<p>Large environmental, health, social and economical problems are connected with the use of</p><p>fossil fuels and, in a dominating part of the world, also the use of firewood. The goal for this</p><p>project was to develop and design an optimal solar oven system intended for food cooking</p><p>and water pasteurisation. Further the advantages and disadvantages, compared with other</p><p>energy resources were evaluated. Tests were carried out in Sweden as well as in Sri Lanka.</p><p>An extensive range of prototypes were tested and sifted out to a small number of designs that</p><p>were tested in Sri Lanka. A large number of evaluations and tests were carried out on many</p><p>different materials, among others tests were conducted according to the international standard</p><p>“Testing and Reporting Solar Cooker Performance ASAE S580 JAN03”.</p><p>The report shows a number of benefits compared to previous reports on the subject, for</p><p>example the development of indoor tests, the extensiveness and objectiveness of the tests, and</p><p>the fact that the report combines extensive practical test results with solid theoretical</p><p>background information.</p><p>The test resulted in two solar ovens with the same parabolic design but made out of different</p><p>materials. One oven is cheaper, simpler to produce and is considered for the target group poor</p><p>people in developing countries. This is made out of a corrugated cardboard that is covered</p><p>with aluminium foil. The second oven is more expensive but also more durable and is</p><p>intended for more wealthy people in the west that wants a good alternative to regular ways of</p><p>cooking food. It is made out of aluminium plate and mirrors.</p>

Large environmental, health, social and economical problems are connected with the use of fossil fuels and, in a dominating part of the world, also the use of firewood. The goal for this project was to develop and design an optimal solar oven system intended for food cooking and water pasteurisation. Further the advantages and disadvantages, compared with other energy resources were evaluated. Tests were carried out in Sweden as well as in Sri Lanka. An extensive range of prototypes were tested and sifted out to a small number of designs that were tested in Sri Lanka. A large number of evaluations and tests were carried out on many different materials, among others tests were conducted according to the international standard “Testing and Reporting Solar Cooker Performance ASAE S580 JAN03”. The report shows a number of benefits compared to previous reports on the subject, for example the development of indoor tests, the extensiveness and objectiveness of the tests, and the fact that the report combines extensive practical test results with solid theoretical background information. The test resulted in two solar ovens with the same parabolic design but made out of different materials. One oven is cheaper, simpler to produce and is considered for the target group poor people in developing countries. This is made out of a corrugated cardboard that is covered with aluminium foil. The second oven is more expensive but also more durable and is intended for more wealthy people in the west that wants a good alternative to regular ways of cooking food. It is made out of aluminium plate and mirrors.

In order to improve the water situation in rural areas of Bangladesh, a research group at the University of Dhaka has been developing low cost domestic methods to remove pathogens from surface water through pasteurisation using free solar energy. Pasteurisation is a process in which water is heated to approximately 60 °C and maintained for about 30 minutes to destroy pathogens. In these methods, the water is also exposed to UV-light from the sunshine, which causes destruction of diarrhoeal pathogens at temperatures somewhat lower than required in normal pasteurisation. However, despite many advantages these devices need to be installed for each time of use. Recently, a semi-permanent device has been developed which is expected to be more user friendly. The objective of this Master thesis has been to study and optimize the low cost semi-permanent device that can deliver safe drinking water to people in rural areas. Two test devices were constructed to determine the most effective treatment e.g. temperature, time, solar radiation, user-friendliness and cost. To replicate the results from the solar heating tests a model, based on the solar radiation and convective heat loss from the device, was used. The model was also able to determine the time duration at a certain solar radiation level to estimate when the water is safe to drink. The results revealed that the performance of the device depends on thickness of the insulation and thickness of the air gap. This is because the most important factors to achieve safe drinking water are solar radiation and time. The modelling indicated that the measured water temperature corresponds well with the calculated water temperature and also showed that the lowest required solar radiation is 390 W/m2 to reach drinking water criteria, at an air temperature of 25 °C. A study of microbiology showed that the semi-permanent low cost device could purify surface water to a safe level.