood, coal, electricity, kerosene and LPG. The short payback period shows that the use of the novel non-tracking solar cooker is economical. © 1998 John Wiley & Sons, Ltd.     

Design, development and testing of a double reflector hot box solar cooker with a transparent insulation material

A double reflector hot box solar cooker with a Transparent Insulation Material (TIM) has been designed, fabricated, tested and the performance compared with a single reflector hot box solar cooker without TIM. A 40 mm thick honeycomb made of polycarbonate capillaries was encapsulated between two glazing sheets of the cooker to minimise convective losses from the window so that even during an extremely cold but sunny day two meals can be prepared, which is not possible in a hot box solar cooker without TIM. The use of one more reflectors resulted in an avoidance of tracking towards sun for 3 h so that cooking operations could be performed unattended, as compared to a hot box solar cooker where tracking ahead of the sun is required every hour. The efficiencies were 30.5% and 24.5% for cookers with and without a TIM respectively, during the winter season at Jodhpur. The energy saving by use of a solar cooker with TIM has been estimated to be 1485.0 MJ of fuel equivalent per year. The payback period varies between 1.66 and 4.23 y depending upon the fuel it replaces, and is in increasing order with respect to the following fuels: electricity, firewood, coal, LPG and kerosene. The estimated life is about 15 y. Therefore, the use of a solar cooker is economical. The double reflector hot box solar cooker with TIM will be a boon in popularising solar cookers in developing countries.     

Performance and testing of large-size solar water heater cum solar cooker

The performance of a novel device has been tested. The device can be used as a collector cum storage type solar water heater during the winter, and, with minor adjustments, it can be used as a hot-box solar cooker. The device can provide hot water at 50–60°C in the evening, which can be maintained at 40–45°C until the following morning. It can also be used for cooking food for about 40 people. The efficiencies of the device as a solar water heater and as a solar cooker have been found to be 67.7% and 29.8%, respectively. The payback period varies between 1.64 to 5.90 years depending on the fuel it replaces. The payback periods are of increasing length with respect to the fuels firewood, coal, electricity, LPG and kerosene.     

Studies on a new combined concentrating oven type solar cooker

This paper describes a combined concentrating/oven type solar cooker. The device can be used for cooking, boiling and roasting of foods on clear days. The cooker makes use of both concentrator and flat-plate collector principles, wherein the sunlight entering the cooker is reflected onto a hood which is provided with a selective solar absorber coating which houses the cooking vessels. Hence, the cooker makes use of both direct and diffuse solar radiation. The important part of this new device is a stationary mode and maximum capture of energy through improved design. The new cooker has been found to be more practical in comparison with either the simple hot box type solar cooker or concentrator type cookers where one needs to direct it to follow the sun. The cooking trial shows that the new device can be used twice a day, even on winter days.     

Design, development and testing of a large-size solar cooker for animal feed

A large-size solar cooker for animal feed has been designed, developed and tested. The cooker employs locally available materials of low cost, e.g. pearl-millet husk and horse excreata. The commercial materials required for its fabrication are plain glass, mild steel angle and sheet, wood and aluminium sheet cooking utensils. The solar cooker is capable of boiling 10 kg of animal feed, sufficient for five cattle per day. The efficiency of the solar cooker is 21·8%. The cost of the cooker is only Rs 1200, which can be recovered in 0·45-1·36 years depending upon the fuel it replaces. The short payback periods suggest that the use of the solar cooker is economic. The use of the cooker will save a lot of firewood, cowdung cake and agricultural waste which are presently used for the boiling of animal feed.     

Energy conservation and payback periods of natural circulation type solar water heaters

Energy savings in relation to different fuels, namely firewood, coal, kerosene, LPG and electricity have been calculated for a pressurized natural circulation type solar water heater with blackboard paint and a selective surface on the absorber. The payback periods have been computed by considering 10% compound annual interest, 5% annual maintenance cost and 5% inflation per year in maintenance cost and fuel prices. The cash flow has also been worked out for both solar water heaters. The cash flow is more for a solar water heater with a selective surface. The payback periods are 2.08–8.67 years for a solar water heater with a selective surface and 2.13–8.96 years for a solar water heater with blackboard paint. The estimated life of a heater is about 15 years. This shows that use of a solar water heater for heating water is very economical.     

Performance and testing of two models of solar cooker for animal feed

Two simple solar cookers, one made of clay and locally available materials, and the other of exfoliated vermiculite and cement tiles, have been designed, fabricated and tested. The comparative performance of both cookers is described, and their efficiencies are 22.6 (clay) and 24.9% (vermiculite), respectively. The cookers are capable of boiling 2 kg of animal feed per day, and represent the equivalent of 1350 MJ of fuel per year at Jodhpur. Payback periods for solar cookers made of vermiculite tiles vary from 0.50 to 3.47 years, depending upon the fuel they replace. The shorter payback period suggests that the use of the cooker is economical.     

