17 May, 2013, Sydney, NSW, Australia
FEI PENGUniversity of New South WalesSydney, NSW, Australia|
With the growing health problems and ecological damage caused by cooking with fossil fuels, alternative energy for cooking must be applied to help solve these issues. Solar energy is clean, free of charge and readily available for everyone to use. Considering this, an environmental friendly and cost effective device, solar cooker has been designed for thermal solar energy conversion. After years of development, solar cooking has been significantly improved and used in rural areas or the places where fossil fuels and biomass is not available. To date, solar cooker not only has been used as alternative cooking device in people’s home, but also has been applied to raw materials processing in industries, such as cashew nut shell oil extraction . In this paper, the history of solar cookers, the thermal characteristics and improvements of each type, the adoption perspectives of solar cooking, conclusions and recommendations to improve the adoption are described.
1. RESEARCH BACKGROUND
Utilization of sun’s power for varieties of purposes has undergone a very long history . Ancient people discovered through concentrating the sun rays could explode nearly any object in flames. But this was only applied for military and a few venal purposes . Horace de Saussure, a French-Swiss scientist, first applied the idea of “solar heat trap” into practically building a miniature greenhouse with five glass boxes one inside the other to cook fruit in 1767 . The first reported solar cooker was utilized at the Cape of Good Hope in 1837 by An Englishman, John Fredrick Herche. In 1869, the first book about solar energy, Solar Energy and its Industrial Applications was published by Augustin Mouchot. In 1884, the first box type cooker was used by Samuel Langel in California . The first adoptable generation of modern solar cooker was revealed in more recent history of the 1950s. The M.I.T. scientist, Maria Telkes designed the forerunner of today’s box type solar cookers, and is used in infinite variation to the present . Unfortunately, due to the inherent defects of this type solar cooker, it did not become popular at that time. It is because the tracking time was long, the cooking was restricted in the mid-day and in the direct sun, the performance was easily affected by dust and wind, and the reflecting surface deteriorates with time cutting down cooking efficiency . The hot box type solar cooker is, therefore, first suggested by Garg et al in 1976 . This design removed some of the defects of the former design and did performed well during summer, but it was uneconomic. Adding to this advantage, its bulky tracking time and inconsistent performance were still limiting its expansion . Almost in the mean period, a heat transfer type / indirect type of solar cooker was also suggested . It allowed the cooking chamber to be located inside the kitchen and kept the collector outside, but its cost was still high and efficiency was fairly low. However, these three approaches of solar cooking, namely box type, concentrator type, and indirect type/heat transfer type, laid the foundation of the solar cooker design. It was noteworthy that, along with the solar cooker research continuing in 1970s, Chinese and India governments started to promote researches on alternative energy to deal with energy shortages and growing populations . In 1980s, a hybrid between box and parabolic type solar cooker, panel cooker was created by Solar Cookers International. This invention was less expensive and was considered as a breakthrough in Solar Cooker’s history . By 1988, it already had over 60 major designs and more than hundreds of variations of solar cooking devices reported worldwide . Numerous researches for...