Course: 22.521 – Solar Fundamentals
Semester: Fall 2006
Instructor: John Duffy
Partner: Village Empowerment Project – Yanacaca, Peru
Peru Solar Dryer Miniproject. Several agricultural products benefit from post-harvest drying in order to more easily commercialize. Solar drying holds benefit for small farmers, especially under conditions of insufficient transport infrastructure or in cases of over production of the agricultural product. In Peru, there is an enduring tradition of drying certain varieties of agricultural and food products exposing them “under de sun” on the soil. Nevertheless, this kind of drying may result in crop loss (e.g. consumption by animals, bird droppings, rain, mold, etc.) and or reduction in the quality of the dried product. Under such circumstances a “conventional” drier that uses electricity or fuel to supply the energy needed to eliminate the humidity of the product could be considered. However, in Peru there is an energy deficit in a number of rural regions that lack access to an energy grid. In addition such options are very expensive and are not accessible to rural farmers.
Researchers from different parts of the world have begun to test solar drier technology. This idea was strengthened by the fact that solar radiation is available in an abundant way, especially in tropical and subtropical countries. It is important to notice that this technology can also be used in a decentralized way, and it is available in the majority of the country. Besides the solar drying technology does not have negative effects over the ecology, and all the arguments lead to a good and harmonious direction of the rural development. The technology is expected to open up new types of market, such as herbs, spices and plants with essential oils adding income for the farmers in the remote villages served by the Peru project. Solar drying should result an economic benefit to the farmer, which means that the additional cost of initial investment, operation and maintenance of a solar drier should be compensated with an increment in the income from the sale of of the dried product
The miniproject’s overall objective was to provide students with the opportunity to put into practice solar engineering concepts studied during the semester through designing systems that provide feasible solutions to real world challenges existing in Peruvians communities. The goals of this project included the development of a solar drier design that was built and tested as a solar herbs drier prototype for the village of Cochapeti, Peru. Furthermore, the design was to be developed with locally available materials, and to monitor data in order to analyze its performance. Students developed a methodology to investigate optimized parameters of a solar drier system at specified conditions, including a recent transpired collector (metal sheet with holes) that avoids the use of glass with inherent danger of breaking. Students estimated the twelve monthly average horizontal global irradiation values based on the analysis of the data available from the village of Cochapeti. They also estimated the optimal tilt of the solar drier plate collector with the data available from Cochapeti to gain maximum energy across a year.
They evaluated the demand of the solar drying: feasibility and market studies through surveys in at least 3 villages, including the socio-cultural barriers to acceptance of the technology from the farmers during Peru Trips conducted in January and June 2007.
Learning objectives met by the S-L project:
- Calculation of solar beam trajectory relative to collector surface
- Estimation of solar irradiation components
- Estimation of solar energy transmitted, absorbed and reflected
- Estimation of heat losses in flat plate collectors
- Use of solar thermal system performance models
- Estimation of energy collected in parabolic collector
- Increase comprehension of fundamentals of solar irradiation and utilization as a function of location
Community needs met by the projects:
- The village of Yanacaca got a solar-powered water pumping and storage system
- A prototype solar crop dryer was built and is being tested in Yanacaca.