An improved solar cooker

An improved hot box type solar cooker (SC-2) has been designed, developed and tested. It is an improvement on the solar cooker SC-1 earlier developed at the institute. The cooking chamber has properly been optimized for cooking the food for a family of five persons. A rubber gasket has been provided at the boundary of the openable door to prevent the leakage of hot air, thus increasing the pressure in the cooking chamber. Different cooking trials like boiling, roasting and baking were successfully conducted and the cooker was found useful from 8.00 a.m. to 5.00 p.m., even during a winter month. The efficiency of the cooker was found to be 41.2 per cent.     

A new solar cooker design

This paper deals with a new box-type solar cooker design with a single reflector at the hood. In this design, the base of the oven acts as the lid, unlike the conventional box-type solar cooker. With the introduction of this concept of the lid as the base of the oven, we solve the problem of preheating, as faced in the conventional box-type solar cooker. Thus, the performance of conventional box-type solar cookers can be appreciably improved by having the lid at the bottom of the oven and not at the top. It has been observed that, having cooked once, the preheating time for further cooking is greatly reduced as compared to the conventional box type. Hence, cooking twice a day by this cooker becomes easier, unlike cooking by the conventional one.     

Mathematical modeling of a box-type solar cooker employing an asymmetric compound parabolic concentrator

A novel design of solar cooker is introduced. The cooker is of box-type equipped with an asymmetric compound parabolic concentrator (CPC) as booster-reflector. It consists of an insulated box equipped with a vertical double glazing cover on a side, and a vertical absorber plate laid out just behind the transparent cover. The booster-reflector is fixed on the glazed side of the box. The absorber plate and the glazing form a vertical channel, open at the top and bottom, and enclosed at the sides. The two openings allow the inside air circulation. A mathematical model of the heat transfer processes involved with this solar cooker, containing a cooking pot loaded with water and deposited on the box floor; was developed and the effects of various parameters, such as solar radiation, load of water and clouds on the dynamic behavior of the cooker are studied.     

Fabrication of and performance studies on a low cost solar cooker having an inclined aperture plane

A low cost box-type solar cooker made of two paper carton boxes with crumpled newspaper balls as insulation has been fabricated with a tilted aperture plane. Comparative tests of this cooker have been conducted against a normal type costlier solar cooker with 1000 ml load of water in each of the cookers. It has been observed that on a sunny day water temperature initially increases more rapidly in the new cooker compared to the normal type cooker. But at temperatures higher than 90°C both the cookers perform similarly. Two figures of merit F₁ and F₂ have also been found to be satisfactory. An arrangement of low cost auxiliary heating using a 100w electric bulb inside a blackened metal casing allows the carton box cooker to reach cooking temperatures under cloudy conditions with ease when the normal type solar cooker fails. The cost of materials for the new cooker is within US $10 and has been observed to be as effective as the normal type solar cooker which requires between US $40 and $65 to fabricate.     

A novel advanced box-type solar cooker

An advanced version of the box-type solar cooker is presented: a fixed cooking vessel in good thermal contact with a conductive absorber plate is set into the glazing; the results are improved thermal performance, easier access to the cooking vessel and less frequent maintenance due to protection of all absorbing and reflecting surfaces. Outdoor tests show that 5 L of water per sq m of opening surface can be brought to full boiling in less than one hour. A finite element simulation model of the advanced box cooker is presented. It is shown that the most decisive parameters are absorber-to-pot heat transfer and absorber conductivity. Field tests in Ethiopia and India are under way, local production in India has started.     

The performance of a solar cooker in Egypt

A simple, efficient solar cooker was designed and its performance in the Egyptian climate was evaluated. The cooker is of the hot box type with a plane booster mirror reflector. The performance of the cooker was measured experimentally for over two years under different working conditions. The test conditions included experiments with and without adjusting the cooker's position for maximum solar radiation and the tilt angle of the booster reflector for maximum concentration. Formulas for calculating the orientation angle of the oven and tilt angle of the reflector were deduced. The shadow effect caused by the sides of the oven was also calculated. The solar cooker proved to be reliable, trouble free and efficient. All kinds of food were cooked including meat, chicken, rice, peas, beans, potatoes, soup, eggs and cakes. A good meal for a family of four was cooked in 3–4 h. It was established that better heat transfer occurred when the cooking pot was covered with an airtight plastic transparent cover rather than using an ordinary metallic cover. The energy balance of the cooker from heat transfer considerations enabled estimates of both over and food temperature to be made. Calculated values agreed well with the experimental measurements.     

