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.     

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.     

Performance and testing of an improved solar water heater cum steam cooker

The paper reports performance and testing of an improved solar water heater cum steam cooker. The efficiency of the system as a solar water heater is 51.5 per cent and as a solar steam cooker is 16.1 per cent.     

Design and testing of Sudanese solar box cooker

This study aimed at developing a solar box cooker to be used in Sudan. The cooker was designed and fabricated in the workshop of Centre for Energy Studies, Indian Institute of Technology (IIT), Delhi. A series of tests were carried out during nine days to determine the two factors of merits F1 and F2 in order to make comparison of the cooker against the other Indian designs. The results obtained verified acceptability of the cooker and found successful.     

Design,development and testing of an improved multipurpose solar energy device

This paper reports the design, development and testing of an improved multipurpose solar energy device. The novel feature of the device is that it can be used as a solar water heater and solar still simultaneously and, when required, as a solar cabinet dryer by incorporating minor changes.     

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.     

Design and development of a solar cooker cum drier

A solar cooker cum drier has been designed and developed. In designing this unit, optimum booster-collector geometry has been considered in order to eliminate the requirement of sun tracking. Tilting arrangements have also been provided to capture more solar energy. This dual purpose device has been found useful for cooking food and dehydrating fruit or vegetables.     

Transmittance-absorptance product of solar glazing with transparent insulation materials

The transmittance-absorptance product of solar glazing containing the transparent insulation material (TIM) of square celled honeycomb is investigated. A method is developed for the determination of transmittance-absorptance product of beam, sky and ground diffuse solar radiations using the individual transmittances of cellular array and encapsulating covers; the internal reflections are taken into account. Three practical cases; cellular array, cellular array with top cover, and cellular array with top and bottom covers are considered. The results are presented for beam radiation as a function of angle of incidence and sky and ground diffuse radiation as a function of tilt angle. The predicted results are tested by measuring the global radiation transmittance of commercial TIM; the predicted results deviate from the measurements by an average of 2.0%.     

Design and measured performance of a plane reflector augmented box-type solar-energy cooker

The design philosophy, construction and measured performances of a plane-reflector augmented box-type solar-energy cooker are presented. The experimental solar cooker consists of an aluminum plate absorber painted matt black and a double-glazed lid. The bottom and sides are lagged with fibreglass wool insulator. The reflector consists of a wooden-framed commercially available specular plane mirror which is sized to form a cover for the box when not in use. Provision is made for four cooking vessels, each capable of holding upto 1 kg of water. Results of thermal performance tests show stagnation absorber plate temperatures of 138°C and 119°C for the cooker with and without the plane reflector in place respectively. Boiling times of 60 min (3600 s) and 70 min (4200 s) for 1 kg of water, for the cooker with and without the plane reflector in place, respectively, were recorded. The solar cooker performance has been rated using the first figure of merit (F₁) on the no-load test and the second figure of merit (F₂) on the sensible heat tests. Predicted water boiling times using the two figures of merit compared favourably with measured values. The performance of the cooker with the plane reflector in place was improved tremendously compared to that without the reflector in place.     

Design, development and testing of a portable parabolic solar kitchen

In this project we describe the design, manufacture and testing of a new portable solar kitchen with a large, parabolic solar reflector that folds up into a small volume. Technical trials carried out with a prototype have determined that the solar kitchen reaches an average power scale of 175 W, with an energy efficiency of 26.6%. This power scale provides sufficient energy to cook a simple meal for two people in an average time of 2 h. Improvements in the design have reduced the weight of the solar kitchen to less than 5 kg and the assembly and disassembly times to 2 and 1 min, respectively. Moreover, its competitive price (48.62 €) encourages the substitution of solar energy for conventional energy. The parabolic solar kitchen described here thus provides a portable, inexpensive, environmentally friendly food heating system that can improve the quality of life of needy people in the Third World and reduce consumption of conventional energy.     

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.     

