Projekt Sunbaker : Utveckling av en solugn för bakning, en fältstudie i Namibia

Sammanfattning: Namibia, southern Africa, suffers from an energy shortage and is therefore facing several challenging problems. The use of firewood as fuel for cooking is common in the whole country and has negative consequences for health and the environment. This work have focused on developing a solar baking oven, called Sunbaker, adapted for Namibian families needs for baking. The development was based on classic solar cooking limitations, specific needs for Namibia and to have a feasible manufacturability. The project started with a theoretical study in Sweden where different solar cookers, information regarding Namibia, technical aspects and end user aspects were studied. To assess the need for a solar baking oven a Minor Field Study took place in Namibia during eight weeks in July to September 2009 and resulted in a product design specification. A finding was that firewood as fuel for cooking was traditionally deep rooted and hard to replace. Baking was not done in large scale, instead bread was often purchased. From the product design specification a concept was formed that enables families to start a smaller bakery. Sunbaker is a concept that works by combining the principle of a parabolic solar cooker and a solar box cooker. A parabolic solar cooker works by concentrating sunlight into one point which makes it effective but also dangerous. Solar box ovens work by reflecting sunlight through a glass sheet into an insulated box. The heating time for a solar box cooker is longer but it is cheaper and easier to use than a parabolic cooker. Sunbaker is based on a box cooker model where the interior has been replaced with a reflective “U” shape and a metal pipe running in its focal line. This means that the “U” shape concentrates incoming sunlight to the metal pipe at the same time as the heat storing principle from the box cooker exists. The advantage is a more effective and simple solar oven. Use of the oven also becomes simple and a user manual has been created. The possible baking area becomes limited to inside the pipe. Sunbaker also gets a higher price than existing solar ovens in Namibia but as it enables the possibility to start a smaller bakery a pay off time of 46 days can be achieved. The work resulted in a concept, a prototype and a product design specification for a new type of solar cooker. There is future work to be done in testing the performance, optimizing the construction and models for implementation in society.