Ultra low cost solar cookers: design details and field trials in Tanzania

A family-sized ultra low cost solar cooker has been developed. The hot box style cooker is designed to be built on site by the users with minimal tools, skills or special materials. It consists of a shallow 1 m² square hole in the ground, insulated with straw and lined with adobe (mud and straw), a glass or plastic roof, and a 1 m² aluminised plastic reflector with guy ropes for adjustment. An insulated fabric door allows access to the oven; pots are slid in, onto a metal base plate. The cost is about £8. The cooker has been shown to provide cooked food for 10–12 people on clear days with meals around midday and dusk (assuming 0.4 kg dry weight of food per person daily). A four litre load of water can be brought up to cooking temperature (80°C) in 60–70 min. The adobe linear provides some thermal mass to even out temperature swings in cloudy weather.The cooker was developed at the Sunseed Trust's Spanish Project, Sunseed Desert Technology. It is being field tested by Sunseed in Tanzania. The paper reports on technical results and observations on how the cooker technology can best be integrated into this particular African context.     

The comparison of three types of Indonesian solar box cookers

This paper describes the influences which govern solar box cookers: HS 7534, HS 7033 and the newest design HS 5521. The best of solar cooker, type HS 7033 gave oven temperature of 202°C between 12:00 and 12:45 p.m. on October 7, 1997. Thirty-four units of this type have been field tested since September 1997. It was found that these solar cookers have a good heat storage capability, therefore they can be used for consecutive cooking. The optimization of the size, the aperture area, the insulator thickness, the oven volume and the reflector area leads to a new design, type HS 5521. Its volume is only 35% of the volume of HS 7033 and cheaper. The performance comparison of the last two solar cookers are described based on the data collected during testing with and without load. The HS 5521 has the same heat collection rate and is able to cook as fast as HS 7033.     

Incentives for solar water heating systems

Life-cycle costing has been used in an economic analysis of three solar domestic hot water installations. These are in operation in Las Palmas (Canary Islands) and are backed by conventional installations consuming either fuel-oil (GG), butane (BB) or electricity (EE). The cumulative cost flows (CCF), including expenditures for purchase, recovery, maintenance, fuel and operating costs, are calculated over the useful life of the installations for expected annual fuel-increment rates. Twenty-seven comparisons are made between the solar (SAS) and conventional systems (CS). Total savings are found over the lifetime and the repayment periods are obtained as a function of discount rate. The SAS and CS are examined with respect to economic incentives such as subvention, tax deduction, loans and their combinations. Finally, the variations of the payback periods and rates of return on investment (IRR) are plotted against the fuel price, annual fuel increment rate and initial investment in the SAS for a wide range of economic parameters.     

Performance analysis of a solar cooker in Turkey

A box‐type solar cooker is designed and its thermal performance is analysed experimentally. The cooker tracks the sun in two axes, altitude and sun azimuth, by hand control for hourly periods. The experimental results show that the tested cooker may be assumed suitable in some cooking processes for specific country conditions. Copyright © 2002 John Wiley & Sons, Ltd.     

Design and performance studies on a solar room heater

Almost all the research and development of solar heating has been directed towards large and expensive buildings in areas where conventional fuel and electricity are plentiful and cheap. Keeping this in mind a solar room heater capable of heating single rooms to comfortable level has been designed and tested for two winter seasons at Roorkee. Simple design curves for finding out the absorber size, for a given heating load for a number of Indian cities, and panel size for the specified requirement are developed and discussed. Water is used as a heat storage media and hot water is stored in a number of storage panels placed inside the room near the wall. Radiative and convective heat losses from the surface of panels heat the room air. Temperature distribution in the experimental and office room with and without heating it along with the ambient air temperature and solar insolation are measured and discussed. It is concluded that conventional rooms can be conveniently heated to comfortable levels by solar energy.     

Experimental investigation of a box-type solar cooker with a finned absorber plate

This article provides the results and finding of an experimental work undertaken in the desert of Algeria. That aimed to compare experimental performance of a box-type solar cooker equipped with a finned absorber plate to a similar box-type cooker which absorber plate without fins. Tests have been carried out on the experimental platform of the Renewable Energies Research Unit in Saharan Environment of Algeria at Adrar. Adrar is located at a latitude 27° 53′ North and a longitude 0° 17′ West. Fins that have been used in solar air collectors enhanced heat transfer from absorber plate to air. Experimental tests have been undertaken as part of this project where was applied this phenomenon to a box-type solar cooker. The results of the experimental investigation have been rigorously analysed and showed that the stagnation temperature for box-type solar cooker equipped with a finned absorber plate was about 7% more than box-type solar cooker equipped with an ordinary absorber plate. The time required for heating water up to boiling temperature in both box-type solar cookers was reduced with about 12% when a finned absorber plate was used.     

Design optimization of solar cooker

Various designs of solar cookers have been theoretically investigated with a view to optimize their performance. Starting from a conventional box type cooker, various combinations of booster mirrors have been studied to arrive at a final design, aimed at providing a cooker, which can be fixed on a south facing window (for countries of northern hemisphere, mainly situated near the tropic of Cancer). This cooker, with a rear window opening, may provide higher cooking temperature for a fairly large duration of the day. Two or three changes in positions of the side booster mirrors, without moving the cooker as a whole has been proposed. The new design has been experimentally implemented and compared with a conventional box type solar cooker. Besides the convenience of a rear window opening, the cooker provides temperatures sufficiently high to enable cooking two meals a day.