Thirty years of domestic solar hot water systems use in Greece – energy and environmental benefits – future perspectives

The effort to reduce the dependence on imported crude oil in Greece, after the oil crises in the '70s, has resulted, among others, in a total installed area of 3.57 million m² solar collectors in 2007, making Greece one of the pioneers in the use of domestic solar hot water system (DSHWS) worldwide.In the present work, the contribution of DSHWS to the reduction of conventional energy and greenhouse gases and other air pollutant emissions in Greece from its early years in mid '70s up to now is assessed. DSHWS market penetration, solar system technological changes and development and demographic changes in association with the climatic conditions in all regions of the country have been taken into account in order to calculate energy conservation and emissions reduction. The results show that the conserved energy ranges from 21.27 GW h_el (0.1% of the domestic sector energy use) in 1978 to 1513 GW h_el (2.4%) in 2007, resulting in an abatement of CO₂ emissions, which for the year 2000 was 1.67 Mt, exceeding by 76% the objectives of the Greek Program of “Climatic Change”, which indicated savings of 0.95 Mt CO₂ for 2000.Moreover DSHWS maximum technical potential is assessed to be about three times the current installed area, showing that they can play an important role in energy end environmental policy of the country.     

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 management in solar thermal power plants with double thermal storage system and subdivided solar field

In the paper, two systems for solar thermal power plants (STPPs) are devised for improving the overall performance of the plant. Each one attempts to reduce losses coming from two respective sources. The systems are simulated and compared to a reference STPP.     

Heating and cooling of a hospital using solar energy coupled with seasonal thermal energy storage in an aquifer

A system is being designed, using solar energy in combination with Aquifer Thermal Energy Storage (ATES), that will conserve a major part of the oil and electricity used for heating or cooling the Cukurova University, Balcali Hospital in Adana, Turkey. The general objective of the system is to provide heating and cooling to the hospital by storing solar heat underground in summer and cold in winter. As the main source of cold energy, ventilation air at the hospital and surface water from the nearby Seyhan Lake will be used.     

Placement of insulation in a concrete wall

In this paper we have investigated the optimum placement of insulation in a concrete slab (wall/roof) for achieving the best levelling in the thermal flux through the slab. It is seen that, for a given thickness of insulation and given total thickness of concrete, this is achieved when the thickness of the outer layer of the concrete is least, consistent with structural considerations.     

Design of a commercial solar hot water system

The paper critically evaluates the design and performance of a commercial hot water system. These systems are installed in IIT Delhi hostels mainly for cooking and washing utensils. In some of these systems, heat exchangers are also used. In specific terms, one can regard the thermal efficiency and the maximum hot water temperature as indicators of the performance of the system. Hence different parameters of the heat exchanger and the number of collector panels directly affect the performance of the system. In the paper, an energy balance for different components of the system under steady state conditions is primarily investigated. It is found that excellent agreement exists between experimental and theoretical results for the proposed design parameters.     

Experimental performance evaluation of a novel heat exchanger for a solar hot water storage system

The performance of a novel heat exchanger unit (‘Solasyphon’) developed for a solar hot water storage system was experimentally investigated. The ‘Solasyphon’ is a simple ‘bolt-on’ heat exchange unit that can be integrated externally to a traditional single-coil hot water cylinder (HWC) avoiding the costly replacement of an existing HWC with a twin-coil HWC. The installation cost of a ‘Solasyphon’ is lower compared to a traditional HWC thus offers greater cost effectiveness. A data acquisition system was designed to compare the thermal performance of an integrated ‘Solasyphon’ HWC with a traditional twin-coil HWC under controlled simulated conditions. The analysis was based on experimental data collected under various operating conditions including different primary supply temperatures (solar simulated); primary supply patterns and draw off patterns. The results indicated that the ‘Solasyphon’ delivered solar heated water directly to the top of the HWC producing a stratified supply at a useable temperature. Under variable solar conditions the ‘Solasyphon’ would transfer the heat gained by a solar collector to a HWC more efficiently and quickly than a traditional HWC. The ‘Solasyphon’ system can reduce installation costs by 10–40% and has a lower embodied energy content due to less material replacement.     

Computer simulation calculations for estimation of the energy conservation in solar heated buildings

The paper describes the development of a simple and handy microcomputer theoretical simulation model, suitable for investigation of the performance of a low cost solar heating system which is believed to be suitable for use under the local meteorological conditions. Hour by hour simulations have shown that substantial solar fractions can be achieved even in existing buildings, and the introduction of easily accessible daily mean meteorological data allows the investigation of the thermal performance and energy conservation in buildings for any location in Greece.     

Design strategy and development of spherical silicon solar cell with semi-concentration reflector system

Structural and economical merits of a spherical silicon solar cell with semi-concentration reflector system have been discussed. The roles of the reflector system have been clarified; the reflector improves short-circuit current density and also open-circuit voltage by 4–6 times concentration to make a light irradiation area comparable to a p–n junction area. We have theoretically demonstrated that the spherical Si solar cell with semi-concentration reflector system can realize a performance comparable to that of conventional Si solar cells, with less amount of silicon material use.